MESOSCALE PRECIPITATION DISCUSSION 0370
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
605 AM EDT FRI SEP 12 2014
 
AREAS AFFECTED...NORTHEAST TX/SOUTHEASTERN OK/SOUTHWESTERN AR... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 121004Z - 121349Z
 
SUMMARY...AN ORGANIZED AREA OF CONVECTION HAS BEGUN TO ALIGN
EAST-WEST ALONG THE 850-MB FRONT. MOISTURE CONTENT IS MORE THAN
ADEQUATE WITH PWATS BEING RESOLVED IN THE 2 TO 2.25 INCH RANGE PER
THE 08Z RAP ANALYSIS. EXPECT HOURLY RAINFALL RATES OF 1 TO 2
INCHES WHICH MAY LOCALLY TRUMP THE FFG VALUES.

DISCUSSION...A RATHER WEAK LLJ HAS EVOLVED OVERNIGHT WITH 850-MB
WINDS REACHING 20 KNOTS ACCORDING TO SOME OF THE VAD WIND
PROFILERS. BROAD ASCENT ACCOMPANYING THIS JET HAS HELPED
INVIGORATE AN EXPANSIVE AXIS OF CONVECTION WHICH HAS BEGUN TO
FOCUS ALONG AN 850-MB FRONTAL ZONE. MODERATE TO HEAVY RAINFALL HAS
SPREAD ALONG THE EASTERN EXTENT OF THE RED RIVER TOWARD THE
OK/AR/TX BORDER. THIS HAS POSITIONED ITSELF ALONG THE NORTHERN
FRINGE OF THE INSTABILITY GRADIENT WITH 1000 J/KG OF MUCAPE NOTED
IN THE OBJECTIVE ANALYSIS. IT WOULD APPEAR THE ACTIVITY WILL NOT
MIGRATE ANY FARTHER NORTH GIVEN THE INHIBITION FURTHER INTO THE
COOL AIR. THE FORECAST STORM PROPAGATION VECTORS SUGGEST THE
INDIVIDUAL CELLS WILL DRIFT EASTWARD WHICH MAY RESULT IN REPEAT
CONVECTION AND/OR MULTIPLE STORM MERGERS. THEREFORE...EXPECT
PERIODIC EPISODES OF FLASH FLOODING...PARTICULARLY IN REGIONS
WHERE FFG VALUES ARE MINIMIZED.

THE HIGH-RESOLUTION GUIDANCE ARE FAIRLY CONSISTENT IN THE
EAST-WEST AXIS OF CONVECTION STRADDLING THE RED RIVER. THE 08Z
HRRR AND 00Z GEM REGIONAL MAINTAIN THE HEAVIER AXIS OF RAINFALL
ACROSS NORTHEAST TX/SOUTHEASTERN OK. OTHER MODELS INCLUDING THE
00Z NSSL-WRF/SPC-WRF/SSEO MEAN SPREAD THE PRECIPITATION FARTHER
EAST INTO SOUTHERN AR. WILL REEVALUATE THE SITUATION IN A FEW
HOURS ONCE 12Z RAOBS AND ADDITIONAL MODEL GUIDANCE ARRIVE.


RUBIN-OSTER

ATTN...WFO...FWD...LZK...OUN...SHV...TSA...

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

LAT...LON   34579518 34519389 34159274 33419254 33089296 
            33009374 33199533 33139638 32939745 33019818 
            33929830 34409682