**MAJOR WARM-UP ON THE WAY FOR THE END OF THE SCHOOL YEAR**

**MAJOR WARM-UP ON THE WAY FOR THE END OF THE SCHOOL YEAR**

Finally.. After months of rather cold, dreary, wet, and sometimes snowy weather, we are finally looking at the possibility of a long stretch of warm-weather, which doesn't look like its going to come to an end any time soon. In fact, for the foreseeable future (10-14 days), temperatures should remain above normal, with highs ranging from the mid-upper 70's, to the mid-80's. In fact, I would not doubt that during one or two of the warmer periods that we see a 90 degree day.

With this stretch of warmer weather, we can also expect periodic showers and thunderstorms, as shortwaves ride along quickly in the weaker upper level jet stream. Chances of thunderstorms will remain across the area everyday through at least Sunday. Although these chances for thunderstorms are relatively miniscule, they will still provide the area with brief heavy rainfall in isolated areas.

Let's look at the details now:

1.) Starting tomorrow, we can expect temperatures to reach the mid-70's and warmer for the foreseeable future. Models are in very good agreement on this (with the exception of the GFS, which will be explained later).

2.) A weak cold front will arrive in the area by late Wednesday night, which will drop temperatures from near 84 down to 77-78. Thunderstorms will accompany this front with scattered rainfall most likely at this time.

3.) Longer-range forecast models are currently predicting that this warmth will last through at least the weekend, with temperatures even rising back into the mid-upper 80's by Sunday/Monday. This is where model discrepancies come into play.

A.) The GFS is showing a strong low pressure system taking shape across the Northern Plains, driving a very warm-air mass into the area. If the GFS were to verify (as well as its winds and boundary layer forecasts), I would expect temperatures possibly exceeding 85-88 on Sunday. It also indicates that dew points will approach the MID-70's. This will create a very humid, and unstable air mass in the vicinity of a **possible** strong cold front Sunday night; allowing for a potential severe weather outbreak. Don't worry though.. This solution isn't all that likely.

B.) The ECMWF shows a relatively "lax" and moderate pattern. It indicates that we will periodic shortwaves move across the United States, which will bring scattered thunderstorm development. It is not expecting any major storm systems, and no waves of cool air. It is the warmest solution, as it keeps temperatures in the 70's, 80's, and possibly 90's for the entirety of its 10-day forecast.

 At this point, I would give more weight to the ECMWF, as the overall pattern seems to be the case of what it is showing. Furthermore, its ensembles are in general agreement with it and the general pattern. It would suggest that later in the period, a strong trough will dig into the West, forcing height rises in the East, and thus a potential "heat-wave" by mid-next week.

Although I don't see any major rainfall events headed our way, scattered showers and thunderstorms on Thursday, Friday, and Saturday could lead to brief periods of heavy rainfall, and thus "ruining" some plans.

And as far as I can see, temperatures look to remain in the lower 80's and upper 70's for the next two weeks, with possibly warmer weather as well.

Cut-off Low in the Plains; Normal, Moderate Pattern on the Horizon

**Post frequency will begin to go up as soon as school gets out. It has been quite hectic for me lately.**

The main story it seems of the past week, has been one of normal early May warmth, all the way to record-breaking May snowstorms. Why is this occurring?

The image above is a chart from the 500 millibar level, which is normally about 5600 meters above the earth's surface. As you can clearly see, there is a large upper level, and nearly stationary low sitting over the Mississippi Valley region. At the same time, you will notice that this same low is producing a band of "retrograding" showers and thunderstorms, which have made very little eastward progress since this morning. In fact, they aren't expected to make ANY eastward progress within the next 48 hours, before dissipating. This means it is very likely that the most rainfall that we see is little more than a trace of precipitation.

Even so.. Conditions will become slightly cooler tomorrow. Temperatures will drop into the upper 60's and lower 70's.

For the next 10 days or so, expect rather tranquil and pleasant weather conditions, with temperatures hovering in the low to mid 70's. Late next week, the possibility of thunderstorms arrives again as a series of weak shortwaves approach the area from the NW.

And then.. The model differences come into play. The GFS is forecasting the continuation of a relatively warm pattern, and in fact, shows the first potential "heat" wave of the season coming for the Midwest by May 15. While I doubt it will get warmer than the middle to upper 80's, this is definitely something to watch.

On the otherhand, the ECMWF forecasts that a deeper trough could come into play in Southeast Canada, which could lead to a series of "backdoor" cold fronts which bring periods of relatively cooler weather (highs in the 60's). In fact, it forecasts that we could have a few additional frosts before mid-month, according to the model.

At this point, it is unreasonable to make any kind of long-range predictions based upon models. What I CAN do is make predictions based upon current observations.

1.) The MJO, which is the main driving force behind the "nature" (speed, curvature, and the wave number) of the Pacific jet stream will become very active, and head into phases 4, 5 and 6 by mid-May. This would allow for a zonal Pacific pattern, but with an active jet stream, which will not allow for the development of any significant troughs or ridges, leading to a warmer pattern.

2.) The continuing weak La Nina/Neutral ENSO points against a cooler May/Summer period.

3.) The drought in the West.

Why should I say the drought in the West? Specifically because whenever the core of the heat across North America focuses in the Rocky Mountain region, it almost always is pushed eastward by an active Pacific jet, which is why I believe there will be several periods of warmth, with increasing frequency into June. And that is when we will see our first heat waves much like last year. But the thing about this season is that it will be much wetter, with a much higher frequency of storm complexes and severe thunderstorms.

More details will be coming in a few weeks, when I create my official summer outlook.

SEVERE WEATHER THREAT.. MORE DETAILS LATER

I am extremely sorry for the lack of updates!

THIS IS AN IMPORTANT UPDATE!

