Friday, December 20, 2013

Saturday Soaker/Severe Update

I really don't have much in the way of changes this Friday morning.  The track of the surface low looks further south compared to the past few days.  This will bring the heaviest swath of rain right through the metro, IF THE MODELS ARE RIGHT.  The favored area of any severe weather will be southeast Arkansas.  This too is uncertain depending on how much instability develops there.  We want thick clouds and rain to reduce the threat.  However, please prepare there and I'll show you a map below which shows the moderate risk area issued by the Storm Prediction Center.  The main threat for the Channel 7 viewing area is flooding rainfall, then severe weather.

There are differences between the models as to where a sharp boundary will set up.  If you're north of it, the severe weather threat is greatly diminished, if you're along or ahead of it, it's enhanced some depending on instability values.  Once again, the favored area is southeast Arkansas.  Can this still change?  Absolutely.  Below are maps which explains this situation.  Some of the maps are from

This is a hires model known as the WRF.  Look at that boundary at 6 AM Saturday.  It's sharp!.  Little Rock well into the 60s while Faulkner county is in the 40s.  Look at Hot Springs.  It's 67, but Mount Ida is 44!  WOW!  There are other models which indicate the boundary will be a little further north, but this is a possibility.  The warm sector (SE AR) has the greatest threat for severe.
By noon, the boundary is through LR... according to this 1 model.  It's in the 40s in NLR while Pine Bluff is 73!  Again, there are other models which have this boundary north.  The surface low will ride along this boundary and this will be the focus for the heaviest rainfall, right through central Arkansas.  The severe threat continues to evolve for SE AR
By 6 PM, the threat is decreasing for most of the state with the main severe threat near the MS River.  Rain is ending from west to east at this time.
The Euro shows heavy, heavy rain in a swath from SW to NE AR from 6 AM to 6 PM Saturday.  The surface low is near Hope and it's moving along that boundary to the NE.
By 6PM, the severe threat is focused to the east, especially SE Arkansas.  More heavy rain across central AR and SE AR.  The surface low is near Little Rock moving NE.
Futurecast shows 3-4 inches all throughout the metro for total rainfall.  A flash flood watch is in effect for most of the state.
9AM Futurecast indicates heavy rain except in SE AR.  We need rain and clouds there to minimize the instability.
At Noon, the heavy rain is continuing across much of the state, especially the area in yellow and orange.
By 4 PM, the rain is decreasing across western and central AR.  Heavy rain and thunderstorms continue across the east, but should diminish around 6-8 PM.
A slight risk for severe weather Saturday for much of the SE half of the state including the metro.  Remember, it's areas south and east of that sharp boundary I showed above.  A moderate risk is possible across eastern and southeastern Arkansas, especially if any destabilization occurs.  STAY TUNED!!!!

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