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Thursday, October 26, 2017

The First Snow of the Season

After temperatures reached the 70s and 80s for many across the Upper Midwest last Friday, the first snowfall of the year is starting to take shape tonight. Winter is definitely showing itself much earlier than recent seasons, with largely warm October/Novembers the past several years.

A strong clipper system will slide south from Canada tonight, bringing just enough cold air to support snow across much of Minnesota and the Upper Peninsula of Michigan. Most of the snow will pile up west of I-35, with a few inches are expected. Snow will still fall in parts further east, but will struggle to accumulate, with temperature above freezing and ground temperatures in the lower 50s. Below is one model's rendition of how this system may pan out over the next 48 hours. Notice the heavier band work through the Minneapolis metro during the afternoon on Friday, some moderate to briefly heavy snow is possible for a period.

Welcome to the start of winter! Look for this blog to become more active over the next 4-6 months. There are some hints of a larger system during the second week of November, so stay tuned to Midwest Weather on Facebook and on Twitter for continued updates.


Friday, April 28, 2017

Winter's Last Stand?

After a warm February, a warm March, April looks to wrap up with a shot for snow across parts of the Upper Midwest. High pressure to the north will usher in cool and dry air from the Canada, This feature will set up an ideal thermo environment for Mid-Spring snow around these parts. Coupled with a strong area of low pressure coming in from the south and west, confidence is increasing that someone will see several inches of snow Sunday or Monday. A safe bet for 6"+ of snow will be across Colorado into western Nebraska. The storm will then push north and east towards Wisconsin. As it takes this path, more cold air will be brought down from Canada, allowing for the likelihood of more snow in northern Minnesota. What happens in between is the question, but there certainly is a chance of at least a few inches of snow. Nonetheless, temperatures look to stay on the cool side through early May. However, there is a light at the end of the tunnel. Temperatures look to rebound by May 5th in the Plains, May 6th in the Upper Midwest, and May 7th in the Great Lakes.


Monday, February 20, 2017

Significant Winter Storm Expected Friday

After a stretch of 5-8 days of well above normal temperatures and widespread record highs, confidence is increasing in a large winter storm come Friday. Computer models have latched on to this idea for several days and the question of "If" is becoming more of a "Where and When." Being 5 days out the exact location and amounts are unclear, but it is starting to look like an axis from northern Iowa through northern Wisconsin has the best shot for 6"+ of snow.

An upper level trough is expected to swing into the northern Plains late week, allowing for the ushering in of colder air from the north. The anticipated storm system will track along this boundary of cold to warmer air, taking it into the Midwest by Friday. Furthermore, a deepening of the low pressure and a high pressure to the north and west will act to increase winds on the back side of the system Friday night into Saturday. It is not impossible for some locations to reach blizzard criteria Friday night. Lots to work out in the next few days, feel free to follow on Twitter and 'like' on Facebook for more frequent updates.

We are also likely headed into a more active wintry pattern, with a couple chances for larger winter storms through early March, stay tuned!

Here is one model's take on the coming storm. Powered by Pivotal Weather.


Tuesday, January 31, 2017

Large Winter Storm to Unleash Bitter Cold

It has been a relatively quiet and tranquil weather pattern across the Midwest lately, with the exception of a few snow makers. The atmosphere is becoming prime to support a larger winter storm with a benchmark track of widespread 6"+ snowfall. Computer models are now coming into agreement of the idea that an area of low pressure will emerge from the Rocky Mountains on Tuesday and press east or northeast through Wednesday. Right now it is way too early to discuss who sees the accumulating snow. Some models take the low through Chicago and some take it through Minneapolis. The impact on where the snow will fall, based on the track, is profound. Expect snow to pile up 50-100 miles northwest to the track of low pressure. Computer model ensembles are further northwest, but the trend had been further southeast. There is a lot to work out over the next several days, but one thing is becoming more clear...the potential for a long swath of 6"+ of snow is increasingly likely. Nevertheless, it does appear that cold air will filter down behind this system, with below normal temperatures for the entire Midwest by mid-next week.


Monday, January 23, 2017

Accumulating Snow Expected To Develop Tonight

Light to moderate snow is expected to develop over the northern Plains later tonight into Tuesday. The snow will linger into Wednesday for parts of the Upper Midwest. This system will deepen tonight, then weaken as it passes to the east over the next couple days. Consequently, the heaviest snowfall will stay in western sections of the region, across South Dakota, but a solid 3-7" of snow will set up east towards Wisconsin. Total snow of 4-5" amounts will be common, but a narrow band of up to 7-8" will fall where the more persistent snow bands line up. Questions still arrive in how much rain and sleet will mix in across southeastern Wisconsin, with a lot of snow coming during the day for much of Wisconsin, snow accumulation on pavements will be somewhat limited, as grassy surfaces will pick up more snow. Below is the total snowfall you can expect over the next couple day, with slightly less on roadways for those that see more snow during the day, as temperatures will hover around freezing. Be sure to follow on Twitter and Facebook for more weather tidbits and updates. 



