Wednesday, March 21, 2012

Flash Flooding Wednesday and What's Ahead


12:30 PM Wednesday Update...  The National Weather Service says it was straight line winds that caused the damage Tuesday in Morrilton.  Those winds were estimated at 80 mph.  This is just another example why severe thunderstorms need to be taken seriously as they can cause damage just like weak tornado.  In 2011, severe thunderstorm winds killed 7 people in Arkansas.

I'm still watching for the possibility for some strong and maybe severe thunderstorms late Thursday as the area of low pressure aloft makes a move to the east.  SPC does not have a slight risk out yet, but I think they might.  This cold pocket of air aloft will be supportive for some hail producing thunderstorms especially in western and northwestern Arkansas late Thursday.  I don't think it will be widespread, but it's something to keep an eye on.

I have flooding and damage pictures on my facebook page if you want to check that out.


I think the forecast has worked out quite well so far.  As of Wednesday morning, amounts are ranging around 4-5 inches in many locations. I talked several times about the rainfall gradient being sharp and it truly is.  You can see in the map below.  I think the rain will continue today into Thursday morning for the state with an additional 1-2'' possible.  The rain which is oriented from the south to the north will become oriented from the southeast to the northwest tonight and Thursday as it makes its slow push to the east.  This is due to the circulation around the upper low.  I'll explain below.  A quick look at the long range models next week shows well above average temperatures and mostly dry conditions.  This will lead to the end of the month and I still think it will end up as one of the warmest March's in Little Rock weather history.

Also, there was some severe weather across the state Tuesday.  Mostly thunderstorm wind damage.  However, there was 1 tornado reported in northwest Arkansas Monday night which brings the state total this year to 8.  Average is 33.

Amazing rainfall gradient where central and western Arkansas has received 3-5''.  If one travels just a little down interstate 40, it has barely rained... YET!
This is the NAM simulated radar late this afternoon into the early evening.  Notice the circulation around the low which is centered in Oklahoma.  The rain band across Arkansas is more oriented from the northwest to the southeast and pushing out of central Arkansas.
The overnight run of the NAM is developing some thunderstorms with the upper low as it makes a move to the east.  This is valid Thursday evening around 10 PM.  Some of those storms could contain heavy rain and I wouldn't be surprised to see some hail out of that.  Not set in stone, but I'm watching it!

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NOAA Winter Guidance