381
FXUS62 KMLB 270146
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
946 PM EDT Thu Sep 26 2024

...New UPDATE...

.UPDATE...
Issued at 945 PM EDT Thu Sep 26 2024

Hurricane Helene is a major Category 4 hurricane, and is located
approximately 65 miles west of Cedar Key, Florida, as of 9 PM.
Helene is forecast to continue moving northward in the northeastern
Gulf of Mexico, where it is forecast to make landfall along the
Florida Big Bend over the next several hours. Locally, outer
rainbands from Helene will continue to move across the Florida
peninsula tonight, moving from the south toward the north. Windy
and gusty conditions and the potential for brief tornadoes persist
into the overnight hours across the area. A Tornado Watch remains
in effect for Lake, Seminole, Orange, Osceola, Volusia, and
Brevard counties through 6 AM. Heavy rainfall will also be
possible with these squalls, and minor localized flooding cannot
be fully ruled out in areas that see repeated rounds of rain.
Residents and visitors are encouraged to ensure they have multiple
ways of receiving weather alerts before heading to bed, and make
sure alerts are loud enough to wake you up.

In addition to the gusty winds and tornado threat overnight,
conditions across the local Atlantic waters and all east central
Florida beaches remains hazardous. Wave run-up to the dune line and
sea walls will result in beach erosion, especially during this
morning`s high tide between 3 AM and 5 AM. Marine conditions will
remain dangerous and small craft operators should remain in port.
Visitors and residents should stay off the beaches and out of the
surf, especially during the overnight hours! Additionally, numerous
life-threatening rip currents and a powerful longshore current will
exist.

Rainbands are expected to become less frequent into Friday as
Helene continues northward into Georgia, though gusty winds and
some scattered showers and storms will likely prevail through most
of the day on Friday.

Made very minimal adjustments to the overall forecast, and bumped up
PoPs slightly across the far western portions of the CWA based on
the rainband that was setting up. Skies are expected to remain
mostly cloudy overnight across east central Florida, with overnight
lows remaining warm and muggy in the upper 70s to low 80s.

&&

.PREVIOUS DISCUSSION...
Issued at 341 PM EDT Thu Sep 26 2024

Current-Tonight... Occasional fast-moving rainbands are expected
to sweep from south to north this afternoon and evening as Helene
moves northward. Tropical storm force winds extend far to the east
from the center of Helene, which includes all of the Florida
peninsula. Frequent tropical storm force gusts will be possible
across the area today into this evening. Winds and gusts will
continue to ramp up and become more frequent by late morning and
continue into the evening, with speeds around 40-50 mph. By
midday, wind gusts up to 60 to 65 mph will be possible,
particularly northwest of I-4, along the Atlantic coast and in
vicinity of Lake Okeechobee. Wind gusts of this magnitude can turn
lightweight objects into flying debris, cause sporadic power
interruptions, and perhaps result in some tree or minor structural
damage. The timeframe for the highest potential for these wind
gusts looks to be between 2 PM and 9 PM. Please remain indoors if
at all possible. Tropical storm force gusts will diminish after
midnight.

In addition to very windy conditions and strong wind gusts, a few to
several tornadoes embedded in the rain bands are also possible
through this evening. The Storm Prediction Center has highlighted
most of east central FL in a Slight Risk (level 2 of 5) for severe
storms (primarily for the threat of a few tornadoes), with a
Marginal Risk for St Lucie & Martin Counties today. A Tornado Watch
is in effect for all of east central Florida into this evening. We
will continue to monitor these fast- moving rain/storm bands for
this potential. Have multiple ways of receiving warnings through
tonight!

Due to the fast nature of these occasional rainbands, rainfall
totals will average about 1-2" through tonight across east central
Florida. While the overall rainfall is not high for the local area,
the threat for flooding in low- lying and urban areas, still
exist, especially in areas which have already received heavy
rainfall this month. A Flood Watch remains in effect for east
central Florida. Remember, if you encounter a flooded roadway,
turn around, don`t drown!

