MESOSCALE PRECIPITATION DISCUSSION 0061
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1112 AM EDT FRI MAY 08 2015
 
AREAS AFFECTED...NORTHWEST TX & SOUTHWEST OK 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 081511Z - 082101Z
 
SUMMARY...THUNDERSTORMS WITH HEAVY RAINFALL COULD CAUSE FLASH
FLOODING DUE TO HOURLY RAIN RATES UP TO 2" AND CELL TRAINING OVER
SATURATED SOILS.

DISCUSSION...MESOSCALE BOUNDARIES ACROSS TX ARE EXPECTED TO BE THE
PRIMARY FOCUS FOR CONVECTION THROUGH 21Z, NEAR AND AHEAD OF A
SHORTWAVE LOCATED NEAR THE BORDER OF SOUTHEAST NM/WEST-CENTRAL TX.
 CIN ACROSS THE REGION IS EXPECTED TO FADE BY 16Z, ALLOWING THE
INVERTED TROUGH BEHIND/NORTH OF THE OUTFLOW BOUNDARY TO BECOME THE
PRIMARY FOCUS FOR CONVECTION. ACROSS WEST-CENTRAL TX, 700 HPA
TEMPERATURES AND REGIONAL SOUNDINGS INDICATE A CAPPING INVERSION,
WHICH SHOULD KEEP ANY CONVECTION IN ASSOCIATION WITH THE
TRANS-PECOS OUTFLOW BOUNDARY ELEVATED.  PRECIPITABLE WATER VALUES
ARE CURRENTLY IN THE 1.1-1.2" RANGE, AND SURFACE BASED CAPE CAUSED
BY CAPPING ALOFT IS IN THE 2000-4000 J/KG RANGE SOUTH OF THE
INVERTED TROUGH.  LOW-LEVEL INFLOW ACROSS THE REGION IS ~25 KTS,
BARELY SUFFICIENT FOR ORGANIZED HEAVY RAINFALL.

THE EXPECTATION IS FOR PRECIPITABLE WATER VALUES TO RISE INTO THE
1.25-1.75" RANGE AFTER 16Z, HIGH ENOUGH FOR THE WET MULTI-CELL
ENVIRONMENT.  INFLOW OF 25-30 KTS AT 850 HPA SHOULD BE BROAD
ENOUGH TO SUPPORT A REGIONAL THREAT.  SATURATED SOILS FROM THE
PREVIOUS COUPLE DAYS OF RAINFALL HAVE LED TO FLASH FLOOD GUIDANCE
VALUES (FFGS) OF 1.5-2" IN THREE HOURS.  THE AMOUNT OF MOISTURE
AVAILABLE SUPPORTS HOURLY RAIN RATES UP TO 2", WHICH WOULD EXCEED
FFGS.  THE AMOUNT OF CAPE AND DIRECTIONAL WIND SHEAR AVAILABLE
INDICATE THAT FORWARD PROPAGATION IS LIKELY -- TO THE TUNE OF 30
KTS TO THE EAST TO EAST-SOUTHEAST ONCE CONVECTION ORGANIZES PER
06Z GFS CORFIDI/ PROPAGATION VECTORS.  SOME BACKBUILDING IS
POSSIBLE AS 850 HPA INFLOW INCREASES/BROADENS ACROSS THE REGION,
WHICH COULD HELP LEAD TO CELL TRAINING ALONG A LENGTHENING
THUNDERSTORM BAND NEAR AND NORTH OF THE BOUNDARIES LOCATED IN
NORTHERN TX.  THE 00Z SPCWRF, 00Z WRF4NSSL, 06Z CANADIAN REGIONAL,
06Z-12Z NAM CONEST, AND RECENT RAP AND HRRR RUNS HAVE A SIGNAL FOR
LOCAL AMOUNTS OF 2-4" IN THIS REGION.  FLASH FLOODING IS POSSIBLE.

ROTH

ATTN...WFO...ABQ...AMA...FWD...LUB...OUN...SJT...

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

LAT...LON   35410089 35409941 34399798 33149784 32449812 
            32479889 33070014 33540182 33680227 33970296 
            34340310 35090249