AWUS01 KWNH 260807
FFGMPD
FLZ000-261405-

Mesoscale Precipitation Discussion 1063
NWS Weather Prediction Center College Park MD
406 AM EDT Thu Sep 26 2024

Areas affected...Apalachicola region of FL Panhandle

Concerning...Heavy rainfall...Flash flooding likely

Valid 260805Z - 261405Z

SUMMARY...As bands of heavy rain located north of Hurricane Helene
approach the eastern FL Panhandle, renewed areas of flash flooding
are expected toward 12Z. An additional 2-4 inches is expected
through 14Z.

DISCUSSION...Hurricane Helene was located about 375 miles SSW of
Apalachicola, FL according to the 06Z position by NHC, moving
north around 8 kt, though an increase in forward speed is expected
late this morning. While this position is still well south of the
FL Panhandle, 0745Z radar imagery showed axes and spiral bands of
heavy rain located in the eastern Gulf of Mexico, grazing the
western FL Peninsula and Gulf/Franklin counties of the Panhandle.
GOES East water vapor and infrared satellite imagery showed
healthy outflow in the northern semicircle of Helene's circulation
and enhanced divergence aloft was present along the FL Panhandle
due to the presence of a potent upper level jet max centered over
the upper TN/OH Valleys.

An increasing frequency of bands of heavy rain are expected to
impact the FL Panhandle over the next 3-6 hours as Helene
continues to advance north. While rain bands oriented generally
west to east should push north without too much in the way of
training concerns, rain bands that are aligned more with the mean
steering flow from SSE to NNW will be favored for training. Even
short term training could still allow for a quick 1-2 inches of
rain in as little as 15-30 minutes due to the tropical environment
in place. It is expected that steady rain will continue throughout
the remainder of the morning, but with bursts of heavy rain
occurring at times and with an increased frequency through 14Z
along with an additional 2-4 inches.

Given multi-sensor MRMS estimates of 5 to 10 inches of rain over
the past 24 hours from near Apalachicola to Lake Talquin, soil
saturation will more easily support runoff from additional heavy
rain. Since instability of 500 to 1000+ J/kg is forecast to remain
along and offshore of the coast, higher rainfall rates may be
limited to coastal sections of the east-central Peninsula, but
longer duration/lower intensity rainfall could still have flood
impacts farther north.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!-uwol5Mp4pDUbDRleBlBuMxXeJNIQI5JtTkfRh_K1Dxz8zgZPVJCvYHKNRwPdm0KYkO7=
wfWPNkuiQ1hSdoFhn3ZNCz8$  for graphic product...

ATTN...WFO...TAE...

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

LAT...LON   30508455 30298420 29738424 29508479 29468531=20
            29588552 29758563 30098552 30318536 30458492=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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