Saturday, December 22, 2012

Update on Christmas Day Snow Event and Severe Weather Potential...


The storm system that will eventually produce a white Christmas literally on Christmas Day across portions of the central and southern Plains is slowly becoming organized just off of the Pacific Northwest Coast this afternoon.  The system is forecast to dive Southeastward into the Great Basin tomorrow, then make its way East/Northeast out over the southern Rockies and into the adjacent Plains on Christmas Eve and Christmas Day.

The $64,000 question, as is always the case with a snowfall forecast, is exactly where the surface low pressure center will become well organized and track.  Typically, the heaviest snow falls to the North of the primary surface low track.

Yesterday, the model consensus tracked the primary surface low near the Red River, which would result in heavier snow from northeast Oklahoma into northwestern Arkansas and southern Missouri.  Last night and today's computer models are developing and tracking the low a bit further to the South, across north Texas, which would generally result in a Southward shift of the heavier snow track, across east-central and southeast Oklahoma into western and central Arkansas.

The latest GFS computer model forecasts generally call for the heaviest snowfall to set up along the axis described above, as shown at 12 Noon CST on Christmas Day:


...6pm CST on Christmas Day:


...and at 12 Midnight late on Christmas Day / early Wednesday morning:


The more Southern track of the surface low would produce the greatest chance of a white Christmas from the Oklahoma City area on Eastward, generally along and 50 miles or so to either side of I-40.  While this would still include the Tulsa area as far as the potential for accumulating snow, the heavier amounts of snow would likely fall to the South of both Tulsa and Fayetteville under this scenario.  In such a case, the the McAlester, Muskogee and Ft. Smith areas would likely fall right in the heart of the action.

It is important to keep in mind that there is still some uncertainty, and the exact track of the surface low could still come in closer to yesterday's solution, we'll just have to wait and see how things start to line up especially on Monday / Christmas Eve.

There is still also the potential for a problem with mixed precipitation and/or ice accumulation, mainly along and South of the heavier snow band.  Folks along the Red River from northcentral Texas into southern Arkansas need to pay particular attention for this possibility, as significant travel problems could develop on Christmas Day in this region.

I am also growing increasingly concerned about the potential for locally significant severe weather potential in the "warm sector" of this system on Christmas Day and Wednesday.  The Storm Prediction Center (SPC) in Norman, OK is also keying in on this potential, as shown in the severe weather outlook for Christmas Day shown in red below:


The potential will exist for damaging winds, large hail and even a few tornadoes in this region on Christmas Day, so please pay attention to the weather if you live or have travel plans across the indicated area.

"Stay tuned" for additional updates on this developing winter and severe weather situation both tomorrow and on Monday...

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