MESOSCALE PRECIPITATION DISCUSSION 0229
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
734 PM EDT THU MAY 18 2017

AREAS AFFECTED...SOUTHERN OK...NORTHERN TEXAS

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 182333Z - 190403Z

SUMMARY...SMALL COMPLEX CONTINUES TO GROW AND SLOWLY MARCH EAST
WITHIN FAVORABLE ENVIRONMENT TO CONTINUE TO POSE FLASH FLOODING
CONCERN.

DISCUSSION...REGIONAL RADAR AND EXPERIMENTAL GOES-16 MESO WINDOW
IMAGERY INDICATE A CLUSTER OF SUPERCELLS THAT HAVE MERGED INTO A
HIGHER SCALE COMPLEX ALONG THE RED RIVER THAT WILL BE MAINTAINED
FROM UNENCUMBERED INFLOW THAT IS CHARACTERIZED BY HIGH INSTABILITY
(3500+ J/KG MLCAPES) FROM UPPER 80S TEMPS AND MID TO UPPER 60S TDS
TRANSPORTED BY 15-20KT SSELY SFC AND 25-35KT 850MB FLOW.  THE
STRONG SHORTWAVE ENTERING THE W OK PANHANDLE IS TRACKING NE AND IS
DISTANT ENOUGH THAT THE MID-LEVEL TROF/FORCING DENOTED BY 10-15
METERS OF 7H HEIGHT FALLS IN THE 18Z GFS ENDS IN THE PROXIMITY OF
THE RED RIVER COINCIDENT WITH THE COMPLEX SUPPORTING AN
ORIENTATION THAT IS ABOUT 70-90 DEGREES FROM THE INFLOW AND WITH
WEAK MID-LEVEL DIVERGENCE...THIS SUPPORTS ADDITIONAL BACKBUILDING
ALONG THE DRY-LINE TO FURTHER SLOW THE EASTWARD PROGRESSION OF THE
COMPLEX ALLOWING FOR COMPOUNDING RAINFALL.

TO EXACERBATE THE FLOODING POTENTIAL... STRONG/LARGE SUPERCELL TO
THE SOUTH IS ALSO SHEDDING LEFT MOVING CELLS TO MERGE INTO THE
COMPLEX.  ALONG WITH NEW CONVECTION/OVERSHOOTING TOPS BREAKING
THROUGH THE DOWNSTREAM CANOPY WETTING THE GROUNDS IN ADVANCE OF
THE COMPLEX.  THERE IS SUGGESTION OF A POTENTIALLY THREATENING
FLASH FLOODING SCENARIO EVOLVING THROUGH THE EVENING WITH THE
COMPLEX.  HI-RES GUIDANCE SUGGESTED CONVECTION BUT HAS FAILED TO
CAPTURE THE ADDITIONAL UPSCALE INFLUENCES TO ALLOW FOR THIS
CULMINATION OF FACTORS FOR A SWATH OF RAINFALL TOTALS OF 3-5"
ALONG THE RED RIVER THROUGH THE LATE EVENING/EARLY OVERNIGHT
HOURS.

GALLINA

ATTN...WFO...FWD...OUN...SJT...TSA...

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

LAT...LON   35399623 34989546 33909557 33419659 33209812
            33279916 33809940 34359888 34979773