MESOSCALE PRECIPITATION DISCUSSION 0233
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
758 AM EDT WED JUL 30 2014
 
AREAS AFFECTED...PORTIONS OF NORTHERN TX AND OK 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 301157Z - 301757Z
 
SUMMARY...THUNDERSTORMS WITH HIGH RAINFALL RATES ARE POSSIBLE OVER
THE NEXT SEVERAL HOURS JUST POLEWARD OF AN EFFECTIVE FRONTAL ZONE.
 FLASH FLOODING IS CONSIDERED POSSIBLE IN THIS REGION.

DISCUSSION...AN EFFECTIVE FRONT IS LOCATED ACROSS NORTHERN TX THIS
MORNING WHICH IS ACTING AS THE SOUTHERN FRINGE OF SHOWER AND
THUNDERSTORM ACTIVITY THIS MORNING.  PRECIPITABLE WATER VALUES OF
~2" LIE IN THE REGION, WHICH ARE 2-2.5 STANDARD DEVIATIONS ABOVE
NORMAL, OR TOWARDS THE 99TH PERCENTILE FOR LATE JULY.  SLIGHT
CAPPING IS INDICATED NEAR THE EFFECTIVE FRONT BY 700 HPA
TEMPERATURES NEAR THE TX PANHANDLE WARMING TO SLIGHTLY ABOVE 12C
THIS MORNING.  AN ONGOING MCV NEAR THE OK/KS BORDER IS SHOWING
DECREASING RAINFALL RATES AS THUNDERSTORMS FARTHER SOUTH AND
SOUTHWEST INTERCEPT AVAILABLE INSTABILITY FROM THE WARM SECTOR. 
BROAD INFLOW AT 850 HPA IS SOUTH TO SOUTHWEST AT 25-35 KTS, WHILE
MOST UNSTABLE CAPE VALUES OF ~1000 J/KG LIE IN THE WARM SECTOR PER
THE MOST RECENT SPC MESOSCALE ANALYSIS.  RADAR IMAGERY SHOWS THE
BACK EDGE OF THE THUNDERSTORM ACTIVITY FORWARD PROPAGATING AT ~20
KTS TO THE EAST-SOUTHEAST.

THE MESOSCALE QPF GUIDANCE SHOWS A MODERATE SIGNAL FOR HEAVY
RAINFALL IN THIS REGION, THOUGH MOST OF THE GUIDANCE APPEARS TO BE
ERRANTLY PLACING IT ACROSS NORTHERN OK AND SOUTHERN KS -- RECENT
HRRR RUNS AND THE 00Z SPC WRF APPEAR TO BE CAPTURING THE
CONVECTIVE EVOLUTION THE BEST, SO FAR.  EXTRAPOLATION OF RADAR
IMAGERY ALONG WITH CURRENT BOUNDARY LOCATION IMPLY A MUCH MORE
SOUTHERLY LOCATION IS LIKELY ACROSS WESTERN AND SOUTHERN OK.  THE
06Z GFS SHOWED A REGION OF UNSEASONABLE LOW- TO MID-LEVEL
FRONTOGENESIS ACROSS WESTERN AND CENTRAL OK WHICH IS BEING USED AS
THE NORTHERN BOUND OF THIS REGION, WITH THE EXPECTED EASTWARD
EXTENT OF 25+ KT INFLOW (WHICH SLOWLY RAMPS UP INTO CENTRAL OK)
BEING USED AS ITS EASTERN LIMIT AND THE EFFECTIVE FRONT BEING USED
AS THE SOUTHERN BOUND.  CAPE VALUES IN THE WARM SECTOR ARE
EXPECTED TO START RAMPING UP BEYOND 14Z DUE TO DAYTIME HEATING. 
CELL TRAINING IS EXPECTED AS FORWARD PROPAGATING CONVECTION
OCCASIONALLY ALIGNS, WITH AVAILABLE MOISTURE IMPLYING HOURLY RAIN
RATES UP TO 2.5" AN HOUR ARE POSSIBLE.  THE MORE RELIABLE
MESOSCALE GUIDANCE ADVERTISES LOCAL AMOUNTS OF 2-4" IN THIS
REGION, WHICH WOULD EXCEED FLASH FLOOD GUIDANCE VALUES.  FLASH
FLOODING IS CONSIDERED POSSIBLE IN THIS REGION.

ROTH

ATTN...WFO...TSA...FWD...OUN...LUB...AMA...

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

LAT...LON   35149627 34199598 33379672 33249750 33409848 33999989
            34580073 35490166 36360188 36509979 36329848 35929714
            35149627