MESOSCALE PRECIPITATION DISCUSSION 0635
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1035 AM EDT SUN AUG 06 2017

AREAS AFFECTED...SOUTHEAST OK...NORTHEAST TX...SOUTHWEST AR

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

VALID 061435Z - 061915Z

SUMMARY...UPSTREAM REDEVELOPMENT HAS POTENTIAL FOR TRAINING/REPEAT
STORM TRACKS INCREASING POTENTIAL FOR FLASH FLOODING.

DISCUSSION...RADAR/SFC ANALYSIS DEPICTS SQUALL LINE/OUTFLOW
BOUNDARY CONTINUING TO PRESS SOUTHEAST AT A MODEST PACE WITH BEST
EASTWARD PROPAGATION CONTINUING FROM COLD POOL RIDGING OVER E OK/W
AR ATTM.  THIS HAS FLATTENED THE OUTFLOW BOUNDARY MORE E-W ALONG
THE OK/TX RED RIVER BACK TO AROUND DUA.  SURFACE CYCLONE IN SW OK
ALONG WITH DEVELOPING WAVE IN NE OK...CURRENTLY SUPPORTS LOW LEVEL
INFLOW (PER VWP NETWORK) INTO THE BACK EDGE OF THE OUTFLOW
BOUNDARY. THIS SUPPORTS ISENTROPIC ASCENT SUFFICIENT TO DEVELOP
NEW CONVECTION ON THE UPWIND SIDE MAINLY IN BRYANT COUNTY.

CURRENTLY MEAN CLOUD BEARING FLOW WOULD BE ABOUT 20KTS TO THE EAST
AND WITH 30-35KTS OF INFLOW...BACKBUILDING IS EXPECTED THOUGH WILL
ALSO ALLOW FOR SOME REMAINING SOUTHEAST PROPAGATION...PARTICULARLY
FURTHER EAST (SW AR). IT SHOULD BE NOTED THAT FURTHER UPSTREAM 
PERCOLATION OF TCU IS NOTICED IN GRAYSON AS WELL BACK TO
CARTER/MURRAY COUNTIES SUGGESTING EVEN FURTHER EXPANSION OF THE
LINE.  GIVEN MUCAPES UP TO 2000 J/KG AND TPWS IN THE VICINITY OF
2"...RAIN RATES WILL CONTINUE TO BE QUITE EFFICIENT AND COMPARABLE
TO VALUES NOTED OVER E OK AROUND 2"/HR.  SO TRAINING OR REPEAT
TRACKS OF MULTIPLE ROUNDS OF CONVECTION POSE A FLASH FLOODING
THREAT WITH 2-4" PERHAPS OVER LOCATIONS THAT HAVE ALREADY RECEIVED
2+" FROM MAIN SQUALL LINE IN SE OK/EXT NE TX.

EXPECTATION IS FOR FURTHER DEEPENING OF THE SURFACE WAVE AS IT
SLIDES EAST INTO N AR/SW MO.  WHILE EXITING DRIVER OF STRONG
FORCING...INFLOW WILL WEAKEN BUT WILL ALSO ALSO SHIFT TO SUPPORT
MAINTAINING THE AXIS OF HEAVY RAINFALL/CELL MOTION IN THE VICINITY
OF THE RED RIVER FURTHER COMPOUNDING TRAINING AND THEREFORE
CONTINUE FLASH FLOODING THREAT INTO THE AFTERNOON HOURS.  THIS IS
SUPPORTED BY RECENT TRENDS IN THE HRRR.

GALLINA

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

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

LAT...LON   34529639 34399562 34289460 34139294 33629262
            33119284 32999335 32929441 32989499 33229559
            33519624 33869665