Sunday, January 22, 2017

Accumulating Snow Returns To Midwest Early Week

An area of low pressure will emerge from the Rocky Mountains into Colorado Monday and move through the Midwest during the first half of the work week. Limited upper level dynamics will keep from a widespread 6"+ snow these tracks often seem to lay down as the low pressure will hold its strength or weaken a touch as it pushes east through Tuesday and Wednesday. The heaviest snows look to occur in South Dakota, trickling off to a few inches further east across the Great Lakes. A more detailed snow map will be released tomorrow morning/afternoon.

Thursday, December 22, 2016

Pre-Christmas Snowfall Expected

While a rain storm is expected across the vast majority of the Midwest by Christmas Day, some light to moderate snow on Friday may help you get in the Holiday spirit. A system currently dropping heavy rain in the Las Vegas area will quickly charge northeast tomorrow. It will not have much to time to develop into a full blown winter storm, like many of these tracks can produce, but will still be capable of impacting travel Friday into Saturday. A general 2-4" of snow is expected from northeast Iowa through much of Wisconsin by late Friday evening.
However, there may end up being a narrow band of heavier snow that the weather computer models did not latch on to. With decent moisture streaming in from the south, and nothing to essentially block it, these systems have a tendency to surprise. Exactly where this heavier band of 5"+ sets up is hard to say, but the darkest swath on the map shows the most likely spot to see near a half of a foot. Again, most places will be in the 2-4" range, but a few cities may see more. Have a great Holiday Season! And travel safe!


Wednesday, December 14, 2016

Another Winter Storm to Hit the Midwest

A complex storm system is beginning to organize off the West Coast this afternoon. Its counter-clockwise flow around the center and open feed to tropical regions in the Pacific Ocean has been pulling moisture from the areas further southwest to the United states. This along with an eventual feed of moisture from the Gulf of Mexico will provide ample moisture for our next winter storm to work with come Friday into the weekend. Heavy snow total will likely be seen through multiple states.


Unlike most systems that move through the Midwest and produce snow, this area of low pressure will drop the most snow from the warm front ahead of the actual center. As warm air is forced north and overruns the cold air already in place a lifting mechanism is created. Anytime you get lift in the atmosphere and moisture is in place, precipitation will likely follow, and in this case it will be cold enough for snow. The best place for this meteorological process will be from South Dakota through Lower Michigan

Much of the Midwest will get in on the accumulating snow, some areas will likely approach a foot of snow. The best chances for 10-12" will be across northern Lower Michigan back through eastern Wisconsin. Meanwhile near 6" of snow will set up further west. Most of this snow will be very light and fluffy, piling up quickly. It will not take too much to blow the snow around. As this system pulls away on Sunday, the coldest air in years will fill in behind. Check out the morning wind chills Sunday, forecasted from the GFS model. For more, follow on Twitter and Facebook!







Thursday, December 8, 2016

Rounds of Snow, Coldest Air in Over a Year


An active pattern is beginning to unfold across much of the Midwest starting this weekend. A system will emerge from the Rocky mountain late Friday into Saturday ans head east across the country this weekend. Two rounds of snow are expected, with the initial round kicked off thanks to a warm front and a tightening temperature gradient through the Plains into the Upper Midwest. Then as the area of low pressure develops another, stronger, batch of snow is expected to develop to the northwest of the track.


This, all on the heals of the coldest air and potentially coldest departures from normal in over 18-21 months! So below for how cold it could get relative to normal next week below.

Over a 48 hours period, some hefty snow totals are possible. With the exact details still in question, exact snow totals are not responsible to forecast quite yet. The map on the right shows the best chance for a swath of a half foot of snow. Those who get in on both round of snow will have the best chance for 6"-10", and this is outlined in darker blue. With the multiple rounds and various dynamics coming into play with this event, the forecast is challenging.  Be sure to follow on Twitter and Facebook for more!




Saturday, December 3, 2016

Some Light Snow Before Cold Air Dives Down

A weak storm system will bring the first round of accumulating snow for many across the Upper Midwest on Sunday. Generally 1-3" is expected for most areas that see persistent snow. With the more moderate snow coming during the afternoon for many, accumulation on roadways will be minimal south of I-90 as temperatures will be hovering right around freezing. Persistent bands of moderate snow may yield up to 3", maybe 4" of snow on grassy surfaces in southwestern Wisconsin. Total snow forecast by Monday morning below.

