MESOSCALE PRECIPITATION DISCUSSION 0027
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
433 AM EST WED FEB 03 2016
 
AREAS AFFECTED...SOUTHEAST...TN VALLEY...SOUTHERN MID ATLANTIC 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 030932Z - 031532Z
 
SUMMARY...WIDESPREAD CONVECTION ALONG/AHEAD OF FRONTAL BOUNDARY
WILL CONTINUE THE HEAVY RAINFALL THREAT OVER THE NEXT SEVERAL
HOURS. 

DISCUSSION...WIDESPREAD CONVECTION CONTINUES TO STREAM FROM
SOUTHWEST TO NORTHEAST ALONG/AHEAD OF A COLD FRONT ATTACHED TO THE
AREA OF LOW PRESSURE MOVING INTO THE GREAT LAKES. CONVERGENCE
ALONG/AHEAD OF THIS FRONT...DIVERGENCE ALOFT IN THE RIGHT ENTRANCE
REGION OF A 150+ KT UPPER JET...AND A STRONG 850 MB JET OF 50-60
KTS PER THE RAP AND VAD WIND PROFILES...ARE COMBINING TO HELP
MAINTAIN THE WIDESPREAD AREA OF CONVECTION ACROSS THE AREA.

PRECIPITABLE WATER VALUES ARE GENERALLY AROUND THE 95TH PERCENTILE
FOR THIS TIME OF YEAR ACROSS THE ENTIRE OUTLOOKED AREA. CIRA
LAYERED PRECIPITABLE WATER SHOWS AN INCREASING PLUME OF DEEP
MOISTURE BEING ADVECTED INTO THE AREA AHEAD OF THE FRONT...WITH A
CONNECTION TO BOTH THE SUBTROPICAL PACIFIC AND THE WESTERN
ATLANTIC AT MID AND UPPER LEVELS. THE STRONG LOW LEVEL WIND FIELD
IS PRODUCING LOW LEVEL MOISTURE FLUX VALUES AS HIGH AS 4-5
STANDARD DEVIATIONS ABOVE NORMAL. THUS APPEARS TO BE AN EFFICIENT
ENVIRONMENT FOR HEAVY RAINFALL.

LOW LEVEL WIND FIELDS ARE NEARLY EQUAL TO OR EVEN STRONGER THAN
THE MEAN STORM LAYER WINDS AND ALSO HAVE A LARGE COMPONENT
PARALLEL TO THE MEAN FLOW. THIS IS AIDING THE CONTINUED
BACKBUILDING AND TRAINING OF CONVECTION AS THE FRONT SLOWLY PUSHES
EAST. HOWEVER RECENT RADAR TRENDS ARE BEGINNING TO SHOW MORE OF A
FORWARD PROPAGATION OF THE HEAVIER CONVECTIVE LINE...WHICH IS
HELPING TO KEEP RAINFALL TOTALS FROM EXCEEDING FLASH FLOOD
GUIDANCE IN MOST LOCATIONS. 

THE HRRR...EXPERIMENTAL HRRR...ARW AND NMMB ALL SEEM TO BE
HANDLING THE EVOLUTION OF THIS SYSTEM PRETTY WELL...WITH A BLEND
OF THESE SOLUTIONS GENERALLY LOOKING PRETTY GOOD THROUGH 16Z. IN
GENERAL THE PROPAGATION OF THE HEAVIER RATES HAS BEEN KEEPING 3
HOURLY TOTALS PEAKING IN THE 1-2" RANGE. HOWEVER GIVEN THE
EFFICIENT ENVIRONMENT AND SOME BACKBUILDING...WOULD EXPECT
ISOLATED POCKETS OF 3" IN THREE HOURS...LEADING TO AN ISOLATED
FLASH FLOOD THREAT. ON THE NORTHEAST EDGE OF THE THREAT AREA THE
PRECIPITATION WILL BE RUNNING INTO A STABLE WEDGED AIRMASS.
HOWEVER CONCERNED ABOUT THE STRONG UPSLOPE FLOW INTO THE SOUTHERN
APPALACHIANS CAUSING LOCALLY HEAVY TOTALS IN THE FAVORED UPSLOPE
AREAS. THE HIGH RESOLUTION CONSENSUS SUGGESTS RAINFALL AMOUNTS OF
1-2" ACROSS THIS AREA THROUGH 16Z...WITH LOCAL AMOUNTS PERHAPS AS
HIGH AS 3-4".
 

CHENARD


ATTN...WFO...BMX...FFC...GSP...HUN...MOB...MRX...RNK...TAE...

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

LAT...LON   36838056 36488071 35618170 35128224 34668268 
            34448299 34018331 33278402 32628459 32338481 
            31948499 31638508 31078583 30628655 30458775 
            30668773 31508780 33568636 35848462 36458417 
            36368289 36668185 36758117