Wednesday, December 31, 2014

Opening 2015... An Icy Mixture It Could Bring


SCROLL DOWN TO THE PREVIOUS POST FOR THE TOP 7 WEATHER STORIES OF 2014

I think most of this precipitation will fall in the form of a cold rain, but we'll have to watch for some ice, especially north and west.  Whenever you're dealing with the interaction between retreating arctic air and a strong area of low pressure aloft, it can throw a couple curve balls your way so that's something to keep in mind.

During the day Thursday, dry, low level arctic air will help lead to a process called "evaporative cooling".  This could bring a period of sleet/rain to much of the area with temperatures falling a couple degrees.  Even with the cooling, temperatures should stay barely above freezing EXCEPT western and northern Arkansas.  The higher elevations will be more susceptible to those colder temperatures. Why not snow?  The air aloft will be too warm.

We should then transition to a cold miserable rain.  By Thursday night into Friday morning, temperatures may drop to freezing across some portions of north and western Arkansas leading to a mixture of freezing rain and/or sleet.  Again, a few slick spots will be possible across those location.  By Friday, temperatures stay very cold, but warm enough for most of Arkansas to see only rain.

Across the metro, I do not expect much in the way of travel issues except wet roads.  Remember, curve balls can be thrown and if it's just a few degrees colder, things can change.  However, this is the best forecast to go with at this time.

The maps below are courtesy of weatherbell.com

This is the GFS for noon Thursday showing precip over the previous 6 hours.  Where you see green, the model is telling us it's rain, but with low level dry air in place, I would not be surprised to see a little sleet.  The blue line is the 35 degree line and the red line is the 32 degree line.  Notice western and northern Arkansas is the place to watch for any slick spots on the roads while the rest of us will be just above freezing even if sleet falls.
By late Thursday, the atmosphere is saturating itself and we should make a transition to a cold rain with temperatures between 32 and 35 degrees.  So you see my concern with how barely above freezing we should be.  It stays below freezing according to this model across the far northwest. 
By 6AM Friday notice, the 32 degree line sinks south and encompasses the northern 1/4 of the state and even the higher elevations of western Arkansas.  Temperatures SHOULD hold steady in the mid 30s for the rest of the state.  Again, just a few degrees can make a huge different, but right now it appears much of the metro will be above freezing.  It's still possible for a couple sleet pellets.
Look at 6PM Friday.  Most of the state will transition to that cold and miserable rain Friday.  The majority of the precip will be a cold rain.
Total precipitation amounts will be heaviest across the southwest and could approach 3 inches.
WPC indicates a good chance for at least .01'' or more of freezing rain for areas across western and northern Arkansas.

1 comment:

Tammy Hagaman said...

Thanks, this is very helpful! Can you give a broad estimate of travel from Hot Springs to Austin, TX on Thursday?

Octo-BRRR