MESOSCALE PRECIPITATION DISCUSSION 0434
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
205 AM EDT MON JUL 03 2017

AREAS AFFECTED...SOUTHWEST OK....NORTHEAST TX...WESTERN AND
CENTRAL AR

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

VALID 030605Z - 031005Z

SUMMARY...CONVECTION ASSOCIATED WITH A LONG LIVED MCV COULD
PROVIDE PRODUCE A FLASH FLOOD THREAT ACROSS SOUTHEAST OK/NORTHEAST
TX INTO MUCH OF WESTERN AR THROUGH THE EARLY MORNING HOURS.

DISCUSSION...MUCH OF THE EARLIER CONVECTION ACROSS SOUTHEAST OK
HAS BECOME OUTFLOW DOMINATED...AS EVIDENCED BY THE LATEST REGIONAL
RADAR LOOP. THE OUTFLOW BOUNDARY HAS PROGRESSED INTO FAR NORTHEAST
TX...AND MAY BE SLOWING ITS SOUTHEAST MOTION. MEANWHILE...A
LONG-LIVED MCV IS CROSSING EASTERN OK INTO WESTERN AR
(AGAIN...BEST VIEWED IN THE REGIONAL RADAR IMAGERY). THE
EXPERIMENTAL GOES 16 CLEAN IR LOOP SHOWED THE CORE OF THE COLDEST
CLOUD TOPS ASSOCIATED WITH THE OUTFLOW BOUNDARY OVER NORTHEAST
TX...AND TRENDS SUGGEST THAT THE CONVECTION HAS REACHED A STEADY
STATE.

AHEAD OF THE MCV...AN AXIS OF 1000-1500 J/KG OF MLCAPE HAS OPENED
UP OVER SOUTHWEST AND CENTRAL AR. THE MOISTURE IS VERY HIGH IN
THIS AXIS...WITH THE LATEST RAP ANALYSIS AND BLENDED TPW IMAGERY
SHOWING PRECIPITABLE WATER VALUES NEAR 2.00 INCHES. IN THE NEAR
TERM...THE GREATEST THREAT FOR FLASH FLOODING APPEAR TO BE AHEAD
OF THE MCV. THE COMBINATION OF INSTABILITY AND DEEP MOISTURE...FED
BY AN INCREASING LOW LEVEL SOUTHWESTERLY FLOW...WOULD SUGGEST THAT
CONVECTION COULD REFIRE OVER PORTIONS OF WESTERN AND CENTRAL AR IN
THE BEST INSTABILITY AXIS.

THE MOST RECENT HRRR RUN SHOWED 3.00 TO 5.00 INCHES OF RAINFALL
AMOUNT OF THE MCV OVER NORTH CENTRAL AR...AND MUCH OF THE
AVAILABLE HIGH RESOLUTION GUIDANCE HAS HIGHER RAINFALL AMOUNTS
ASSOCIATED WITH THE MCV. OTHER SOLUTIONS...LIKE THE 00Z NAM CONUS
NEST AND THE 00Z NSSL WRF...KEY MORE HEAVILY ON THE OUTFLOW
DOMINATED CONVECTION FOR THE HIGHER RAINFALL AMOUNTS.

AT THIS POINT...THE BEST FORCING AND INSTABILITY APPEARS TO BE
LINKED TO THE MCV...AND TO A LESSER DEGREE CONVECTION ON THE
OUTFLOW BOUNDARY INTO FAR NORTHEAST TX. SINCE THERE IS A SPLIT IN
THE GUIDANCE CONCERNING THE PLACEMENT OF THE HIGHER QPF...AND SOME
CONCERN THAT THE FORECAST PROCESSES DO NOT COME INTO PHASE FOR
FLASH FLOODING...THE THREAT FOR FLASH FLOODING APPEARS TO BE
POSSIBLE.

HAYES

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

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

LAT...LON   36529208 36329167 35139149 34699192 33679329
            33119537 33039623 33419662 34099633 34339610
            34679576 34869534 34949494 35179426 35849388
            36259346 36469298