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.

Warmth Continues...

As of  4 p.m. this afternoon, the official high temperature at Fort Wayne International Airport was 88 degrees (note: this will likely change as temperatures continued rising after 4 p.m.).  It is very likely that across the area, mainly west of Defiance, that many areas reached or exceeded 90.  In fact, most of the warmer temperatures were west of here, with some areas, such as Chicago, reaching into the lower 90's.  The reason for this well above normal warmth, is because of the incredibly dry ground.  In fact, it has been almost two weeks since some areas in the region even saw rain.  Dry ground combined with completely clear skies lead to large diurnal temperature swings, with low temperatures this morning near 50, and high temperatures in the upper 80's and lower 90's.  Also, a strong upper level ridge is currently located over us, which is basically a large bubble of relatively warm air in the upper atmosphere.  This "warm bubble" is causing downward motion over the area, which is causing the warm temperatures aloft to be carried to the surface, plus the added subsidence is causing adiabatic warming which also warms the surface.  With warmer lows tonight near 60, expect even warmer temperatures for tomorrow afternoon, with highs possibly reaching well into the 90's (91-93) in some localized areas.  With increasing moisture into the area, high temperatures may not reach that high tomorrow.  By Monday, a dying upper level system will reach the area, causing scattered showers and thunderstorms.  Because of the weak forcing associated with the system, and meager moisture in the lower atmosphere, do not expect much shower and thunderstorm activity in the area.  Because the cold front will be moving through, temperatures will be quite a bit cooler on Monday then on Sunday, with highs only reaching the lower 80's.  On Tuesday, the core of the upper level low will move over the area, bringing the chance for an isolated shower, but this is highly unlikely.  The cold core of the upper level low will cause much cooler temperatures on Tuesday, with a high near 73.  By Wednesday, the next upper level ridge will build into the region with yet another warming trend for Memorial Day weekend.  Wednesday's highs will peak in the upper 70's under partly cloudy skies.  By Thursday, temperatures will approach the mid 80's yet again, under sunny skies.  On Friday, Saturday, and Sunday, I am expecting temperatures to rise into the upper 80's and lower 90's, with temperatures possibly peaking in the mid 90's on Sunday and Monday.  This will have to be monitored in the future because this could be a sign the season's first heat wave could hit the area.

Fair weather through the weekend

With temperatures approaching the low to mid 70's this afternoon (west of Defiance anyway), along with plentiful sunshine, it has been one beautiful day.  The cold front that I was predicting on Tuesday did more "damage" than I thought it would, as brought temperatures tumbling down to the upper 60's yesterday, and the same anticyclone is bringing cooler weather to the area today.  Tonight, temperatures probably will not be as cool as last night, mainly because high and mid level clouds from a weak shortwave crossing the upper Mississippi Valley will keep temperatures from dropping nearly as fast.  Also, veering low level winds from the southeast and weak warm air advection will also be a caveat to lower temperatures.  By tomorrow, plentiful sunshine (possibly some puffy cumulus in the afternoon), upper level ridging and weak return flow, will cause temperatures to jump about 10 degrees from today, with temperatures ranging from the mid 70's near Toledo, to the lower 80's near Antwerp and Fort Wayne.  By Saturday, in response to a major trough entering the west coast, upper level height rises and ridging will allow for warmer 850 millibar temperatures, stronger mixing throughout the low levels, and thus even warmer temperatures.  In fact, I would not be surprised for some areas on Saturday to see temperatures as high as 87 or 88, especially west of Fort Wayne.  Saturday night lows will be much warmer than previous nights, with temperatures dropping only to near 60.  I expect pretty much the same on Sunday, with temperatures easily approaching the 90's under mostly sunny skies.  By Monday and Tuesday, a shortwave will approach from the plains, possibly bringing the chance for showers and thunderstorms, mainly on Tuesday.  Temperatures on both days look to range in the upper 70's and 80's.  In the long-range, there is a lot of discrepancy, but the ECMWF, which has been pretty consistent with its solutions of a ridge over most of the United States, is forecasting a rather strong upper level ridge to form over the Eastern and Central United States, and persist for several days.  It is forecasting 850 millibar temperatures to be in excess of 20 degrees Celsius by next Thursday (it is a week away so a lot can change by then!), which translates to surface temperatures in the 90's, which could mean our first heat wave may be on the way.  We'll just to have to wait and see, but it is a good bet that we see some hot weather in the near future, as the ground is incredibly dry and the pattern is very conducive to warm spells (as we have seen all winter long!).  Enjoy the nice weather!

