MESOSCALE PRECIPITATION DISCUSSION 0375
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
802 PM EDT TUE JUL 21 2015
 
AREAS AFFECTED...SOUTHERN AND CENTRAL OKLAHOMA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 220000Z - 220600Z
 
SUMMARY...INCREASE IN COVERAGE AND INTENSITY WITH SLOW MOVING
CONVECTION EXPECTED OVER THE NEXT FEW HOURS...WITH POSSIBLE
POCKETS OF FLASH FLOODING.

DISCUSSION...EARLY MORNING CONVECTION DEVELOPED AN MCV THAT STILL
REMAINS DEFINED NEAR ENID...THIS HAS LEAD TO SIGNIFICANT CLOUD
COVERAGE ALL DAY WHICH HAS STRENGTHENED THE THERMAL GRADIENT
(UPPER 70S TO LOW 90S) ACROSS THE FRONTAL BOUNDARY THAT IS WELL
DEFINED IN SURFACE OBS FROM NEAR SPS TO PVJ TO SOUTH OF MLC.  A
VERY MOIST ENVIRONMENT EXISTS ACROSS BOTH SIDES OF THE FRONT WITH
GPS NETWORK SHOWING A BROAD AREA OF TPWS IN EXCESS OF 2"...WITH
SFC TDS WELL INTO THE 70S WITH SOME SITES SOUTH OF THE FRONT AS
HIGH AS 77 SOUTH OF THE FRONT.  THIS HAS LEAD TO AN ENVIRONMENT OF
HIGH INSTABILITIES WITH CAPES INTO THE 3500 J/KG RANGE.  RAP
ANALYSIS SHOWS STRONG SFC AND LOW LEVEL MOISTURE CONVERGENCE TO
ALLOW FOR CONVECTIVE INITIATION...EVEN THOUGH THE FLOW IS
CURRENTLY WEAK.  WITH THE MCV LOCATION...CELL MOTIONS ARE GOING TO
BE QUITE SLOW ALLOWING FOR QUICK COMPOUNDING OF TOTALS WITH THESE
HIGHLY EFFICIENT CELLS.  CURRENTLY FDR RADAR SHOWS SOME INITIAL
OUTFLOW BUT MESO SITES SHOW WEAK WINDS AND LIMITED TEMPERATURE
DROP TO INDICATE VERY LITTLE WORK NEEDS TO OCCUR TO SATURATE THE
PROFILE FOR EFFICIENT RAINFALL PRODUCTION.  RAP AND OTHER HIGH-RES
MODELS FORECAST STRENGTHENING LOW LEVEL FLOW (THOUGH NOT DRAMATIC
- TO 20 KTS) SHOULD BE SUFFICIENT FOR MST FLUX FOR CELLS RATES OF
2-2.5"/HR LIKELY.   THOUGH FFG VALUES ARE QUITE HIGH...THESE RATES
WITHIN A REGIME OF VERY SLOW CELL MOTIONS -FCST TO 5-10 KTS-
SHOULD ALLOW FOR POCKETS OF FLASH FLOODING TO OCCUR.  

CURRENT HRRR AND FSL-HRRR PAINT A GOOD PICTURE OF THE AXIS BETWEEN
THE SURFACE FRONT AND 850 FRONT (LOCATED NEAR/ALONG I-40) OF
INCREASED THREAT OVER THE NEXT 6 HOURS PLUS.  EARLY 12Z GUIDANCE
SUCH AS WRF-NMMB AND WRF-ARW SHOWED HIGHER TOTALS FURTHER
NORTH...WHEN CENTRAL OK ENVIRONMENT WAS FORECAST TO NOT BE CAPPED.
 THOUGHTS OF THESE HIGHER TOTALS ARE POSSIBLE ALONG THE HRRR AXIS
GIVEN THE MOISTURE ENVIRONMENT IS NOT DRAMATICALLY CHANGED JUST
THE LOCATION OF FOCUS.    

ATTN...WFO...OUN...TSA...

ATTN...RFC...ABRFC...

LAT...LON   36059604 35329542 34759564 34429698 34089796 
            33829882 33989929 34559936 35359823 35649756