Flash Flood Guidance
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000
AWUS01 KWNH 231519
FFGMPD
VAZ000-NCZ000-GAZ000-TNZ000-232102-

MESOSCALE PRECIPITATION DISCUSSION 0138
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1118 AM EDT SUN APR 23 2017

AREAS AFFECTED...EASTERN TN...NORTHERN GA...EXT SOUTHWEST VA...EXT
WESTERN NC

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 231517Z - 232102Z

SUMMARY...INCREASINGLY FAVORABLE DYNAMIC SETUP WITH SHALLOW
EMBEDDED CONVECTION MAY POSE ISOLATED FF CONCERN DUE TO SATURATED
GROUND CONDITIONS.

DISCUSSION...GOES-16 CONUS VISIBLE IMAGERY DENOTES A STEADY UPTICK
AND EXPANSION OF SHALLOW CONVECTIVE GROWTH ACROSS E TN WITHIN THE
GREATEST DIFFLUENCE/SHORTWAVE RIDGING ALOFT AS THE MEAN UPPER LOW
PIVOTS ACROSS CENTRAL TN.  RAP ANALYSIS AND HRRR SUGGEST A NARROW
RIBBON OF WEAK SLANTWISE INSTABILITY UP TO 100-150 J/KG ADVECTING
THROUGH THE WARM CONVEYOR (OF S AND SELY LOW LEVEL FLOW) ACROSS N
GA INTO TN TO CONTINUE SUPPORTING THIS SHALLOW CONVECTION.  LOCAL
1HR OBSERVED TOTALS ARE IN THE .5"/HR RANGE CURRENTLY ACROSS SE TN
THOUGH WITH INCREASINGLY BETTER DYNAMICS (INCREASED
DIVERGENCE/DPVA) AND INSTABILITY...CELLS HAVE THE POTENTIAL TO
FURTHER INCREASE AND WITH SATURATED PROFILES BELOW CLOUD BASE
LIMITING LOSS DUE TO EVAPORATIVE PROCESSES...THIS SHOULD BRING
SOME SCATTERED RAIN RATES/1HR TOTALS VERY CLOSE TO ECLIPSING THE
SUB 1" FFG ACROSS THE CUMBERLAND PLATEAU AND WESTERN AND SOUTHERN
FACING FOOTHILLS OF THE APPALACHIANS.  EVEN OUTSIDE OF THESE
ISOLATED ENHANCED SHALLOW CONVECTIVE ELEMENTS...MODERATE
PERSISTENT RAINFALL WILL CONTINUE TO POSE LONGER-TERM/SLOW RISE
FLOODING CONCERNS WITH 1-2" EXPECTED OVER THE NEXT 6HRS ACROSS E
TN AND N GA.

GALLINA

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FFC...GSP...MRX...OHX...RNK...

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

LAT...LON   36928202 36298190 35748299 34958368 34408440
            34338531 35288551 36318587 36578501 36538351



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