Strong to severe thunderstorms are possible tonight, tomorrow, and tomorrow night, based upon the latest trends. Models have continued to shift northward with this very dangerous severe weather threat. In fact, it would NOT surprise me if the SPC expands the MDT (Moderate) risk into most of the area (it currently resides west of our area), and places a high-end risk for Western Indiana/Eastern Illinois. At this time, based upon the latest observational and model trends, it looks likely that the warm front will surge northward this evening and tonight. Currently, the warm front resides in Central Indiana, and should continue pushing northward, before evaporational cooling caused by heavy thunderstorms forces the warm front to remain stationary during the night. THIS IS WHERE THE FORECAST GETS VERY TRICKY! If thunderstorms do NOT form as expected, and head mainly north of us, I will expect a very quick passage of the warm front late this evening and early tomorrow morning. The warm front will bring very warm, and humid air to the region, with dew points approaching the mid-upper 60's tomorrow area wide. High temperatures under partly to mostly cloudy skies will approach 75-80 degrees, ESPECIALLY south of U.S. Route 6.

But.. For this post, I will deal with tonight's "precarious" threat. The SPC has issued a tornado watch for Western and North Central Indiana, all the way into Eastern Illinois. This deals with the very DANGEROUS threat for low-level vorticity and rotation along the warm front to couple with thunderstorms to produce tornadoes, and large hail (due to the very stable nature of the low level atmosphere, damaging winds will not be a primary concern.). But this is for Western Indiana. These storms will travel east-northeast into the region, producing heavy showers and thunderstorms later this evening. Although I don't expect much, if numerous thunderstorms develop, we could be looking at heavy rain tonight, instead of a drier night with a few showers. I will keep watch on this threat. Don't expect much rain, if any, before the 8 p.m. timeframe though. 

Current radar imagery

As for tomorrow.. It's looking increasingly likely (as stated before), that dew points will increase into the upper 60's by late afternoon, with temperatures in the upper 70's. If this occurs, we can expect moderate to strong instability across the region, with the potential for discrete supercell thunderstorms, and squall line segments. THIS WILL ALL DEPEND UPON THUNDERSTORM DEVELOPMENT TONIGHT AND THE MOVEMENT OF THE WARM FRONT. Don't get me wrong... The strongest potential WILL remain farther west at this time, but severe thunderstorms will still impact the area. I will continue to watch this, as the main threat could expand east (especially due to the very progressive nature of the cold front). Deep-layer shear will also be very conducive to tornadic development, and so we will have to watch for this threat. Other than that, tomorrow will be a very warm, humid day.

MORE UPDATES LATER.. STAY TUNED.

Thunderstorm, and Severe Storm Potential Wednesday

FIRST POSSIBILITY OF SEVERE WEATHER FOR THE SEASON LIKELY WEDNESDAY AFTERNOON AND EVENING:

The Storm Prediction Center in Norman, Oklahoma has placed most of the area, especially south of Route 6, in a slight risk zone for severe weather, usually indicating that we have a 15-30% chance of seeing any type of severe weather within 10 or so miles of any given location. By the usual standards of probability within the atmosphere, this is fairly significant (although the chance is much higher farther south and west).

At this time, there are still too many model discrepancies to make a sound judgement of the forecast, but the best guess at this time is that DISCRETE SUPERCELLS are possible. Why? Because low level helicity (rotating winds in reference to a storm-relative framework with height in the atmosphere) will be on the increase (due to our proximity to the warm front), deep-layer shear will be rather strong (in the 40-50 knot; ideal for classic supercells), and instability will range from 1500-2000 J/kg on Wednesday afternoon (J/kg is a measure of the amount of potential energy in the atmosphere; another way of measuring atmospheric instability). What is a discrete supercell? A discrete cell is a storm that is rather isolated and scattered. There may be numerous in a region, but a discrete storm is one that can be differentiated from other storms (and is therefore not part of a storm complex or system such as a squall line). They can be violent producers of severe weather, and have been known to do quite a bit of damage in this area. Any type of severe weather will be possible from these storms, from damaging winds and large hail, to frequent lightning and tornadoes. Tornadoes look to be a problem, especially if they interact with the warm front. Hail will not be as much of a concern unless CAPE increases, and moisture amounts decrease. This doesn't look to happen, so I would elevate the tornado and wind risks over the hail risks. Widespread damaging winds would be more likely if the squall line from the west arrives earlier. This doesn't appear all that likely at this time, but it is possible. Damaging winds in these discrete supercells could be threatening, especially if evaporational cooling and momentum transfer can occur with steeper-lapse rates in the low levels. Dry air will be non-existent from this storm, so I would not be as worried about intense downbursts or microbursts. At this time, the most prevalent "danger" might be tornadoes and damaging winds. This will be monitored. 















Forecast soundings from the NAM indicate a fairly moist, and moderately unstable atmosphere on Wednesday afternoon, precluding the possibility of such dangerous storms. At this time though, the NWS and SPC believe that the NAM may be reflecting its bias towards more instability, and thus, should probably be disregarded. It is possible that we see this kind of instability, then we WILL see some intense thunderstorms, but its highly unlikely right now. 

Before you get the idea that we have a high chance of severe weather, let me emphasize that it is still early in the season, and it may be that the NAM model is overestimating instability and thunderstorm coverage. If so.. The thunderstorm threat, and especially severe threat, will be greatly diminished. REMEMBER, I do NOT expect widespread severe weather. Only the POSSIBILITY of severe weather. As we get closer to Wednesday, details will become clearer in regards to the type of weather, and the possiblities. 

Other than that, if severe weather doesn't happen, expect scattered thunderstorms to become more likely as the afternoon progresses Wednesday. Temperatures will likely approach the mid-70's, especially south of Route 6, making for a very warm, and humid day. Thunderstorms will become numerous to widespread during the evening and overnight hours, producing heavy rain, and frequent lightning. It appears that rainfall amounts may approach 1 to 2 inches, but most areas will likely see 0.5 to 1 inch of rain.

Rain will continue on Thursday as well as the system exists the region. By Friday, conditions will continue to clear as cooler air arrives. But don't worry, temperatures will begin to rebound by the end of the weekend and next week.

