MESOSCALE PRECIPITATION DISCUSSION 0721
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
446 PM EST MON DEC 28 2015
 
AREAS AFFECTED...SE TENNESSEE...NE GEORGIA...W NORTH CAROLINA...NW
SOUTH CAROLINA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 282200Z - 290400Z
 
SUMMARY...STRONG OROGRAPHIC ASCENT WITHIN DEEPLY ANOMALOUS
MOISTURE FEED TO FOSTER POSSIBLE FLASH FLOODING.

DISCUSSION...WV/IR LOOP SHOWS WEDGE APPEARANCE TO ACTIVE
CONVECTION ACROSS S AL MOVING INTO SW GA WHICH INDICATES THE
INCREASINGLY DIVERGENT ZONE BETWEEN THE SUBTROPICAL JET STREAM
FROM THE MOUTH OF THE MS RIVER ACROSS CENTRAL GA AND RIGHT
ENTRANCE OF HIGHLY CYCLONICALLY CURVED 120KT POLAR JET ACROSS THE
TENNESSEE RIVER VALLEY.  THE PRE-FRONTAL SQUALL LINE ACROSS THIS
AREA HAS ALSO BEGUN TO SLOW AND ORIENT MORE IN LINE WITH THE
SUBTROPICAL STREAM...EVENTUALLY EXPANDING INTO A BROADER MODERATE
RAIN SHIELD CROSS E AL INTO N AND CENTRAL GA.  FURTHER WEST A
WEAKER BAND OF MODERATE SHOWERS FILL IN ALONG THE HIGHLY ANOMALOUS
MOISTURE AXIS WITH UP TO 1.8" TPWS BEING TRANSPORTED ON 50-60KT
SWLY 850 FLOW.  AS THE DIFFLUENCE/DIVERGENCE ZONE SHIFTS NORTHEAST
ACROSS CENTRAL GA INTO THE SOUTHERN APPALACHIANS THESE FEEDERS
BECOME MORE CONFLUENT AND ACCELERATE TO 60-70KT OF 850 FLOW INTO
THE DISCUSSION REGION.  THIS WILL FAVOR HIGH UVVS CAPABLE OF
PRODUCING OF 1-1.5"/HR THROUGH THE PROPERLY FACING OROGRAPHY
THROUGH 00-03Z...WITH THE POTENTIAL OF TOTALS IN 1.5-2.5" AS
SUGGESTED BY RECENT ERSL EXP. HRRR...OPERATIONAL HRRR AND 12Z
ARW/NMMB WHICH HAVE BEEN PERFORMING WELL.  SSEO NEIGHBORHOOD PROB.
OF EXCEEDING FFG VALUES ARE IN THE 30-40% RANGE.  AS MST AXIS/SWLY
FLOW SLIDES EAST BY 04Z...FLOW WILL BECOME LESS FAVORABLE FOR
OROGRAPHY INFLUENCES...REDUCING FLASH FLOODING THREAT.

GALLINA

ATTN...WFO...FFC...GSP...MRX...

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

LAT...LON   36248223 35838162 35328209 34838270 34338398 
            34548469 35268465 35758350