Sunday, December 23, 2018

Highest Impact Winter Storm Thus Far in the Season

Parts of the Midwest will be digging out from their largest snow storm since last year by the end of the week. A storm system is expected to develop in the southern Plains Wednesday and slide to the north and east through Thursday and Friday. Heavy snow will begin to breakout Wednesday night into Thursday morning as it overspreads the entire Upper Midwest through the day Thursday. A swath of 6"+ of snow is expected to fall to the northwest of the track by Friday, with rain further east.

With the storm system still 3-5 days out there are still more questions than answers at this point. As per usual, the exact track of the low pressure system will greatly determine who sees the heaviest snow and who sees mainly rain. In addition to the usual track error in the models, there are major differences in the temperature profiles of the atmosphere ahead of the system. While an area of high pressure is expected to develop north of the Dakotas, there just isn't the amount of cold air in place we would usually have at this time of year. The low will have to generate some of its own cold air through advection and latent heat release. The GFS and the EURO have varying opinions. The GFS for example has a much more saturated atmosphere ahead of the first batch of precipitation, which will impact temperatures as dry air and precipitation can act as a cooler process due to latent heat release. Whereas the EURO model has more dry air to help cool the column ahead of the heavier snows. Furthermore, the grid spacing on the EURO is smaller so will better resolve the cooling process over the GFS, so the cooler solution is currently favored. Below is a look at the GFS model, with the main EURO rain and snow line overlayed. The GFS has a much larger percentage of the storm as rain, while the EURO suggests more snow. Still a lot to work out with this one, so be sure to follow on Twitter and Facebook for continued updates. Can always check out the Computer Snow Output page as well.

Friday, November 30, 2018

Heavy Snows Return this Weekend for Some

Another winter storm is poised to move towards the Midwest by the weekend. Rain will develop late Friday night across the Plains and begin to changeover to mainly snow through the day on Saturday. Snow will eventually spread north and east into the Upper Midwest late in the day Saturday. Some of the precipitation will begin as a light wintry mix of freezing rain and sleet, but will change over to all snow through a lifting mechanism that will act to cool the layer. The area of heaviest snow will be localized across Nebraska, with lesser amounts outward from there.

The lack of a large swath of heavier snow has to do with the life stage of the low pressure system. In many cases storms emerge from the Rockies and develop from that point forward. With similar systems across this part of the world, the life stage of strongest precipitation usually last 1-3 days. However, the weekend winter storm developed on the west coast and dumped heavy rain and snow across the Southwest Thursday. Being in its mature stage, the area of snow will quickly develop Saturday, then quickly fall apart Saturday into Sunday. It can also be seen in a 500mb chart below, where the closed upper low is a sign of future weakening, as the system become occluded. Nonetheless, a band of snow is expected to sit and pivot over Nebraska, where many will see over a foot of snow by Sunday. Areas further south across the Mid-Lower Mississippi River Valley will see severe weather Friday and Saturday, as the cold front provides a mechanism for lift in an unstable environment. Isolated tornadoes are possible, with an upper jet superimposed over the same locations, providing turning with height for tornadic thunderstorms. As always, be sure to follow on Twitter for more updates and weather content.

Saturday, November 24, 2018

First Round of Heavy Snow for Many Sunday-Monday

A storm system will emerge from the Rockies this afternoon and march towards the north and east through the overnight into Sunday. A very narrow strip of heavy snow will develop to the northwest of the low, as warm air is tossed over a warm front into colder air. The storm is expected to drop several inches of snow over a wide area, but a narrow area of only 15-30 miles will see amounts in excess of 6". Some spots could surprise with almost a foot of snow as bands park over the same area for a long period of time. It is difficult to see exactly where the heaviest snow will set-up, but chances favor somewhere between Milwaukee and Chicago into Michigan. Below is a computer simulation of what the radar may look like heading through Monday morning. As we march more into winter, be sure to keep it to Midwest Weather for updates throughout the winter. More weather content will be posted on our Facebook page and especially on Twitter.

Friday, November 2, 2018

Official Midwest Weather Winter Outlook 2018-2019

It's about that time, when everyone is asking, what will the winter be like? Well, we have some of the answers you are looking for. The winter forecast is not as clear cut as some years in the past, but there are some trends out there that show clues into what the fine winter enthusiasts of this site should expect.

