MESOSCALE PRECIPITATION DISCUSSION 0431
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
441 PM EDT SUN JUL 02 2017

AREAS AFFECTED...CENTRAL/EASTERN OK...FAR NORTHERN TX

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

VALID 022040Z - 030200Z

SUMMARY...SHOWERS AND THUNDERSTORMS WILL DEVELOP AND EXPAND IN
COVERAGE THIS AFTERNOON WITH INCREASED ORGANIZATION TOWARD
EVENING. SOME FLASH FLOODING WILL BECOME POSSIBLE WITH TIME TOWARD
LATE AFTERNOON.

DISCUSSION...THE LATEST EXPERIMENTAL GOES-16 0.64 MICRON/VIS
IMAGERY SHOWS A VERY WELL-DEFINED AND LONG-LIVED MCV MOVING SLOWLY
ACROSS WEST-CENTRAL OK...WITH A TROUGH EXTENSION EXTENDING SOUTH
OF THE RED RIVER INTO NORTHERN TX. THERE IS A BROAD AREA OF SOUTH
TO SOUTHWEST LOW TO MID LEVEL FLOW AHEAD OF THE VORT CENTER WHICH
IS ALLOWING FOR A STRONGLY UNSTABLE AND VERY MOIST AIRMASS TO POOL
ALONG AND NORTH OF THE RED RIVER. IN FACT... THE LATEST RAP
ANALYSIS SHOWS A NOSE OF 3000 TO 3500 J/KG OF MLCAPE AND PWATS OF
1.8 TO 2 INCHES ACROSS THIS AREA.

RADAR IMAGERY IS SHOWING THUNDERSTORMS ALREADY BEGINNING TO
DEVELOP ACROSS PARTS OF CENTRAL OK WITHIN THIS MOSTLY UNCAPPED
ENVIRONMENT...AND WITH ADDITIONAL DIURNAL HEATING/INSTABILITY
EXPECTED THROUGH THE AFTERNOON AND THE APPROACH OF THE VORT
DYNAMICS...A FURTHER UPTICK IN CONVECTIVE EXPANSION/ORGANIZATION
IS EXPECTED. IN FACT...THE LATEST RAP ANALYSIS SHOWS A TIGHTENING
OF THE VORTICITY IN THE 850/700 MB LAYER BETWEEN 21Z AND 00Z ALONG
WITH A RESULTING STRENGTHENING OF THE WIND FIELDS AROUND THE
SOUTHERN FLANK OFF THE VORT CENTER NEAR THE RED RIVER.

THE HIRES MODELS LED BY THE 12Z NSSL-WRF AND THE LATEST HRRR/HRRRX
GUIDANCE APPEAR TO HAVE THE BEST HANDLE ON THE DEGREE OF
CONVECTIVE INITIATION THAT IS UNDERWAY...WITH THE 12Z ARW AND 12Z
NMMB ALREADY A BIT TOO SLOW TO DEVELOP CONVECTION.

THE HRRR/HRRRX GUIDANCE SUPPORTS CONVECTION EXPANDING ACROSS
CENTRAL/EASTERN OK THROUGH THE AFTERNOON...BUT WITH DEVELOPMENT
EXPECTED TOWARD 00Z CLOSER TO THE RED RIVER AND PERHAPS EVOLVING
INTO A RATHER FOCUSED AXIS OF CONVECTION IN A SW/NE OR W/E FASHION
THAT WILL BEGIN TO BE CONDUCIVE FOR CELL-TRAINING GIVEN THE
STRENGTHENING WIND FIELDS ACROSS THIS REGION AND TRANSPORT OF VERY
MOIST/UNSTABLE AIR.

RAINFALL RATES OF 2.5 INCHES/HR WILL BE EXPECTED WITHING THE
STRONGER CONVECTIVE CORES...AND THE LATEST HIRES MODEL SIGNALS
SUGGEST AS MUCH AS 3 TO 5 INCHES OF RAINFALL TO BE POSSIBLE AT
LEAST LOCALLY THROUGH MID-EVENING...WITH MORE RAIN LIKELY
OVERNIGHT ACROSS AREAS ADJACENT TO THE RED RIVER...AS WELL AS
SOUTHEAST OK AND POSSIBLY WESTERN AR. FLASH FLOODING WILL BECOME
AN INCREASING CONCERN WITH TIME OVER ALL OF THESE AREAS THROUGH
THE EVENING HOURS.

ORRISON

ATTN...WFO...FWD...ICT...OUN...SHV...TSA...

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

LAT...LON   37029743 36819582 36039483 35109459 34229496
            33539596 33269668 33169750 33299799 33449823
            33789821 34529764 35359753 35949774 36489819
            36829807