Slighty Cooler Tomorrow

After such a beautiful day today, with temperatures near 85 (an impressive diurnal temperature range, 49 this morning to 85 in the afternoon) and incredibly low humidity, a weak cold front from Canada will invade the area, bringing the possibility of weak scattered showers, but more importantly temperatures back into the 70's for a few days.  This cold front diving southward in response to a high amplitude trough sitting in southeastern Canada.  This will send a bit of a reality check to the region, with temperatures only reaching the mid 70's tomorrow.  I am not expecting really any rain except for the possibility of a few sprinkles, as moisture return from the Gulf of Mexico is incredibly meager and any significant upper level forcing is too far north of here to produce anything of consequence.  This will likely mean a partly cloudy rather warm night with temperatures dropping into the mid 50's.  By tomorrow, cooler temperatures with make their way into the area with highs dropping near 73 or 74.  Much cooler temperatures tomorrow night could mean lows in the mid 40's, quite a bit cooler than in recent nights.  By Thursday, temperatures will begin making their recovery with highs back into the upper 70's underneath a very dry air mass.  For the rest of the weekend and the beginning of next week, strong upper level ridging will cause much warmer temperatures, with highs as warm as the upper 80's and lower 90's.  A lot of the models are tend to under do warm events like these, mainly because they cannot account for soil moisture very well.  When soils are incredibly dry and the air mass is also dry, temperatures tend to rise much faster and to higher temperatures as well.  Temperatures also tend to drop considerably at night, making for large diurnal temperatures ranges.  This means very hot temperatures for the weekend under mostly sunny skies as ridging continues to build.  After this, the forecast gets a little out of hand.  The GFS has a small amplitude wave moving through the Midwest on Monday and Tuesday, with ridging building back into the region after that.  To me, this seems like the most logical conclusion, as a rather strong trough will build onto the West Coast, causing an amplification of the Central and Eastern ridge.   After a couple of days of being in the upper 70's on Monday and Tuesday, expect temperatures to warm back into the mid to upper 80's, with continuing warmth possible.

Warm, dry weather pattern

For all the people who love summer-like weather, there is yet another batch of much above normal temperatures coming, with highs by the end of this week reaching into the 80's.  This will come on the heels of a long dry spell, which will likely last through the next week or so.  So far this month, we have only received 0.8 inches of rain, and with little or no rain in the next week and a half, this could end up as the second month in a row with below normal rainfall.  With the below normal rainfall and record warmth over the past several months, drought will likely ensue, with parts of the area already in the first category of drought status.  This could have huge implications for this summer's weather, with widespread dry ground over the Midwest leading to hotter daytime temperatures (dry ground heats up faster and longer than wet ground does).  As late spring and summer progresses, the large amount of heat radiated from the ground level will cause a deep layer of warm air to form, making it nearly impossible for cold fronts from Canada to penetrate into the Midwest.  Not only will this occur, but building warm air will cause higher pressure aloft, causing greater subsidence, clear skies, more sunshine, no rain, and higher temperatures which will all continue to cause warmer temperatures throughout the summer.  Obviously, this is an idealized process, with many complications which will act to counteract the warmer temperatures, such as isolated summer thunderstorms.  What I'm trying to say is that the warm and dry weather pattern of this spring will likely continue through the summer.  According to Accuweather, they are expecting a much different pattern.  They believe that this summer will hold above normal storms and rainfall for the area but normal temperatures.  Unless there is some kind of major pattern reversal, I do not see this happening in the near future, as blocking is characteristic of an El Nino pattern, which we are entering into.  Also I have found correlations with other years that had warm winters, warm and dry springs, and they have also had very warm and dry summers (the summer of 1955, one of Fort Wayne's hottest summers).  Otherwise, over the next week, due to dry soils and relatively little moist air entering the region, I do not see much rain nor cooler weather.  In fact, each day will see large diurnal temperature swings, which could mean lows in the lower 50's during the morning but temperatures in the mid to upper 80's and lower 90's by afternoon.  It is entirely possible that temperatures reach into the 90's by the beginning of next week.  Though, it is very hard to tell, as the long-range is very difficult to forecast.  If computer model forecasts are correct, then 850 millibar temperatures could approach the lower 20's degrees Celsius, which translates to surface temperatures in the lower 90's.  This pattern won't last forever, but it will likely last quite a while.  My forecast is that this type of pattern will continue throughout the summer months, bringing our area quickly into drought.  Before we hit the 80's though, expect temperatures in the upper 70's through Thursday, before they rise into the 80's.  Enjoy the beautiful weather this week!