First, let's start with the process into how the outlook was constructed. We will use 4 major teleconnections that are useful to forecast the weather out several months to a year in the future. The most influential and most common lies in the level that ENSO is expected to be in. ENSO is essentially a measure of how warm the ocean temperatures are in the Central Pacific. If the specific region is warmer than normal it is classified as an El Nino, colder is classified as a La Nina, and near normal is in the neutral phase. The phase tends to flip from El Nino to La Nina every 8 month to over a year at times. For our purposes in the winter forecast, we are currently in the neutral phase and expected to trend towards an El Nino moving into winter. Consequently, we will only use years that followed the same trend.

The Pacific Decadal Oscillation (PDO) is a similar measure or oscillation that goes from the warm to cold stage every 5-10+ years, and examines ocean temperatures in the northern Pacific. It is near neutral and is likely to hover around the neutral stage through the winter, we will give it 2x weight. The Atlantic Multidecadal Oscillation (AMO) is similar to the PDO, and should stay in the warm phase through 2019, as its period of change can be well over a decade. Since the AMO is a measure in the North Atlantic, we will use less of a weight, since it is downstream of the weather in the United States. Finally the Quasi-Biennial Oscillation (QBO) is a regular variation in the wind direction near the equator located in the stratosphere and can influence the weather around the world. It is a wind that blows in the same direction for roughly 14 months then completely flips direction. Based on history, the QBO should eventually flip direction, which should occur sometime during the winter, so years with a flip from negative to positive during the winter will be used for the forecast.

Putting it all together, 5 similar years since 1950 were looked at then averaged against the values from the entire period. Essentially, the map above is what we may expect in terms of temperatures during the months of December through February this winter. Notice the colder air from the Plains down through the Southeast. Some warmer temperatures are housed in the Great Lakes, but overall cooler than normal temperatures are expected this winter across the Midwest.

Looking and precipitation now, we see an above normal signal across the Midwest, and a well above normal signal across the West Coast. Colder than normal and above normal precipitation will also favor above normal snowfall overall. However, notice there are some southwest to northeast strips of above/below normal areas east of the Rockies. It may signal the risk for larger storm systems, and more hit/miss events in aggregate through the winter season. At the end of the day, slightly above normal snowfall is favored, but as always it will come down to where each individual storm track goes. There will be an above normal amount of chances for snow this winter, so be sure to keep up to date with Midwest Weather through the winter, as the blog becomes much more active. You are also going to want to 'Like' us on Facebook and follow on Twitter for continued weather updates and conversation.

Tuesday, April 17, 2018

Accumulating Snow Returns Wednesday

Winter is at it again, more snow on tap for the some of the same locations that saw over a foot of snow over the weekend. A quick hitting Alberta Clipper system will slide into the region Wednesday and spread a swath of moderate snow to the region. Snow rates of 1-2" are possible for a period during the day, which could be enough to pile up over 6" of snow in spots. Temperatures will return closer to normal by the weekend and near normal by next week, so the snow will be gone as quickly as it came. 

Monday, April 2, 2018

April/Baseball Begin, with a Major Winter Storm Tuesday

Say it ain't snow, the winter that keeps giving has another trick up its sleeve. For many in the Upper Midwest this winter has dragged on far too long. Even though the calendar may say April and baseball is underway, a major winter storm will drop a wide swath of around a half foot of snow by Tuesday night. Snow will begin to develop today, with the more moderate snow coming into the region as the low pressure begins to develop near Chicago. Much of the snow will fall during the day, so ongoing melting is expected with the strong April sun angle, which will hamper some of the accumulations of a heavy wet snow for most. Meanwhile, in the warm sector, an area of strong to severe thunderstorms will develop across the Ohio Valley down through the Lower Mississippi River Valley. Large hail, damaging winds, and a few isolated tornadoes are all threats Tuesday afternoon and evening. Below is one model's take on how the storm system will evolve into Tuesday, powered by Tropical Tidbits. After the low pressure slides east of the region, winds will kick to out of the northwest, with cold temperatures expected to hold right on through the weekend, with a couple additional chances for snow into the middle of the month. More weather info always on Twitter.

