MESOSCALE PRECIPITATION DISCUSSION 0699
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
625 PM EDT TUE AUG 15 2017

AREAS AFFECTED...NORTHEAST OK & NORTHWEST AR

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

VALID 152224Z - 160324Z

SUMMARY...THUNDERSTORMS ARE ATTEMPTING TO FORM A TRAINING BAND
NEAR INTERSTATE 44.  HOURLY RAIN TOTALS TO 2.5" WITH LOCAL AMOUNTS
TO 4" ARE EXPECTED.

DISCUSSION...A TRAILING SOUTHWEST FLANK OF A FORWARD PROPAGATING
THUNDERSTORM COMPLEX IN NORTHEAST OK IS ATTEMPTING TO LINK UP WITH
NEW ACTIVITY NEAR OKLAHOMA CITY TO FORM A NEW TRAINING BAND OF
CONVECTION, WITH ADDITIONAL THUNDERSTORMS TRYING TO MERGE IN FROM
THE SOUTH.  DIVERGENCE ALOFT IS BEING AIDED BY A WEAK SHORTWAVE
MOVING THROUGH NORTH-CENTRAL OK WITH AN ADDITIONAL WEAK UPSTREAM
SHORTWAVE NOTED NEAR THE TX PANHANDLE.  PRECIPITABLE WATER VALUES
ARE ~2" PER RECENT RAP MASS FIELD FORECASTS.  INFLOW AT 850 HPA IS
SOUTHWEST AT 20 KTS -- NEAR THE MAGNITUDE OF THE MEAN 850-400 HPA
WIND -- WHICH IS IMPORTING ML CAPE VALUES OF 1000-3000 J/KG INTO
THE THUNDERSTORM AREA.  EFFECTIVE BULK SHEAR IS 30-35 KTS PER SPC
MESOANALYSES. 

CIN CONTINUES TO ERODE HERE WHICH SHOULD ALLOW FOR ADDITIONAL
CONVECTIVE EXPANSION.  SLOWLY INCREASING 850 HPA WINDS COULD LEAD
TO SOME BACKBUILDING.  AT SOME POINT AFTER 01Z, CONVECTION SHOULD
ATTEMPT TO ELEVATE TOWARDS THE 850 HPA REFLECTION OF THE BOUNDARY
TOWARDS THE EASTERN KS/OK BORDER.  THE 12Z SSEO NEIGHBORHOOD
PROBABILITIES HAVE THE STRONGEST SIGNAL FOR HEAVY RAINFALL BETWEEN
NOW AND 01Z BEFORE SHOWING A WEAKENING SIGNAL THEREAFTER.  THE
MESOSCALE GUIDANCE HAS SOME GRASP ON THIS ACTIVITY, AND GENERALLY
ADVERTISES LOCAL AMOUNTS UP TO 3-4".  AVAILABLE MOISTURE AND
INSTABILITY COULD LEAD TO HOURLY TOTALS UP TO 2.5".  SOME
LOCATIONS IN THIS REGION HAVE SEEN TWO WEEK RAINFALL OF 300%+ OF
NORMAL; SOILS IN SOME AREAS ARE PARTIALLY SATURATED.  THE BIGGEST
HEAVY RAIN THREAT WOULD BE TO PARTIALLY SATURATED SOILS AND URBAN
AREAS.

ROTH

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

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

LAT...LON   37189588 37169427 36079402 35249486 34859666
            34929769 35249801 36059733