Wednesday, February 11, 2015

Winter Isn't Going Down Without A Fight

1:20PM Wednesday update.... The GFS and Euro both show winter comes back BIG time next week.  this video goes over both models.



Better late than never huh?  Yes, it's going to get colder Thursday, but it will be even colder Sunday.  The core of the weekend cold will be northeast of the state so there should be a significant temperature gradient from northeast to southwest.  I think highs stay in the 20s northeast with lower 40s southwest.

On Monday, the models have been very consistent in developing a storm system to our west and throwing moisture on top of the cold air.  The data looked very ominous Tuesday, but I was very, very hesitant about buying into that scenario and wanting to wait a little bit longer and look at new data.  While things can still change (my usual disclaimer), I have two concerns and they are connected.  First, the arctic air is retreating.  You really need an east to northeast surface wind to keep cold, dry air in place at the surface as moisture overrides in the upper levels.  With a retreating high, the surface winds will be out of the east and southeast.  They could even start to come out of the south late Monday.  That leads me to the "Arctic Oscillation Index" or "AO" for short.  Most of the time, for significant wintry weather around here, you really need it to be negative.  This suppresses the storm track to the south and cold air can really lock in place.  Instead, the guidance says the AO will be neutral to even positive.  Don't get me wrong, I still think there's a good chance for wintry weather.  However, I think this is going to turn out to be a situation where a wintry mix (mostly ice) changes to a cold rain.  The longer you're below freezing, the worse it will be.  As stated yesterday (Tuesday), it's going to target northern Arkansas.  I think western and central areas will have some icing, but the duration could be limited.

Once again, my usual disclaimer.... this is Arkansas, it's 5 days away, and it can change.  I really hope the cold air can lock in and we can get some snow instead of ice.  So let's watch this as I think there could be some travel trouble by the beginning of next week.  Beyond this period, the cold shots keep on coming and winter rocks through the end of the month!

The following maps are from

After a somewhat milder Saturday.  (It will still be cool), the arctic boundary plunges south late Saturday into Sunday morning.  You can see it clearly on this map entering north Arkansas by midnight Sunday morning.
Highs Sunday only in the 20s northeast closer to the core of the cold air with highs in the lower 40s southwest.  The arctic air is firmly in place with the boundary near the I-10 corridor.

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