Post by SKYSUMMIT on Jun 17, 2015 12:44:17 GMT -6
MESOSCALE PRECIPITATION DISCUSSION 0233
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
229 PM EDT WED JUN 17 2015
AREAS AFFECTED...PORTIONS OF EASTERN AND SOUTHERN TX
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 171828Z - 180028Z
SUMMARY...INFLOW BANDS INTO TROPICAL DEPRESSION BILL REMAIN
CAPABLE OF HOURLY RAIN RATES UP TO 3". FLASH FLOODING IS
CONSIDERED LIKELY FOR AREAS THAT HAVE RECEIVED 6-12" LOCALLY.
DISCUSSION...TWO AREAS OF THUNDERSTORMS -- ONE A BAND NEAR THE
LA/TX BORDER AND A SECOND A MORE DISORGANIZED CLUSTER ACROSS
SOUTH-CENTRAL TX -- HAVE BEEN SPREADING OUTWARD AT ~10 KTS BY A
GROWING COLD POOL ACROSS SOUTHEAST TX. HOURLY RAIN RATES AS OF
LATE HAVE BEEN CLOSE TO 2.5" (NEAR THE PRECIPITABLE WATER VALUES
IN THE REGION). LOCAL RAINFALL AMOUNTS IN BOTH AREAS ARE IN THE
6-9" RANGE, WITH 10-13" AMOUNTS INDICATED BY RADAR INLAND OF THE
MIDDLE TX COAST. DESPITE RAP FORECASTS TO THE CONTRARY,
CONVERGENT 850 HPA INFLOW IS SEEN ACROSS BOTH AREAS, WITH
INSTABILITY ON THE ORDER OF 1000-2000 J/KG SEEN ACROSS THE
NORTHWEST GULF AND LA WITH 2000-3000 J/KG CAPES ACROSS SOUTHERN
TX. VAD WIND PROFILES INDICATE 25-45 KT INFLOW INTO THE REGION,
2-3 TIMES THE MAGNITUDE OF THE MEAN 850-400 HPA WIND.
THERE IS A FAIRLY UNIFIED SIGNAL IN THE MESOSCALE GUIDANCE FOR
LOCAL 3-5" AMOUNTS NEAR THE TX/LA BORDER AND LOCAL 5-7" AMOUNTS
ACROSS SOUTH-CENTRAL TX THROUGH 00Z, WHICH COULD OCCUR WITHIN 2-3
HOURS. WITH HOURLY RAIN RATES UP TO 3" POSSIBLE, FLASH FLOODING
IS CONSIDERED LIKELY OVER QUICKLY SATURATING SOILS.
ROTH