Saturday, January 20, 2018

Heavy Snow Targets Plains and Upper Midwest

The most significant threat of a winter storm for many across the Midwest is coming to fruition in the West and is poised to slide east through the day tomorrow. Computer models are coming together in agreement with the track and banding features expected to fall northwest of the low pressure system. A long yet narrow swath of 6"+ is expected to pile up, with an even more narrow band of 10"+. An isolated total of 15"+ is certainly possible, but too early to pin exactly where this may occur. Some indications suggest northeastern Nebraska has a good chance to see 15" with increased cold air and higher liquid to snow ratios expected here. Furthermore, anywhere along the narrow red strip may see a couple isolated totals in excess of 15", depending on where banding feature tend to stall out and pivot. The heaviest snow is expected to fall during the day on Monday. While, widespread blizzard conditions are not expected, gusty winds and blowing/drifting of snow will also occur due to the deepening area of low pressure. Now, with any weather forecast there is some inherent error in the exact track. Located below is a chart of 20+ model runs and what they suggest for snow totals in Minneapolis (left) and Green Bay (right). Still some spread, but overall not to bad for still being 36+ hours out. Based on the best science, the trends and snow ratios, the forecast above was reached. As always you can get further updates on Twitter and Facebook or find links on the right hand side of the page. Enjoy the snow, if you want it, and stay safe either way. If you care to check out some of the weather model snow outputs Click Here!

Tuesday, January 16, 2018

Odds Increasing for a Winter Storm Sunday-Monday

With all the cold weather settling in the past month or so, people are asking, "where's the snow?" The big snows at least. Well, the next best chance will arrive Sunday into Monday. While it is not advantageous to post a winter weather forecast 5-6 days out, confidence is above average during this time frame. The edge of accurate winter storm evolution forecasts across the Midwest is usually around the 5 day time frame. However, the difference in this case is the method of storm development. Models have consistently shown a large price of energy coming on-shore the West Coast Friday and pushing due east through the weekend. As this energy emerges on the lee side or east side of the Rocky Mountains, significant cyclogenesis is expected. In many case, including this winter, there are multiple pieces of energy that the models need to resolve and issues in accuracy arise from sampling and future progression differences. Nevertheless, the expectation is that an area of low pressure will move from the Central Plains towards the Upper Midwest Sunday into Monday. Heavy snow is expected to fall to the northwest of the track, 6"+ of snow is possible, but it's simply too early to get more specific. Keeping in mind, we are still 5+ days out, there is some uncertainty in the exact track. Below is a look at the GEFS. It is a model that is ran 20+ different times at a lower resolution with slightly different inputs to quantify error. The individual red numbers are low pressure locatations and are where the storm may end up. Notice the spread is still from southeast MN to northern IL, with the reminder that the heavy snow will fall 50-200 miles northwest of the where the low tracks. Lots to work out over the next several days, so check back for updates when necessary. Be sure to follow on Twitter and 'like' on Facebook.

Monday, January 1, 2018

Frigid & Dry Conditions Persist into 2018

Happy New Year, everyone! Weatherwise, 2018 looks to pick up right where 2017 ended, with a cold and dry pattern. When people claim they hate to see snow during the winter, but also hate the cold, be sure to remind them they do not always go hand in hand. Most of the moderate snow events across the Midwest occur with temperatures in the upper 20s to near 30. Prolonged dry periods, are often associated with arctic high pressure systems, which bring their arctic cold temperatures. Often during the winter, if the jet steam can dig south of the area and usher in cold temperatures from the north, the storm track will run well south of the Midwest and shut down large snow makers from developing. What's left in its wake is lake effect snows (which are significant in these outbreaks) and weak little disturbances that may put down an inch or two of fluffy snow from time to time. This recent cold spell is no exception. The pattern looks to hold through the first week of 2018, with the only snow across the region near the lakes. Below is expected precipitation through January 7th, showing only scattered snow showers from time to time across most of the Midwest, with lake effect snows dropping 12"+ as they tap into the relatively warm lake water and cold air above them. A pattern change is possible by the second week of the month, which should lend more snow chances, along with warmer temperatures!