Extended Heat Wave Possible.

Even as the post-clean up process from Friday's storms is underway, another heat wave is on the horizon. Except this one will last an entire week. In fact, the National Weather Service has issued an Excessive Heat Warning for the area. The National Weather Service said that they are expecting a period of heat which will feature temperatures in the upper 90's to the lower 100's and heat indices well above that. This heat wave will be characterized by high humidity and maximum sunshine, which only make it worse for the many thousands of people who still need power. Even the heat does not exactly fit criteria for the excessive heat warning, it was issued because of its duration and impact. This heat wave is caused by a building heat dome or upper level ridge moving in from the west. This will allow for several days of quiet weather. By next weekend though, temperatures will reach their maximum on Saturday, near or over 100. Then a cold front will be forced through the area, cooling temperatures back into the lower 90's and upper 80's.

The Mechanics of Heat Waves. Updated Forecast.

When forecasting heat waves, there are many variables that are needed to be considered. Some of these include soil conditions, cloud cover, vegetation cover, climate region, low level temperatures, upper level wind flow, and low level wind flow. These are only a few of the many factors that meteorologists take into account when forecasting periods of extremely high temperatures. To start, the definition of a heat wave for the southern Great Lakes region is a period of three days with temperatures of 90 degrees or higher. The standard definition of a heat wave is a period of three days or longer with much above normal temperatures (10 degrees above normal or more). This would make the March warm spell that we had a heat wave, because temperatures were almost 40 degrees above average. The onset of a heat wave comes as an upper level ridge builds into a region. According to the hypsometric equation, upper level ridges (or regions of high pressure) must be associated with a warm column of air. That means, the stronger the ridge, the hotter it has to be at the surface. Not only does the ridge bring a wave of warmer air, but subsidence also brings warmer air into the region. At the far eastern edge of a ridge, subsidence is strongest due to upper level height rises, usually low level cold air advection (because of a passing cold front from the last storm system), and NVA, which is negative vorticity advection increasing with height. All of this leads to subsidence, which warms the low level air mass through time. As the surface high moves east of a region, warm air advection increases into a region, allowing for even warmer low level temperatures. For a temperature forecast, you have to take into account how long the ridge was over a specific region such as a dry region. The current ridge was located over the West for over a week, located right over the Intermountain West and American Southwest desert, which will strengthen the ridge. Since the surface temperatures over the West are actually the low and mid level temperatures when they advect into our area, mixing of these hot temperatures in the presence of solar heating will lead to even hotter temperatures. Soil conditions and type are an enormous factor in summer heat waves. If soils are wet and a clay-type mixture (such as what is usual in our area), then dew points will be quite high during heat waves (75 or higher) while temperatures are usually cooler. If soils are incredibly dry and of a sandy texture (which is what is happening now, our soils have become so dry that some of the soil has turned into a sandy texture), temperatures are quite a bit hotter. I've already talked about the upper level flow, but what may be more important it the low level flow. If low level flow is from the Gulf of Mexico, then a very warm and moist air mass will become present over the area, making outside conditions very uncomfortable. Even in drought conditions, moist flow can bring higher dew points from the Gulf of Mexico, its just that a moist air mass will cause haze in the sky and clouds to form, limiting daytime heating, which is one reason why higher dew points leads to lower temperatures. You also have to take into account cloud cover. This means that you need to thoroughly analyze the jet stream for shortwaves which could induce cloud cover and thunderstorms.

As for the updated forecast, the National Weather Service has just issued an Excessive Heat Warning for temperatures 104-107 tomorrow. Heat indices will approach 110, especially if dew points are higher than expected. Tomorrow night, there will not be much relief with temperatures only falling to near 76 or 77 (which would break records). On Friday, expect yet another dry day as temperatures will soar into the upper 90's, but with slightly cooler low level temperatures. Some meteorologists are predicting rain for tomorrow, but it is highly unlikely due to the fact that the area is moisture deprived and far removed from upper level dynamics. Plus, the storms would have to break through the incredibly strong cap, which is not entirely likely. In fact, expect dry weather for the next week at least. Enjoy the hot days!

Near Record High Temperatures Possible

It may not seem like it now, with the polar air mass over the area, causing temperatures to drop just slightly below normal into the lower 80's and upper 70's, but by the end of the week, we may be seeing record highs shattered, and maybe even a few all-time record highs shattered. Before I explain Thursday's and Friday's weather, I will explain how the current weather will allow for the warmer weather later in the week. First off, if it wasn't for Tropical Storm Debbie, many areas would have seen thunderstorms during the afternoon yesterday. This is because the tropical storm blocked the main synoptic scale flow from the Gulf of Mexico. If there were no tropical storm in the Gulf, southerly flow into our area would have brought a deep and moist tropical air mass that was highly unstable. This coupled with some upper level forcing would have caused the development of numerous thunderstorms. This is what has been happening ever since March. A large thunderstorm complex or system in the Gulf states blocks the flow of moisture northward into the Midwest, not allowing for storm systems to strengthen. In reality, if this natural flow of air northward would not have been blocked, we could've have had quite a bit more snow this winter. Instead, that is not how it happened. This is one of the first and most prominent signs of the transition to an El Nino phase in the atmosphere. When the El Nino begins to show its ugly face, the southern part of the jet stream becomes more active. This is why many of the systems that hit the area this winter came up from the southwest and south, bringing warmer air northward and rain with it. Any northern stream that hit the region was moisture starved and produced little more than clouds and a few snowflakes. This may have been one of the reasons for the development of the drought across the region. Back to what I was saying before, the thunderstorms, if they would have developed, would have saturated the soil, allowing it to be cooler but more moist. The drier weather is allowing temperatures today and tomorrow to climb into the lower 80's. As the low level southerly flow causes a nose of incredibly warm and dry air to move into the Upper Midwest, upper level heights will build across the region, especially as the upper level low over New England weakens. This will likely happen starting on Tuesday night and continue through Wednesday. By Wednesday, strong warm air advection and subsidence will cause clear skies once again, but this time with highs approaching 90. By Thursday, upper level ridging will cause subsidence and a nose of hot, dry to move into the area, allowing temperatures to soar to near record levels. The hot, dry nose of air from the west combined with near desert and drought conditions in our will allow temperatures to rise into the 100's for Thursday, and possibly again for Friday. If we reach 102 or higher for Thursday, we could tie or break the record set in the 1930's. On Friday, though, depending on the timing of a weak front, temperatures will likely only make it into upper 90's. Humidity levels will significantly increase for Friday though, allowing the atmosphere to feel very uncomfortable. Don't get too excited about this frontal boundary though, thunderstorms aren't likely even with the highly unstable atmosphere, because of mid level capping and subsidence across the region. Even after Friday, the frontal boundary will do little more than cool temperatures into the middle 90's. By next week, yet another surge of hot air will occur, allowing temperatures to rise back into the upper 90's and lower 100's. This is still way out, so take this forecast with a grain of salt. With no tropical storm to block flow from the Gulf of Mexico, expect much more humid conditions for next week.

