MESOSCALE PRECIPITATION DISCUSSION 0720
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
249 PM EST MON DEC 28 2015
 
AREAS AFFECTED...CENT KENTUCKY...N CENT TENNESSEE...EXT SE
ILLINOIS...S INDIANA...EXT SW OHIO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 282000Z - 290200Z
 
SUMMARY...NARROWING BAND OF MODERATE TO HEAVY SHOWERS WITH UP TO
2" TOTALS TO FALL OVER SATURATED SOILS FOR POSSIBLY LOCALIZED
FLASH FLOODING. 

DISCUSSION...VERY MATURE OCCLUDED CYCLONE LIFTING NORTH WITH 120
KT SLY 3H POLAR JET CENTERED NEAR THE BOOTHEEL WITH RIGHT ENTRANCE
REGION OVER S IN/SW OH TO SHRINKING OUTFLOW CHANNEL/WESTERLY JET
ACROSS THE GREAT LAKES INTO NEW ENGLAND.  SUBTROPICAL JET CROSSES
THE FRONTAL BOUNDARY ACROSS CENTRAL AL INTO N GA TO KEEP MUCH OF
THE SOUTHERN PORTION OF THE DISCUSSION AREA WITHIN GOOD DIFFLUENCE
BETWEEN IT AND THE SOUTHERLY POLAR STREAM. MOISTURE FLUX REMAINS
WELL OVER 3 STANDARD DEVIATIONS ACROSS THE CENTRAL TN AND OHIO
RIVER VALLEYS MAINLY ON 70-75KT LLJ PUMPING 1.75" TPW ACROSS TN
AND UP TO 1.5" ACROSS S IN.  SOME WEAK INSTABILITY REMAINS WITHIN
THIS WARM/MST SOUTHERLY CHANNEL TO MAINTAIN CONVECTION ALONG
SQUALL LINE ACROSS W CENTRAL KY INTO TN.  RATES OF 1.0-1.5"/HR ARE
EXPECTED WITH THIS LINE BUT EASTWARD PROGRESSION SHOULD REDUCE
TOTALS AOA 1.0".  THIS LINE IS ALSO PRECEDED BY AN HOUR OR SO OF
MODERATE SHIELD PRECIPITATION DUE TO THE LARGE SCALE ASCENT...AS
SUCH AN ADDITIONAL 1-2" CAN BE EXPECTED ACROSS KY/TN...REDUCING TO
.75-1.25" OVER S IN.  THIS COULD LEAD TO ISOLATED FLASH FLOODING
PARTICULARLY NEAR THE OHIO RIVER WHERE PRIOR MODERATE/HVY RAINFALL
HAS REDUCED FFG AS WELL AS FURTHER NORTH NEAR THE I-70 CORRIDOR
THAT ALSO RECEIVED INCREASED TOTALS OVER THE PAST FEW DAYS. 
EITHER WAY AMOUNTS WILL COMPOUND ANY ONGOING LARGER STEM RIVER
FLOODING.

BY ABOUT 22-23Z...SOUTHERLY INFLOW WILL START TO BE CUT OFF DUE TO
THE SOUTHERN APPALACHIANS ACROSS THE MID-UPPER OHIO RIVER VALLEY
SIGNIFICANTLY REDUCING RAINFALL RATES/AMOUNTS...AND LESSENING
FLASH FLOOD THREATS ACROSS S CENTRAL OH/W KY.  

GALLINA

ATTN...WFO...ILN...ILX...IND...JKL...LMK...MRX...OHX...PAH...

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

LAT...LON   40328668 40148566 39738468 39258412 38798395 
            37808407 36818434 36028481 35608606 35778694 
            37398758 37908801 39038857 39998785 40158755