Flash Flood Guidance
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000
AWUS01 KWNH 300734
FFGMPD
TNZ000-ALZ000-MSZ000-LAZ000-301203-

MESOSCALE PRECIPITATION DISCUSSION 0780
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
233 AM EST WED NOV 30 2016

AREAS AFFECTED...SOUTHERN LA/CENTRAL MS/NORTHERN AL/EXTREME
SOUTH-CENTRAL TN...

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

VALID 300733Z - 301203Z

SUMMARY...VERY STRONG CONVECTION CONTINUES ACROSS CENTRAL LA INTO
WESTERN MS WHERE CLOUD TOPS HAVE SIGNIFICANT COOLED. GIVEN THIS
SQUALL LINE HAS GENERALLY ALIGNED WITH THE MEAN CLOUD-BEARING
FLOW...THE THREAT FOR TRAINING WILL PERSIST. EVENTUALLY THIS
ACTIVITY SHOULD WORK ITS WAY NORTHEASTWARD INTO AREAS WHICH HAVE
ALREADY SEEN A GREAT DEAL OF RAINFALL. FLASH FLOODING WILL REMAIN
POSSIBLE INTO THE MORNING.

DISCUSSION...AN ACTIVE NIGHT ACROSS THE LOWER MS VALLEY INTO THE
MID-SOUTH WHERE CONVECTION HAS FOCUSED ALONG THE NOSE OF A POTENT
SUBTROPICAL JET. THIS SYSTEM HAS CONTINUED TO ACCESS ABUNDANT GULF
OF MOISTURE WITH LOCAL PWATS ACTUALLY INCREASING THE DURING THE
PAST SEVERAL HOURS. MUCH OF THE GPS SOUNDER DATA ACROSS CENTRAL
MS/AL HAVE SHOWN PWAT VALUES IN THE 1.50 TO 1.75 INCH RANGE. AMPLE
INSTABILITY ALONG THIS ENHANCED PLUME OF MOISTURE IN CONJUNCTION
WITH STRONG JET DYNAMICS WILL FAVOR A CONTINUED HEAVY RAINFALL
THREAT OVER THE REGION. THERE IS NO REAL SIGN OF WEAKENING GIVEN
THE CLOUD TOP TEMPERATURES HAVE REMAINED STEADY AND ABUNDANT
LIGHTNING STRETCHES ALONG MUCH OF THE CONVECTIVE LINE. HOURLY
RAINFALL AMOUNTS BASED ON THE LATEST MESONET DATA HAVE SHOWN
WIDESPREAD 0.50 TO 1 INCH AMOUNTS WITH POCKETS NEARING 1.50
INCHES. SEE LITTLE REASON TO BELIEVE THIS WILL CHANGE WITH
LOCALIZED TRAINING BEING THE PRIMARY MECHANISM FOR FLASH FLOODING.
FFG VALUES REMAIN HIGH BUT THEY MAY HAVE COME DOWN GIVEN THE
ONGOING PRECIPITATION. THE 00Z CAMS ALONG WITH THE PAST FEW RUNS
OF THE HRRR SEEM TO HAVE A DECENT HANDLE ON THIS COMPLEX.
PARTICULARLY LIKED THE 00Z NSSL-WRF AND 00Z HRW-NMM-B WHICH
SUPPORT A WIDESPREAD 1 TO 2 INCHES ALONG THE LINE THROUGH 12Z WITH
LOCAL POCKETS APPROACHING 3 TO 4 INCHES.


RUBIN-OSTER

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

ATTN...WFO...BMX...HUN...JAN...LCH...LIX...MEG...MOB...MRX...
OHX...

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

LAT...LON   35298566 34438559 33648650 32738767 31618943
            30719064 29829216 30239283 31149197 32299052
            33588873 35068693



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