Wednesday, January 22, 2014

Cold and Dry, Cold and Dry, Cold and Dry, MOISTURE?


Like spokes on a tire, we have to tread very carefully here.  See what I did there? LOL.  Cold without snow is just a waste in my opinion.  The cold talked about here on the Arkansas Weather Blog for at least a week now is here and it's here to stay for at least the next 7 days.  I can't help but think, at some point, moisture is going to get involved and the overnight run of the Euro even hints at that, but I'm not completely sold on it right now.  I'll have more on that down below.  Nevertheless, right now, the flow of air around the main vortex in southern Canada is overpowering everything.  The highly amplified pattern is making the cold, dry air overwhelm areas east of the Rockies.

The vortex over southern Canada is just sitting and spinning.  You have to think about this like it's a tire on a bicycle.  Each spoke rotating (counterclockwise) around it is a surge of cold air.  Between each arctic high is a brief and minor warm up.  Also, each surge will have the potential to bring strong winds both ahead and behind of it.  This will not only make the fire danger worse, but bring very cold wind chill values.  As a matter of fact, a wind chill advisory is in effect for Thursday across northern Arkansas as the "feels like" temperature goes well below zero.

According to the European model here's the cold air schedule

1. Thursday
2. Late Sunday
3. Next Wednesday January 29th
4.  If you believe the GFS, the following weekend as well.


Later this week, the upper air pattern from the Euro really shows that bicycle tire.  Look at that deep area of yellow over southern Canada.  That massive upper low (vortex) spins counterclockwise sending waves of cold air south.  With the northwest flow, it's incredibly difficult to get moisture here.   The fire danger will remain elevated.

Let's go down to the surface.  This is the Euro valid Thursday at noon.  The black circle over the plains is a massive arctic high.  Those black lines around it are closely spaced over Arkansas.  This is a pressure gradient which results in high wind speeds.  So while the bitter cold air pours into the state, wind chill values will be brutal.


How about ANOTHER surge next Monday!  Same thing.  Another strong high comes down just east of the Rockies.  The pressure gradient is strong and wind chills will be brutal once again.  The only thing good I can tell you (if you don't like cold weather), we'll be between these cold surges this weekend so there will be a brief warm up Saturday and Sunday before this arrives.

Next Wednesday, there's ANOTHER surge of cold air.  Look at that arctic high over north Dakota!  This time however, there COULD be a wave of moisture..... COULD.  The grey and green areas show precip over the past 6 hours.  The blue dashed line (540 line) is over south of Arkansas.  This is usually a descent indicator of the rain/snow line.  So while nothing too heavy, it does show some moisture.  HOWEVER, being in the long range, doubts are high.   STAY TUNED.

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NOAA Winter Guidance