MESOSCALE PRECIPITATION DISCUSSION 0119
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
452 AM EDT SUN MAY 24 2015
 
AREAS AFFECTED...NORTHEAST TX, EASTERN OK, WESTERN AR 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 240851Z - 241351Z
 
SUMMARY...AN APPROACHING MCV INTERACTING WITH AN OUTFLOW BOUNDARY
COULD LEAD TO CELL TRAINING.  RAINFALL RATES UP TO 1.5" AN HOUR
COULD LEAD TO FLASH FLOODING OVER SATURATED SOILS.

DISCUSSION...AN MCV MOVING BY DALLAS TX HAS LED TO SOME NORTHWEST
RETURN TO AN OUTFLOW BOUNDARY.  TO THE SOUTH AND SOUTHEAST OF THE
BOUNDARY, CAPE VALUES OF ~1000 J/KG ARE BEING LURED IN BY
SOUTH-SOUTHWEST WINDS OF 35-40 KTS PER REGIONAL VAD WIND PROFILES,
JUST ABOVE THE MAGNITUDE OF THE MEAN 850-400 HPA WIND.  RAINFALL
RATES WERE CLOSE TO 1" AN HOUR PER RECENT MESONET OBSERVATIONS,
WITH RADAR ESTIMATES RE-APPROACHING 1.5" AN HOUR DURING THE PAST
COUPLE SCANS.

AN APPROACHING MCV SHOULD ALLOW HOURLY RAIN RATES TO PEAK NEAR
1.5" DUE TO INCREASED CELL TRAINING TO ITS NORTHEAST.  ALTHOUGH
PRECIPITABLE WATER VALUES REMAIN ~1.75", THE THERMAL GRADIENT
ALONG THE BOUNDARY HAS WEAKENED OVERNIGHT, WHICH HAS LED TO SOME
FRONTOLYSIS.  HOWEVER, FLASH FLOOD GUIDANCE IN THE REGION REMAINS
LOW.  THERE REMAINS A SIGNAL IN THE MESOSCALE GUIDANCE (THOUGH A
BIT FARTHER WEST) FOR LOCAL AMOUNTS OF 2-4" OVER THE NEXT SEVERAL
HOURS, WITH RECENT HRRR GUIDANCE AND THE 00Z SSEO NEIGHBORHOOD
PROBABILITIES SUGGEST THAT THE HEAVY RAIN THREAT SHOULD END BY 14Z
IN THIS AREA.  HOURLY RAIN RATES UP TO 1.5" COULD LEAD TO FLASH
FLOODING OVER SATURATED SOILS.

ROTH

ATTN...WFO...FWD...LZK...OUN...SGF...SHV...TSA...

ATTN...RFC...ABRFC...LMRFC...WGRFC...

LAT...LON   36819331 36729285 35369278 33629390 32839546 
            32909696 33639741 34519710 35999602 36729467