POTENTIAL WINTER STORM... AGAIN

This looks to be our *last* winter storm of the season, as northern stream blocking and the Pacific longwave patterns WILL be shifting after this storm. Warmer weather looks to be well on its way by early-mid April.

Here are some of the main points, with more details below them:

1.) Track of the low is becoming more confident. The low looks to track through the Ohio Valley in an ideal position to bring the area heavy snow, ice, and gusty winds. 

- Current ensemble consensus is shown in this map:

There are several arguments in favor of going against the ECMWF (which is shown below):
      - Blocking is too strong on the model. This is a result of its amplification bias, which tends to split the jet stream apart too "much" and for too long of a time because it amplifies the Polar blocking pattern more so than it needs too. 
      - The ECMWF has been showing a southern bias all winter (which is unusual), and therefore, its likely that its both too weak, and too far south. 

GFS (below the ECMWF chart) vs. ECMWF

12z ECMWF has the primary low down near the Gulf Coast.

12z GFS has a more reasonable solution with the primary low in Kentucky, before transferring to the secondary farther east.

This is the 06z GFS, which is a bit further north than the 12z GFS is. These discrepancies are being resolved though, and we now have general model agreement (disregarding the ECMWF).

2.) Moisture will be quite sufficient with this system. The system itself will tap into the Subtropical Jet, which will provide it with more than enough moisture to produce heavy precipitation.

      - The GFS has circumvented the deepest moisture further to the southeast due to the development of the secondary low off of the coast of the Carolinas. The development of the secondary low will determine the extent of the precipitation due to the fact that if the secondary low forms much quicker than expected, the flow of moisture will be cut-off into the Ohio Valley. This will depend heavily on the strength of the blocking, and strength of the low pressure system itself, which is discussed below.

06z GFS 6 hour precipitation forecast at hour 102

12z GFS trended slower with the system, but with heavier precipitation in the Ohio Valley/Lower Great Lakes. This needs to be watched.

      - The GGEM is also quite moist with this system, bringing heavy snow banding, but mainly for areas along and east of North-Central Indiana (Fort Wayne, Toledo, Southeast Michigan, NW Ohio, etc.). 

3.) Cold air will definitely be in place. Based on the latest forecasted thermal profiles, they look to be nearly IDEAL for snow late Saturday night through Sunday. 850 millibar temperatures will be in the -3 to -8 degree range across the area during the snowstorm, which is more than sufficient for excellent ice crystal production ("efficient" snowfall).

      - The 06z and 12z GFS forecasts clearly show the ideal thermal profiles for snow AREAWIDE. Although it is possible that sleet, freezing rain, and even plain rain mix in (especially in the initial stages of the storm), the majority of the time, precipitation will be in the form of snow. Surface temperatures during the times of heaviest snow on both GFS runs were below 30, while 850 millibar temperatures were in the range of -4 to -6. Low level thermal properties is also trending colder on the models, so I don't see precipitation type being a major issue with this winter storm.

   

4.) Strength of this system is still in question, because it will depend on the strength of the downstream blocking pattern, the strength of the lead shortwave, and how quickly a secondary low pressure system develops to our east, just off of the coast of North Carolina. Other than that, this system looks to fairly strong, and probably strong enough to produce strong, gusty winds. 

      -It's likely that the system maintains a strength in between 993 and 997 millibars, before the primary takes over. This is all depending on the strength of the lead shortwave, which could be underestimated, especially in a pattern like this. I won't make a call like that though, as its only based on speculation. This will be resolved in coming days.

That's about all of the details I will provide now.

Also, I will be leaving this Friday afternoon for the wonderful state of Florida. NO updates will be released after that until I have a chance to access the internet on Tuesday. For updates on this potential winter storm, refer to your local broadcast meteorologist, and/or visit the NWS's website at www.crh.noaa.gov/iwx for further details.

Don't forget to like NWS Northern Indiana on Facebook as well for the latest updates.

Remember.. This event is FAR from set in stone, and some details, especially with regards to initial precipitation types and amounts are still in question, but its ENTIRELY possible that we see at least moderate snow amounts (3-6 inches of snow), and moderate icing amounts (0.05 to 0.25 inches of ice.).

Overview of the Rain Event; Week's Outlook through March 19

I'm very sorry for not posting any updates this weekend, but now I will be posting more often.

As for today, periods of rain moved through the area for most of the morning and afternoon hours. At KFWA (Fort Wayne International Airport), approximately 0.5 inches of rain has fallen in the past 8 hours, but I will have to wait until the official release of today's weather observations later tonight to confirm this. Right now, rain has stopped over most of the area, mainly all areas west of Defiance, as the cold front slides through. Expect temperatures to fall back into the 30's as the cold front pushes through, and possibly an increase in gusty winds for a short time. 

Last hour's radar imagery

Tomorrow, expect much cooler temperatures than this morning, as a shallow polar air mass settles into the area for a brief time. Temperatures will dip into the lower 40's and upper 30's tomorrow areawide. By Wednesday, temperatures should drop even further to the mid and upper 30's under partly to mostly cloudy skies. An upper level trough will continue building as it digs into the area, allowing a reinforcement of the cold air Wednesday afternoon. Although it will not be significant, it could allow nighttime lows to drop below 20. By Thursday and Friday, the upper level trough will lift out of the region, bringing in a much warmer air mass, and a much flatter jet stream pattern. With this in place, a few weak shortwaves rounding the edge of a flat upper level ridge across the American Southwest could allow for periods of gusty winds, and even the chance for showers, especially if enough moisture gets involved. Temperatures will also begin approaching the middle 50's as well by Friday and Saturday.

