Tuesday, October 28, 2014

OFFICIAL 2014-2015 MIDWEST WEATHER WINTER FORECAST

There are many factors to look at when creating a winter forecast.  Distinguishing between the relevant and more successful ways to predict a long range forecast is very important.  Over the past few years we have found the best indicators for the upcoming winter and will explain their influence on Midwest weather.  The following will examine the main factors and we will out it all together in the end of this post as our winter forecast.

The Siberian Snow Pack:

So let's begin....with Siberian snow cover with one of the easiest factors to understand. Simply put, more snow in Siberia, the colder of a North American winter. Because weather flows around the planet at an arguably 25 day rate (see LRC Cycle), it is only natural to examine the characteristics of what is upstream of the Midwest. Snow cover in this region increases the albedo (a measure of reflectivity). The increase in reflectivity of the sun's radiation surely leads to a decrease of temperature in Russia. This will in turn lead to more snow, and even more reflected radiation back into space. The cycle, we call winter, has started early for Russia and is even more pronounced than it was at this time last year (using October 23rd data). The Polar jet then advects this colder air into Canada, decreases the temperatures in the area and increases snow cover. The increase in snow cover over Canada tends to increase the magnitude of cold shots, by the same principal and the Russian snow pack.

Analog Years:

While the former made a decent case for a cold winter, there are several other (larger) factors in whether the winter will be above or below normal.  Let's dive into, with arguably, the most efficient and accurate method to seasonal prediction...analog years (which are basically years that recorded similar atmospheric conditions and values as this year).

The best analog years: 1958-1959, 1960-1961, 1977-1978, 1978-1979, 2003-2004, 2009-2010.
The winter of 1978-1979 was a brutally cold winter across the eastern half of the country, and came after a already cold winter (1977-1978) hmm, coincidence?  The following uses a analog climate modeler through NOAA, which can be found at This Page.


As you can see above, the analog years really put a grip on the Eastern half of the country in terms of cold and cold shots.  It is actually a similar result to the Last Year's Midwest Weather Winter Forecast, which had success, especially in terms of temperature.

ENSO Factors (La nina/El nino):

Possibly one of the more well known and highly used season predictor, ENSO (the temperature of the Pacific Ocean near equatorial regions. La nina being a cooler than normal water temperatures and El nino being warmer than normal.  Over the past few months there has been a decent amount of El Nino hype in the weather community as computer models were showing a increase in temperature over the key regions. It never materialized, and we currently sit at an exact average, or neutral stage. Below is the typical pattern of a neutral winter:


The CPC and other computer models poke to the idea that a light El Nino will form for the winter. Even if this pans out, ENSO values will still be near 0.0 and the above pattern seems likely. A great example comes from just year, where an El Nino was predicted, but was never a major one with values topping out around -0.6.  The exact ENSO values for the winter are unknown, but either way I expect a neutral like pattern across the Midwest this winter!


Above is a plot of temperature in El Nino years for Madison, as example.  Notice the weak el nino has minimal correlations for the average temperature across the region. It is important to take more in account than just the ENSO, as evident by the plot above.


Great Lakes Water Temperatures:

Another, more localized, player in the upcoming winter is the sea surface temperatures of the Great Lakes. A product of the past winter, all five of the Great Lakes are running well below normal in terms of average water temperature. On the right is water temperatures of Lake Superior, for example, notice the 2014 plot compared to the past 5 years. It is well below average and the trend of the past five years. Without using water temperature models, a simple interpolation suggests water temperatures will continue to stay below average and on par of this past winters water temperatures.
We will use Lake Superior as another example, as it the largest and most upstream to weather patterns.  The plot on the right (from GLERL) shows the historic average and 2014 values over time. Water temperatures have yet to recover from this past winter and Remember this?, Lake Superior still had ice sheets in June! While it has retreated closer to the 22 year average, computer models project water temperatures to decrease in the coming weeks to follow the general trend of 3-6 degrees below normal.


If you have ever stood by a lake during the springtime with a onshore breeze, you certainly understand the effect a lake can have on local weather. The larger the lake the larger the effect. In the fall the Great Lakes actually keep surrounding states warmer, as the water cools slower than the land, so winds will blow warmer air over the surface.  However, subtract 3-6 degrees from the water temperature and a whole different story is told. The Great lakes will simply lose a degree or so from the cooler lakes than usual. At the same time, lakes will freeze over more quickly, which will limit the lake effect snow machine. We still expect near average snow in the snow belt regions of the Great Lakes.


