MESOSCALE PRECIPITATION DISCUSSION 0698
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1127 AM EST FRI DEC 25 2015
 
AREAS AFFECTED...AR/LA/MS BORDER INTO NRN MS/AL...CNTRL/ERN
TN...NWRN GA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 251626Z - 252200Z
 
SUMMARY...TRAINING CONVECTION WILL CONTINUE A HIGH END FLASH FLOOD
THREAT ACROSS PORTIONS OF NRN MISSISSIPPI/ALABAMA...BACK WEST
TOWARD THE MISSISSIPPI RIVER. THE AXIS OF HEAVIEST RAINFALL MAY
SHIFT SOUTH BY 22Z WHILE LOCATIONS FARTHER EAST TOWARD THE
APPALACHIANS ARE EXPECTED TO SEE MORE OF A PROGRESSIVE NATURE TO
THE HEAVY RAIN.

DISCUSSION...MOISTURE ANOMALIES ACROSS PORTIONS OF THE LOWER
MISSISSIPPI VALLEY INTO THE TENNESSEE VALLEY REMAIN HIGH...+3 SD
ABOVE THE MEAN...WITH RECORD OR NEAR RECORD PRECIPITABLE WATER
VALUES REPORTED ON THE 12Z JAN SOUNDING. AT 16Z...A WEAK LOW WAS
ANALYZED IN ERN KENTUCKY WITH A SLOW MOVING TO NEARLY STATIONARY
FRONT EXTENDING WSW ACROSS SERN KENTUCKY...W-CNTRL TENNESSEE INTO
THE LOWER MISSISSIPPI VALLEY. 850-700 MB FLOW OF 30-40 KTS WAS
SEEN ON VAD WIND PLOTS TO BE NEARLY PARALLEL TO THE FRONTAL
BOUNDARY ACROSS THE MISSISSIPPI VALLEY AND HAS ALLOWED PERSISTENT
REGENERATION OF CONVECTION IN THE VICINITY OF NRN MISSISSIPPI.
FARTHER EAST...CONVECTION HAS BEEN A BIT MORE PROGRESSIVE TOWARD
THE EAST THROUGH TENNESSEE/NERN ALABAMA. HOWEVER...DUAL POL
ESTIMATED AND GROUND TRUTH RAINFALL RATES HAVE SUPPORTED VALUES OF
2-2.5 IN/HR WITHIN SOME OF THE TRAINING BANDS CAUSING WIDESPREAD
FLASH FLOODING.

OVER THE NEXT 3-6 HOURS...THE SLOWLY PROGRESSIVE NATURE OF THE
FRONT ACROSS KENTUCKY IS EXPECTED TO KEEP THE EASTERN PORTION OF
THE RAINFALL ON THE MOVE TOWARD THE EAST WITH STRATIFORM RAIN IN
ITS WAKE. BACK TO THE WEST...INCLUDING NRN ALABAMA/MISSISSIPPI
INTO EXTREME ERN LOUISIANA/ARKANSAS...NO SIGNIFICANT CHANGE TO
THERMODYNAMIC OR KINEMATIC PROFILES IS EXPECTED OVER THE NEXT
SEVERAL HOURS BUT THE DEVELOPMENT OF A COLD POOL AND CONTINUED
DAYTIME HEATING SOUTH OF ONGOING RAINFALL MAY SET UP A RAIN COOLED
BOUNDARY AND A NEW FOCUS FOR CONVECTION FARTHER SOUTH THAN ONGOING
ACTIVITY. INSTABILITY IS EXPECTED TO BE GREATEST ACROSS THE WRN
PORTION OF THE MPD THREAT AREA AS WELL HELPING TO CONTINUE
SUPPORTING 2-2.5 IN/HR RAINFALL RATES. THE TIMING OF THE SHIFT OF
HEAVIEST RAINFALL SOUTH IS UNCERTAIN BUT THIS SCENARIO MAY SLOWLY
TRANSITION BY 22Z.

OTTO

ATTN...WFO...BMX...FFC...GSP...HUN...JAN...LZK...MEG...MRX...
OHX...

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

LAT...LON   36608328 36548217 35978235 34778422 33978590 
            33438743 33028920 32689179 33579234 34519033 
            35068903 36068672 36338580 36458439