After that, it is rather uncertain what will happen, given the relative lack of agreement among computer models, but its likely that we continue in a flatter, more zonal and progressive pattern, allowing for much more spring-like weather. In fact, its likely to stay quite dry through the end of next week. With a strong Pacific jet, and the Alaskan vortex building into Western North America, a -PNA pattern will likely develop. Even with a very strong blocking regime, the -PNA and the Alaskan vortex will nullify any development of an East Coast trough. This will also allow for warmer conditions, and the potential for the Bermuda High/SE ridge to redevelop across the Southeast, further enforcing the northward placement of a warmer, moist air mass. This, I believe, will allow for the beginning of spring. Have a great day!

GFS Hour 108 forecast for 850 millibar temperatures.

Spring 2013 Seasonal Outlook

Since we are in meteorological spring, I'd like to briefly recap the weather across the United States for the past three months. For the entire winter season, most of the Eastern United States has been above to well above normal on average. Only the far Southwestern United States has averaged even slightly below normal from December 1, 2012 through  February 28th, 2013. This winter has also been characterized by above normal precipitation in portions of the Ohio Valley, Great Lakes, and lower Mississippi Valley.

And we all know how winter went for the Ohio Valley and Great Lakes. For the Ohio River region, snowfall was above normal due to the prevalence of clipper systems in that region, as well as Southwest Flow Events. The lower Great Lakes largely ended with well below normal snowfall over a large area (discounting the Western Michigan snow belts), with most of the snow falling this winter over portions of the Central Plains, and Upper Midwest, as well as Southern New England.

The first spring outlook will be rather brief, but I'll explain a few of the factors involved.

The first two factors I will talk about is the PDO (Pacific Decadal Oscillation) and the ENSO state (El Nino/La Nina Southern Oscillation). For the weather geeks out there, the general SST anomaly pattern that you see in the above image clearly indicates a re-strengthening negative PDO. Although the PDO index progressively rose since October, it seems now that it may be going back negative once again as the climate wind patterns shift to allow for the fledging development of a weak, east-based La Nina. With the ongoing warm SST anomalies in the Caribbean, as well as the enhancement of the Northern Pacific jet, this seems to suggest that spring will be rather warm and wet over a large portion of the Untied States.

The EPO continues in its negative phase, as well as the WPO, which is the reason why we continue to see a large vortex situated near Alaska. This is the main reason why we haven't been able to see a more suitable pattern for winter weather all winter. This will largely act to "recreate" the Bermuda ridge, which will likely dominate the United States during the middle and second half of spring.

Other factors in the spring forecast include the North Atlantic Oscillation, the Arctic Oscillation, and the Pacific North American index. The trends in all of these variables seem to clearly indicate that a warmer pattern is on the horizon. In fact, its likely that in combination with widespread drought across the United States, most of the country will end up above normal in temperatures for a large portion of the spring.

Here's my official forecast:

• March 2013- As we've already seen, March 2013 will likely remain cooler than normal, or near normal through the middle part of the month. With an active, progressive pattern likely, precipitation will be near to slightly above normal, providing a few more chances for snow and rain across the area. By mid-March, temperatures are likely to rebound to normal, or possibly above normal. This will be in accordance with a deepening, east-based La Nina, a strengthening -PDO, and a relaxation in blocking across the Arctic. The Pacific jet will remain active, providing above normal precipitation to the region, and keeping drought conditions away from the area. 
•  April 2013- April will likely see more fluctuation than March will. In fact, it's likely that April remains near to slightly above normal as well, especially if we see long-term "after-effects" of stratospheric warming, which could allow blocking to rebuild for a brief time. Even so, this will be more likely in the earlier part of the month, with warmer conditions towards the end of the month. Fluctuations in the PDO, PNA and the ENSO will lead to varying strengths in the jet stream, and thus, its likely that we see near to above normal precipitation for the month of April. Overall, temperatures and precipitation won't be too far from normal. The warm latter part of April will also lead into May (note: When I mention warmth, I mean departure from normal, and not actual temperatures.).

•  May 2013- May will likely be a warmth month, and more than likely, very similar to May 2012, which was incredibly warm, but also incredibly dry. Due to changing climate patterns, its likely that the drought re-extends farther east once again this summer, likely leading to intense heat once again. Several analogues seem to suggest that we could see at least one heat wave towards the end of May (much like last year). Early May could feature wetter conditions due to an active severe weather season as well, but transition to much drier conditions towards the end of the month.

This is my preliminary forecast for the spring, and it will likely change over the next few weeks. For now, it is my best "guestimate" for the spring 2013 season. For more information in regards to severe weather, continue to visit the blog for further updates.

WINTER WEATHER UPDATE

WINTER WEATHER UPDATE:

The NWS has issued a winter weather advisory for the entire area through noon tomorrow. This winter weather advisory was issued due to growing concerns for icing potential as well as snowfall potential. Here's the scoop.

The mesoscale models have been rather insistent on bringing in at least a period of moderate to heavy snowfall for one or two hours across the area, especially around 5 a.m. tomorrow morning. I'm rather doubtful that we see heavy snowfall tomorrow morning, due to the presence of dry air at the onset of the event, but it appears to be reasonable, given the potential for jet-streak induced low-level frontogenesis, and snow-banding, as well as the wet-bulb cooling effects, which will tighten the baroclinic zone. Also, it appears the system will take a further southeast track than originally indicated due to the strong blocking pattern to our north and east. This will then cause stronger forcing to clip the area (though not in the deformation zone, which will feature the heaviest farther west over the Mississippi Valley), potentially leading to more snowfall than originally indicated. Not only this, but NAM and RAP forecast soundings, when compared with actual soundings from this morning, were way off in regards to water vapor amounts in the mid-levels. Actual soundings were showing dew point depressions of 15-20 degrees, while forecast soundings were showing dew point depressions of 40 degrees, indicating that these models have an inherent dry bias. For this reason, I can see credibility going to a forecast of heavier precipitation tonight. 

Another reason that I think that precipitation amounts will be higher is due to the fact that the strongest moisture flow is currently east of what was originally forecasted. In fact, the main heavy precipitation regions (snow, ice and rain) have shifted eastward, and are contributing to snow banding on the eastern edge of the warm-frontal system.