The Final Product:

Here it is...the official forecast.  Below normal temperatures are favored throughout all of the Midwest.  With a southeast flowing jet, the regions with the highest probability of colder than normal are indicated in the darker shades.  For precipitation, expect a near average total, with above average favored further south.  However, similar to our analog years, snowfall will likely be above normal by virtue of the ratio of snow to rain.  An active "Alberta Clipper" pattern could set up after an established snow pack in January.

Be sure to like our Facebook Page for more updates throughout the winter














Sunday, October 26, 2014

Hurricane Ana Remnants to Amplify Halloween Cold Spell

On the right we have a 24 hour height tendency off the European model from Penn State E-Wall. In a typical pattern we have a ridge, trough, ridge, trough and so on. However, vorticity (a measure of spin) from Ana is noted in the model and can be seen as the small "kinks" in the area circled.  While Ana will not have a noticeable effect on weather over Montana and points south, it will affect the pattern at upper levels for the eastern half of the country, which will have an effect on temperatures across the region by the end of the week.

While models were showing a large ridge over the eastern half of the country the past few days by the end of the week, a complete opposite is now the norm in the models. The GFS and EURO are lagging behind with the unusual influence of Ana in Pacific Ocean. The GFS and EURO are both showing this profound trough over the Midwest and points east by Halloween.  The trough will allow the significant surge of colder Canadian air to filter in. Imagine pushing down on a pool of water and building your own "trough," the discontinuity made will fill in with an attempt to reach a balance.


Here are the 850mb temperatures off the GFS (left) and European (right) computer models.  The robust GFS has temperatures of 10-14C below zero over the Great Lakes, which translates to high temperatures in the 30s.  The Euro has highs in the 40s and 50s for the same region.  No matter what model proves to be fully accurate, a below normal Halloween should be expected.  I would expect the Official CPC 6-10 Day Outlook to be updated in the coming days to reflect this shot of colder air.


Saturday, October 25, 2014

Once a Hurricane, Ana has its Sights set on British Columbia

Once Hurricane Ana will transition into and ex-tropical system and make "landfall" in Canada! This is certainly a rare event. Some of the remnants will be advected into the Midwest by late next week, and will have an effect on our weather. (post coming Sunday morning) There has never been a tropical system that held its characteristics long enough and made landfall on the Pacific side of Canada. It still appears Ana will transition from a warm core system to a cold core, deeming it extratropical.  However, it will be something to watch for as we head into the beginning of next week, when landfall (either tropical or ex-tropical) of Ana occurs!

Winter Forecast Announcement

OFFICIAL MIDWEST WEATHER WINTER FORECAST to

be released Tuesday evening (Oct. 28th)! Just how similar 

will it be to last year's record breaking year??

Pleasant Weather Across the Midwest Saturday

17z Surface Analysis
A strong area of high pressure is settling into the Northern Great Plains. With a clockwise rotation around the center, northwest winds are ushering in drier and slightly cooler air from Canada. With a diffluent flow along the cold front, and a maximum in cold air advection, precipitation is not favored. This feature is not cooling the area significantly, but it is keeping temps from reaching into the 70s for almost everywhere, as 850mb temps last night favored this. As the high pushes away, warm air advection will ensue for Monday.

Friday, October 3, 2014

Early October Snow, say it aint snow

Light to moderate snow has been reported in Northwestern Wisconsin during the overnight hours! The snow is expected to drop south overnight and eventually pivot around a strong area of low pressure to the east during the early morning hours on Saturday, any accumulation will be light. May we remind you its October...5 days ago many of these locations will in the 80s!

The first map below is of the HRRR (experimental run) of total snowfall over the next 14 hours! It has a pretty good handle on how this system is evolving.

Finally, the last map is of 850mb temperatures for 6z Saturday.  It is showing the expansive cold encompassing much of the Midwest.  Record low maximums are in jeopardy Saturday! The well below normal temperatures appear to hold strong right on through the next week and beyond.




Wednesday, September 10, 2014

Cold Front Passing Through

Those narrow strips of reflectivity on the NEXRAD radar are actually the leading edge of a strong cold front, which will continue to push south and east today. Much cooler weather is on the way for tomorrow and even more so on Friday, where some places will be stuck in the 40s! 

