MESOSCALE PRECIPITATION DISCUSSION 0771
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
107 AM EDT THU AUG 31 2017

AREAS AFFECTED...NRN LA...NWRN MS...ERN AR...WRN TN

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

VALID 310505Z - 311105Z

SUMMARY...GROWING POTENTIAL FOR MODERATE TO HEAVY RAINS NORTHEAST
OF HARVEY...LEADING TO LOCALIZED RUNOFF CONCERNS.

DISCUSSION...40-50 KT SOUTHERLY LOW LEVEL WINDS EAST OF HARVEY ARE
EXPECTED TO PERSIST THROUGH THE REMAINDER OF THE OVERNIGHT
HOURS...DRAWING DEEP MOISTURE INTO A REGION OF ENHANCED LIFT TO
THE NORTHEAST OF HARVEY.  LATEST SPC MESOANALYSIS SHOWS AN AXIS OF
2.3 TO 2.4 INCH PWS COINCIDING WITH AN INVERTED LOW LEVEL TROUGH
EXTENDING NORTHEAST OF HARVEY ACROSS SOUTHWESTERN AR INTO WESTERN
TN.  AS STRONG LOW LEVEL WINDS CONTINUE TO DRAW MOISTURE INTO THE
REGION...A QUASI-STATIONARY UPPER LEVEL SHORTWAVE TROUGH TO THE
WEST WILL SUPPORT AN AXIS OF STRONG DIVERGENCE ALOFT.  THIS IS
EXPECTED TO HELP DEVELOP A GROWING AREA OF MODERATE TO HEAVY RAINS
NORTHEAST OF THE CENTER. 

WHILE DIFFERING ON THE DETAILS...THE GENERAL CONSENSUS OF THE 00
UTC OPERATIONAL AND PARALLEL VERSIONS OF THE HRW-ARW AND NMMB...AS
WELL AS RECENT RUNS OF THE HRRR...SHOW WIDESPREAD 1-2 INCH
AMOUNTS...WITH LOCALLY HEAVIER AMOUNTS DURING THE 6 HR PERIOD
ENDING 11 UTC.  FLASH FLOOD GUIDANCE VALUES ARE RELATIVELY
HIGH...SUGGESTING A MORE LIMITED FLASH FLOODING THREAT ACROSS MUCH
OF THE HIGHLIGHTED AREA.  AN EXCEPTION WOULD BE ALONG AND NEAR
PORTIONS OF THE SOUTHERN AR/MS AND NORTHERN MS/LA BORDERS...WHERE
THERE ARE SOME LOCALLY 3-HR FLASH FLOOD GUIDANCE VALUES OF 1.5
INCHES OR LESS.

PEREIRA

ATTN...WFO...JAN...LZK...MEG...SHV...

ATTN...RFC...ABRFC...LMRFC...

LAT...LON   35898941 35498915 35218972 34659032 33629017
            32959022 32319036 32089055 32179095 32659155
            32729201 32289263 32289309 32709330 33419297
            34449237 35279149 35869039