MESOSCALE PRECIPITATION DISCUSSION 0685
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1051 PM EDT SUN AUG 13 2017

AREAS AFFECTED...NORTHWEST TX....FAR SOUTHWEST OK

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 140250Z - 140730Z

SUMMARY...HEAVY RAINFALL WILL CONTINUE TO ACCOMPANY A STRONG MCS
THROUGH THE OVERNIGHT HOURS. SOME RUNOFF CONCERNS AND/OR FLASH
FLOODING WILL BE POSSIBLE.

DISCUSSION...NON-OPERATIONAL GOES-16 10.3 MICRON/IR IMAGERY SHOWS
AN IMPRESSIVELY COLD-TOPPED MCS MOVING SOUTHEAST THROUGH THE TX
PANHANDLE AND PORTIONS OF FAR SOUTHWEST OK. THE CONVECTIVE MODE
HAS BEEN GENERALLY SEVERE THROUGH THE EVENING SO FAR AS IT FORWARD
PROPAGATES TO THE SOUTHEAST...HOWEVER THERE HAVE BEEN SOME
RAINFALL TOTALS OF 1.5 TO 2 INCHES/HR...AND SOME RADAR ESTIMATES
OF SLIGHTLY HIGHER STORM TOTALS THAT ARE OVER 3 INCHES.

THE ENVIRONMENT AHEAD OF THE MCS REMAINS FAVORABLE FOR THE MCS TO
CONTINUE PROPAGATE OFF TO THE SOUTHEAST AS IT WILL BE ENCOUNTERING
MLCAPE VALUES OF 1500 TO 2000 J/KG WITH PWATS OF 1.5 TO 1.75
INCHES. EFFECTIVE BULK SHEAR VALUES ARE ALSO ON THE ORDER OF 30 TO
40 KTS WHICH SHOULD FACILITATE A LARGE DEGREE OF CONVECTIVE
ORGANIZATION OVER AT LEAST THE NEXT FEW HOURS.

THE FORWARD MOTION WILL BE SUCH THAT THE FLASH FLOODING THREAT
WILL TEND TO BE MITIGATED...BUT RAINFALL RATES OF UP 2 INCHES/HR
WILL BE EXPECTED. THE RADAR TRENDS ARE SHOWING A FEW DISCREET
CELLS OVER PARTS OF WEST-CENTRAL AND NORTHWEST TX AHEAD OF THE
MAIN MCS...AND IT APPEARS LIKELY THAT THERE WILL BE A FEW CELL
MERGERS OVER THE NEXT COUPLE OF HOURS. THIS WOULD ENHANCE THE
RAINFALL RATES A BIT FURTHER...AND MAY ENHANCE THE THREAT FOR AT
LEAST SOME SHORT-TERM RUNOFF CONCERNS AND POSSIBLE FLASH FLOODING.
OVERALL...THE STORMS TOTALS SHOULD TEND TO BE GENERALLY 2 TO 4
INCHES FOR THE EVENT BASED ON RECENT HRRR GUIDANCE. THE SAME
GUIDANCE ALSO SUGGESTS SOME WEAKENING OF THE CONVECTIVE
ORGANIZATION AFTER 06Z...BUT THESE TRENDS WILL BE MONITORED.

ORRISON

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

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

LAT...LON   35380084 35089972 34589887 33999834 33309815
            32869844 32749916 32840001 33160093 33710172
            34080251 34570293 34970298 35200275 35350180