MESOSCALE PRECIPITATION DISCUSSION 0091
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
937 AM EDT SUN APR 02 2017

AREAS AFFECTED...CENTRAL AND EASTERN TEXAS

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

VALID 021336Z - 021636Z

SUMMARY...FLASH FLOODING IS LIKELY ACROSS PORTIONS OF CENTRAL AND
EASTERN TEXAS THROUGH NOON. THIS FORECAST SUPERCEDES MPD NUMBER 90.

DISCUSSION...RADAR TRENDS CONFIRM THAT THE CONVECTIVE LINE WEST OF
SAN ANTONIO IS STRONGER, BETTER ORGANIZED, AND LONGER LASTING THAN
DEPICTED BY NEARLY ALL AVAILABLE HIGH RES AND GLOBAL GUIDANCE,
WITH THESE TRENDS LIKELY DUE TO MODELS' INABILITY TO COMPLETELY
RESOLVE DOWNDRAFT DEVELOPMENT AND THE REAR INFLOW JET PUSHING THE
LINE FORWARD. DESPITE THESE SHORTCOMINGS HOWEVER, HIGH-RES
GUIDANCE, PARTICULARLY THE HRRR, SPC-WRF, NSSL-WRF, ETC, SUPPORT A
NORTHEASTWARD TREND WITH TIME, AS THE MID LEVEL FLOW BACKS AND
STRENGTHENS WITH THE APPROACHING SHORTWAVE TROUGH, WHICH IS
SUPPORTED BY GOES-R MID LEVEL WATER VAPOR IMAGERY DEPICTING THE
SLOWLY NORTHWARD EXPANDING ELEVATED MIXED LAYER OVER SOUTH TEXAS.

THE SQUALL LINE IS EXPECTED TO CONTINUE MOVING EASTWARD AROUND 25
KNOTS THROUGH LATE MORNING, AND SHOULD EVENTUALLY MERGE WITH THE
CLUSTER OF EXPANDING SUPERCELLS OVER EAST TEXAS, WHICH HAVE
DEVELOPED IN RESPONSE TO STRONG MOISTURE FLUX FROM THE LEADING
EDGE OF DEEPER MOISTURE AND DECELERATING LOW LEVEL JET. THE
INVERTED TROUGH EXTENDING NORTHEAST OF THE SURFACE LOW IS A THIRD
REGION FOR ENHANCED CONVECTIVE DEVELOPMENT AND HEAVY RAINFALL.

WHILE ALL REGIONS OF CONVECTION WILL BE ACCOMPANIED BY STRONG TO
INTENSE RAIN RATES, THAT COULD PRODUCE LOCALIZED FLASH FLOODING,
THE REGION NORTH OF THE STATIONARY FRONT THAT IS BETWEEN THE
CONVECTIVE LINE AND CLUSTER OF SUPERCELLS HAS THE BEST CHANCE OF
TRAINING DUE TO  VEERING WIND PROFILES. WHILE FFG IS RELATIVELY
HIGH, THE POTENTIAL FOR HOURLY RATES TO APPROACH 1.5 TO 2 INCHES
PER HOUR WITH POTENTIAL FOR REPEATING EVENTS, SUPPORTS THIS
LIKELIHOOD.

JAMES

ATTN...WFO...EWX...FWD...HGX...LCH...SHV...

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

LAT...LON   32159538 31409441 30429493 29939624 29469701
            28669833 29069899 30269859 31829721