Warm weather yet again

When it seems it can't get any better (80's in March, lots of sunshine), it just keeps getting better.  For example, today, it is expecting to be partly cloudy ahead of a cold front with temperatures rising into the mid 70's.  It isn't ideal, because of the chance for thunderstorms, but it is pretty nice, even compared to last May (last May was the wettest May on record.).  Looking over the week ahead, temperatures will be soaring into the upper 70's, especially by Wednesday, and then into the 80's by Friday.  Guidance continues to suggest that the surge of warmth will continue through the following week also.  It is possible that we will be hitting the 90's by the following week, which will be well above normal and possibly record-breaking.  Given dry conditions and plenty of sunshine, long-range forecasts will definitely have a cooler bias to them, which means that if they say upper 70's and lower 80's for the end of the week, expect mid 80's.  As for today's forecast, I am not that worried about it, because there is not a whole lot of upper-level forcing nor instability.  According to my analysis of a skew-T log P chart, instability could be high enough to produce scattered thunderstorms but nothing horrible or severe.  One caveat to this is the fact that we are located in the right entrance region of a jet streak, which would produce strong upward motion, aiding thunderstorm development.  But, due to the limited availability of moisture (dew points only in the low 50's), thunderstorms will not be widespread.  Expect tomorrow to be a cooler day, with cloudier skies ahead of a weak shortwave trough axis, with highs in the upper 60's and lower 70's.  By Monday, temperatures once again will be rising into the mid 70's under sunny skies.  I am also expecting the same for Tuesday through Thursday, with Friday showing a marked jump in temperatures into the lower 80's, due to upper level ridging aloft.  This will definitely be a very nice week of weather, just like the rest of spring 2012.

Nicer weather on its way

After a cold front moved through yesterday, cooler conditions began settling in the area, albeit still rather warm for this time of year.  This cold front is currently moving off to the east in Central Pennsylvania, pushing the warmth and humidity away from the area, but leaving us with a beautiful day to contend with.  The upper level ridge is pushing away from the area as a rather strong upper level shortwave or low pushes southeastward in Minnesota.  This upper level cold core low is causing the development of a numerous, but scattered showers and thunderstorms over Minnesota and Wisconsin due to the high lapse rates in the mid-levels.  As this upper level cold pool progagates towards the area, expect an increase in clouds tonight ahead of the storm system.  By tomorrow, the cold pool will cause temperatures to fall even further, with highs only in the mid 60's.  Even though temperatures will be in the mid 60's, a few thunderstorms could form due to the cold core nature of the system.  This event will not be as widespread nor as heavy as Monday's heavy rain event was, with only scattered showers and a few thunderstorms possible.  By Wednesday evening showers will continue and then cease overnight.  Over the next several days, I expect moderating temperatures and nicer weather to arise once again, with temperatures hitting the mid and possibly upper 70's by Saturday, with the chance for a few thunderstorms.

