MESOSCALE PRECIPITATION DISCUSSION 0419
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
107 AM EDT SAT OCT 11 2014
AREAS AFFECTED...ARKLATEX INTO CNTRL/SRN ARKANSAS
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 110502Z - 111100Z
SUMMARY...PERIODS OF TRAINING CONVECTION WITH RAINFALL RATES OF
1-2 IN/HR ARE EXPECTED TO DEVELOP BETWEEN 07-10Z FROM THE ARKLATEX
INTO SRN/CNTRL ARKANSAS LEADING TO POSSIBLE FLASH FLOODING.
ALTHOUGH FFG IS 3-4 INCHES IN 3 HOURS...THIS COULD BE EXCEEDED IN
A FEW LOCATIONS.
DISCUSSION...05Z SURFACE ANALYSIS PLACED A 1010 MB LOW JUST E OF
GVT...WITH A QUASISTATIONARY FRONT EXTENDING ENEWD ACROSS CNTRL
ARKANSAS. THE WRN EDGE OF AN OUTFLOW BOUNDARY INTERSECTED THIS
FRONT JUST NORTH OF TXK. SHORT TERM MODEL FORECASTS TAKE THE
SURFACE LOW SLOWLY NEWD INTO SERN OKLAHOMA BY 11Z...WITH A NARROW
CORRIDOR OF ENHANCED 850 MB FLOW DEVELOPING BY 07Z..JUST SOUTHEAST
OF THE LOW ACROSS NERN TEXAS INTO ARKANSAS. IN ADDITION...THE
RIGHT ENTRANCE REGION OF A 70-90 KT UPPER LEVEL JET ALONG WITH A
BIT OF UPPER DIFFLUENCE ALOFT SHOULD SET UP ACROSS THE THREAT
AREA...COINCIDENT WITH THE ENHANCED LOW LEVEL FLOW.
AS WINDS AT 850 STRENGTHEN INTO THE 30-35 KT RANGE BETWEEN 07-10Z
THIS MORNING...WHICH WILL MATCH VERY SIMILARLY TO THE MEAN CLOUD
BEARING LAYER WINDS...TRAINING OF CONVECTION IS EXPECTED TO SET
UP. GIVEN INSTABILITY IN EXCESS OF 1000 J/KG SHOULD STILL BE IN
PLACE IN PARTS OF ERN TEXAS PER RECENT RAP AND HI-RES MODEL
FORECASTS...RAINFALL RATES OF 1-2 IN/HR WILL BE POSSIBLE WITH
TRAINING LEADING TO RATES OF 3-4 INCHES IN 3 HOURS. HI-RES
MODELS...INCLUDING THE 00Z ARW...NSSL WRF...NAM CONEST AND RECENT
RUNS OF THE HRRR ARE SUPPORTING THIS IDEA. ONE NEGATIVE FACTOR IS
THE RECENT DRY CONDITIONS AND RELATIVELY HIGH FLASH FLOOD GUIDANCE
ACROSS THE REGION...3 IN/3 HR...BUT STILL FEEL THIS WILL BE
EXCEEDED IN A FEW SPOTS BY 11Z.
OTTO
ATTN...WFO...JAN...LZK...MEG...SHV...
ATTN...RFC...ABRFC...LMRFC...
LAT...LON 34749223 34369125 33959089 33439112 33099184
33039404 33189499 33659521 34199478 34519425
34679304
Last Updated: 107 AM EDT SAT OCT 11 2014