Technological Improvements: Radiosonde Part III

       Last week, I talked about how long the radiosonde flight lasts, how data is screened, and how wind direction and speed was determined from the flight path of the radiosonde. This week, as I mentioned in the previous article, I will talk about some of the improvements in the data collection process has improved forecasting.

       

      Due to government spending, budget cuts, and a limited money supply, the NWS is forced to slowly cut down on its work force and the amount of money it spends on forecasting and saving lives. If no changes were made to this, all kinds of weather would kill thousands more than already are killed. One of the ways that the National Weather Service can make up for this, is through researching more modern and advanced technology in use for forecasting. Right now, radiosondes are sent up only a twice a day to receive upper air conditions and many other useful products for weather forecasting. The problem with this extremely inefficient system is that the atmosphere changes so quickly, that many factors can be missed. Take for instance on the day of a severe weather outbreak. Usually, the morning sounding will show almost no instability, due to the fact that the surface has not had time to heat from the sun. This will lead to extremely inaccurate calculations when trying to determine when the severe thunderstorms, which could end up meaning the difference between several hundred to over a million lives at stake (depending on the area). During the 1990's, to obtain meaningful wind measurements at all times of the day, the National Weather Service and the National Severe Storms Laboratory set up network of wind instruments called wind profilers across the Central Plains. These wind profilers are similar to Doppler Radars, except the fact that their parabolic dishes which sent out the microwaves are mounted vertically. As long as the microwaves which are sent out into the vertical can be scattered from dust particles or other particulate matter (including water vapor), wind speed and direction can be determined at many different levels of the atmosphere. Three other dishes are mounted at different angles to help determine the wind speed and direction. The NWS thought that this would give a much greater advantage to severe storm forecasters, as it allowed them to accurately determine wind shear throughout the low levels of the atmosphere. Then, in 2004, the wind profilers were cut out of the National Weather Service budget, and now they are funded by other means. The data is available online at several websites. Its data has other uses to, some of which have been described by other meteorologists. They claim that it may be possible to calculate the upper level wind, pressure, and temperature patterns just by knowing the wind speed and direction at a certain height. This could give a great advantage to many meteorologists, as long as these profilers are not shut down. There have been several cases where profiler data has made a huge difference in the forecast, one of which happened during the infamous May 3, 1999 tornado outbreak near Oklahoma City. Because of the profiler in central New Mexico, forecasters determined that there was a jet streak that missed by the radiosondes. Jet streaks are known to cause strong upward motion and destabilization, which would definitely help initiate severe thunderstorms. Also, jet streaks can also strengthen the vertical wind shear, which causes thunderstorms to become more organized.

       There are other ways that upper air data is obtained, and one of them is through a system called AMDAR. AMDAR come from air planes who are flying at specific pressure levels. Usually, these planes are commerical flights as they usually fly in the upper troposphere. The onboard instruments measure temperature, wind, pressure and humidity. The data is then relayed to the World Meteorological Organization, which collects and disperses the data. This data is especially useful in Africa and the Middle East, where the countries have Weather Services that are not funded by the government, or the country is so poor, there is no weather service. Another way data is collected is through weather satellites. Not only can they detect wind speed and direction and most levels (through tracking cloud movement), but through their radiation detection systems, they can determine temperature and dew point levels throughout all levels of the atmosphere. This system was implemented with the Terra series of satellites in 1999. In October of 2011, NOAA's next generation of earth monitoring satellites, called Suomi NPP, were sent up into space. This new generation of satellites have much more advanced equipment, which could eventually make them more accurate then radiosondes themselves. Plus, atmospheric soundings and wind profiles can be computed for any airport location in the world, and at each and every hour. The one problem with GOES soundings (their proper name) is that they have really coarse resolution, which affects certain small scale features. This being resolved with the NPP satellites which not only have better resolution, but they can also determine data in the presence of clouds. This will greatly improve forecasting within the next 10 or even 20 years.

      Next week, I am going to write about my trip to the National Weather Service on June 12, 2012, and then the following week's article is going to be about the history of the National Weather Service and its future plans. Have a great week!

Drought Conditions and Medium Range forecast

Many of you probably have heard by now, but a large portion of Northwest Ohio and Northeast Indiana have been updated by the Drought Monitor and put in the severe drought category.  Included with the upgrade was the possibility that this may end up as a long term drought, which is one that lasts longer than six months.  This may very well happen, as I have described before, atmospheric blocking has been rather strong for the past two months, and when blocking patterns come into place, drier weather and more extreme weather is usually the result.  This is one of the main reasons for the drought.  Other reasons include but are not limited to developing El Nino conditions around the globe causing a shift in the jet stream patterns, very warm winter and very warm and dry spring, and changing long-term climate variables. These factors have all combined to create the worst drought in the area since 2007 and possibly since 1988.  In fact, just to get back to normal, we need about 7 to 8 inches of rain in a short amount of time and we need 9-12 inches of rain to get out of the drought! That does not look like its going to happen very soon. Remember, the worse the drought the hotter it gets, and the hotter it gets the worse the drought gets.
As for the general medium range pattern that will persist across the area, by tonight and tomorrow and strong upper level shortwave will clear the area, forcing the cold front through the area, and dropping temperatures into the low to mid 80's under sunny skies for tomorrow. By Saturday and Sunday, a rather large longwave trough will build itself into the area, as an arctic cold front moves into the main wave over Northern Canada.  This will cause the entire longwave to shift southward into New England and Eastern Canada.  Compared to previous model runs, the entire pattern looks to settle farther east than originally expected so I would expect temperatures to remain a few degrees warmer than the upper 70's. By the very end of June and beginning of July, the ridge will finally begin to build into the area, allowing temperatures once again to soar into the 90's.

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Article from the West Bend News

This article is from this week's issue of the West Bend News.

Last week, we talked about how weather variables in the upper atmosphere are measured, such as temperature, humidity, and pressure. This week, I will talk about how the data is screened, and how wind throughout all levels of the atmosphere is measured.

Usually the radiosonde is sent off by balloon on two separate occasions each and every day. These times are 12 UTC and 00 UTC. For everyone who does not know what UTC means, it stands for Universal Coordinated Time, or Zulu time. It is not the same as military time, as it does not vary with time zone. For instance, if it is 12 z (or UTC) in New York, it is also 12 z in Los Angeles. This Universal Coordinated Time is the same as Greenwich Mean Time (GMT), accept for the fact that it does not change with Daylight Savings Time. If you want to know what the UTC time is right now (depending on your time zone), just subtract five hours from the current military time to obtain the UTC time, if you live in the Eastern Standard Time, while under daylight savings time just subtract four hours. Right now, 8 a.m. Is at 12 z and 8 p.m. is at 00z. The balloon which is sent off is filled with either helium or hydrogen.

