Saturday, December 3, 2011

Update on Winter Weather Event #2 - Snow for Southern Plains on Monday...

A complex weather situation continues to unfold across the southwest and into the southern and central Rockies today, as a broad trough of low pressure continues to generate disturbances that lift out to the Northeast across the adjacent High Plains.

The next couple of stronger disturbances to be ejected from the through are forecast to track further South as compared to the one we're dealing with today.  The image below is a snapshot of the NAM forecast model's presentation of the next disturbance valid at 6pm CST on Sunday (disturbance circled in red):

This disturbance will lift Northeastward across West Texas and into Oklahoma and Arkansas during the day Monday, while the next disturbance in line drops down into the Southern end of the trough over the Southwest.

Meanwhile, cold air will be spreading Southward in the low-levels of the atmosphere, with the temperature forecast to reach freezing a few thousand feet above the surface by 6am CST on Monday morning (I have traced over the hard to see freezing line in blue on the image):

...meanwhile, at the surface level, the temperature is forecast to reach freezing during the day on Monday across much of the same area - the question is just exactly when and in what geographic orientation.

With the above in mind, all of the ingredients are coming into place for a snow band to develop from central and/or eastern Oklahoma into adjacent portions of Arkansas and Missouri on Monday.  The question now becomes how rapidly the lowest-levels will cool, thus allowing rain to change over to snow.

In general, I believe that the NAM computer model's snowfall forecast image below does a good job estimating the likely area for a potential band of accumulating snow to set-up in Oklahoma, Arkansas and Missouri on Monday, I'm just not confident in the amount of snow that is being indicated at this time:

We will have to await additional data and later computer model runs in order to pinpoint this event further.  In the meantime, folks living from Oklahoma City (although it is looking more likely East or Southeast of town), through Tulsa, on into southwest Missouri and northwest Arkansas should keep an eye on this situation and watch for later updates on this developing weather situation.

Further West, a new round of snow, some locally heavy, will fall as this system lifts out on Sunday night and early Monday.  The latest run of the SREF model is forecasting widespread new snow amounts of 3-6 inches, with local amounts over a foot in the higher elevations of southern Colorado, New Mexico and into the northwestern Texas panhandle (image below valid 6pm CST on Monday):

Please check back to the blog for additional updates as this situation continues to unfold...

For more information on the cold air invasion that will overspread much of the nation over the next few days, please see this earlier post.

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