MESOSCALE PRECIPITATION DISCUSSION 0392
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
821 AM EDT SAT JUN 24 2017

AREAS AFFECTED...NORTHERN/CENTRAL TX

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

VALID 241220Z - 241820Z

SUMMARY...HEAVY SHOWERS AND THUNDERSTORMS WITH EXTREMELY HEAVY
RAINFALL RATES WILL TEND TO PERSIST FOR AT LEAST A COUPLE MORE
HOURS. SOME LOCALIZED FLASH FLOODING IS POSSIBLE.

DISCUSSION...EXPERIMENTAL GOES-16 10.3 MICRON/IR IMAGERY SHOWS
SOME IMPRESSIVELY COLD CONVECTIVE TOPS THIS MORNING OVER NORTHERN
TX AND DROPPING GRADUALLY SOUTH TOWARD THE TX HILL COUNTRY. SOME
OF THE COLDEST TOPS ARE OVER EASTLAND...ERATH AND COMMANCHE
COUNTIES...WHERE A COUPLE OF OVERSHOOTING TOPS HAVE PUSHED CLOUD
TOP TEMPS DOWN TO BELOW -80C. THE CONVECTION IS ASSOCIATED WITH
THE SOUTHWARD ADVANCE OF A COLD FRONT INTO A VERY MOIST AND
UNSTABLE AIRMASS OUT AHEAD OF IT AND IS BEING FOCUSED ALSO RATHER
CLOSE TO A WAVE OF LOW PRESSURE. THERE ARE ALSO MULTIPLE OUTFLOW
BOUNDARIES PUSHING SOUTH AND EVEN SOUTHWEST AHEAD OF THE SYNOPTIC
BOUNDARY.

THE UPPER LEVEL FLOW IS RATHER DIFFLUENT OVER THE REGION AND WITH
AS MUCH AS 2000 J/KG OF MUCAPE STILL POOLED OUT ACROSS THE TX HILL
COUNTRY...THE CONVECTION SHOULD TEND TO PERSIST STILL FOR A WHILE
AND GRADUALLY SETTLE FARTHER SOUTH. AREAS FARTHER NORTH ESPECIALLY
OVER NORTHERN TX WHERE THERE HAVE ALREADY BEEN SOME HEAVY RAIN
WILL STILL SOME MODERATE TO LOCALLY HEAVY STRATIFORM RAIN...ALONG
WITH SOME EMBEDDED CONVECTIVE ELEMENTS WITH HEAVIER RAINFALL RATES.

PWATS ARE GENERALLY BETWEEN 1.75 AND 2 INCHES WHICH IS
FACILITATING RATHER EFFICIENT RAINFALL PROCESSES FOR HEAVIER
RATES. THIS COUPLED WITH A FEW OVERSHOOTING TOPS WILL LIKELY PUSH
RAINFALL RATES UP TO BETWEEN 2.5 AND 3 INCHES/HR. IN FACT...THE
WACO AIRPORT ASOS MEASURED 2.88 IN ONE HOUR ENDING AT 10Z.

THE LATEST HRRR/HRRRX GUIDANCE SUPPORTS SOME IMPRESSIVELY HIGH
RAINFALL TOTALS BETWEEN THE 12Z AND 18Z TIME FRAME...WITH AMOUNTS
UP TO 3 TO 6 INCHES. THE HEAVIEST TOTALS SHOULD TEND TO BE DOWN
ACROSS THE TX HILL COUNTRY WHERE THE COLDEST CONVECTIVE TOPS AND
ORGANIZATION SHOULD FOCUS OVER THE NEXT FEW HOURS. SOME FLASH
FLOODING WILL BE POSSIBLE GIVEN THE THESE TOTALS AND ESPECIALLY
WITH SUCH INTENSE RAIN RATES.

ORRISON

ATTN...WFO...EWX...FWD...LUB...OUN...SJT...

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

LAT...LON   33979877 33979800 33919739 33839674 33749592
            33289568 32619585 32059637 31649665 30749734
            30179823 29869953 29940068 30490112 30980110
            31660081 32250045 33040021 33629983 33839945