During a normal flight, it will take in between 37 and 40 minutes for the balloon to reach its maximum height (usually about 15 kilometers), before bursting and descending through the atmosphere. The weather conditions at the time of lift off will determine whether the balloon will go up or not. For example, usually weather balloons will not be sent up in or near a thunderstorm (unless it is conducted for research purposes), because this will cause noise in the data when sent to the National Centers for Environmental Prediction. Usually, the temperature, humidity and wind profile of a thunderstorm is characterized by by a moist adiabatic lapse rate (temperatures decreasing with height at about 6 degrees Celsius/ kilometer), with 100% relative humidity throughout the entire atmosphere, and chaotic wind patterns due to turbulence, mesocyclones, tornadoes, and other small scale circulations within the thunderstorm. Since the grid-spacing of most models is too large for thunderstorms, if this data was placed into the model's analysis grid, to fit with physical equations that govern model, it would have to generate quite a bit of convective precipitation and latent heat to keep the atmospheric conditions accurate. This can cause quite a problem because the model will either 1.) have to assume that the storm is at least the size of its grid spacing (this will cause problems with global models, such as the GFS, ECMWF, and the GEM), or 2.) it will have to smooth out the latent heating throughout several grid spaces, especially for convective complexes. Latent heating has an enormous impact on our weather (a topic saved for another article), and since model physics are fairly close to the real world (not quite though), they will have to account for this incredible area of heating. Then, the models, when run, will disperse the enormous amount of heating, destabilizing the atmosphere even further, which will generate something called a convective or “QPF” bomb, which is basically a giant land hurricane on the model's grid, as a result of the latent heating, which can completely offset all accuracy of forecasting. This is why the data has to be screened for accuracy. Until the day at which models can actually physically create thunderstorms on their grids, this will be a problem. Other noise problems are also taken care of such as inaccurate data due to broken instruments, or elevation problems. Areas such as the Rocky mountains can not measure variables at levels such as the 850 and 925 millibar levels, so after the data is decoded and sent to the NCEP for use in model grids, the pre-processing that the model does before it runs the data uses the hypsometric equation, which relates atmospheric thickness to the average temperature. Using the atmospheric standard lapse rate, (which is rarely the case in a mountainous and dry region), it calculates data for levels that do not exist in the mountains so that the model can run properly. This why model forecasts of mountain conditions are rarely correct.

I never talked about how radiosondes measure wind speed and direction last week, but now I will. In reality, wind is not actually measured by radiosonde, as they do not mount an anemometer to the side of the radiosonde. What they actually do is use a radar tracking device to measure the angle of elevation, the balloon's displacement from its original position, and calculate the wind vectors from the balloon's movement. By doing this though, it leaves a rather large margin of error for the calculation of wind vectors (wind direction and speed) throughout all levels of the troposphere. When put into the archives, this wind information is put into the format of degrees of direction and wind speed in knots. In meteorology, the scale used for direction is: 0 degrees for a north wind, 90 degrees for an east wind, 180 degrees for a south wind, and 270 degrees for a west wind. This wind information is then plotted on atmospheric soundings, called skew-T charts, and hodographs, on which wind information is the only thing plotted. A hodograph is a chart on which many weather variables can be evaluated, such as total shear, bulk shear, and storm-relative winds. These are very important in determining the severity of storms and their structures.

Next, week we will talk more about improvements in the current technologies that are used in obtaining the weather information (I was trying to get to that this week!).

New Forecast Developments

Over the past few days, some areas in Northeast Indiana and Northwest Ohio received beneficial rain.  Though, it wasn't nearly enough to vanquish the drought, the plants and grass are just a tad bit greener, making everything seem more beautiful.  I don't about any of you who live around here, but in the town of Antwerp, I have estimated that there was about a quarter of an inch that fell within the town.  With the rain came quite a bit of lightning also, which was really neat since we haven't had any real thunderstorms since the beginning of May.
As for the weather pattern over the next few days, expect near record high temperatures for today, and tomorrow.  It is possible that Thursday we see highs in the low to mid 90's, but it also depends on the amount of cloud cover and how fast the cold front moves through the region.  Right now, I would expect highs on Thursday to reach near 90, given our dry soils and warm low level temperatures. For today, the 500 millibar ridge will amplify considerably, with 500 millibar heights already approaching 590 dekameters.  This amplification will cause strong subsidence (also coupled with subsidence from the right exit region of the jet streak located over Northern Minnesota) over the region, allowing for completely clear skies by afternoon, and combined with nearly maximum insolation from the sun (remember tomorrow is the longest day of the year), will cause temperatures to jump to near 100 yet again.  The good news is that this extreme heat will cause strong mixing within the planetary boundary layer, mixing dry air aloft to the surface, reducing humidity and dew point values, making the heat more bearable. It is possible that subsidence is so strong that it will not allow for the mixing of drier air to the surface, but this is not a good possibility.  As the ridge axis shifts off to the east, I am expecting that a more humid and moist air mass will move into the region for tomorrow afternoon and evening, making it feel quite a bit more uncomfortable.  By tomorrow, the ridge will reach maximum strength, with 500 millibar heights approaching 594 dekameters.   This will cause temperatures to be very similar to today's, with highs tomorrow probably a few degrees cooler into the mid 90's.  The 00z ECMWF is showing an expansive area of 20 degrees Celsius temperatures at the 850 millibar level over the area by tomorrow afternoon, which would allow for warmer temperatures than what I am forecasting. On Thursday, the cold front will approach the area, causing moisture pooling (a term which refers to the fact that dew points tend to increase ahead of a front.) and a more humid air mass. By the time we get to afternoon, depending on the speed of the cold front, temperatures will likely reach the lower 90's.  As the cold front approaches and passes through the region, expect only a few showers, as upper level forcing and low level convergence will be lacking.  By Friday, temperatures will moderate into middle 80's with mostly sunny skies. 