Sunday, September 7, 2014

Severe Weather ---> Excessive Cold ----> Snow Flurries?

After a tranquil Sunday and relatively quiet Monday, the world of weather in the Midwest will become much more active by Tuesday.  A developing area of low pressure will push through the Midwest early Tuesday and drift NE through Wednesday.  East of the system a more humid and unstable airmass will encompass the shaded area.  Severe T-storms should develop in and around the shaded areas. Damaging winds and large hail appear to be the primary threats.


Flooding will also pose troublesome with much of the Midwest saturated from recent heavy rains.

As the system pulls away Thursday, winds will shift out of the northwest and usher in the coldest air of the season. It will certainly feel like fall with a cool dry airmass in place. High temperatures on Friday will be running 15-20 degrees below normal across most of the central part of the country. Areas north of a line from Green Bay to Minneapolis to Rapid City could deal with some frost by the end of the week, or maybe even a hard freeze. Much of the Midwest will see highs in the 50s and 60s respectively.




On the left is the latest 6-10 day temperature outlook from the Climate Prediction Center.  It shows the likelihood of temperatures below the normal mean temperature during a specified time period.  For those that follow these maps, dark shades of blue are extremely rare. In recent days the dark blues are appearing as frequently as the did earlier in the Spring during the winter that never seemed to end. Another prolonged period of even colder weather has popped up in the computer models. The European model has another strong cold front passing through early next week with accumulating snow in northern Minnesota, we will see how this one plays out in coming days.




The WPC is forecasting high temperatures in the 50s for the NW half of the Midwest. Going conservative 5 days out, these highs could even be lower than depicted on the right. High pressure builds in for Thursday night and Friday night, which could set the stage for near record low temperatures during this time period.

With it being the first major shot of cold air, we will closely watch how the models handle it to get a gauge on the rest of the summer and into Autumn for future forecasts.



Just for kicks, below is the EURO model for next Monday as the cold front pushes through...






Friday, September 5, 2014

Exceptional Chill on the Way Late Next Week

The coldest air of the season is building up in northern Canada and will dive south into the continental United States by late next week.  The jet stream will pinch out a trough in the midsection of the country and allow for the ushering of much cooler air.  Temperatures will run 10-20 degrees cooler than average. The map on the left shows the likelihood of below normal temperatures, notice the substantial area of dark blues encompassing the northern Great Plains. This weather will likely bring the first 30s in northern Minnesota and a couple snow flakes cannot be ruled out, as 850mb temperatures dip below 0C. The map on the bottom shows the expanse of the cold, with the 0C line dipping excessively south.





USE MAP WITH CAUTION---->

Just to give a snapshot of what some of the models are outputting...here is the latest EURO model run for minimum temperatures next Friday night and Saturday morning. Showing widespread lows in the 20s! While this scenario is extremely unlikely, record low temperatures may be within reach. The GFS is outputting similar, yet more conservative numbers. One rule of thumb this summer is that the EURO does tend to go cold a week out, it will be interesting to watch the cold unfold in the models throughout the next several days.

   


After record high temperatures across the Midwest the past few days, this weekend will begin to serve as relief for most areas.  By Sunday we return to near average highs and stay around average until late next week when the reinforcing shot of cold air comes in! Happy Fall.

































Friday, July 11, 2014

NO POLAR VORTEX, A Quick Explanation and Misconseptions

Thoughts on Recent "Polar Vortex" Forecast:

Well....Polar Vortex coming next week, good joke. To clear up one of the largest misconceptions in the public weather belief, this winter we never had the polar vortex over us....just various pieces of cold air from this synoptic scale circulation that someone decided to call the whole "polar vortex" in the media somewhere! Furthermore, the polar vortex is formed by pools of cold air of which are caused by long dark nights and significant snow cover. It is then trapped near the north pole by a strong west to east jet stream....but since its summer and light 20-24 hours a day this pool of very cold air never fully develops and the snow pact sees and large dent in its depth.  Yes, early next week will bring a "similar" upper level pattern to January, but NO Polar vortex.  Anyways....if you are stuck in clouds Monday and Tuesday highs will be nearly 20 degrees below normal in most places!
Please spread the word if you hear friends chatting about the upcoming polar vortex or share on Facebook! Good night all.