What are potential caveats and mishaps that may leave us with little more than a dusting of snow? One could be the fact that some of these mesoscale models usually have a slight bias towards higher QPF, Quantitative Precipitation Forecast. Because of this, they will tend to forecast heavier precipitation. So, the NAM's 0.3 to 0.5 inches of precipitation tonight may be an overestimation. On the otherhand, the RAP has an inherrent "dry" bias. It is showing less than 0.09 inches of precipitation tonight, which indicates that its inaccurate calculations of upper level forcing, as well as low level flow and moisture calculations are inaccurate. Another could be increased dry Canadian flow off of a strong high pressure system located to our northeast. If I somehow miscalculated the influence this high pressure system will have on our weather, then we may be in for a bit of a surprise when less precipitation falls tonight. Other factors could include the destruction of snow bands as they impinge upon the area (related to mid-level dry air, which at the time, does not seem apparent on WV imagery. But since WV imagery is quite obsolete with a thick overcast, its not a good idea to make an analysis from it), moisture flow which is diverted south and east of the area (due to the developing convection to our south.). As of this time, though, I believe these valid reasons will become obsolete, and probably have less effect on our weather tonight.

Here's a forecast reflectivity chart from the latest RAP. As you can see, it has a heavy band of precipitation (presumably snow) moving slowly north across far Eastern Indiana and Western Ohio. This could be a significant factor (if it verified. I believe it will because the RAP has been rather consistent with such a band of precipitation over the last four runs). The one problem I have with it though, is that the RAP is exhibiting its usual bias; it brings in the precipitation way too quickly. The time stamp says 06z Friday, which translates to 1 a.m. tomorrow morning. It's kind of obvious that its a few hours too early with this. On another note, based on the latest radar trends, it seems as if the NAM may be too slow with bringing in precipitation. So, I will go with a compromise, which leads me to believe that snow will begin lightly falling at about 11 p.m. southwest of Fort Wayne, 1 a.m. from Fort Wayne to Antwerp, and 2 a.m. farther east. The precipitation will begin intensifying and become heavier by about 5 a.m., before snow begins to mix with and change to freezing rain. This will lead to ice accretion upon roads and other surfaces, making for very hazardous driving during the morning commute. This will likely result in school delays (possibly closings, but I'm highly doubtful of the amount of ice that falls tomorrow). 





As for my forecasted precipitation amounts, I believe they will end up in between 0.2 to 0.5 inches, with the higher amounts southwest of Fort Wayne. Some of this precipitation looks to remain as snowfall due to strong mid-level cooling from dynamics and evaporational cooling, while a significant portion could end up as icing accretion. This will lead to snowfall amounts of around 1-3 inches areawide, with corresponding icing amounts of 0.1 inches. Freezing drizzle/light snow mix will continue through the midday hours before tapering off. I'm expecting little or no liquid precipitation. If there is, I suspect that significant cooling from snow and ice will continue to allow for ice build-up.

Have a great evening everyone!

Significant Winter Storm Potential To End the Winter Season

I'm very sorry for the lack of updates once again..

Regardless, I have some very important things to discuss in regards to the forecast. For the rest of weekend, expect numerous lake effect showers, especially tonight into Sunday as low level moisture increases. Temperatures will remain below 25, possibly reaching 28 tomorrow, with only light winds. By Monday, expect a brief warm-up, back into the 40's, with periods of heavy rain possible, but changing back over to snow during the overnight hours. Tuesday and Wednesday will feature highs back into the 20's and lower 30's, with partly cloudy skies. By Thursday, clouds will begin overspreading the region, with the chance of snow coming into the picture as well. This is the part I wanted to discuss.

Models continue to show the potential for a major Midwest storm to develop in the lee of the Rocky Mountains and move east-northeast towards the area. At this time, models continue to indicate a wide "spread" in the intensity of the storm, as well as the eventual track. A few models take the storm farther south, thus allowing for a better potential for a MAJOR snowstorm by Thursday night and Friday across the area. There are also a few models that take the storm farther north, but are weaker, and bring the area a nasty ice storm. Either way, a significant winter storm looks imminent across the area by the end of the week. But at the same time, I'm not very confident on what exactly is going to happen, as a few hundred-mile difference in track and amplitude of the upper level wave could mean the difference between a mix-event of sleet and slush, or a heavy snowstorm with totals over 8 inches. From what I've seen, it looks as if the storm would take a farther south track, especially in light of a developing block across Greenland, which would suppress the storm southward. This would make the event similar to the December 26th storm just about two months ago, except with heavier precipitation, and possibly worse road conditions due to ice and snow. This system will have plenty of precipitation along with it, as well as favorable conditions for heavy snowfall, especially north of Indianapolis. The reason I say Indianapolis is because there is too much uncertainty with this system, and it could still shift either north or south on the models.

As for the latest trends among models, the 12z GFS is indicating a further south and east displacement of the surface low after lee-side cyclogenesis in Eastern Colorado. This would seem to indicate that the storm would take a further southeast track towards the area, which is more favorable for heavy snow. Given expected snow ratios (this area averages near 14:1 snow ratios), and ample amounts of moisture, we may be looking at 3-7 inch snow event, even if the ice storm verifies (3-7 inches of snow at the onset would significant favor an ice storm anyway). If the colder solution verifies, I would expect a significant snowstorm. I will be releasing a map that shows where I think this major winter storm will set up either late today or tomorrow. 

New Long-Range Pattern likely to Return

After quite a long break from blogging, I've finally come back (I'll admit, I've been busy with several things), and I'll probably be blogging much more often. The topic of this post will be rather grim (in regards to the end of the winter, as well as the immediate long-range forecast).

