Terry’s Take: A snowy winter! I’m not drinking the Kool Aid

Posted on: 10:50 pm, December 5, 2013, by

Terry Swails Weather Blog

For many in the Midwest, Fall (September-November) has been dry and void of significant storms. Isolated events have popped up from time to time like the big Black Hills blizzard in early October and the November 17th tornado outbreak. However, those have been the exceptions to the rule and you can see this in the graphic below.  Much of the Midwest has had only 50 to 75% of its normal fall precipitation. Here in the Quad Cities we have built up a 9″ precip. deficit since July 1st. The last good rain here was more than 5 weeks ago.

fall precip

The reason for the dry conditions has been a persistent jet stream flow out of the west/northwest. This blocks moisture from the gulf that would typically fall as rain or snow. Below you can see a representative portrayal of the mean storm track the past 5 months.

heights cool dry
Mean jet stream flow since mid-summer

What concerns me is that we are now locked into a pattern where what we’ve been seeing could be what we’re going to be getting moving forward. Winter precipitation is lighter to begin with. Add a west or northwest flow and it’s extremely tough to develop significant storms until the jet can amplify further east around the Ohio Valley or east coast.

Take a look at the graphic below of the 500mb jet out to Dec 15th. More of the same, blocked gulf moisture. Below that you can see the GFS total precip ensembles and not a one shows rain or snow after Sunday’s little event.

ZOnal flow
Mean jet stream flow December 15th…zonal!
precip ensembles dec 5-13
GFS ensemble-total precipitation

I’m not saying there won’t be occasional storms. I am saying they may be few and far between during the heart of winter. In fact, I’ll go so far as to say I will be very surprised if the winter as a whole does not end up with both below normal precipitation and below normal snowfall. I think we’ll also see some pretty good temperature swings but when it’s all said and done, end up colder than normal for the 3 month period. In fact, if blocking develops and the NAO goes negative as many experts expect, it could be a pretty cold winter…just dry!

A good case study for one of the rare storms I’m expecting is the one that hit the upper Midwest yesterday. It plastered much of Minnesota, the Dakota’s and NW Wisconsin with some hefty snows and high winds. Look at the snow cover before and after.

Snow cover Dec 1st
Snow cover Dec 1st
Snow cover Dec 5th
Snow cover Dec 5th

These types of systems may come by once in awhile but getting them on the right track with the cold air in place is always a challenge. My hopes for a snowy winter are at their lowest levels tonight. Being a fan of snow, I sure hope I’m wrong on this one!