What Happened To All That Snow?

Many people are asking/wondering what happened to all that snow that was predicted. Why all the "hype" for nothing.  Well, there were big snows, just a bit farther north than expected.  Here's what happened.

Last week we posted a story talking about the potential for a big storm system moving through the western Great Lakes.  We were careful not to put snow amounts in or be too specific with details. At that time frame, many things can change. We just want to have a conversation.  Details in our forecast didn't show up until early Sunday morning.  You may remember this graphic that showed the expected track of the storm system from January 24th through February 2nd, 2016. 

This was six days out and the track of the low was almost perfect, off by about 100-200 miles for a storm system that was nearly 1000 miles in diameter.   If you know anything about the complexity and chaos that defines the atmosphere, you have to be impressed with where atmospheric modeling has come.  But, that doesn't really answer the question about the "busted" snow forecast.

We'll get there.  Here's a closer view of the 6-day vs observed low pressure track for 6 am Tuesday and 6 am Wednesday morning.  See the graphics below.

Again, this is an impressive forecast for 6 days out.  The key to any winter storm is determining exactly where the low pressure system will track.

Here are low track forecasts by the Weather Prediction Center leading up to the storm's arrival.

Forecast made 3 pm 1/30/2016

Forecast made 4 pm 1/31/2016

Forecast made 4 pm 2/1/2016

For southern Wisconsin to get into decent snowfall, the low has to track over Chicago or just south of Chicago.  What happened, in this case, the low tracked about 70-100 miles farther north, pushing the heavier snow north into central Wisconsin.  They got hit pretty hard.  See the graphic below for a description of snow vs low track for southern Wisconsin.  We'll have observed snow graphics available on Wednesday.  Preliminarily...Fond du Lac got about 4 inches, northern Marquette and Sauk counties saw about 7 inches and Madison was around 2 inches.  But, Madison also had some crazy thundersnow during the day, it was dicey for a time.

For quite a while leading up to this event, all of the weather model simulations had the low tracking across Chicago.  Thus the snow forecast was hitting parts of southern Wisconsin (mainly Madison, then north and west) with decent accumulations.  We always felt the Milwaukee metro area would be spared any big impact from wintry weather.  But, you can see the low shifted a bit farther north and that shoved the heavy snow band north as well.  For somebody living in Madison,  expecting 6-8 inches of snow and ending up with 2, this seems like a major bust.  Well, it is, but this highlights how such a subtle shift by a massive storm can spell huge changes in a forecast.  This is something we highlighted every day leading up to the event.  Every day.

Here's a loop of our snowfall forecast from Sunday morning through Tuesday morning:

Weather prediction has come a very long way and it continues to improve.  It is far from perfect.  The changes are slow, but they are happening.  It was unthinkable just 10 or 15 years ago that we could almost perfectly forecast the track of a low pressure system 6-7 days out...and get its intensity to match.   A track shift of 100 miles (causing huge localized forecast adjustments) is a rather subtle move given a storm system that stretches from Lake Superior to the Gulf Coastal States.   We are an agency who's main focus is weather and we talk about weather...a lot.  So, when we see a big storm coming, we are going to talk about it (sometimes for days) and that may come across as hype.  That is not our goal.  We hope to keep people aware of potential impacts and hope they make well reasoned decisions going forward, knowing all the possible scenarios.  

Davis