First, let's have a recap of the winter so far. On December 1, 2012, the vast majority of the United States began with increasingly above normal temperatures. In fact, many areas were breaching records that had not been breached in over 30 years. Widespread 60's and even 70's came as far north as Indianapolis in the Ohio Valley. Although warmth was experienced last year, this season's warmth has been mitigated by intense cyclones, and strong cold fronts from the northwest. A strong cyclone plowed through the Upper Midwest, bringing blizzard conditions to the Upper Midwest, while bringing chilly air into the East. While it was not substantial, as some have been in the past, it was quite a reversal from the record warmth of the beginning of December. As December progressed, it became cooler and cooler (as is expected), with more frequent storm systems, and RAIN (ugh). Yet, we had an exceedingly lack of accumulating snowfall. In fact, until about December 20th or the 21st, no more than 0.1 inches of snow was recorded at both South Bend AND Fort Wayne International Airports. Even so, an abrupt (more of a gradual pattern response though) pattern change commenced after a large cyclone traversed the Great Lakes in the days leading up to Christmas, bringing heavy rain to the Ohio Valley and East (once again). The cold front swept through, bringing high winds and much-needed colder air to the region. By that time, the threat of a major storm system was on the horizon, and it was predicted that the storm would mainly impact the Interior regions of the Northeast, largely sparing the coastal areas. Over the next few days leading up to Christmas, model forecasts began a quick reversed trend west with the cyclone, which shifted the snowstorm threat to the Ohio Valley through the Interior Northeast and New England. By Christmas Day, not only had a heavy snowstorm commenced over the Southern Plains, but a deep low pressure system was causing the development of widespread heavy, and sometimes severe thunderstorms across the Deep South. By Christmas Night, the low pressure system was moving northeast bringing widespread heavy snow from Arkansas to Indiana/Ohio, icing to Kentucky and parts of Tennessee, as well as heavy rain and thunderstorms to parts of the East. Heavy snow continued to spread northward and eastward, producing a large swath of 6-12" inches of snow. December ended with very cold weather across the nation, and record snow cover as well.

January began very cold across most of the United States, with temperatures well below normal over a large area. Snow cover was also well above normal as several weak, southern stream systems spread snow across the Midwest, Ohio Valley and Northeastern States. Lake effect snow continued as well from Lake Michigan, to Lake Ontario. By early to mid January, a notable warming trend began, causing once again, record-warmth to engulf most of the Midwest and East for several days. Even this warmth did not last long, as a series of low pressure systems dragged a massive cold front into the East, not only producing heavy, flooding rainfall, but snowfall on the backside of the system. This cold blast was rather weak though, only producing a minimal lake effect response. In a few days time, a very strong cold front was dragged into the Midwest by a clipper system, which caused rapid temperature drops across a large region. Temperatures became unseasonably cold; the coldest weather of the season. High temperatures ranged from the -10's in the far Northern Midwest to the lower 10's in the lower Midwest and Ohio Valley. This generated a substantial lake effect response which lasted several days. Even so, dry air limited the amount of lake effect formation. By the end of January, temperatures began moderating before another major blast of cold air sent temperatures diving into the 10's, and high winds to a large portion of the Midwest and Great Lakes. It was during this time that several clipper systems delivered several periods of moderate snowfall to these regions.

By February, the month began rather cold for the East and Midwest. In coming days though, conditions began moderating over a large area, although this warm-up was mitigated by a deep snow pack just to the north. It was because of the pre-existing snow pack, as well as a few other conditions which lead to a monster Nor'easter to blast Southern New England with 3' to 4' of snow, winds to 90 mph, and whiteout conditions for a long period of time. This monster Nor'easter will not easily be forgotten on the minds of New Englanders, as it may turn out to be one of the top Nor'easters of all time. In fact, it landed in Boston's largest snowstorms of the city's records. The highest snow total was observed in Connecticut, with snowfall totals exceeding 40" of snow. By the middle of the month, temperatures have moderated again, and forecasters are once again very uncertain about the rest of the season. And this is the main subject of the latter half of this article.

It is looking more and more likely that the United States is impacted by a rather transient, progressive flow pattern, which will lead to near or just above normal temperatures through Friday, before a major trough dives into the Midwest and brings a shot of Arctic air (albeit not all that cold). It is possible that most of the area receives lake effect snow, as the largest lake effect event of the season possibly unfolds Friday and Saturday. By Sunday and Monday, a storm system will begin formation in the Southern Plains (possibly, but other model guidance such as the JMA and the NAVGEM-- the new version of the NOGAPS/GEM-- are suggesting a major coastal storm. While that isn't out of the question, I'm still rather skeptical of an earlier phase of the northern and southern stream waves), which could bring an icy mix of snow/freezing rain/sleet to the region. If the storm trends warmer, we could be looking at yet another rain event, but if it trends colder and further south, we may end up with a significant snowstorm. This remains to be seen, and it does bear watching for the time being. If it does occur, a large area from the Ozarks to the Ohio Valley/Great Lakes could receive over a foot of snow. At this time, the early week storm looks to be the warmer storm, and a possible, second storm could impact us by mid-week or later. As for the rest of the winter, its likely that it never does get truly cold and snowy, but rather bursts of intense winter weather, followed by tranquil periods of nearly spring-like weather, especially by the final days of February and early March. Early March looks to feature near normal temperatures, with possibly wetter than normal conditions, followed by an uptick in severe weather and warmer temperatures.

This is an image of tropical convective activity as viewed from infrared satellite imagery. As you can tell, the majority of the convective activity has shifted east of Indonesia and into Oceania. While this may seem very good for the MJO cycle to stall in Phases 1 and 2, another indicator from velocity potential and IR satellite suggests that the MJO is beginning to revamp back in the eastern Indian Ocean, causing the MJO cycle to propagate back into Phases 3-6, especially by the end of February. While these phases generally mean warmer than normal weather for the region, this time it may not due to the overwhelming presence of developing blocking, as well as a deep snow pack just to our north.

Tomorrow's Snow Event.

