Saturday, December 17, 2011

Update on Major Storm System for Monday-Tuesday...

In a post 2 days ago, I remarked as to the likelihood that a major storm system would impact the central and southern Plains at the first of next week.  This projection is still on track, and it now appears that enough cold air will become involved for a changeover to snow, some of which will likely be heavy, across portions of the region as well.

You can see the system currently spinning around just off of the southern California coast on the latest water vapor satellite image:

Stronger winds in the middle and upper levels of the atmosphere are already spreading out ahead of the system across the Southwest, as indicated by the yellow arrows on the same image.  

The system is forecast to slowly begin to lift out toward the East/Northeast tomorrow and into Monday.  The latest GFS computer model forecasts are shown below, valid at 6am CST Monday, 6pm CST Monday and 6am CST Tuesday, respectively.  I have noted cold and warm front locations on the upper right panel of each image, and circled the center of the upper-level storm system in yellow on the upper left panel of each image:

GFS Forecast Valid 6am CST Monday

GFS Forecast Valid 6pm CST Monday

GFS Forecast Valid 6am CST Tuesday

Rain will develop and increase in coverage and intensity across the southern Plains Sunday night and into Monday, with widespread amounts of 1-2 inches likely across much of Oklahoma:

I think the above rainfall forecast from the HPC is underestimating the true potential of this system.  Locally higher amounts of 2-4 inches are likely across portions of Oklahoma with this system on Monday and into Monday night.  This would especially be likely near the light purple shaded areas on the above image.

A few strong to locally severe thunderstorms may take place across east-central or northeast Texas into western Louisiana and possibly extreme southern Arkansas on Monday afternoon or evening.

Meanwhile, it does appear likely now that rain will change to snow over the northwestern portions of the region on Monday.  Locally heavy amounts of 4-8 inches are likely in a band extending generally from northeast New Mexico and portions of the Oklahoma/Texas panhandle, into southwest Kansas and extreme northwest Oklahoma:

There is still some uncertainty as to the exact timing and location of the heaviest band of snowfall on Monday, but folks across the general areas outlined above definitely want to keep an eye on the progression of this system over the next few days and listen for updated forecasts, watches and warnings.

Speaking of watches, a Winter Storm Watch has already been posted from the Texas/Oklahoma panhandle into southwestern Kansas for Monday:

"Stay tuned" for updates on this situation over the coming days...

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