Sunday, December 15, 2013

Peering into the crystal ball: Christmas Day 2013 weather outlook

Yesterday I posted on Facebook and Twitter that those who were interested in what the crystal ball said about Christmas Day weather in Memphis should tune in today.  I nearly jinxed myself - when I went to the computer this morning to update today's forecast, it wouldn't power up.  (Un)fortunately, I was able to resuscitate it this afternoon and now am obligated to bring you this update... unless a bolt of lightning from the blue strikes me down before I hit "Publish."

Ten-day forecasts are kind of like looking in the crystal ball, polishing it off, then looking again, shaking the Magic 8-Ball four or five times, then averaging it all together.  It's where the science of meteorology becomes the art of dancing around a forecast with just enough vague and non-committal wording to be able to say "I told you it would ____" no matter what happens! So here goes nothing...

First I point you to our updated "History of Christmas Day weather in Memphis" blog, which doesn't give you high hopes, other than that 3 of the past 4 years we've gotten VERY close to being snowy.  Then, I'll show you a video both entertaining and depressing at the same time, from Christmas Day 1963 - the only time this scene has played out in Memphis since records began:

Then, there's this:

So what about this year?  The long-range models (including the U.S.-based GFS, the European ECMWF, and Canadian GEM) just barely reach out to Christmas Day.  The last couple of runs of each of these don't provide much hope for scenes like that above.  Leading up to Christmas, a ridge of high pressure builds over the region this week, bringing warmer temperatures than we have seen in the past 10 days with highs reaching into the 60s by week's end.  Next weekend is where models begin to diverge, but all point to some sort of significant trough of low pressure and associated cold front pushing through between late Friday and early Sunday.  We expect a good deal of rain, likely some thunderstorms, and perhaps - if instability can be realized and dynamics are strong enough - a chance of severe storms.  Stay tuned.

Behind that trough early the following week (or basically around Christmas) is where we see multiple solutions from the models. The most recent GFS model run actually delays the weekend storm system (or perhaps I should say, gives us round 2 of a 1-2 punch) on Christmas Eve with very warm temps and storms, followed by a cold, dry Christmas Day. The rest of the models move the system out next weekend and settle high pressure in for the start of Christmas week with high temperatures averaging in the mid 40s to near 50 Christmas Eve, or roughly "near normal."  Most of these also point to a dry Christmas Day.

The Climate Prediction Center (part of the National Weather Service) has also been leaning towards next weekend's system moving out before Christmas with high pressure trailing.  Today's outlook for Christmas week gives us equal chances of above/below normal temperatures and a 50% chance of below normal precip with only a 17% chance of above normal precip.

The bottom line? I'll dance until the music stops to keep from making a call. :-) But typical December patterns and the timing of next weekend's system, as well as current forecast model data, point to a cool and dry Christmas Eve and Day.  Or just about what one would expect from any given Christmas in Memphis with an average high of 50 and average low of 33!  Those who know my propensity for playing down snow in Memphis until there is some degree of certainty won't be surprised by this outlook at all!  For those who prefer the glass-half-full approach,  I give you some classic Jim Carrey:

As any of our regular followers also know though, we promise to keep you updated as the number of shopping days diminishes and the magical day draws closer.

Erik Proseus
MWN Meteorologist

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JosephAlsarraf said...

I take heart to this being a Houstonian who loves snow. I'd wish for a snowy Christmas, or a snowy day for that matter, but with average temps of mid 40's to mid 60's during winter, I don't think that is going to happen.
We did get a sleet storm during Christmas eve a couple of years ago that lasted until midnight Christmas morn and there was still some sleet on the trees on Christmas day! So I guess we had some sort of a white Christmas? Not really...
I liked your videos and pictures. Thanks for sharing. I hope you get your white Christmas!

Meteorologist Erik Proseus said...

Maybe some day Joseph! I'm sure any wintry precip down on the Gulf coast is a pretty big event! Have a Merry Christmas and thanks for chiming in!


bridgetb said...

Didn't it start snowing last year at about 11:30-11:45pm on Christmas night? That was enough for a White Christmas for me! :-) I also had a "White Birthday" 2 years ago on my Dec. 7 birthday...the first ever on my birthday, so being a lover of snow, I guess I really can't complain if I don't get a White Christmas this year!

I was around in '63, but I think a bit too young to really know or enjoy that snow! I know my mom and older siblings always talk about it!