MESOSCALE PRECIPITATION DISCUSSION 0696
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
613 PM EDT SAT SEP 24 2016
AREAS AFFECTED...PORTIONS OF THE SOUTHERN TX PANHANDLE
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 242215Z - 250215Z
SUMMARY..CONVECTION TRAINING AHEAD OF A COLD FRONT IN A HIGH
MOISTURE CONTENT AIRMASS COULD RESULT IN FLASH FLOODING THROUGH
THE EARLY EVENING HOURS.
DISCUSSION...REGIONAL RADARS SHOWED A SLOW INCREASE OF CONVECTIVE
ACTIVITY STRETCHING FROM THE TX/OK BORDER THROUGH THE BIG BEND
REGION. THE CONVECTION IS FORMING IN AN AXIS OF 1500-2000 J/KG
MLCAPE...ON THE WESTERN EDGE OF A PRECIPITABLE WATER GRADIENT.
THE IR LOOP SHOWED BURSTS OF DEEPER CONVECTION WITHIN THIS
AREA...WITH CLOUD TOP TEMPERATURES NEAR -70 CELSIUS. WHILE MODEL
SOUNDINGS SHOWED DRY AIR IN THE MID LEVELS (SUGGESTING THAT THE
CONVECTION SHOULD AT LEAST INITIALLY BE MORE OUTFLOW
DOMINATED)...BOTH THE KMAF AND KFDR RADARS SHOWED HOURLY RAINFALL
RATES BETWEEN 1.50 AND 2.00 INCHES OVER PORTIONS OF NORTH TX.
CONVECTION IN A SIMILAR AIRMASS HAS PRODUCED RAINFALL AMOUNTS OF
2.50 INCHES THIS AFTERNOON ACROSS PORTIONS OF CENTRAL OK.
THE INFLOW AHEAD OF THE FRONT...FEEDING THE CONVECTION...IS
EXPECTED TO SLOWLY INCREASE DURING THE LATE AFTERNOON HOURS. THE
COMBINATION OF MOISTURE AND MODERATE INSTABILITY SHOULD CONTINUE
TO FOSTER AT LEAST SCATTERED CONVECTION IN A QUASI UNIDIRECTIONAL
FLOW...WHICH WOULD PROMOTE TRAINING...ESPECIALLY ACROSS PORTIONS
OF TX BETWEEN KCDS AND KSPS.
THE LATEST HRRR SUGGESTS LOCAL 2-4 INCH RAINFALL AMOUNTS ACROSS
AREAS WHERE TRAINING OCCURS...AND BASED ON WHAT HAS OCCURRED
ACROSS WEST CENTRAL OK...THESE AMOUNTS SEEM PLAUSIBLE. WHILE ONE
AND THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE FAIRLY
HIGH...HOURLY RAINFALL RATES NEAR 2.00 INCHES IN TRAINING BANDS
COULD RESULT IN FLASH FLOODING.
HAYES
ATTN...WFO...FWD...LUB...MAF...OUN...SJT...
ATTN...RFC...ABRFC...WGRFC...
LAT...LON 34679954 34299832 31179986 30870138 32040184
33550122 34440043
Last Updated: 613 PM EDT SAT SEP 24 2016