Thursday, January 24, 2013

Still Some Icing Concerns Tonight and Severe Weather Next Week


11:50 AM Thursday morning update... This video will go over hi resolution model data for tonight and Friday morning.  Here are the key points to this: anything that falls will be light, gone rapidly Friday morning, and mainly target northern Arkansas.  Watch the video for more in-depth analysis.

Remember, when you step outside today, the computer models said it would be 70 degrees today on its runs earlier this week.  I'll address that and how it pertains to next week further down this post.

The key to this forecast is the word "LIGHT".  I still don't think this will turn out to be anything like the Christmas storm as amounts will only reach .01-.1'' across much of central and northern Arkansas.  This WILL be enough to cause slick spots on the roads.  

Temperatures will fall today under mostly cloudy skies and northeasterly winds.  This is setting the stage for a weak disturbance tonight to bring areas of light freezing rain and drizzle.  It's very important to note that whatever light accumulations do occur, will melt rapidly Friday morning as temperatures go well above freezing.  The target area continues to be northern and MAYBE some portions of central Arkansas.  As mentioned in the previous post, we must watch to see how far south the subfreezing air penetrates.  Also, we'll watch the dewpoints.  A significant difference between this and the surface temperature could lead to greater evaporational cooling.  This lowers temperatures even further than what the computer model guidance suggests once the light precipitation begins.

I'm going to use the Euro maps below since this computer model has shown remarkable consistency.  However, please note, other models do show the freezing line further south...the NAM.

This is the latest version of the Euro indicating light precip in gray moving across the state around midnight.  The dark blue line is the 32 degree line.  Look how that covers only the higher elevations of northern AR.  Remember, other models show this much further to the south.
This only moves a little by 6AM Friday and stays across northern AR with areas of light freezing rain and sleet up there.
NOAA's HPC manual guidance is buying more into the NAM scenario at this time.  This map indicates a high likelihood of at least .01'' of freezing rain across much of central, western, and northern Arkansas.  So even at this stage, there are significant differences as to how far south the subfreezing air gets.
The next big weather maker I'll be following here on the blog is the severe potential next Tuesday.  For the second day, the Storm Prediction Center has outlined all of Arkansas in an area for concern.  Most of the guidance agrees with this and we must watch this carefully for the threat for severe thunderstorms as significant energy comes out of the western United States and develops a surface low from the TX panhandle to the Great Lakes.  This will put Arkansas in the warm sector with plenty of humidity.  I will caution you though, this is several days away.  We saw how much things changed within 72 hours this week.  The models showed 70 today and we know how wrong that was.  Glad I didn't buy into that!!!!!  With that said, there is good agreement among all the model outputs we will be in the warm sector so let's watch this!!!!

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