Wednesday, July 9, 2014

WELL BELOW NORMAL HIGH TEMPERATURES TO CONTINUE

Here is the latest 6-10 day outlook from the Climate Prediction Center, this is looking like the same weather pattern in late winter and early spring!

Some computer models have low temperatures in the upper 30s over the weekend in the far northern Great Plain, nonetheless in the lower 48!

For the Midwest....any days of complete cloudiness during the afternoon will likely keep highs 15-20 degrees below normal!

Saturday, July 5, 2014

Strong and Severe Thunderstorm Across the Midwest Sunday

An area of low pressure will pass through the Northern Great Lakes on Sunday bringing the threat for severe weather across Iowa, Wisconsin and northern Illinois.
Winds will shift into a more southerly direction on Sunday, this flow ushers in a much more humid and unstable atmosphere during the afternoon building a high CAPE values. With a cold front trigger and upper level shear the atmosphere will be primed in the yellow area and especially in the red shaded area on the map to the left.


On the right is the NAM Hi-Res Simulated Radar off the 00z model run. It shows a line of strong to severe thunderstorms developing in the Upper Mississippi River Valley during the late afternoon and passing through Wisconsin and Illinois in the evening hours. This is one solution, but this model has been fairly reliable in recent weeks.







The 18z GFS run develops the heaviest thunderstorms around 8-10pm and puts the location of the cold front from Lake Superior to Central Iowa around 10pm Sunday.  With this in mind, any storms to do form into an MCS or line should hold together into the early overnight hours as severe dynamics should still be in place, according to the GFS.

The latest model run can be found in the "Computer models" tab at the top of this screen.

Monday, June 16, 2014

Widespread Damaging Wind Event Likely Monday into Tuesday


Severe thunderstorms capable of potentially widespread damaging wind...very large hail and tornadoes...a couple of which could be significant...will occur today into tonight from parts of southeast South Dakota and central and eastern Nebraska eastward across much of Iowa...southern Minnesota...into Wisconsin.


A trough over the western United States will intensify during the day one period in response to the equatorward progression of mid and upper-level jet streaks from the far northern pacific into the trough base over the great basin. Downstream from these developments...morning water vapor imagery indicates a low-amplitude short-wave trough progressing into the northern and central plains with this feature continuing eastward development into the upper great lakes by late tonight/early Tuesday.

Tuesday, June 3, 2014

Major and Destructive Severe Weather Outbreak Underway

Property and life threatening severe weather event is evolving at this hour. The atmosphere is primed for excess severe weather and will continue to become worse throughout the evening hours.  A possible derecho will form as we head into the evening and overnight hours. I line of severe thunderstorms will form and push east, mostly concentrated in the "extreme" shaded area on the left. Large hail, damaging winds and extremely heavy rain will be the main threat this evening. There have been reports of rain rate of 8" per hail and hail over 4" already. This is a dangerous situation and any severe thunderstorm warnings need to be taken with a serious attitude. Be sure to watch the local forecasts and local alerts if you reside in these areas!

Below is the forecasted supercell composite for late this evening ~10pm CDT.  These values are extreme!! Anything over 10 is a dangerous situation, we are seeing values of 44! Crazy, stay safe!

Monday, June 2, 2014

Severe Weather Likely Tuesday Afternoon and Evening

Numerous strong to severe thunderstorms are forecasted to develop in the Great Plains on Tuesday.  Damaging winds and large hail are certainly on the way for tomorrow, but the threat for a few strong tornadoes also persists through the afternoon and evening on Tuesday. The highlighted area in red/dark orange appears to be the hot spot tomorrow. Outdoor plans and location of parked cars should be considered for those who resides in these areas. 16 millions people are in the highest risk area tomorrow.

More information will be posted later tonight.

Lake Superior Continues to Hold Ice

For the first time ever, (since records were kept) Lake Superior has a concentration of ice over 2% as of the first of June.  All of the ice or ice burgs have drifting to the southern shore. Even with the recent warm weather over the past several weeks, the ice had held its own, with high concentration of ice in some locations. For example, the map on the left side shows concentration near Marquette, Michigan of over 50%.  As expected, water temperatures are in the 30s and 40s across the lake. May a June Polar Plunge be in store?...

