286
AWUS01 KWNH 262308
FFGMPD
FLZ000-GAZ000-ALZ000-270500-

Mesoscale Precipitation Discussion 1070
NWS Weather Prediction Center College Park MD
707 PM EDT Thu Sep 26 2024

Areas affected...Florida Big Bend well up into Georgia

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

Valid 262305Z - 270500Z

Summary...Hurricane Helene will make landfall late this evening
along the Florida Big Bend with inner bands progressing up Georgia
and converging on a stationary front over eastern AL. The eyewall
will impact the Big Bend area 02 to 05Z which will include heavy
rainfall that will exacerbate the extreme impacts from wind and
storm surge there.

Discussion...
GOES-E IR imagery and regional NEXRAD here at 23Z depict a well
defined eye on Helene with a central dense overcast extending into
Apalachee Bay. Outer bands extend north through the Atlanta metro
with a sharp cutoff on the west side on the stationary front that
is just into AL. Extreme moisture advection persists ahead of
Helene on ever strengthening cyclonic flow with 2.5"+ PW in the
inner core of the storm. This exceptionally moist air continues to
pivot northward into an area of intense deep layer ascent driven
via strong mid-level divergence overlapping the diffluent right
entrance portion of a northward arcing jet streak over northern
AL.

Continuous rainfall with rates around 1"/hr will persist ahead of
Helene with embedded areas of 2"/hr in the heaviest bands through
midnight. Training of these rates will result in widespread
additional rainfall of 2-3" by midnight. A corridor of 3 to 6"
along and west of the eyewall, which includes Tallahassee, is
forecast through 05Z by the 20Z HRRR which seems reasonable given
the increasing forward speed of the hurricane. The area southwest
of Tallahassee which has seen 6-10" over the past 24hrs is progged
to be just west this eyewall maxima through 04Z.

Expect flooding concerns to continue in the Atlanta metro this
evening with the additional couple inches. However, the greater
threat for Atlanta is early Friday morning as the remnant eye
passes to the east. Further details on rainfall from that will
come from overnight products.


Jackson

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...FFC...JAX...TAE...TBW...

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

LAT...LON   34218470 33868416 32948314 31568276 30448259
            29618275 29158322 29818392 29518483 29658539
            30228586 30348596 31698596 32868571