MESOSCALE PRECIPITATION DISCUSSION 0026
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1014 PM EST TUE FEB 02 2016
 
AREAS AFFECTED...LOWER MS VALLEY...TN VALLEY...OH VALLEY... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 030313Z - 030913Z
 
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. SYNOPTIC SUPPORT
IS BEING PROVIDED FROM HEIGHT FALLS ASSOCIATED WITH ADDITIONAL
SHORTWAVE ENERGY MOVING EAST IN THE APPROACHING LONGWAVE
TROUGH...AS WELL AS A 150+ KT UPPER LEVEL JET PLACING THE REGION
IN THE FAVORED RIGHT ENTRANCE QUADRANT.

LOW LEVEL WIND FIELDS ARE VERY IMPRESSIVE...WITH VAD WIND PROFILES
AND RAP FORECASTS SHOWING 850 MB WINDS OF 55-75 KTS...WHICH IS
EQUAL TO OR EVEN STRONGER THAN AND ALIGNED WITH THE MEAN STORM
LAYER WINDS. THIS IS AIDING THE CONTINUED BACKBUILDING AND
TRAINING OF CONVECTION. THE FRONT IS SLOWLY PROGRESSING EAST...BUT
GIVEN THE WHOLE SYSTEM IS SHEARING OFF TO THE NORTH...THE
PROGRESSION IS SLOW ENOUGH TO ALLOW FOR A LONGER DURATION OF
HEAVIER RAINFALL RATES. PER 0Z RAOBS...BOTH PRECIPITABLE WATER
VALUES AND WET BULB ZERO HEIGHTS ARE NEAR RECORD VALUES FOR THIS
TIME OF YEAR FROM PORTIONS OF THE LOWER MS VALLEY INTO THE OH
VALLEY. COMBINE THIS WITH THE VERY STRONG MOISTURE FLUX INTO THE
REGION...AND LOOKING AT A HIGHLY EFFICIENT RAINFALL SETUP.

RAINFALL RATES SHOULD LOWER FROM NEAR THE KY/IN/OH BORDER AND
POINTS EAST...AS THE PRECIPITATION OUTRUNS INSTABILITY. HIGHER
RATES ARE EXPECTED TO CONTINUE FURTHER SOUTH FROM CENTRAL KY INTO
AL AND EASTERN MS. A COMBINATION OF THE HRRR...EXPERIMENTAL HRRR
AND TO A DEGREE THE 18Z 4KM NAM SEEM TO BE HANDLING THE EVOLUTION
OF THE CONVECTION RECENTLY. THE 12Z HIGH RES ARW/NMMB ARE BOTH TOO
SLOW WITH THE CONVECTIVE EVOLUTION AND DO NOT HAVE A GOOD HANDLE
ON THINGS. 

LOOKING AT RAINFALL RATES LOCALLY AS HIGH AS 1.5" AN HOUR...WITH 6
HOUR TOTALS THROUGH 09Z RANGING FROM 1-3 INCHES...WITH LOCAL
AMOUNTS APPROACHING 4" POSSIBLE FROM EAST CENTRAL MS INTO
CENTRAL/NORTHERN AL AND CENTRAL TN. THIS IS GENERALLY BELOW FLASH
FLOOD GUIDANCE...BUT GUIDANCE IS LOWER ACROSS PORTIONS OF THE
TN/OH VALLEY...WHICH COULD BE LOCALLY EXCEEDED. FURTHER SOUTH
ACROSS PORTIONS OF LA/MS/AL...SEEING A CONTINUED AXIS OF TRAINING
CONVECTION...WITH HIGH RES GUIDANCE UNDER DOING THIS ACTIVITY.
THIS WILL CONTINUE THE FLASH FLOOD THREAT ACROSS CENTRAL MS FOR
THE NEXT SEVERAL HOURS...WITH THE THE THREAT EVENTUALLY SHIFTING
INTO CENTRAL/NORTHERN AL AND CENTRAL TN...WHERE ALREADY BEGINNING
TO SEE TRAINING DEVELOPING ON RADAR.

CHENARD

ATTN...WFO...BMX...FFC...HUN...ILN...IND...JAN...JKL...LCH...
LIX...LMK...MEG...MOB...MRX...OHX...PAH...

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

LAT...LON   40228388 39608348 38378371 36378470 34138539 
            32538647 31788707 31158757 30828808 30698825 
            30618889 30948970 31019029 30819090 30689160 
            30999173 31339170 31809127 32359069 34268899 
            36618773 37838722 38738689 39508637 39558629 
            39648605 39998472