By next week, things get very interesting with a large closed low system over eastern Canada and New England, which may be stuck in that position for a while. With atmospheric blocking continuing across the Atlantic, the trough that will eject out of the plains and into Canada will not be allowed to progress (all of this depends on the actual strength of blocking over Canada, in fact blocking is expected to weaken considerably over the next week or so, leaving this forecast completely invalid.).  Here is where models are all over the place.  The ECMWF has an incredibly strong closed low retrograding with the pattern into New England, and even south into the Appalachian Mountains.  At this point, it seems very unreasonable for this to happen, as the degree of atmospheric is not that strong, and it doesn't look to get stronger with time. Also, the ECMWF has a tendency to be too strong on cool air invasions, especially during the summer time, so even if this trough were to progress south and westward, our high temperatures would still reach the low to middle 80's, especially given the drought conditions (usually troughs of low pressure bring periods of heavy rain to areas, but given the dry air mass out of Canada, we'll be lucky if we even get a few clouds out of it.).  Depending on the extent of the atmospheric blocking, the trough will begin to weaken by early to mid next week, and shift out of the region, according to the GFS, which has had a good handle on the weather patterns lately.  This will allow the entire pattern to shift, with the ridge over the Central Plains eventually shifting into our area, bringing us yet another heat wave by the beginning of July.  Have a great day!

New and Interesting Developments

As I said yesterday, the forecast was incredibly likely to change, and it has! Over the past several model runs, the models have trended to a much more amplified ridge developing over the area, which seems likely, given the strength of the jet streak which will amplify the Northern Plains trough, introducing what I like to call the "teeter totter" effect.  What happens is that when a jet streak or a strong trough moves into the West, usually strong height falls (equivalent to falling pressure over time) accompany them, causing a deepening of the trough.  This strong trough then progresses eastward, "squeezing" the ridge, eventually causing it to amplify.  The reason I call it the "Teeter Totter" effect, is because usually when there are height falls in the west, there are usually height rises occurring in the East, kind of like a kid sitting on the end of a teeter totter, causing the other end to go up.  Even with the ridge developing, I do expect that a weakening shortwave will move north of the area into Canada.  This will cause a cold front to approach to the area, but not pass through.  The good news about this front is that it COULD produce rain (even if it does it will probably occur west of here), given enough moisture and lift, which will not be in good supply over the area.  If any of you ever happen to look at recent model runs, you will notice that these models are forecasting that dew points into the lower 70's by Sunday afternoon. Do not believe this for one minute, because most models have well known moisture biases, which can cause major problems with convective feedback.  When models forecast more moisture than there actually will be, and since instability is related to the low level moisture profile, this will create a bias towards higher instability and thus more widespread thunderstorm activity.  In actuality, the models are having a problem with this insane drought, due to the fact that they are overestimating evapo-transpiration from crops such as corn, soybeans, and wheat.  The ground is so dry and the plants are so dry right now, that the models moisture parameterization schemes implement this into the  model, causing an extreme overestimation in moisture.  Therefore, I do not believe that thunderstorm activity will be very widespread, if there are thunderstorms that develop.  My second reason for not anticipating thunderstorms, is the fact that a strong cap will still be located over the region (even though it could be effectively reduced depending on where the shortwave tracks).  This will effectively block most thunderstorm activity.  If there is widespread thunderstorm activity it will be to the northwest of here in Illinois and Wisconsin on Sunday afternoon and evening.  The third reason is for the fact that over the past few weeks and months, models have consistently overdone convective potential.  There are a multitude of other reasons, but those are based on my opinions on how the situation is going to develop, not on actual facts. For these reasons, I don't think we will have as much cloud cover on Sunday, allowing temperatures to reach the lower 90's
     As for most of next week, the ridge appears to be stronger than what I thought yesterday.  Ridging will begin to build back in by Monday, sending temperatures back into the low to mid 90's.  On Tuesday through at least Thursday, temperatures could soar into the middle 90's to near 96 (according to the HPC and other guidance) with nighttime lows in the lower 70's. By Friday, the ridge will break with the approach of an upper level trough, as blocking breaks down in the Atlantic. After a few cooler days in the 80's looks likely, with highs returning to the 90's soon after.

New and Difficult Weather Pattern

        Originally, this next "interesting" weather pattern looked like a classic heat wave/ridge style pattern when I last had a blog post several days ago. Things have changed significantly since then, with models trending towards, a Rex block pattern.  In a Rex blocking pattern, a significantly large trough of low pressure has cut itself (but not completely, as in the case of a cut-off low) off from the main jet stream flow, shoving itself into the middle of a ridge.  As long as there is no warm air advection into the trough, the blocking pattern can persist for quite a while.  As the ridge strengthens, the low "shoves" itself underneath the entire thing, causing the entire pattern to retrograde, or move in a direction opposite of the normal motion (which is moving eastward).  This kind of block is amplified by the fact that upper level blocking, even though it is still weak, is still persisting over Greenland.  This should cause a situation for our area that is extremely similar to the Greek story about Tantalus, who was in a lake of water up to his neck, but every time he tried to reach down for a drink, the water level would drop, not allowing him to get a drink. Around, a large upper level trough is going to build into the Northern Plains over the weekend, as a series of shortwaves "runs" into the amplifying ridge, which will cause the ridge to deamplify for a few days.  This series of shortwaves will carve out a rather large longwave trough over the Northern Plains, which will allow for a series of storm systems to traverse the upper plains. At the same time that the trough tries to dig into the Midwest and Great Lakes, the Rex blocking pattern will set up in the western Atlantic and near the East Coast.  This will cause these same storm systems to move across the same areas, Minnesota and South Dakota, causing several very heavy rain events. At the same, the heat wave will build north and westward into our area, with 500 millibar heights building into the 5900-5940 meter range, which is about as high as 500 millibar heights get (the highest 500 millibar heights were recorded last summer over Wichita, with heights of over 6000 meters above sea level!).  This will eventually lead to a strengthening of the heat by next Tuesday and Wednesday, with temperatures rising back into the mid 90's by Wednesday and Thursday of next week.  After that, there is incredible model uncertainty as to what will happen (there is a lot of uncertainty with what will happen this weekend!), but some of the models are indicating that the longwave trough will weaken and move over the area, causing temperatures to cool back into the 80's by next weekend.  Other models are indicating that either nothing will happen or keep flipping back and forth between solutions!  Ensemble consensus indicates that the longwave trough will retrograde back into the western United States (according to the HPC, or the Hydrometeorological Prediction Center), forcing the ridge to reamplify over the area.  In my opinion, the models are certainly having problems with the blocking pattern setting up and their forecasts should be considered with a grain of salt.  At this time, the GFS is probably the most progressive, while the ECMWF is probably the most amplified. If I had to use one model with the best forecast, I would say the ECMWF, as it seems to be handling the pattern quite well, as a Rex block will not allow the longwave patterns to progress very easily.  I would not take even the ECMWF for face value, as it breaks down the pattern quite rapidly, even though the Pacific ridge should retrograde, which would mean the entire pattern should shift west, including the trough in the Northern Plains, which would eventually cause the ridge axis to move back over the region.  I will have to keep updated on the pattern as it very confusing and not giving many meteorologists confidence.  There is always the possibility for cooler and wetter weather (hopefully)!
           As for this weekend, a shortwave will rapidly move through the upper Midwest by Saturday and Sunday, which could force a rather weak cold front close to the area.  Due to the amplifying ridge, I would highly doubt that the cold front will make it much past Chicago.  From my understanding, the only reason the NWS dropped temperatures into the upper 80's and lower 90's for Sunday and Monday is because of increasing clouds and lower low level temperatures associated with the approach of the cold front.  If the models end up having their well known moist bias, then they are likely having convective issues. Since they could be overestimating convection development, they may be forcing the cold front to far south, which could have a rather large effect on the entire weather pattern, especially with high temperatures and precipitation (for all of you who are hoping for rain, don't get your hopes up, rain chances for this weekend are less than 5%, in other words, don't expect rain). With a continuation of the drought (in fact, there is a moderate drought over most of the area, with the development of severe drought likely soon), expect high temperatures to be warmer than what is expected, and (possibly) cooler lows depending on the moisture profile of the low levels. Other than that, expect nice, sunny weather, with much warm and drier conditions developing. For more updates, I should have another blog post by tomorrow or Saturday, or you can come talk to me personally and I will answer your questions (usually I am at the West Bend News from 9 a.m. to 4 p.m.).