On the right is a computer model forecast of ice concentration over Lake Superior.  It shows the continuation of ice cover or parts of the southern shore into the weekend, which will likely break more ice cover records after one of the coldest winter off all time across parts of the Midwest this year. For a perspective the map below is the average date of the last ice cover over the Great Lakes, notice how March into early April is usually the last date of ice cover, not June!




Tuesday, May 20, 2014

Warm and Summer-like Temperatures Through the Next 10 Days

Well above normal temperatures are on the way for all of the Midwest this week and into next week as the jet stream lifts north into Canada for much of the next two weeks. A small cold pocket of air will rotate on through parts of the western Great Lakes on Thursday, but will be short lived as winds kick over to a more southerly direction yet again on Friday.

Memorial Day Weekend will be nice across all of the Midwest, temperature-wise with highs in the 80s for much of the area. A few strong to severe thunderstorms are possible across the entire area on Sunday and Monday as a disturbance passes through, stay tuned for severe weather updates for the Memorial weekend.

On the right is a snapshot of 850mb temperatures Memorial Day morning. It is a good example of the general pattern that will shape the Midwest over the next couple weeks...A strong area of high pressure to the east allowing for a southerly wind around the clockwise rotation of a high pressure. This wind direction will usher in warm Gulf air as a continuous fetch of wind will set up from the Gulf all the way into southern Canada. A summer pattern indeed.

Severe Weather Threat Rapidly Increasing Tonight


A brand new severe thunderstorm watch has just been posted for much of Iowa and Northern Illinois. Strong to severe clusters of thunderstorms are developing behind a strong warm front and an area of strong convergence. With a hot and humid air mass in place, the atmosphere is primed for further development this evening and into the overnight. The severe thunderstorm watch is in effect until 11:00pm CDT.






Below are the current CAPE values, basically a general telling of the amount of energy a T-storm has to work with at the given time. It can be increased by surface warming and environmental factors.











Below is current (5:00CDT) Bulk-Richardson number across the Midwest, a basic composite value for severe weather.


Below is the Craven-Brooks severe weather composite value.
It is the product of 100mb MLCAPE and 0-6km magnitude of the vector difference (m/s; often referred to as "deep layer shear") accounts for the compensation between instability and shear magnitude. Using a database of about 60,000 soundings, the majority of significant severe events (2+ inch hail, 65+ knot winds, F2+ tornadoes) occur when the product exceeds 20,000 m3/s3.


Monday, May 12, 2014

Low Pressure System to Pose Severe Weather Threat

The severe threat will continue late afternoon through the overnight hours and a slow moving are of low pressure passes through. Strong Gulf moisture and southerly winds are creating ideal conditions of thunderstorm development. Once the cold front passes, the threat will rapidly diminish from west to east tonight and into Tuesday. Behind the cold front temperatures will run 10-20 degrees below average, this weather will last into the weekend before we see moderating temperatures yet again.

Saturday, May 3, 2014

Summer Weather on the Way for Many!

After a prolonged area of low pressure separate from the jet stream controlled the cool and active weather for the eastern half of the country, called a cut off low, a change is on the way. Temperatures will run above average by the middle of the next week, if not earlier. The jet stream will bump north allowing for warm southern air to filter in all week. An area of low pressure will develop and sift out of the Rockies and push towards the Midwest. Exactly where the track of the system falls will be a major factor for the weather in the Midwest next week.
The map on the above is showing the current model consensus of where this system will be near on Thursday.
The warm sector (to the east of the
cold front and to the south of the
warm front) will see highs in the 70s and 80s area wide. This will likely be the first 80 for many in the Midwest. With dew points on the rise and ample surface heating, the atmosphere will become prime for severe weather, with CAPE values approaching 3000 J/KG from Wisconsin on south. A severe weather outbreak is certainly possible on Thursday in the warm sector and ahead of the cold front. We will have to see just where and when this system sets up. The 00z GFS (below) is firing up some thunderstorms for Thursday evening along the cold front. While the front will not bring much in the way of colder air, it will create necessary lift and convergence to develop strong to severe thunderstorms with heavy rains. Back to the temperatures, the chart above is forecasted high temperatures for late next week off the 00z GFS model run. Another temperature map is attached below coming off the European weather model, showing a major range of temperature across the Midwest. The barrier between warm and cool with depend solely on the track of the system mentioned above, either way warmer weather and a kick start to severe weather is on the way for the first full week of May.
data/gfs/00/gfs_namer_153_850_temp_mslp_precip_l.gif












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