Flash Flood Guidance
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401
AWUS01 KWNH 061107
FFGMPD
FLZ000-GAZ000-061604-

MESOSCALE PRECIPITATION DISCUSSION 0790
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
605 AM EST TUE DEC 06 2016

AREAS AFFECTED...NORTH FL

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

VALID 061104Z - 061604Z

SUMMARY...POCKETS OF TRAINING CONVECTION WILL LEAD TO TOTALS
RAINFALL AMOUNTS LOCALLY AS HIGH AS 4-7"...WHICH MAY BEGIN TO POSE
SOME RUNOFF ISSUES ACROSS PORTIONS OF THE AREA OVER THE NEXT
SEVERAL HOURS.

DISCUSSION...A NARROW BAND OF HEAVY CONVECTION CONTINUES TO TRAIN
ACROSS PORTIONS OF NORTH FLORIDA THIS MORNING. THIS CONVECTION IS
OCCURRING IN A VERY EFFICIENT ENVIRONMENT WITH RECENT GPS
OBSERVATIONS SHOWING PRECIPITABLE WATER VALUES AROUND 2.25".
VALUES THIS HIGH ARE WELL ABOVE THE CLIMATOLOGICAL RECORD...AND
MORE TYPICAL OF SEPTEMBER AND OCTOBER RECORD VALUES. THUS NOT
SURPRISING THAT RADAR AND GAGE OBSERVATIONS SHOW RAINFALL AMOUNTS
OF 1-2" IN AN HOUR...AND AMOUNTS AS HIGH AS 4-6" OVER THE LAST
FOUR HOURS OR SO. RECENT SATELLITE IMAGERY SHOWS AN UPTICK OF
ADDITIONAL CONVECTION OVER THE EASTERN GULF OF MEXICO. MEAN FLOW
IS OUT OF THE SOUTHWEST...PARALLEL TO THE CONVECTIVE
ORIENTATION...SUGGESTING CONTINUED TRAINING WILL BE POSSIBLE UNTIL
THE COLD FRONT PUSHES THINGS MORE PROGRESSIVELY OFF TO THE
SOUTHEAST. ALSO CORFIDI VECTORS ARE VERY LIGHT...SUGGESTIVE OF A
CONTINUED BACKBUILDING POTENTIAL.

THUS THE CONCERN IS THAT WE MAY SEE SEVERAL MORE HOURS OF
POTENTIAL REPEAT AND TRAINING CONVECTION OVER PORTIONS OF NORTH
FLORIDA. FLASH FLOOD GUIDANCE IS VERY HIGH ACROSS THE AREA...WHICH
WILL LIKELY LIMIT THE OVERALL FLOOD THREAT. HOWEVER WITH RAINFALL
RATES APPROACHING 2" IN AN HOUR...WHEREVER TRAINING IS
MAXIMIZED...COULD SEE TOTAL RAINFALL AMOUNTS CONTINUE TO RANGE AS
HIGH AS 4-8". THIS MAY CAUSE LOCALIZED FLOODING ISSUE OVER THE
NEXT SEVERAL HOURS. WOULD EXPECT THE THREAT TO BEGIN TO DECREASE
AFTER 15Z AS THE FRONT APPROACHES AND WINDS BEGIN TO VEER MORE TO
THE WEST ALLOWING FOR MORE EASTWARD CONVECTIVE PROPAGATION.

CHENARD

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

ATTN...WFO...JAX...MLB...TAE...TBW...

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

LAT...LON   30438136 29878105 29388144 29158196 28838275
            28718316 29598353 30398214



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