Rainfall not as promising

I hate to be the messenger of bad news, but I have to give you the truth. Heavy rainfall for Monday does not look near as promising as it did yesterday.  In fact, some parts of the area may only receive a tenth of an inch by Monday night. Here's what's likely to happen. Right now, a rather weak upper level shortwave is located over the Gulf Coast, while a strong upper level trough is swinging into the Northern Plains, forcing a cold front eastward, which at the same time is sparking severe weather over Minnesota. The weak shortwave near the Gulf Coast is currently "trying" to move eastward, but its forward progress is being halted by the strong upper level ridge which is currently located over the area.  This is forcing to slowly move northward, especially in advance of the upper level trough over the Northern Rockies.  Overnight, this will cause the deep layer mean wind to becoming southerly, as the upper level shortwave is absorbed into the main upper level storm system.  These southerly winds will "pump" an incredibly moisture "rich" air mass into the region, with precipitable water (the total amount of "useable" water vapor in the atmosphere above a location, usually it is a good indication of heavy rainfall) values approaching 2 inches by the morning hours. Convergence from a surface trough and weak upper level forcing (along with moisture convergence along the initial surge of rich moisture) will cause the development of scattered showers tomorrow morning.  At this point, thunderstorms are unlikely tomorrow morning (from 8-noon is the best chance for rain), due to the advection of a mid level cap into the region, limiting atmospheric instability.  After this first wave of rain, skies should clear for a while before the initial storm system arrives, as a pocket of drier air aloft arrives in the area.  As for afternoon and evening, if the initial moisture surge has not shifted eastward yet, the cold front should be able to produce a few showers and thunderstorms across the area, but they will not likely be numerous, although some could be strong (assuming they do form). As for temperatures, depending on the amount of rainfall and cloud cover, temperatures should range from the low to mid 80's across the area.  Current model trends have been toward the moisture surge shifting eastward rapidly, bringing a rapid end to the rainfall, or the rainfall completely missing us.  Right now, I very skeptical of this, as the NAM may be having convective feedback issues associated with the closed low over the Gulf of Mexico, pushing the low too far east.  For now, we will have to see because this is a very unusual situation.  The cold front will push through sometime Monday night, still allowing warm overnight temperatures in the upper 60's.  By Tuesday, much cooler air will arrive with highs nearing the lower 80's (depending on the amount of rainfall we receive Monday).  Wednesday and Thursday, temperatures should start out in the middle 70's for highs on Wednesday, then jumping upward into the lower 80's.  By the weekend, highs will likely be in the 90's yet again as yet another ridge of high pressure builds into the area.

Rainfall Update

Well, it turns out that weak upper level disturbance over the Gulf of Mexico may have a much more profound effect on our weather by Monday and Tuesday.  By my forecast reasoning, I expect that the weak upper level circulation will shift northward and weaken.  The circulation of the strong upper level trough over Canada (as seen on water vapor imagery) coupled with the weakening low over the Gulf of Mexico, will enhance deep moisture transport northward from the Gulf of Mexico, especially after mid-morning Monday.  In my opinion, models are still too fast with the cold front progression through the area, which is why they continually forecast temperatures much cooler than Sunday.  With a slower frontal progression (due to lack of upper level support), clouds will take a little longer to reach the region.  With deep moisture in place by Monday at noon, conditions may feel humid and uncomfortable, with dew points approaching the upper 60's and lower 70's by late afternoon.  By 5 or 6 in the afternoon, depending on the strength of upper level forcing, numerous showers and thunderstorms look to form in the moist air mass, which could hit the area for several hours.  This time, with a lack of deep layer shear, slower frontal progression, and strong storm relative inflow, some areas in the region (especially east of Fort Wayne) could see heavy rainfall amounts, especially in the overnight hours Monday.  Usually, lack of strong upper level storm-relative winds cause slow storm movement and back-building storms, which enhance rainfall amounts.  Also, precipitable water values will be over 2 inches, which indicates an unusually moist air mass.  In some areas, this might turn out to be the heaviest rainfall since January!

Much Warmer Weather.

