MESOSCALE PRECIPITATION DISCUSSION 0120...CORRECTION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
539 PM EDT SUN APR 16 2017

AREAS AFFECTED...SOUTH-CENTRAL OK & VICINITY

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 162136Z - 170136Z

SUMMARY...AN EXPANDING THUNDERSTORM COMPLEX JUST NORTH OF THE RED
RIVER HAS BEEN PRODUCING RAIN RATES OF AT LEAST 3" AN HOUR.  A
CONTINUATION OF THESE RATES APPEARS LIKELY OVER A BROADER AREA FOR
THE NEXT FOUR HOURS.

DISCUSSION...A THUNDERSTORM COMPLEX HAS BEEN SLOWLY GROWING IN
COVERAGE WHILE BACKBUILDING, WITH THE FIRST THUNDERSTORMS FORMING
AT 1830Z AND THE RAMPING UP OF THE SMALL CLUSTER AT 1930Z.  CLOUD
CLOUD TOPS CONTINUE TO EXPAND IN COVERAGE WITHIN SATELLITE
IMAGERY.  VENTILATION ALOFT APPEARS TO BE AIDED BY AN OLD MCV FROM
YESTERDAY'S CONVECTION, MOVING INTO THE TX HILL COUNTRY AT THIS
TIME, AND A SHORTWAVE MOVING BY TO ITS NORTH ACROSS KS.  THE
CONVECTIVE EXPANSION HAS CONTINUED AS 850 HPA INFLOW HAS SLOWLY
INCREASED FROM 15-20 KTS OUT OF THE SOUTH.  PRECIPITABLE WATER
VALUES ARE NEAR 1.5".  INSTABILITY IS SIGNIFICANT, WITH MLCAPES
BETWEEN 2000-4000 J/KG, WHICH IS KEEPING THE CONVECTION TIED TO AN
OLD OUTFLOW BOUNDARY IN ITS VICINITY.  BULK SHEAR IN THE 0-6 KM
LAYER IS ABOUT 25 KTS, JUST SUFFICIENT FOR ORGANIZATION.  NEW
ACTIVITY HAS BEEN BUILDING TO ITS WEST WHERE INSTABILITY IS
GREATEST, THOUGH THE BEGINNING SIGNS OF FORWARD PROPAGATION TO THE
EAST-SOUTHEAST HAS BEEN EVIDENT OVER THE PAST 30-60 MINUTES ON
RADAR IMAGERY OF THE HEAVY RAIN CORE(S).

WITH 850 HPA INFLOW EXPECTED TO RAMP UP FURTHER TOWARDS 30 KTS BY
01Z, EXPECT A CONTINUATION OF THE BACKBUILDING TO THE
WEST-NORTHWEST AND A SLOW WEST-NORTHWEST/ EAST-SOUTHEAST EXPANSION
TO THE CONVECTIVE CLUSTER, EVENTUALLY AT A PACE OF 15-20 KTS. 
WITH THE COMBINATION OF BACKBUILDING AND TRAINING, HOURLY RAIN
RATES UP TO 3", WITH LOCAL AMOUNTS OF 4-8", APPEAR LIKELY, WHICH
WOULD CONTINUE AND BROADEN THE FLASH FLOODING CONCERN.

ROTH

ATTN...WFO...FWD...OUN...

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

LAT...LON   34939842 34589753 34039660 33419693 33749797
            34339870 34839891