MESOSCALE PRECIPITATION DISCUSSION 0441
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
651 PM EST SAT DEC 27 2014
 
AREAS AFFECTED...MS...ERN LA...WRN AL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 272350Z - 280350Z
 
SUMMARY...THUNDERSTORMS WILL TRAIN ACROSS SOME AREAS. A VERY MOIST
ATMOSPHERE FOR DECEMBER COULD LOCALLY YIELD 1.5 INCHES IN AN HOUR
AND MORE THAN 2 INCHES OVER THREE HOURS. FLASH FLOODING IS
POSSIBLE.

DISCUSSION...THUNDERSTORM COVERAGE HAD INCREASED DIURNALLY...BUT
ALSO WITH THE STRENGTHENING OF MID AND UPPER LEVEL SUPPORT FOR
LIFT. THE LEADING EDGE OF GREATEST MOISTURE TRANSPORT WILL PUSH
EAST THROUGH ALABAMA THIS EVENING...BUT THE THREAT OF HEAVY AND
REPEATED RAINS IS INITIALLY GREATEST BACK TO THE WEST IN
LA/MS...WHERE INSTABILITY IS SOMEWHAT GREATER NEAR A SLOWLY
LIFTING WARM FRONT. THE EVENT AS A WHOLE IS ONLY LOOSELY
FOCUSED...BUT A LARGER SCALE COLD POOL WAS ENTERING CENTRAL MS AT
2330Z. CONVECTION HERE AND CONVECTION OCCURRING OR FORECAST TO
OCCUR IN BANDS FARTHER SOUTH ACROSS LA/MS MAY BECOME ALIGNED TO
ALLOW TRAINING OF CELLS WITHIN DEEP UNIDIRECTIONAL FLOW ABOVE THE
EFFECTIVE INFLOW LAYER.

THE RAP AND HRRR FORECAST A SEMI-FAVORABLE ENVIRONMENT FOR DEEP
CONVECTION TO PERSIST INTO THE NIGHT...ALTHOUGH THE POOL OF
500-750 J/KG MUCAPE WILL ONLY INCH ITS WAY EAST ALONG THE GULF
COAST...STRUGGLING TO COME NORTHWARD. SEVERAL HIGH RESOLUTION
MODELS ALIGN WELL WITH THE HRRR CAPE FORECAST...RAP 925-850 MB
MOISTURE CONVERGENCE FORECAST...AND THE WPC QPF FORECAST...PLACING
THE AXIS OF GREATEST RAINS FROM SOUTH OF JACKSON MS TO WEST OF
MONTGOMERY AL. RECENT RUNS OF THE HRRR...AS WELL AS THE NSSL WRF
AND CANADIAN GEM REGIONAL MODEL SUGGEST SWATHS OF 2 OR EVEN 3
INCHES OF RAIN LOCALLY THROUGH 05 TO 06Z. THIS MAY BE SUFFICIENT
TO PRODUCE FLASH FLOODING IN MORE SUSCEPTIBLE LOCATIONS.

BURKE

ATTN...WFO...BMX...JAN...LIX...MOB...

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

LAT...LON   33608848 33278729 32678667 31578657 30598727 
            30298760 29658860 29538927 29738974 30369024 
            31049076 32239119 33369048