We will not have to worry about cooler weather probably for quite a while, as most of the arctic air has shifted to the very northern reaches of the earth, with westerly winds in Canada keeping the coldest air "locked" up.  This will also mean a lack of strong storm systems, meaning that any severe weather and for that matter, rainfall will be rather limited most likely through the rest of the month.  I still expect chances for thunderstorm complexes on the edges of upper level ridges (commonly called the "Ring of Fire").  This doesn't even seem that likely this year, especially with how quickly these ridges of warm air expand eastward, pushing most rainfall into the Northern United States and into Canada.  As for the next few days, expect sunny skies with our hot June sun, allowing for rather warm temperatures.  Tomorrow, Saturday, June 9, 2012, expect highs to jump into the lower 90's with excellent fire weather.  I would definitely recommend not planning any bonfires tomorrow, as the relative humidity will likely drop to around 20% by afternoon, combined with the much above normal temperatures, and already drought conditions across most of the area, this would make for large wildfires if anything gets out of hand. By Sunday, I would not worry as much about fire weather, as I expect return flow from the Gulf of Mexico will cause dew points to rise into the lower 60's, which would cause much higher relative humidity.  Besides that, I expect highs likely rising above what the MOS guidance would have, with highs approaching 92 or 93.  Increasing mid level clouds and higher moisture content will only allow temperatures to drop into the upper 60's and lower 70's.  On Monday, depending on the amount of cloud cover and thunderstorm development, temperatures will likely make to at least the mid or upper 80's, especially east of Fort Wayne.  Moisture will be on the increase, but I have a hunch that computer models are overdoing the amount of moisture present, which probably means that guidance may also be overdoing cloud cover and thunderstorm activity, especially with how far north the system will be located (Central Canada).  More than likely, the strongest areas of lift will occur well north of the area, and with lower moisture, most areas will probably receive some rain, but not a whole lot, if any.  This will likely lead to a worsening of drought conditions across the area. An upper level low (a rather weak one at that) could lead to enhance moisture transport into the region, which could bring a better chance for rain, but at this time, I really don't think that is all that likely.  In opinion, most of the rainfall will end by noon Tuesday (if it hasn't already).  If most places do not get much rain, I expect dry conditions to continue well into next week, with temperatures in the low 80's for a few days before yet another heat wave appears on the horizon, which at this time appears to reach the area by Friday and Saturday, bringing 90+ heat to the region.  This next heat wave looks quite a bit more incredible than the one this weekend, for several reasons.  One, with the incredibly dry conditions continuing, along with the intense June sun, temperatures can rise rapidly.  Two, a break in the Atlantic block, and then a restrengthening of the block will keep a strong ridge located over the area for at least several days, allowing for warm temperatures and sunny skies to prevail.  Three, moisture transport will be rather limited into the region (even though dew points may be quite high on some days), which will allow for limited cloud cover and virtually no thunderstorms.  Four, even if moisture transport is enhanced, thunderstorms will not be likely, as a mid level cap from subsiding air within the zone of high pressure will limit little or any clouds.  All in all, this will all just act to enhance the ongoing dry conditions across the area, with moderate or severe drought likely overspreading the region by mid or late June (assuming little or no rainfall).  For the most up to date information: visit Midwest Drought Monitor.

Dry, Quiet Pattern Prevails

After a very turbulent week, featuring everything from record heat, to well below normal temperatures, to rainy afternoons, and windy days, this week will be rather relaxing and enjoyable.  This week, I am expecting sunshine on most if not all of the days.  Even though a cold front will likely move through the area late tonight into tomorrow morning, a huge temperature drop is NOT expected, with temperatures only dropping into the mid 70's.  This is how I expect temperatures to remain through most of the week, with a gradual moderating trend after Wednesday.  During the same timeframe, I am not expecting any precipitation, with only the possibility of a few showers ahead of the shortwave tomorrow, but mainly southwest of here.  By next weekend, an upper level ridge will build into the region, resulting in increasingly warmer temperatures.  In fact, temperatures will most likely reach the 90's by next Sunday, with a week or more possible of above normal warmth and humidity.  Because of the overforecasted rainfall amounts on Friday, the drought was not impacted and will likely continue to rage in the area, only getting worse over the next week and a half or so.  In fact, light to moderate drought has already hit areas in Northeast Indiana, with this area likely to spread eastward as the week moves on.  Enjoy the weather!

Significant Rainfall on the Way.

Our first significant and possibly heavy rainfall looks to be on the way by Thursday night and Friday.  This will really help the plants to shoot up after the long and hot dry spell we have been having.  Here's what's going on: currently a weak shortwave trough is located over the western portions of North and South Dakota.

This shortwave will amplify and strengthen rapidly during the overnight hours, as the jet streak, a region of stronger winds in the jet stream, enters and "digs" into the trough.  By tomorrow morning, widespread high and mid level clouds will enter into the region from the west, bringing the first signs of the storm system.  As it strengthens tonight, it will slow its quick pace due to several processes occurring within the storm's structure.  One of these processes is the latent heat release from the large area of convection currently located over South Dakota.  Latent heat release slows the system's pace, due to processes that occur near the tropopause, which are so complex, is it not entirely understood by most operational meteorologist.  In response, a low pressure system will begin to form and move along the frontal boundary that is currently located over the Ohio Valley region.  This will cause the front to strengthen rapidly, first strengthening the storm system, but also causing a low level jet to form, which will cause the front to move northward as a warm front into the region.  Increasing isentropic lift and frontogenetical forcing will foretell the coming of rain by late afternoon on Thursday.  This is where model differences come into play.  As the upper level wave strengthens, the low pressure system will deepen rapidly, drawing moisture northward above the warm front.  This, combined with strong upper level forcing and frontogenesis will cause the development of heavy rain bands over the area by 9-11 p.m. Thursday night.  Some of the models, such as the NAM, are too weak with the storm system, causing less rainfall, less moisture transport, and an obvious impact on the precipitation patterns.  The GFS on the otherhand (this is kind of surprising), is much stronger with the storm system, has much more intense moisture transport into the region, which positively impacts the storm system, making it stronger.  Usually, computer models do not have a good handle on rapidly developing storm systems in positive feedback processes.  Actually it is kind of surprising that the GFS is stronger with the entire storm system, due to the fact that it does not have a good handle on convective development (thunderstorms, heavy rain, etc.).  Therefore, my forecast will call for a stronger storm system, stronger moisture transport, and thus heavy rainbands, and much heavy rainfall.  In fact, if the forecast goes as predicted, I would expect rainfall amounts in excess of an inch, especially west of Defiance.  After the system moves out of the region by Friday afternoon, clouds will prevail, along with gusty winds and cool temperatures.  By Saturday, clouds will still persist, but will allow some sunshine through.  Temperatures will also moderate into the lower 70's.

Much Cooler Weather On the Way

After five days in a row of near or record breaking temperatures, daytime highs will finally begin to cool, with highs today only reaching the mid to upper 80's (still pretty warm).  This cooler weather will be brought on by a strong cold front moving through the region today, with a noticeable decrease in humidity also.  Temperatures will not be that cool today as strong cold air advection will not reach the area until later this evening, causing lows tonight to fall into the low to mid 50's.  By tomorrow, highs will be 25 degrees cooler than what they were on Sunday and Monday, with highs only approaching the lower 70's.  If upper level ridging were to build in behind this shortwave, temperatures would likely warm back up to the 80's and 90's, but not so this time, because the amplified jet stream is expected to break down this week into a more zonal flow pattern.  This will allow several disturbances to phase or "morph" into one stronger wave, which could cause more rain for Thursday night into Friday.  The bad side about this is that temperatures are likely to become very cool, with daytime highs well below normal by Friday, along with the rain.  In fact, I am only expecting highs to make it to the mid-60's on Friday, while Thursday, temperatures should still be near 70.  By Saturday and Sunday, the upper level wave moves away from the area, causing upper level height rises, and warmer temperatures.  Ridging will then build into the region for the foreseeable future, with highs back into the 80's and 90's by next Tuesday and Wednesday.

