MESOSCALE PRECIPITATION DISCUSSION 0393
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1002 AM EDT SAT SEP 20 2014
 
AREAS AFFECTED...WEST TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 201401Z - 201701Z
 
SUMMARY...A SMALL STATIONARY MCV FEEDING ON A TROPICAL AIRMASS
WILL PRODUCE DRAMATIC RAIN TOTALS...ABOVE 8 INCHES...IN BORDEN
COUNTY TX. OTHER ISOLATED CELLS PRODUCING INTENSE RAINFALL ARE
POSSIBLE THROUGH MIDDAY.

DISCUSSION...LOW LEVEL CONVERGENCE WAS FOCUSED ALONG A NARROW WEST
TO EAST AXIS FROM ROUGHLY TERRY TO FISHER COUNTIES IN TEXAS.
THIS...COMBINED WITH NEARLY SATURATED LOWER AND MID LEVEL
PROFILES...HAD ALLOWED DEVELOPMENT OF STATIONARY CONVECTION AND A
RESULTANT MCV OVER BORDEN COUNTY. OWING TO LITTLE COLD POOL
POTENTIAL AND WEAK MID LEVEL STEERING...THE MCV HAD REMAINED
STATIONARY FOR AN UNUSUAL LENGTH OF TIME. THE WEST TEXAS MESONET
SITE LOCATED 2 SSE OF GAIL HAD RECORDED 6.7 INCHES OF RAIN SINCE
MIDNIGHT...WITH 1.3 INCHES IN THE LATEST HOURLY OBSERVATION AT
1335 Z. THE BORDEN COUNTY EVENT WAS EMBEDDED WITHIN THE 15-20 KT
850-700 MB INFLOW. ADDITIONAL CELLS WERE INTENSIFYING ALONG THE
WESTERN EDGE OF THIS ENHANCED LOW LEVEL FLOW...NEAR A 700 MB
TROUGH AXIS THAT WILL DRIFT SLOWLY EAST. 

THE RAP FORECASTS 850-700 MB INFLOW AND MUCAPE OF 500-1000 J/KG TO
PERSIST THROUGH AT LEAST 17Z. THE 11Z HRRR HANDLES THE EVENT
FAIRLY WELL...AND PRODUCES A NARROW SWATH OF 7 TO 8 INCHES OF
RAIN. THE MODEL ALSO SUGGESTS SOME EVENTUAL SOUTHWARD PROPAGATION
INTO THE INFLOW...BUT WITH 600 MB STEERING FLOW FOR THE MCV BEING
LIGHT AND VARIABLE...THE EVENT MAY MOVE VERY LITTLE. DRAMATIC
LOCAL RAIN TOTALS AND FLASH FLOODING ALONG ANY SUSCEPTIBLE CREEKS
AND STREAMS IS LIKELY.

BURKE

ATTN...WFO...LUB...MAF...SJT...

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

LAT...LON   33430197 33400114 32950035 32360033 31790113 
            31840232 32340270 33050259