MESOSCALE PRECIPITATION DISCUSSION 0101...Correction
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
827 AM EDT WED APR 05 2017

AREAS AFFECTED...PORTIONS OF AL, GA, AND SC

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

VALID 051220Z - 051805Z

SUMMARY...BURGEONING CONVECTION IS EXPECTED TO SHOW PERIODS OF
TRAINING OVER PORTIONS OF AL, GA, AND EVENTUALLY NORTHWEST/CENTRAL
SC.  WITH HOURLY RAIN RATES UP TO 2", AND LOCAL AMOUNTS UP TO 4",
FLASH FLOODING IS POSSIBLE IN HILLY TERRAIN AND URBAN AREAS.

DISCUSSION...THUNDERSTORMS CONTINUE TO INCREASE IN COVERAGE AND
INTENSITY (WITH COOLING CLOUD TOPS) UP TO 100 NM NORTHEAST OF A
WARM FRONT, WITH A RECENTLY DEVELOPED LONG CONVECTIVE BAND ACROSS
PORTIONS OF CENTRAL AL AS OF 12Z.  INFLOW AT 850 HPA TO THE
SOUTHEAST OF AN OCCLUDED CYCLONE IS BROADLY 30-40 KTS OUT OF THE
SOUTHWEST PER VAD WIND PROFILES, WHICH IS IMPORTING MUCAPES OF
2000-3000 J/KG OVER THE BOUNDARY.  DIVERGENCE ALOFT IS PLENTIFUL
SOUTHEAST OF THE DEEP CYCLONE.  PRECIPITABLE WATER VALUES, PER THE
BMX SOUNDING, ARE ABOUT 1.5" (GPS PW INFORMATION LOOKS WAY TOO LOW
ACROSS AL/GA).

A LONG BAND HAS ALREADY SET UP IN AL (WHICH HAS BEEN HANDLED
REASONABLY WELL BY THE 06Z NAM CONEST).  UNFORECAST CONVECTION HAS
BEEN FORMING ACROSS PORTIONS OF GA AND RAP BASED MASS FIELDS DO
NOT APPEAR TO BE MOIST ENOUGH PER THE BMX SOUNDING.  BELIEVE LOCAL
AMOUNTS IN THE 2-4" RANGE SHOULD BE EXPECTED, MAINLY WITHIN LONG
TRAINING BANDS THOUGH SOME BACKBUILDING IS POSSIBLE AS LOW-LEVEL
INFLOW RAMPS UP SLIGHTLY FURTHER, WITH BACKBUILDING MOST LIKELY
NEAR THE WARM FRONT.  LONG BANDS WILL GENERALLY BE NECESSARY FOR
HIGHER RAIN RATES AS FORWARD PROPAGATION TO THE EAST-NORTHEAST AT
40-50 KTS IS EXPECTED.  WITH INCREASING MOISTURE/INSTABILITY BEING
IMPORTED AHEAD OF THE OCCLUDED CYCLONE, HOURLY RAIN RATES SHOULD
LOCALLY PEAK IN THE 2" RANGE, WHICH WOULD BE PROBLEMATIC IN URBAN
AND HILLY AREAS WITHIN THE REGION.  THERE IS A WINDOW ROUGHLY
BETWEEN 14-16Z WHERE CONVECTION SHOULD EVOLVE FROM MORE ELEVATED
TO MORE SURFACE BASED AS CIN ERODES, WHICH COULD ALSO ALLOW FOR
POTENTIAL BACKBUILDING.  FLASH FLOODING IS MOST POSSIBLE WITHIN
URBAN AREAS AND HILLY TERRAIN.

ROTH

ATTN...WFO...BMX...CAE...FFC...GSP...HUN...MRX...

ATTN...RFC...LMRFC...SERFC...

LAT...LON   35198266 35168121 34828073 33898064 33078200
            32458363 32338592 32278631 32238636 32368659
            32898694 33338708 33588712 34218631 34778470