Stormy forecast for Tomorrow

After an absolutely gorgeous week of near-record breaking warm temperatures, things have finally started to get back to near normal, with temperatures back down into the 70's and much less humidity.  Before things get back to normal, a storm system will move towards the area, bringing with it the chance for showers and thunderstorms.  Right now, the main threat appears to hit the area from around 2 or 3 a.m. tonight until about noon tomorrow.  As for details, right now, there is quite a strong temperature and dew point gradient (difference in a weather variable over a given distance; strong dew point and temperature gradients often indicate strong frontal boundaries) across Northwest Ohio, with dew points in the 50's in Antwerp and towards Fort Wayne, and dew points in the 40's and 30's over Toledo, indicating quite a stable air mass across the area.  The higher dew points over Antwerp and Fort Wayne have moved into the area due to the approaching warm front, which is slowly easing its way into the area.  As for temperatures, here in Antwerp, temperatures are approaching the upper 70's while just to the west in Illinois, temperatures are soaring into the 90's with dew points in the lower 70's.  I am not expecting this kind of warmth here tomorrow, but if some sunshine can come out during the afternoon, temperatures could quickly make it into the lower 80's, which could heighten the potential for severe thunderstorms.  Due to the absence of large scale deep layer shear throughout the atmosphere tomorrow, storms will have a hard time organizing into large supercells.  This could mean multicell clusters with isolated severe weather will hit the area tomorrow, especially south of Route 6 and Napoleon.  IF the warm front lifts farther northward, instability could be a lot higher and thunderstorms a lot stronger by tomorrow evening.  As for tonight, as seen on current radar imagery, large thunderstorm clusters are developing in western Illinois, which will move slowly toward the area during the evening hours.  During the evening hours, high-resolution model guidance is suggesting that thunderstorms will become numerous and widespread by midnight, overspreading the area by about 2 a.m.  Heavy rain and gusty winds will be the main threat with these storms, with some of the storms closer to the warm front producing large hail.  These bands of rain could cause localized heavy rainfall in isolated areas, with general rainfall amounts just over a half an inch by noon tomorrow.  I am very uncertain with this forecast, as instability is very low over the area right now, which is causing thunderstorms to weaken considerably as they move toward the area.  As the low level and upper level warm front move over the area, instability will gradually increase, allowing thunderstorms to develop ahead of the them.  Back to Monday afternoon, instability should cause thunderstorms to form, but they will be fairly disorganized, unless the warm front lifts farther north past the area.  If the instability moves into our area, the thunderstorms that form will quickly become organized due to the better shear profiles over the area.  Even then, shear will not be that strong, which will hinder any tornado threat or long-lived thunderstorms.  It will be quite favorable for squall lines, which could move through by the early evening around 5 or 6 p.m.  Monday evening, a scattered thunderstorms will continue moving into the area, with a gradual decrease after 8 p.m.  The cold front moves through by Tuesday, as an upper level wave approaches the area from the northwest.  This upper level wave will produce little or no precipitation because of little moisture available.  Temperatures will continue their fall throughout the week, until rising slightly by the end of the week.

Storms possible this afternoon

After an unusually warm afternoon (in some areas), thunderstorms are erupting to the west and quickly moving eastward.  With building surface based instability and lingering deep layer shear across the area, areas mainly southeast of U.S. Highway 24 could receive severe weather this afternoon and evening.  Originally, I was not anticipating the warm front to move north of U.S. 6, but it did, and temperatures in Antwerp and surrounding areas have soared into the lower 80's, with dew points in the lower 60's.  With this unexpected surge of warmth and moisture, moderate instability has developed in areas south of U.S. 6.  This could pose a threat for severe weather to some parts of the area, as the Storm Prediction Center has placed parts of the area in a Slight Risk outlook.  They are expecting mainly damaging winds and possibly a few supercell thunderstorms.  Over the next few hours, storms will continue to become more widespread throughout the late afternoon and evening hours, with eventually all convection ending with a line of thunderstorms moving through by about 6:30 p.m.  Overnight, skies will begin to clear with temperatures falling into the mid-50's, as a weak cold front pushes through the area.  Tomorrow, partly cloudy skies will prevail with temperatures rising into the mid to upper 70's and possibly 80's, depending on the degree of cloud cover.  Humidity levels will be much lower tomorrow, so don't expect it to be as humid as today.  By Wednesday, temperatures will approach the upper 80's with high humidity levels returning, along with a slight chance for thunderstorms.