MESOSCALE PRECIPITATION DISCUSSION 0121
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
218 AM EDT TUE JUN 10 2014
 
AREAS AFFECTED...SOUTHEAST TX...CENTRAL LA...SOUTHWEST MS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 100617Z - 101217Z
 
SUMMARY...A THUNDERSTORM BAND IS EXPECTED TO SLOW DOWN SLIGHTLY
AND POSSIBLY BACKBUILD OVER THE NEXT SEVERAL HOURS AS THE
LOW-LEVEL JET STRENGTHENS.  SEVERAL POCKETS OF FLASH FLOODING ARE
POSSIBLE.

DISCUSSION...A BAND OF THUNDERSTORMS HAS BEEN DEVELOPING DURING
THE PAST FEW HOURS AHEAD OF A COLD FRONT LOCATED IN EASTERN TX,
MOVING EASTWARD AT 10-15 KTS.  THE HEAVIEST RAINFALL RATES IN THE
STORMS SO FAR HAS BEEN ON THE ORDER OF 2" PER HOUR, ON PAR WITH
THE AVAILABLE MOISTURE PRESENT; PRECIPITABLE WATER VALUES ARE
APPROACHING 2".  THE WARM LAYER ON THE SOUNDING FROM LCH IS
SUMMERLIKE, WITH THE WET-BULB ZERO HEIGHT APPROACHING 13000 FT,
INDICATING THAT THE CONVECTION SHOULD NOT BECOME INCREASINGLY
FORWARD PROPAGATING.  THE 0-6 KM BULK SHEAR IS SUFFICIENT FOR
ORGANIZED CONVECTION, AND THE 0-3 KM WIND SHEAR IS CURRENTLY NEAR
THE LOWER EDGE OF THE WET MULTI-CELL ENVIRONMENT.  CAPE VALUES
SOUTH OF AN OUTFLOW BOUNDARY ACROSS SOUTHERN LA ARE IN THE
2000-3000 J/KG RANGE.  CELLS WITH THE HIGHER RAINFALL RATES ARE
NOT MAKING IT MORE THAN ABOUT 100 NM NORTH OF THE OUTFLOW BOUNDARY
BEFORE MOVING INTO THE MORE STABLE AIRMASS.

AS 850 HPA INFLOW INCREASES OVER THE NEXT SEVERAL HOURS, 0-3 KM
SHEAR WILL BECOME MORE FAVORABLE FOR WET MULTI-CELL CLUSTERS AND
CORFIDI VECTORS LESSEN.  SOME BACKBUILDING, TRAINING, AND SLOWING
OF THE CONVECTIVE LINE IS POSSIBLE.  RAINFALL RATES IN STRONGER
CONVECTIVE CELLS COULD INCREASE FURTHER TO 2.5" AN HOUR AS THE
CONVECTIVE SYSTEM FURTHER ORGANIZES.  FLASH FLOOD GUIDANCE VALUES
ARE RELATIVELY HIGH AND THE CONVECTIVE LINE HAS BEEN MOVING,
LOWERING THE THREAT FOR SIGNIFICANT FLASH FLOODING.  THE MESOSCALE
GUIDANCE GENERALLY AGREES THAT HEAVY RAINFALL SHOULD STRETCH FROM
THE GOLDEN TRIANGLE OF SOUTHEAST TX INTO SOUTHWEST MS, WITH A
MODERATE SIGNAL FOR HEAVY RAINFALL PRESENT -- THE BEST OVERLAP OF
THEIR MAXIMA IS BETWEEN SOUTH-CENTRAL AND CENTRAL LA.  SEVERAL
LOCALES COULD EXPERIENCE FLASH FLOODING, PARTICULARLY ACROSS
SOUTHERN AND CENTRAL LA.  LOCAL AMOUNTS OF 4-6" ARE POSSIBLE
WITHIN THIS REGION, WHICH COULD CAUSE SEVERAL POCKETS OF FLASH
FLOODING.

ROTH

ATTN...WFO...JAN...LIX...LCH...SHV...HGX...

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

LAT...LON   29429220 30239146 31469046 32219026 32409125 32429306
            31499411 30579517 29749498 29579349 29449241 29429220