Current SPC mesoanalysis in the upper levels continues to indicate a slightly stronger shortwave than was originally forecasted by the mesoscale models. This could have strong implications, especially in regards to the amount of snowfall, and its duration. Generally, a stronger clipper in a NW flow pattern will generally head slightly farther south, given all other variables are constant, due to the fact that northwest flow patterns are highly conducive to mid and upper level frontogenesis. Sometimes, especially in highly mesoscale events, this can lead to a phenomena known as "foldogenesis", which is what can occur in intense cyclogenesis events. While this event is not related to any strong storm system, mesoscale areas of intense frontogenesis and folding of the tropopause could lead to precipitation banding at times, especially by the early morning tomorrow (6-10 a.m.) across the area. Also, precipitable water values are currently increasing to near 0.5 across parts of the Northern Plains, which will eventually be drawn into the system itself. If it is drawn into the clipper system, we may see higher snowfall totals than what the NAM is currently forecasting. Frankly, the mesoscale models neither handled Saturday or Today's snow events all that accurately, especially farther west, and so I would like to give lower credence to their forecasts. 

Even though conditions do seem slightly ideal for this event, there are some caveats to a much heavier snowfall than 2-5 inches across the area. One.) The presence of a strong dry air mass will likely impede much heavier or widespread snowfall from developing (unless the system ingests the 0.4 to 0.5 PW values over the Northern Plains, which is entirely possible given the fact that a stronger surface cyclone is currently noted on surface analysis across the Plains.). Two.) Lack of widespread upper level forcing will also limit coverage of snowfall (though conditions are slightly more ideal than they were for Saturday's clipper system). The main forcing mechanisms involved will be whether areas of strong low level frontogenesis and upper level frontogenesis can couple with each other, producing a strong ageostrophic circulation along the warm frontal boundary, which could in itself not only strengthen the surface storm, but also the coverage and intensity of precipitation bands. This, we are already seeing across parts of the Upper Midwest.

In other words, there is the possibility that some areas, especially north of Route 30, see isolated higher amounts over 2-4 inches due to mesoscale banding. Anywhere south of the Route 30 corridor will likely see around an inch or two of snow. The snow event will likely start around 3 or 4 a.m. tomorrow morning, possibly later due to the presence of strong low level dry air.

Train of Clippers Continue...

All right.. After a solid 1-3 inches of snow falling across the area today (of the fluffy variety), there seems to be several more light snow events on the way to the area over the next 72 hours. The first one will occur from late tonight into tomorrow across many areas. This will mainly be due to LES and a weak wave of warm-air advection. This will produce scattered snow showers tomorrow, likely accumulating up to an inch in some areas tomorrow, with heavier snow amounts in the lake effect region. By Sunday night, snow will "rev" up again with some lake enhancement, which will generally produce light totals across the region. By late Sunday night, the next clipper system will be approaching the region, bringing us a solid 2-4 inches, possibly up to 5 inches by late Monday night. This clipper system will be the most significant of this train of clippers. So, this is the one I will focus on.

Thermal profiles seem to suggest that ratios will be rather high for this event once again. The DGZ (which is the dendritic growth zone, where conditions are maximized for the most efficient snow crystal, dendrites) will be rather thick (approaching 200 mb, which is ideal for heavier snowfall), with max. omega also in this layer (upward vertical velocities look to be at least slightly stronger than today's event.). And then factoring in modest low-level WAA and moisture advection, we seem to have a decent event on our hands. The only negative factors seem to be a lack of higher moisture, as well as a stronger storm system (clippers generally are weak and very dry). But because of the positive factors, it seems to me that ratios could approach 20:1, and possible 30:1 over NW Ohio. With forecasted liquid precipitation amounts for this next event at 0.2 to 0.3 areawide, it seems that we will have a solid 2-5 inch snow event, and if things become even more favorable a 4-6 inch snow event (but that'll probably happen in the lake effect regions). Regardless, this snow event is something to be watched, especially because it is a clipper, which usually "surprise" the area with heavier snowfall. I'll keep my eye on this as well, and update you tomorrow on any changes.

Significant Icing Event Tomorrow; Heavy Rain Early Next Week

The NWS has issued a winter weather advisory for most, if not all of the forecast region. They are expecting ice totals to accumulate to near 0.1 inches. I'm expecting higher icing totals, as I believe it'll take longer for the warm air mass to begin mixing to the surface, and thus, temperatures will remain below freezing for longer, possibly until after midnight. Even when temperatures go above freezing, freezing rain will persist for several more hours due to the frozen nature of the ground. Thus, icing amounts could be as high as 0.25 inches, especially in light of the recent NAM (which indicates icing amounts of up to or over 0.3 inches, especially north of Route 24). My forecast is calling for 0.1 to 0.25 inches of ice area wide, with some sleet and snow accumulation also possible. By early Monday morning though (around 5 a.m. or so), freezing rain to change over to rain as temperatures rise into the upper 30's. Light to moderate rain showers will persist throughout the day Monday and into the night hours. Rain will continue to persist through Tuesday as another wave of low pressure develops.

Wednesday is when the forecast gets tricky, and rather inconsistent with the models. The GFS indicates that another surface wave of low pressure will develop along the frontal boundary in Eastern Oklahoma and move northeast, rapidly developing into a strong low pressure system. If this were to occur, I would expect another day of highs in the middle 50's on Wednesday. The NAM, on the otherhand indicates that the second wave of low pressure will be weak, and won't cause a secondary warm-up, but will allow the cold front to slide through with heavy rain and a few rumbles of thunder Tuesday night.

Models are more consistent on the arrival of a cold wave for Thursday and Friday. In fact, temperatures could rival that of what we saw during the past week. This time around though, it is likely that we see a more substantial wave of lake effect snow, possibly extending far inland. After that, a snow event is possible for next Saturday ahead of a strong clipper system. Other than that, have a great evening!

