MESOSCALE PRECIPITATION DISCUSSION 0724...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1227 PM EST WED DEC 30 2015
 
CORRECTED FOR SPELLING

AREAS AFFECTED...SOUTHEAST 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 301722Z - 302122Z
 
SUMMARY...FLASH FLOODING IS LIKELY ANYWHERE FROM SOUTHERN VIRGINIA
ACROSS THE CENTRAL CAROLINAS INTO GEORGIA THIS AFTERNOON.

DISCUSSION...A STATIONARY FRONT WITH MULTIPLE AREAS OF LOW
PRESSURE CONTINUES FROM GREENSBORO TO CHARLOTTE TO ATLANTA...WITH
A SHORTWAVE TROUGH OVER ALABAMA APPROACHING THE FRONT. THROUGH THE
MORNING THE MAJORITY OF CONVECTION WAS HIGH-BASED...THUS
MAINTAINING MODEST RAIN RATES. HOWEVER...RECENT CLEARING EVIDENT
IN VISIBLE SATELLITE IMAGES HAS ALLOWED THE BOUNDARY LAYER TO WARM
AND COUPLE WITH THE LAYER ABOVE...WITH SBCAPES RISING TO 500-1500
J/KG...ALONG WITH LITTLE OR NO INHIBITION.

GIVEN THE WEAK CAP AND MESOSCALE NATURE OF THIS EVENT...BOTH
GLOBAL AND HI-RES GUIDANCE IS RESOLVING IT POORLY.
HOWEVER...EXTRAPOLATING THE LATEST TRENDS SUPPORT A GREATER
POTENTIAL FOR DEEPER CONVECTIVE CORES AND SLOWER CELL MOTIONS AS
THE EFFECTS OF PROPAGATION INCREASE. WITH THE SHORTWAVE TROUGH
OVER ALABAMA APPROACHING THE FRONT AND NUMEROUS LOWS ALREADY
FORMED ALONG IT...IT APPEARS LIKELY THAT ONE OR MORE LOWS WILL
CONTINUE TO DEVELOP AND DISSIPATE PERIODICALLY AND MAY ALLOW THE
FRONT TO LEAN FORWARD AND MORE DIRECTLY INTERSECT THE INFLOW THUS
SLOWING CELL MOTIONS AND CONTRIBUTING TO EVEN HIGHER RAIN RATES.

HOURLY RATES OF 1.5 TO 2 INCHES WILL BE POSSIBLE ON AN ISOLATED
BASES ALONG AND AHEAD OF THE FRONTAL BOUNDARY THROUGH THE
AFTERNOON AS IT MOVES SLOWLY EASTWARD...WITH 3-HOURLY RATES
POSSIBLY IN EXCESS OF 3 INCHES WHICH IS SLIGHTLY HIGHER THAN FFG
VALUES. GIVEN ALREADY HIGH RIVER LEVELS...ITS APPEARS LIKELY THAT
THESE RATES WILL BE SUFFICIENT TO CAUSE FLASH FLOODING.

JAMES 

ATTN...WFO...AKQ...CAE...CHS...FFC...GSP...ILM...MHX...RAH...
RNK...

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

LAT...LON   36787879 36737680 35767695 34757855 33318088 
            32408268 32458395 33098414 33888313 34278216 
            34878115 36038010