Thursday, November 17, 2016

Winter Storm To Kick-Off Winter Season

A developing storm system is emerging from the Rocky Mountains and is poised to move towards the Upper Midwest Friday. The area of low pressure will deepen with time and so will the amount of snow on the northwest side of the track. An area of 5-10" is expected through parts of Minnesota, with isolated locations picking up over a foot of snow. Some lake effect snow is expected in parts of Michigan as the cyclone pulls away from the area. Much of the lift, needed for heavy snow, is thanks to an area of large temperature gradient, see below.


At 700mb, temperatures vary almost 40 degrees across the state of Minnesota,  allowing for avlarge amount of frontogenesis. This process of cold air brushing into warm air creates a large scale rolling motion in the atmosphere and aids in favoring upward motion where we expect the heaviest snow.

We seem to be headed towards a more active winter pattern, with more snow chances next week and beyond. More info always on my twitter account: Link

Tuesday, October 25, 2016

OFFICIAL MIDWEST 2016-2017 WINTER FORECAST

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It's that time of year again, the leaves are changing, the presence of hoodies is on the rise and the burning question on everybody's mind seems to be, "What should we expect this winter?" Long range forecasts are used by businesses to manage risk or manage supply of weather-demand products, and they are becoming increasingly important. Some people live for the snow and cold, and some could do without. No matter what side of the spectrum you fall, you likely have an interest of what to expect this winter. Alright, let us dive into the Midwest Weather Winter Forecast for 2016-2017! Full forecast at the bottom of the page.

2015-2016 Recap:


The story of last winter was the extensive warmth across the entire country. This was, in large part thanks to a strong El Nino in the Central Pacific. A strong El Nino is described as a warming episode in the Equatorial regions of the Pacific. In fact, last year was a top 3, possibly top, warming event since 1950. It had a profound effect on temperatures in the Midwest and last season was no exception. Overall, the warmer temperatures favored below normal snowfall, yet some places were caught under a few storm tracks and saw above normal snowfall. Here is a link to how the forecast panned out last year: The Midwest Weather 2015-2016 Winter Forecast

2016-2017 Discussion:

In most winter forecasts the state of ENSO, or El Nino/La Nina is examined and much of the forecast is based on this index. However, this year we are sitting at a neutral state to eventual weak La Nina and are forced to look elsewhere for more clues. Contrary to last year, a lot of the weight was given to the El Nino, this will not exactly be the case this time around. Putting too much emphasis on the projected weak La Nina may prove to be a flaw in other published winter forecasts. We will examine the state of other regions in the Pacific and Atlantic Ocean to help create analog years, or years with similar conditions to use as a proxy for the 2016-2017 season. This process has been proven successful in the past several years for Midwest Weather. And because every year is different, we will look to pick out the major differences and potential factors that will have the largest impact on the upcoming winter. 

ENSO:


The state of ENSO has been hovering around -0.5 since the summer and most models continue to hold steady at this rate. It implies a neutral to weak La Nina, or slightly below normal ocean temperatures in the Central Pacific Ocean. Usually in the transition to a La Nina, up-welling will occur in the eastern Pacific, bringing colder water to the surface. This cooling process has yet to establish itself as the water temperatures in the mid to upper level of the ocean have stayed warm. Confidence is high that we will not turn to a moderate La Nina anytime soon. For our case, we will examine years in which the ENSO index was within 0.0 to -1.0. Below are the top 20 winters that best resemble a 0.5 ENSO value for December through February; their results on temperature are plotted below: 


Pacific Decadal Oscillation (PDO):

The Pacific Decadal Oscillation (PDO) is a pattern of Pacific climate variability similar to ENSO in character, but which varies over a much longer time scale. The PDO can remain in the same phase for 20 to 30 years, while ENSO cycles typically only last 6 to 18 months. The PDO, like ENSO, consists of a warm and cool phase which alters upper level atmospheric winds. Currently we are in the positive phase of the pattern and should last through the winter, its effect on the overall weather pattern is a major factor.


The positive phase of the PDO is described as warmer than average water in the Gulf of Alaska down through the Pacific Coast of the United States. The subsequent result of this warm water is a cold blob of water further off to the south and west, by virtue of ocean currents and areas of up-welling. The plot from Unisys shows the SST anomalies resembles these exact conditions. 

The figure below shows how positive PDO winter have influenced temperature anomalies over the period from 1951-2010. 


A bit contradictory to the state of ENSO right? This is why we will continue to examine other factors around the globe for the sake of our winter forecast.