Light LES for the weekend/Freezing Rain-Icing Potential Sunday Night

There are a few things I'll discuss this evening with regards to this weekend's weather, and early next week:

First item on the agenda is today's event. Most of the area saw just under an inch of snow, with higher amounts east of Defiance. The storm really did "underperform". One of the major reasons for this (and something I hinted at in my blog post yesterday) is due to the fact that dry air was incredibly strong in the low and mid levels. It was so dry, in fact, that relative humidity levels in the 850 millibar layer were in between 1-10%! That is incredibly dry, and a lot to overcome for only a light snow event. In fact, I was even impressed that the area saw as much as we did see. The lower snowfall totals could have a bigger impact on the weather conditions for early next week as well.

For the weekend. expect periods of light snow showers, especially W of NW Ohio, which will allow for a bit more of an accumulation. For far Western and Northern Ohio, as well as Northeast Indiana, expect an inch or less of lake effect this weekend. Closer to the lake, expect several inches of snow.

Sunday night into Monday looks to get interesting, in regards to wintry precipitation and possible icing. At the current time, it looks like a period of icing is possible. The latest NAM even hints at the potential for several hours of sleet, freezing rain and snow. Right now, it looks like temperatures will be cold enough for a period of moderate snowfall late Sunday afternoon, which will evolve into sleet, and eventually freezing rain by early Monday morning. Snowfall accumulations will likely be near or under one inch, with little or no sleet accumulation. Freezing rain accumulations will be slightly harder to pinpoint, but if I had to make an educated guess, it looks like we have the potential to see over 0.10 inches of ice (which is fairly significant to driving, especially on colder surfaces). This could reek havoc on driving conditions early Monday morning. Farther north, especially in Southern and Central Michigan, there is the potential for a significant ice storm, with over a 0.3 inches of freezing rain accumulation possible north of the Indiana state-line. This will all likely change, but if you live in Michigan, I would pay attention for the possibility of a significant ice storm. 

As for Tuesday and Wednesday, we could be seeing very warm, spring-like conditions, with temperatures well into the 50's (GFS indicates temperatures in the 60's possible, but given the cold ground, this isn't all that likely). Periods of heavier rain and possibly thunderstorms will be likely during the same period before the cold front slides through late Wednesday, ushering much colder weather again. By late week, the area will be back in the deep freeze, with the potential for Lake effect and clippers to bring us light accumulating snow.

Light Snow Tomorrow; Ice/Warm-up Next Week

Cloud cover will overspread the area once again tonight, with light snow spreading into the region by early tomorrow morning, possibly as early as 4 a.m. Light to moderate snow will continue through the early to mid afternoon hours, with the possibility of 1-3 inches by the end of the day. After the main snow bands pass through, lake effect will develop and likely impact quite a few areas for most of Friday night and Saturday, possibly accumulating another inch.

As for tomorrow's main event, there are some discrepancies in snowfall amounts and precipitation amounts that models are forecasting. In the 12z NAM forecast, a good portion of the area will likely receive up to 0.2 inches of precipitation, and combined with 20:1 snow ratios (equating to a very fluffy snowfall) would produce up to four inches of snow across the area. The problem with this is that the 18z run is now forecasting about 0.1 to 0.15 inches of precipitation, which would translate to 2-3 inches of snowfall. For now, I would go conservative with this event, especially due to low level dry air at the onset of this event. I will stick with a conservative amount of 1-2 inches.

As for early next week a low pressure system will traverse the Plains from eastern Colorado into the Great Lakes region, dragging a strong cold front through the region as well.. This will likely bring a bout of showers and thunderstorms to the area on Tuesday and Tuesday night. As for Sunday night and Monday, the warm front will begin to pass through the area, bringing warmer air, and the potential for sleet and freezing rain. At this point, it is rather uncertain how much freezing rain and sleet will fall on the area Monday morning and afternoon, but it could be significant, especially if this system ends up drawing quite a bit of moisture from the Gulf of Mexico. If the low level air mass continues to trend colder for Sunday night, we may be in for a bit of snowfall as well before the sleet and freezing rain arrive. Regardless, we could have a rather dangerous commute on our hands Monday morning. While I am not expecting a major ice storm (although it is possible), any amount of ice will make things hazardous. More updates coming soon.

Arctic Blast to Impact the Area.

The coldest and worst Arctic outbreak of the season is set to hit by early Sunday, and continuing through at least Wednesday. In fact, this Arctic wave could be one of the coldest since January 2009 and January 1994. It will bring high temperatures down to near 10 on both Monday and Tuesday, and it will also bring lows down to near 0 for both Monday and Tuesday night. The main reason that it won't be significantly below zero is the fact that we have seen a lack of snow, and snow cover for that matter. Eventually though, it looks like we will see a return of a winter pattern after a warm-up by the end of next week. But that will be elaborated upon towards the end of the article.

The above image is from today's 12z run of the ECMWF ensembles. As you can see, 850 millibar temperatures will approach, and drop below -23 degrees Celsius across the area next week. Climatologically, temperatures at this level of below -20 usually produces very significant cold, and if model biases are accounted for, true high temperatures will likely be colder than what is suggested by models at the time, especially if we have accumulating snowfall on Saturday and Sunday night. Other than that, its likely that temperatures fall into the lower teens and upper single digits across the area both Monday and Tuesday. By Wednesday, temperatures will approach about 16 or 17, before rising into the lower 30's on Thursday. Thursday looks to get slightly interesting in regards to frozen precipitation, as the surface is likely to be below freezing, and the mid levels are likely to be near or above freezing. This could promote freezing rain and sleet with the approaching warm front. While it doesn't exactly look significant in terms of total precipitation, it could allow for some significant icing, especially if high temperatures trend cooler.

As for the long range forecast, it is rather uncertain what happens now, but I can honestly say that we may not actually have winter again this year. We are currently below normal in snowfall, well above normal in temperatures, and even below normal in regards to precipitation. BUT, there is still a significant chance that February becomes snowier than normal. This fact can especially be attested to due to the prevailing nature of the Southeast ridge. I don't believe that any significant blocking ever sets up over the North Atlantic (though it will likely be east-based when it does), which will keep the main trough axis in the Midwest. I am rather confident that this will set up a much snowier, wetter pattern, though it may continue to be near normal temperature wise.