MESOSCALE PRECIPITATION DISCUSSION 0444
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
135 AM EDT WED JUL 05 2017

AREAS AFFECTED...THE RED RIVER VALLEY OF TX/OK INTO FAR SOUTHWEST
AR

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

VALID 050540Z - 051000Z

SUMMARY...CONVECTION FORMING AHEAD OF A FRONTAL BOUNDARY IS
EXPECTED TO TRAIN ACROSS THE RED RIVER VALLEY OF TX/OK...
RESULTING IN A FLASH FLOOD THREAT EARLY THIS MORNING.

DISCUSSION...REGIONAL RADARS SHOWED A SLOWLY EXPANDING LINE OF
CONVECTION STRETCHING FROM NORTH OF KTLS TO SOUTH OF KMLC IN OK.
THE CONVECTION IS FORMING IN AN AXIS OF 500-1000 J/KG OF MUCAPE
AHEAD OF THE FRONT. THE RED RIVER VALLEY LIES ON THE WESTERN EDGE
OF A PRECIPITABLE WATER AXIS...WITH VALUES BEAR 1.90 INCHES OVER
FAR SOUTHEAST OK  AND FAR SOUTHWEST AR.

THE LOW LEVEL CONVERGENT FLOW ALONG THE LOW LEVEL BOUNDARY IS
EXPECTED TO HELP FOCUS THE CONVECTION INTO A FAIRLY NARROW BAND.
LIFT AHEAD OF A VORTICITY MAXIMUM MOVING EAST FROM THE NORTHERN TX
PANHANDLE SHOULD PROVIDE SUFFICIENT LIFT TO SUPPORT EXPANDING
CONVECTION ALONG THE LINE...AND RAP SOUNDINGS ALONG THE RED RIVER
SHOWED MUCAPE VALUES INCREASING TO BETWEEN 1000-1500 J/KG BETWEEN
06Z AND 10Z.

THERE IS A STRONG HIGH RESOLUTION MODEL GUIDANCE SIGNAL FOR 3.00
TO 5.00 INCHES OF RAINFALL CENTERED OVER SOUTHEAST OK AND FAR
NORTHEAST TX...MAINLY BETWEEN 08Z AND 10Z. THESE AMOUNTS ARE
SUPPORTED BY THE MOST RECENT RUNS OF THE HRRR...AS WELL AS THE 00Z
WRF-ARW. ONE AND THREE HOUR FLASH FLOOD GUIDANCE VALUES HERE HAVE
RECOVERED TO NEAR 1.50 INCHES AFTER THE HEAVY RAINFALL ABOUT 48
HOURS AGO.

HOWEVER...THE MOST RECENT HRRR SOIL MOISTURE PRODUCT INDICATES
THAT SOILS ACROSS PORTIONS OF SOUTHEAST OK AND NEARBY SOUTHWEST AR
MAY BE CLOSE TO SATURATION... AND THE ABOVEMENTIONED RAINFALL
AMOUNTS COULD TRIGGER FLASH FLOODING.

RAP PROPAGATION VECTORS SUGGEST A SLOW SOUTHWARD MOVEMENT AFTER
THE CONVECTION DEVELOPS...AND THERE IS SOME SUGGESTION THAT THE
CONVECTION AFTER 12Z.

HAYES

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

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

LAT...LON   35379930 35019812 33999483 33799414 33799414
            33119435 33759700 34519911 34679940 35199959