Sunday, December 23, 2012

Update on Christmas Day Snowstorm for Oklahoma, Arkansas & Missouri...

"As advertised" for the last several days, a white Christmas is on the way for a good portion of Oklahoma and Arkansas, as well as at least some portions of southern Missouri.  To make it even better, most of the snow will fall on the big day itself, which is very unusual for this region.

After examining the latest computer forecast model data as well as how the parent storm system is currently organizing over the Pacific Northwest at this time, I believe we can confidently say that snow will be on the ground to some degree or another on Christmas Day at each of the following locations:  Oklahoma City, Enid, Ponca City, Stillwater, Tulsa, Muskogee, Fayetteville, Rogers, Bentonville and Eureka Springs.



I am less confident in predicting accumulating snow in the Ft. Smith (Arkansas) as well as the Springfield, Joplin and Branson (Missouri) areas at this time, as there are still too many questions about exactly how this storm will track as it moves to the East of Oklahoma.  I'll describe the details of the two possible scenarios for these areas below...

As I mentioned in the update yesterday, the primary focus for where the heaviest snow band will set up will be the track of the surface low pressure center on Christmas Day.  The heaviest snow will fall to the North of the surface low track.  The Western and Central portions of the track which would impact Oklahoma is becoming more and more clear, while some question remains as to the Eastern portion of the track which would affect the Arkansas and Missouri snowfall rates.

Right now it appears that the surface low will track along or just immediately to the South of the Red River in Oklahoma and extreme north Texas.  This would produce the heaviest band of snow along and to the North of I-40.  

This scenario has been picked up on the best by the high resolution NAM computer forecast model, which is forecasting accumulating snow, some heavy, centered between I-40 and the Oklahoma/Kansas border through 6pm CST on Christmas Day:



It is beyond this point that some differences in the model solutions remain, with the NAM model curving the surface low toward the East/Northeast, which would then take the heaviest snow into southern Missouri as shown on the forecast image below valid at 12 Midnight CST late on Christmas Day:



Meanwhile, the GFS computer model wants to keep tracking the surface low more directly toward the East, which would result in less snow in southern Missouri and more snow in northern Arkansas, as shown by that model's depiction of the snow cover below, valid at 12 Midnight CST late on Christmas Day:


So, right now if you live in the OKC and Tulsa areas, I'd rest relatively easily (at least as much as you can in this type of tricky forecast situation) in that accumulation of snow appears likely for you on Christmas Day, as well as in most other portions of Oklahoma along and to the North of I-40.

Below are snapshots of the latest computer model forecasts of specific snow depth at Tulsa and Oklahoma City, respectively.  I have circled the "model average" snowfall forecast in red and drawn a red arrow to the resulting amount on each graph:



Note that the computer model forecast average for Tulsa is a healthy 6 inches  of snow (with a maximum of just over 1 foot and a minimum of around 1 inch).  The average for OKC is 4 inches (with a maximum of 6 inches and a minimum of one-half inch).

Again, the exact track of the surface low will be critical in determining, for example, whether Tulsa receives 4-8 inches or 8-12 inches, and so on.  It frankly won't be until the event gets underway until we'll be able to know this for certain, but the current best guess is presented above.

With all of the joy and excitement of snow on Christmas, it will be easy to lose track of the significance of this storm.  The combination of locally heavy snow and strong, gusty winds will produce very dangerous conditions in the affected areas.  All those with travel plans should take some extra clothing and supplies along in case you are "stuck" at your destination longer than you intended to be.  Power outages will also be a distinct possibility across portions of Oklahoma, especially along and North of I-40, so please be prepared for that possibility if you live or will be staying in that region.  More details on those impacts will be forthcoming tomorrow...

Beyond Oklahoma to the East, if you live in Joplin, Springfield and Branson, you want to root for the NAM computer forecast model and its East/Northeastward track of the surface low beyond Oklahoma in order for you to see more accumulating snow.  If you live in northern Arkansas, you are rooting for the GFS model and its more Southern track so that you'll see more accumulating snow than your neighbors to the North would under the other solution.

Stay tuned, I'll post another detailed update tomorrow, with any relevant information that comes in before then likely to be presented in a twitter or facebook post, so please be sure to follow me there if you aren't already.

Special Note on Updates:  this blog post has been linked at several external websites and is getting a lot of "referral" traffic.  If you are reading this post from one of those links, please be sure to go out to the main blog homepage to check for the latest updates, as I will not be updating individual posts as the situation unfolds.  Thanks for visiting!

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