MESOSCALE PRECIPITATION DISCUSSION 0832
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
848 PM EDT TUE SEP 26 2017

AREAS AFFECTED...CENTRAL/NORTHERN TEXAS

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

VALID 270045Z - 270645Z

SUMMARY...SOME ADDITIONAL HEAVY RAINFALL IS EXPECTED OVERNIGHT.
SOME RUNOFF CONCERNS AND AT LEAST LOCALIZED FLASH FLOODING REMAINS
POSSIBLE.

DISCUSSION...THERE WILL REMAIN A FOCUS FOR SOME HEAVY RAINFALL
WELL INTO THE OVERNIGHT HOURS ACROSS AREAS OF MAINLY CENTRAL TO
PERHAPS NORTH TEXAS. THIS IS BEING FACILITATED BY LARGE SCALE
ASCENT ASSOCIATED WITH A BROAD SHORTWAVE MOVING THROUGH WEST TX
WHICH IS INTERACTING WITH DEEPER LAYER SOUTHERLY FLOW OVERRUNNING
A SURFACE FRONT. SOME WEAK ELEVATED INSTABILITY ADVANCING OVER THE
BOUNDARY WILL ALSO CONTRIBUTE TO SOME POTENTIAL FOR LOCALLY
HEAVIER RAINFALL RATES AND ESPECIALLY SINCE PWATS ACROSS THE
REGION REMAIN RATHER HIGH AT BETWEEN 1.8 AND 2.0 INCHES.

THE LATEST RADAR TRENDS SHOW SOME OF THE HEAVIEST RAINFALL
OCCURRING JUST EAST OF SAN ANGELO WHERE SOME STRONGER CONVECTIVE
ELEMENTS ARE NOTED. SOME ADDITIONAL POCKETS OF HEAVIER RAIN ARE
ALSO NOTED FARTHER NORTH IN BETWEEN THE MINERAL WELLS AND WICHITA
FALLS AREA.

OVER THE NEXT SEVERAL HOURS...SOME POCKETS OF HEAVY RAIN WILL TEND
TO CONTINUE GIVEN THE FAVORABLE SYNOPTIC SCALE FORCING
ENVIRONMENT...HOWEVER SINCE THIS IS OCCURRING MAINLY NORTH OF THE
SURFACE FRONT...IT IS NOT JUXTAPOSED WITH A PARTICULARLY FAVORABLE
INSTABILITY PROFILE. THE AVAILABLE INSTABILITY IS QUITE MODEST AND
GENERALLY ELEVATED.

THE LATEST HRRR GUIDANCE FAVORS SOME 2 TO 4 INCH RAINFALL TOTALS
GOING THROUGH 06Z. THEREFORE...CONCERNS FOR RUNOFF AND SOME FLASH
FLOODING EXIST...BUT OVERALL THE THREAT SHOULD BE RATHER LOCALIZED
AT LEAST THROUGH 06Z.

ORRISON

ATTN...WFO...FWD...LUB...MAF...OUN...SJT...

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

LAT...LON   34059834 33929772 33509727 32919721 32589737
            32089807 31699881 31429954 31010032 31070094
            31580125 32130102 33019994 33719915