Post by SKYSUMMIT on Jun 18, 2018 23:44:11 GMT -6
MESOSCALE PRECIPITATION DISCUSSION 0324
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
113 AM EDT TUE JUN 19 2018
AREAS AFFECTED...SOUTH-CENTRAL TO SOUTHEAST TX
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 190510Z - 191010Z
SUMMARY...A GRADUAL INCREASE IN COVERAGE OF SHOWERS AND
THUNDERSTORMS IS EXPECTED THROUGH DAWN. VERY HEAVY RAINFALL RATES
ARE EXPECTED...AND SOME FLASH FLOODING WILL BE POSSIBLE.
DISCUSSION...RADAR IMAGERY IS SHOWING THE GRADUAL REDEVELOPMENT
AND EXPANSION OF SHOWER ACTIVITY ACROSS COASTAL AREAS OF
SOUTH-CENTRAL TO SOUTHEAST TX...ESSENTIALLY FROM THE CORPUS
CHRISTI NORTHEAST UP TO THE HOUSTON/GALVESTON METROPOLITAN AREA.
THE CONVECTION IS FOCUSING IN AROUND THE EAST TO NORTHEAST FLANK
OF A MID LEVEL LOW CENTER THAT IS NOW MOVING VERY SLOWLY WEST
ACROSS SOUTH-CENTRAL TX. THERE APPEARS TO BE SOME TIGHTENING OF
THE MID LEVEL VORTICITY AXIS AND CONVECTION HAS BEEN DEVELOPING
RATHER CLOSE TO THE CENTER OF THIS OVER THE LAST COUPLE HOURS
WHICH IS VERY NEAR CORPUS CHRISTI. FARTHER NORTHEAST UP ALONG THE
TX COAST IS PROXIMITY OF A LOW LEVEL TROUGH AXIS WHERE THERE ARE
MULTIPLE SURFACE MOISTURE CONVERGENCE MAXIMA AND THIS HAS ALLOWED
FOR SOME MODEST CONVECTIVE BANDING.
THE DEEP LAYER CYCLONIC FLOW OVER THE REGION MEANWHILE CONTINUES
TO TRANSPORT A DEEP COLUMN OF TROPICAL MOISTURE ACROSS MUCH OF THE
WESTERN GULF COAST REGION. PWATS REMAIN VERY HIGH AND GENERALLY
BETWEEN 2.3 AND 2.5 INCHES BASED ON HOURLY GPS-DERIVED DATA.
HIGHLY EFFICIENT RAINFALL PROCESSES ARE IN PLACE GIVEN THE
CONCENTRATION OF MOISTURE SEEN IN THE 500/300 MB LAYER AND THERE
WILL BE SUFFICIENT WARM RAIN PROCESSES FOR HIGHLY EFFICIENT AND
ENHANCED RAINFALL RATES OVERNIGHT AS CONVECTION ATTEMPTS TO BECOME
BETTER ORGANIZED AROUND THE EASTERN SEMICIRCLE OF THE MID LEVEL
LOW.
THE HRRR/HRRRX GUIDANCE SO FAR THIS EVENING HAS BEEN TOO WET...BUT
THE LAST FEW RUNS IN CONJUNCTION WITH THE 00Z ARW/NMMB SOLUTIONS
ARE FAVORING THE REDEVELOPMENT OF SOME HEAVY CONVECTIVE
RAINFALL...ESPECIALLY BETWEEN 06Z AND 12Z ACROSS THE MPD THREAT
AREA...AND ESPECIALLY ACROSS PORTIONS OF SOUTH-CENTRAL TX.
GIVEN THE MID LEVEL VORT ENERGY AND FAVORABLE LOW LEVEL
MOISTURE/INSTABILITY TRANSPORT INTO REGION...EXPECT A GRADUAL
EXPANSION OF HEAVY RAINFALL THROUGH THE REMAINDER OF THE
NIGHT...WITH TOTALS THROUGH DAWN OF AS MUCH AS 3 TO 5 INCHES WITH
ISOLATED HEAVIER AMOUNTS. SOME FLASH FLOODING WILL BE POSSIBLE AS
A RESULT.