Season's First Heat Wave

As of 6 a.m. Sunday, May 27, 2012, the National Weather Service has issued a heat advisory for parts of the area, including the counties of Lagrange, IN; DeKalb, IN; Defiance, OH; Paulding, OH; Putnam, OH; Allen, IN; Whitley, IN; Noble, IN; Van Wert, OH; Adams, IN; Wells, IN; and Huntington, IN (this is the area that I consider when I forecast the weather with a few exceptions.).  The National Weather Service is expecting heat indices near 100 today in most areas except extreme Northern Indiana and extreme northeastern Indiana (mainly northeast parts of the forecast area).  With dew points in the mid to upper 60's by this afternoon, combined with temperatures rapidly rising into the lower 90's by noon, I expect it will feel like one of the hottest days that Antwerp has seen since last July (which is true!).  It is possible that by afternoon that mixing is so deep that it mixes extremely dry air to the surface from the 700 millibar level, which would drop dew point readings into the lower 60's, but causing hotter temperatures closer to one hundred.  The main reason for this kind of record-breaking heat is because of the strong ridge of high pressure just above us.  In the upper atmosphere, an area of high pressure is equivalent to a deep layer of warm air (due to equations such as the ideal gas law and the hypsometric equation).  Therefore, a ridge of high pressure in the upper atmosphere could be used to define where a surface warm air mass is located.  Strong subsidence within the high contribute to the warmth too, because air sinks it warms quickly if it is unsaturated (below 100% relative humidity).  Not only that, but during the summer months, as warm air masses advect into a region and solar heating commences, strong mixing occurs within the boundary layer, which deepens the layer and mixes warm air to the surface.  For example, 850 millibar (a height of about 1560 to 1590 meters today) temperatures will be close to 24 degrees Celsius by afternoon.  As the winds increase today, strong mixing will occur, bringing that warm to the surface.  The mixed air will increase its temperature at the rate of 10 degrees Celsius per 1000 meters.  Since the height of the 850 millibar level this afternoon will be about 1590 meters, first divide the number by a thousand and then multiply it by 10 to get 15.9.  Add this to 24 to get 39.9.  Right now, I do not think temperatures will approach 104 this afternoon (mainly because 850 millibar temperatures probably will not make it past 22, which would yield highs near 98 or 99).  Back to the forecast.  Areas generally northeast of Route 6 will not see temperatures that hot, mainly because of the slow movement of the warm front and cold outflow boundaries from storms farther north last night, which will keep temperatures up there below 95.  If we're talking about Fort Wayne's weather, it's a completely different story.  If temperatures reach over 95 today, it will break the all-time record high for May. That's two all-time records broken in one year (a high of 87 back in March, broke the 100 year old record)!  Since I am expecting Fort Wayne to be one of the hottest int the region due to its dryness, my forecast is calling for high temperatures from 97-99 by this afternoon, which is incredibly hot.  In fact, of the last 12 years of the 21st century, in only one year (other than this year) has Fort Wayne seen temperatures higher than 95 and for more than one day in a row, and that was in 2011.  The year before that saw 95 degrees was in June 2005, and that was for only one day.  In 2011, we hit 95 or higher for 7 or 8 consecutive days (but that was in July).  I nearly certain that temperatures will shatter May's all time record.  Even tonight's low could shatter the record high minimum low (for those of you who are confused by this the warmest nighttime low).  If we only get down to 73 by tomorrow morning, it will break the previous record for May which was 72.  As for any rainfall today, there is a near 0% of rainfall anywhere south of Route 6.   If you are north of the highway, the cap may be weak enough and instability strong enough to cause isolated showers and thunderstorms, which could also limit daytime highs.  By tomorrow, temperatures will drop slightly but still be in the mid 90's, but with higher dew points, which could make it feel unbearable.  Thunderstorms are also possible area wide, but in my opinion, the shortwave that will drop a cold front through the area will be too far north to cause widespread thunderstorm activity, even with the strong instability forecast by afternoon.  By nightfall, though, I do expect a better chance of thunderstorms, but then again, given the dry pattern, it certainly isn't all that likely.  After the cold front moves through temperatures will drop into the lower 80's by Tuesday, and then the lower 70's by Wednesday and Thursday, and yet another cold front will drop temperatures into the upper 60's by Friday.  For all you warmth lovers, don't fret just yet, according to long-range guidance, after this Friday, yet another strong ridge will build into the Central Plains and East, bringing another heat wave that could be even worse than this one.  Right now, this looks to happen around June 6-12.  Enjoy the warm weather!

Warm, Humid this morning

After an overcast morning, the skies have cleared partially, allowing for rapidly warming temperatures along with increasing humidity levels.  In fact, most areas now are seeing temperatures in the mid 80's with dew points in the mid 60's, making it very uncomfortable.  The reason for the warm temperatures and high humidity is because of the fact that the cold front has slowed down significantly and has almost stalled.  Current short range model forecasts are still showing the front move through by noon, only bringing lower humidity not cooler conditions.  For this reason I am going to raise high temperatures for today into the lower 90's, especially south of Route 6.  Dew points will decrease considerably during the afternoon (below 50 to be exact), leading to much more comfortable conditions even with 90 degree temperatures.  By tonight, the same stalling front will surge back north as a warm front, bringing extremely humid conditions along with even warmer temperatures.  A few showers and thunderstorms may accompany the frontal passage, but it is likely that upper level ridging will hamper much thunderstorm activity, with areas west of Fort Wayne the most likely to see any kind of showers and thunderstorms.  For tomorrow, expect temperatures to surge into the low to mid 90's with dew points in the upper 60's.  Not every place in Northwest Ohio will see this kind of warmth and humidity, especially north of Route 6, where periodic showers and storms will possible in the morning north of the warm front.  By Saturday Night, a nice, warm and humid night is in store, with most places not dropping below 71 or 72.  On Sunday, a very hot, humid and oppressive day is in store, with high temperatures soaring to the upper 90's and some areas might even see 100.  It will be one of the hottest days ever recorded in May and one of the earliest 95+ temperatures on record.  By Monday, temperatures will not be as warm as on Sunday, but it will still be hot and humid, with high temperatures approaching the low to mid 90's once again.  By nightfall, storms will be possible as a frontal system approaches the area.  This will front that ends it all, with temperatures plummeting back into the lower 80's on Tuesday, and the lower 70's by Wednesday and Thursday.  After that, it seems as if we will be seeing cooler for a few more days before returning back to the 90's.  Enjoy the nice summer weather!

