Deconstructing Decima; Assessing the Week Ahead

Like every other science, the study of weather is a continual learning experience.  When I see professional meteorologists use a term or idea that I don't know, I study it.  For the last month, I've been geeking out on Atlantic/Pacific oscillation patterns and how they impact the lower 48.  The learning part is a lot of fun for me.

I also try to learn by evaluating my own forecasts.  For instance, with this latest storm, I've learned that many Rippeology followers don't have the appetite for a 13-minute video.  If I do video again, I'll cut that down by two-thirds.  Promise.

But I just watched that video again and took inventory of what I got right and what I got wrong.  Here's that:

Got right:

• Issuance of Winter Storm Warning to cover southernmost counties on Thursday;

• Dusting of snow Friday morning;

• Snow totals of 7-11”;

• Highest snow totals (lake enhancement) in the east and southeast;

• Frozen precipitation in northern Illinois;

• Extreme cold behind the storm

Here are the preliminary snow totals from the National Weather Service out of Sullivan/Milwaukee, which shows the concentration of 8-12" (in orange) in the eastern part of the state.

 

 Got wrong:

• Timing/intensity: didn’t expect the 9-hour lull between rounds one and two, and thought heaviest snow would be Friday night;

• Leaning on Kuchera conversion ratio from liquid to snow (10:1 method averaged out much better);

• Low track – slightly farther south/east than anticipated

So that's a learning experience for me.  Thanks to all of you for being patient (and interested) as I continue to study.

That's the look-back.  Now, let's look ahead at what the coming week might bring...especially as we get closer to weekend holiday travel.

First, you'll be happy to know that today's sub-zero high temperatures are the coldest we should see for the rest of December.  As I mentioned in Wednesday's video, we're going to get a bit of a warm-up as the week wears on.  The upper 20s and low 30s (maybe mid 30s by Friday) will feel downright balmy.  Shorts weather!

There are a couple shots at precipitation in the next 7-8 days.  The first is Wednesday.  A relatively weak Alberta Clipper is forecast to move through -- mostly impacting the northern part of Wisconsin.  This could be a 2-3" snow event, if it materializes at all.  If you're traveling north Wednesday, I'll help you keep an eye on that.

The second potential system will be Saturday or Sunday.  Both GFS and ECMWF set up a boundary in our area between that milder air and some colder air pushing in from the west/northwest.

GFS has this boundary at 6am Sunday...

While the Euro sets it up 12-18 hours later...

Generally, a transitioning of air masses results in some precipitation in between.  But it's too soon to tell if this sets up in the Great Lakes region or a little farther south.  I'll watch the Saturday through Monday models throughout the week and keep you posted.

If you're getting on an airplane Thursday, Friday or Saturday, I don't see anything major in the lower 48 that would cause widespread delays or cancellations.  Of course, it's still very early.  Sunday/Monday bears watching.

If you have specific travel plans that you want to discuss, just let me know!  Otherwise, I'll update this post throughout the week as models begin to show more clarity.  In the meantime, stay warm!

~Scott