MESOSCALE PRECIPITATION DISCUSSION 0121...CORRECTION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
815 PM EDT SUN APR 16 2017

AREAS AFFECTED...CENTRAL & EASTERN KS/OK BORDER, SW MO, & NW AR

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

VALID 170008Z - 170608Z

SUMMARY...BUILDING CONVECTION ALONG THE KS/OK BORDER IS EXPECTED
TO INCREASE IN COVERAGE OVER THE NEXT SEVERAL HOURS.  HOURLY RAIN
RATES TO 1.75", WITH LOCAL AMOUNTS OF 2-4", COULD LEAD TO FLASH
FLOODING.

DISCUSSION...A THERMAL BOUNDARY NEAR THE CENTRAL AND EASTERN KS/OK
BORDER HAS BEEN ACTING AS A FOCUS FOR THUNDERSTORMS AS OF LATE.  A
SHORTWAVE HAS BEEN MOVING ACROSS CENTRAL KS AS OF LATE, HELPING
UPPER LEVEL OUTFLOW.  A WANING CONVECTIVE COMPLEX IN SOUTHERN OK
MAY ALSO BE PRODUCING A WEAK OUTFLOW JET AIMING TOWARD THE REGION.
 INFLOW AT 850 HPA IS 20 KTS FROM THE SOUTHWEST, AND 0-6 KM BULK
SHEAR VALUES ARE NEAR 35 KTS.  PRECIPITABLE WATER VALUES ARE NEAR
1.5".  LOW-LEVEL INFLOW IS IMPORTING MLCAPES OF 1000-2000 J/KG
INTO THE REGION.

THE MESOSCALE GUIDANCE SHOWS A RELATIVELY COHERENT SIGNAL FOR
HEAVY RAIN.  CONVECTIVE COVERAGE IS EXPECTED TO INCREASE AS THE
850 HPA INFLOW RISES TOWARDS 40 KTS, WHICH IS 10-15 KTS ABOVE THE
MEAN 850-400 HPA WIND -- THIS SHOULD INCREASE PRECIPITATION
EFFICIENCY.  AS LOW-LEVEL INFLOW RAMPS UP, THUNDERSTORMS COULD
SHOW BACKBUILDING CHARACTERISTICS.  WHILE COLD POOL GENERATION
COULD ALLOW THE SURFACE BOUNDARY TO SAG SOMEWHAT SOUTHWARD IN
EASTERN OK,  IN A FEW HOURS, CIN SHOULD SET IN WHICH SHOULD ALLOW
THE 850 HPA SLICE OF THE FRONTAL BOUNDARY TO BECOME THE MAIN FOCUS
FOR CONVECTION.  BY 06-07Z, LOW-LEVEL INFLOW VEERS TO WEST-
SOUTHWESTERLY, MAKING THE FLOW REGIME UNIDIRECTIONAL WITH HEIGHT,
IMPLYING CELL TRAINING CONCERNS.  PROPAGATION OF THE HEAVY RAIN
CORES SHOULD START OUT AS WEST TO EAST AT 20-25 KTS BEFORE
SHIFTING MORE IN AN EAST-SOUTHEAST TO SOUTHEAST DIRECTION AS
INSTABILITY ERODES/WANES OVERNIGHT.  HOURLY RAIN RATES UP TO 1.75"
ARE EXPECTED, WITH LOCAL AMOUNTS OF 2-4".  WITH SLIGHTLY DEPRESSED
FLASH FLOOD GUIDANCE FROM LAST NIGHT'S RAIN (DOWN TO 2-2.5" IN
THREE HOURS), FLASH FLOODING IS CONSIDERED POSSIBLE.

ROTH

ATTN...WFO...ICT...LZK...OUN...SGF...TSA...

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

LAT...LON   37469531 37379398 36999327 35509372 35479564
            35369787 35219897 36489899 37159760