Atlantic Multi-Decadal Oscillation (AMO):

The Atlantic Multi-decadal Oscillation (AMO) is a mode of natural variability occurring in the North Atlantic Ocean and which has its principle expression in the sea surface temperature (SST) field. The AMO is identified as a pattern of variability in North Atlantic SSTs. We are in the positive phase of the AMO as well. However, we may be making a turn towards the negative phase. The SST anomalies plot from Unisys plot above also shows some pooling of colder water, which is part is due to sea ice melt adding fresh water to the ocean , locally changing the water density is some spots. Given these factors and since the Atlantic is downstream to the United States, the AMO will  be less of a factor on the winter forecast than it has in other years. The winters closely related to the positive phase of the AMO:


Quasi-Biennial Oscillation (QBO):

The quasi-biennial oscillation (QBO) is an oscillation of the equatorial zonal wind between easterlies and westerlies in the tropical stratosphere with a mean period of 28 to 29 months. The alternating wind develops at the top of the lower stratosphere and propagates downwards at about 1 km (0.6 mi) per month until they are dissipated at the tropical tropopause. This wind pattern has an influence on the weather patterns in North America. Coincidentally, we are also in the positive phase of the QBO as well. The winters that best resemble the current state of the QBO are averaged below:


Siberian Snow Cover:

Dr. Judah L. Cohen has done research on the state of the snow pack in Siberia (His research). He has shown a correlation in snow cover to the level of cold air intrusion to North America. When October snow cover is above average, cold air has a better chance of manifesting itself into the Midwest. Below are the top closest years that best resemble the current state of snow cover across Eurasia: 


Putting it all Together: The Best Analogs

Clearly each factor in the forecast gives a different result on temperatures and the subsequent winter forecast. A way to resolve this is to use analog years, using winters that best take into account each factor. The process was to first find years that best held these conditions:

ENSO: 0 to -1 | PDO: Pos (+) | AMO: Pos (+) | QBO: Pos (+) | Sib Snow: Above Ave


Below are the best analogs based on all factors and are given weights that best describes how related each year is to the upcoming winter:


Here is the result on temperature for December through February:


And the result on precipitation: 


And the result on geopotential height at 500mb and surface pressure:


The analogs suggest the midwest is at an increased chance for below normal temperatures, near to possibly above average snow and an increased risk for large winter storms. Yet every year is different, so let's continue...

A Look at the Models:


Models are starting to trend towards a cooler solution for the winter, which coincides with our analogs, but still suggest some spots could still be at or slightly above average. The CFS model, which is a low resolution model that run 4 times a day out to a year, also has an increased chance for slightly above normal precipitation in parts of the Midwest.

State of the Arctic Ocean:


A more organic method in forecasting is to directly look at the current conditions. For a North American winter, the Arctic Ocean plays a major role in how cold the winter can get, and it's actually counter intuitive. 

The extent of Arctic sea touched a record low this week. Furthermore, the ocean water temperatures are well above average and approaching records as well. These two factors have implications on the polar vortex, yes the polar vortex. The strength/magnitude of the vortex, or jet stream around the Arctic Circle depends the temperature gradient, which is the change in temperature from the north pole to areas further south. The colder the North Pole is, the largest the temperature gradient and the stronger the polar jet gets. A warmer north pole leads to a weaker polar vortex by the opposite logic. Consequently,  strong polar vortex spins fast and locks in the colder air for areas further north, while a weak polar vortex spins slower with more wobbles, allowing colder air to reach areas further south, including the Midwest. Think of it as a top spinning, as it slows there is more wobbles, just like the polar vortex. Each one of these wobbles has the potential to bring colder air to the mid-latitudes. In summary, conditions favor better chances for more shots of cold air into the United States than prior years. And it's all thanks to warm Arctic Ocean temperatures! Isn't weather strange sometimes? Here is a look at sea surface temperature departures from average:



THE OFFICIAL 2016-2017 WINTER FORECAST:

Overall, the forecast suggests a much cooler winter than last year with the potential of more snow for many. Expect several cold spells, yet each arctic blast is not expected to last long. There should be more variability in temperatures from week to week than average, setting up a higher potential for large winter storms to develop. Warm waters (5-6 degrees above average) will prolong and enhance the lake effect snow season. There will also be an increase in Alberta Clipper-like systems that drop a quick 1-3"/2-4" snowfall during cooler periods this winter. Spring may come earlier than usual, even with cooler temperatures through the winter. While only Mother Nature will have the final say, it looks to be a good 'ol fashion winter for the Midwest.

Bachelors in Atmospheric & Oceanic Science
University of Wisconsin-Madison

Thank you for reading. You can find more by following on Twitter and on Facebook.

Here is the final forecast:




**Be sure to keep it here to Midwest Weather for updates throughout the winter!

References:

- National Center for Atmospheric Research
- Earth System Research Laboratory
- Zack Labe for his arctic sea ice plot
- Tropical Tidbits for CFS plots
- Midwest Regional Climate Center
- Unysis 
- Climate Prediction Center