Wednesday, January 23, 2013

Thursday/Friday Trouble?


3:30 PM Wednesday Update... Here's a video update I intended to be short, but I talk wayyy to much sometimes.  Although, I think you will find it entertaining AND informative.




10AM Wednesday Update... The new GFS is in and there are differences.  Here's a look.

Thursday morning at 6AM shows very light rain/drizzle over central AR with the strong high over MN.  Northeasterly winds are pushing dry low level arctic air into the state.
Just like the other pieces of data, at 6AM Thursday the freezing line is over northern AR.
 
By Friday AM, the GFS shows more precip over central AR with a wave of low pressure.
Here's the difference...  The freezing line is on the MO/AR border so whatever is falling according to this data, is plain ol rain.  Not sure if I buy that, but it's possible.  Stay tuned and please read the post below.
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I alluded to this possibility early this week and it's looking more and more likely we'll have some light icing problems Thursday into Friday morning.  Remember, at one point the NAM and even the GFS indicated high temperatures would be near 70 degrees Thursday.  They both indicated the surface low and warm front would surge far enough north to allow this to happen.  However, as is usually the case, the modeling does not handle low level arctic air well.  This is why I thought the area HPC highlighted in southern Missouri earlier this week for ice would shift south and indeed it has.  Remember, arctic air can be shallow and only a few hundred to a few thousand feet deep while temperatures aloft are mild.  This temperature profile results in ice and not snow.  With that said, I DO NOT EXPECT SIGNIFICANT ICE ACCUMULATIONS, BUT WE ALL KNOW IT TAKES VERY LITTLE TO CAUSE PROBLEMS.  This is NOT going to be anything like the Christmas storm.

I'm going to use the NAM model below even though I have recently bashed its performance.  I think it may actually have a decent handle on the situation.  If anything, it might be too cold.  I'll also show you Euro maps.  Once the new GFS is in, I'll update with that.

This is the North American Model valid Thursday at 6AM.  The cold arctic high is located across MN.   Check out the faint gray arrows over AR indicating a significant NE wind out of that high.   This advects cold, dry low level air.  There's a developing area of low pressure to our SW and VERY light precip developing in the gray shaded areas of western into southern AR.


These are surface temperatures at the same time.  Look at the strong 1044mb high over MN.  The white line is the freezing line at the surface and that's over northern AR.  This suggests what's falling around central and southern AR would be cold light rain or drizzle, BUT if it's just a couple degrees colder, then there's bigger problems.
The bigger problems may not arrive until Thursday night into Friday morning.  Here's the NAM at midnight Friday.  This is very light precip over much of Arkansas mainly in the form of light freezing rain/ drizzle
At midnight, the 32 degree line is well south and much of central, western, and northern AR would be at or below 32 degrees.  Not much ice, but enough to cause a problems.
Now onto the Euro at 6 AM Thursday morning.  The 32 degree line is over northern AR, much like what the NAM shows.   There's light rain or drizzle south of that line so the Euro indicates it would be plain light rain or drizzle.  HOWEVER, I caution you once again.  If just a few degrees colder, then we're talking about problems further south.  That's just something to watch.
The Euro Friday morning at 6AM shows the freezing line (dark blue) over northern AR.  This is the location with the highest potential for icing as a more significant wave of low pressure moves through Thursday night into Friday morning.  Notice the Euro is less aggressive bringing the freezing line south compared to the NAM.  Areas from near Fayetteville to Clinton, up to Paragould northward could have some travel problems with this scanario.
HPC shows a very high likelihood of at least .01'' of freezing rain across much of western, northern, and some portions of central Arkansas from Thursday morning to Friday morning.

1 comment:

Donny said...

i can help the ninja out with his fishing technique, I am quite the fisherman LOL