Drought Advancing

I said I would post an article on the drought and so I will.  For "official" measurements, visit www.crh.noaa.gov/iwx.  So far this May, most of the area has seen less than an inch of rain (excluding areas north of Route 6 and east of Defiance, with the epicenter of this rainfall deficit centered between Fort Wayne and Antwerp (including the two places).  In fact, it has been so dry that in the last 14-20 days, most areas have not seen rain, which is extremely rare in a spring month.  This has created a rainfall deficit of nearly 2-3 inches since the start of May, and an inch and a half rainfall deficit for the month of April.  Most of you probably have noticed that your yard does not look like it was May, but rather August.  WE really have a serious situation on our hands which will continue to impact our weather throughout the summer and into the fall.  My bet is that we end May with little more rainfall than we have right now, given the fact that most of the rainfall from the next two storm systems will bypass the area well to the north, I do not expect much if any rainfall when this heat wave comes to an end.  As I have talked about before in past blogposts, rainfall deficits lead to dry ground, and dry ground is able to heat up faster and to higher temperatures than wet ground.  Obviously, this is probably one of the most pronounced affects of the drought, with the sun causing warmer temperatures, which may lead to a hotter summer than originally forecast.  One less obvious effect of the drought, is the fact that it will lead to a positive feedback process (a process in which one variable "positively" influences another variable, leading to an enhancement in the process).  I am expecting that this drought will lead to more drought, due to the fact that quite a few storms that form during the summer depend on soil moisture for them to grow.  With less moisture for the storms to feed off of, there will be less rainfall, ultimately making the drought worse.  My theory on what is causing this drought is a combination of the extremely warm winter (even though we had near normal snowfall, the water did not stay in the ground very long because it never froze for more than a couple of days.), the "hot" weather we had in March, and a virtually rainless spring.  There are some other long-term factors, such as the changing positions of the ocean currents during the El Nino phase of the Southern Oscillation, and the changing ocean temperatures, but they likely have less effect than the other factors involved.  Due to the persistence in the heat this spring, I am expecting yet another hot summer across the area, as upper level ridges have seemed to dominate the weather across the East and Central U.S. for large portions of the spring.  This will all lead into next winter's weather, which could once again feature above normal temperatures, but below normal precipitation.  That is too far out to accurately predict so I will not say anything else.
As for this week's weather, temperatures will likely soar into the lower 90's across the area, especially in the aforementioned dry areas.  Even with strong mixing in the boundary layer, southeast winds will transport 60+ degree dew points into the area, giving the air quite a humid feel compared to recent days.  By tomorrow, the front that I mentioned in yesterday's post will cross into the area, causing temperatures to cool slightly (probably to near 88-89 with less humidity).  I am not expecting thunderstorm development with this front (even with the instability in place), due to the fact that the "cap" in the mid-levels is quite strong, which limit any thunderstorm development.  Second, much of the upper level lift will exist to far north of the area to even break the cap for the storms.  By Saturday, that same front will surge back northward, causing temperatures to jump to near 93, along with dew points approaching the mid to upper 60's, making for very humid weather.  On Sunday, temperatures will reach their highest, with some areas (especially areas near extreme eastern Indiana and western Ohio, including Antwerp and Fort Wayne) reaching from 96-98 from time to time.  This will also occur along with humid conditions, so don't be surprised if the National Weather Service issues a heat advisory.  During this same time period, low temperatures will become very warm, with lows in the upper 60's and lower 70's.

This chart shows how far behind in rainfall we are for the year to date

Hot weather on the rise

Most of you will notice that temperatures will take a hike today, with highs being almost 10 degrees warmer than yesterday.  This will lead to increasing wind speeds (greater lapse rates and deeper mixing within the boundary layer) today, making for a rather comfortable day.  Tomorrow, moisture return flow (strong and deeper winds originating from the Gulf of Mexico which transport tropical air masses northward) will increase, causing even warmer temperatures and a significantly more moist air mass.  With this, I am expecting highs tomorrow approaching 90, probably leveling off in between 88-90 (depending on the depth of the mixing within the boundary layer).  By Friday, several computer models are persistent in driving a "cold" front into the area, bringing showers and thunderstorms to the area, along with cooler temperatures.  I do not believe this, even though the National Weather Service has started to accept this idea.  I do not believe this will be the case mainly because strengthening upper level ridging will act to push the front farther north and weaken it.  In my opinion, I do not expect much if any thunderstorm activity in the area, and if there is any, it will likely be west of Fort Wayne due to strong capping and weak subsidence over the area (though that shortwave may cause some upward motion over the area, leading to the possibility of destabilization of the atmosphere and thunderstorms.)  If the low levels are moist enough (short-range models are indicating that dew points are going to be in the low to mid 60's), an isolated shower or storm can not be ruled out.  As for highs on Friday, this will be a bit tricky, as some of the computer models are indicating temperatures dropping into the upper 70's (such as the GFS).  More than likely, it is showing this bias due to the fact that it may be over aggressive with the shortwave that will be passing to the northwest of the area, especially because the same shortwave is not very well-defined over the Intermountain West, embedded in the main trough.  I would forecast a less amplified shortwave than what the GFS and some other models are forecasting, and with upper level ridging, I expect that the surface front will quickly weaken, stall, and race back northward as the strong upper level ridge builds into the region, generally around the time frame of Friday Night.  I would expect Friday high temperatures near 90 if the front fails to stall in the area by late afternoon, with dew points surging to near 60 (this dew point surge may be a bit overdone, as the models tend to be too strong with moisture return flow, meaning that dew points are probably going to be a bit lower.)  By Saturday, there are some differences in regards to timing of the front pushing back northward, with the GFS being the slowest.  In my opinion, a faster push northward is the best option right now, especially given the strength of the upper level ridging that will be in place by Saturday.  With 850 millibar temperatures nearing 15-20 degrees Celsius, expect highs to reach the lower 90's (unless the front does not lift through the area until afternoon), with even more humid conditions present across the area (dew points reaching into the mid and upper 60's), which will make the air mass very uncomfortable (unlike last weekend, which featured a very dry air mass).  On Sunday, 850 millibar temperatures could reach from 22-25 degrees, indicating surface temperatures at least into the mid 90's (94-96) if not near 97 or even 98 in isolated areas.  This combined with dew points right near 70 throughout the day, will cause extreme instability and a very hot and humid day.  In fact, it could be so hot and humid that the National Weather Service is considering issuing a heat advisory on Sunday, and possibly into Monday.  On Monday, temperatures will be a bit cooler, with temperatures making it into the lower 90's under mostly sunny skies.  With mid-level temperatures cooling, we have a greater likelihood for thunderstorms, especially as the upper level trough passes to the northwest of the area, but I am not expecting much.  Tuesday, though, may be the day that brings us much-needed rain, as the upper level ridge breaks down, and gives way to much more zonal flow, which will allow for warm temperatures (low to mid 80's), but not to the extremes that we will see this weekend.