Tropical storm force gusts will diminish after midnight.
Hazardous marine and dangerous beach conditions into tonight. Wave
run-up to the dune line and sea walls will result in beach erosion,
especially during this afternoon`s high tide. Marine conditions will
become dangerous and small craft operators should remain in port.
Visitors and residents should stay off the beaches and out of the
surf through tonight! Additionally, numerous life-threatening rip
currents and a powerful longshore current will exist.

Otherwise, afternoon high temperatures will reach in the upper 80s
to low 90s due to the breaks in the rain and cloud cover. Conditions
are expected to improve late tonight, mainly after midnight. Winds
will back to the southwest and decrease gradually through the
overnight hours (especially after midnight) with speeds becoming
around 20 mph with gusts up to 30 mph possible around sunrise. The
number and frequency of the outer rainbands moving over east central
Florida will also decrease after midnight. Isolated to scattered
showers and embedded lightning storms will be possible late tonight
and into early Friday morning. Warm and muggy tonight, with
overnight lows in the mid to upper 70s to around 80 degrees.

Friday-Sunday... (Modified Previous Discussion) Once Helene makes
landfall in the Big Bend region of Florida this evening, it will
quickly push inland across Georgia and Tennessee Friday. Models
are in pretty good agreement that Helene will merge with the cut-
off low over the Tennessee Valley on Friday and Saturday. The
upper level low will slowly weaken over the weekend as a high
pressure ridge over the western Atlantic builds westward over the
Florida peninsula and the Deep South. Locally, winds will remain
southwesterly through the weekend, with speeds around 15 mph
Friday, decreasing to around 10 mph on Saturday, and 5-10 mph on
Sunday. Deep tropical moisture from the Caribbean will remain over
the local area through the weekend, with the moisture oscillating
from South-Central FL on Friday to Central Florida on Saturday
and Sunday. Beneath it, scattered-numerous (50-70%) shower and
storm coverage is forecast particularly in the afternoon/evening
hours. Additional rounds of heavy rainfall can not be ruled out,
thus increasing concerns of flooding over locations that have
already seen a lot of rainfall this month.

With deep moisture in place, high humidity will persist over the
area, with dew points in the mid to upper 70s. Combined with the
offshore flow, afternoon highs will be in the low 90s. These
temperatures combined with humidity will produce near heat advisory
criteria with heat indices ranging from 102-107F each afternoon.
Overnight lows will be in the low to mid 70s each night.

Monday-Wednesday... (Modified Previous Discussion) The upper level
ridge will begin to retreat into the Atlantic through mid week. As
the upper ridge sits nearby, the deep tropical moisture overhead
will trend closer to normal. Some members show bouts of even drier
air infiltrating the area from time to time, but confidence lessens
overall. This yields continued 30-50% shower/storm coverage each day
with highs in the upper 80s to lower 90s. Heat indices will subtly
"dip" closer to 98-103F as surface moisture trends toward normal
values. Overnight lows will remain in the low to mid 70s.

&&

.AVIATION...
(00Z TAFs)
Issued at 830 PM EDT Thu Sep 26 2024

Rain bands associated with Hurricane Helene gradually shift east
thru 06z-09z, impacting LEE now and eventually reaching
MCO/ISM/SFB by 02-03z. Activity will push toward coastal sites
like DAB/TIX after 06z. Frequent gusts above tropical storm force
will continue through 09z before gradually decreasing to 25-30kt
by 12z Fri. Locally higher gusts may remain at coastal terminals
for several hours longer Fri. morning. Lingering SHRA will
persist as conditions improve, turning drier from midday thru the
end of the TAF.

&&

.MARINE...
Issued at 341 PM EDT Thu Sep 26 2024

Today/Tonight... (Modified Previous Discussion) Major Hurricane
Helene will produce extremely dangerous marine conditions. All
operators should remain in port through tonight. Nearshore seas are
forecast to peak from 9-11 FT by this evening, increasing to 10-15
FT in the Gulf Stream. Sustained tropical-storm-force winds are
likely along with southerly gusts as high as 50-55 KT. Winds will
start to decrease overnight but tropical storm force gusts will
persist through the overnight. Numerous showers and storms with
waterspouts are possible!

Friday-Sunday... (Previous Discussion) Seas quickly subside through
the period: 5-7 FT nearshore / 6-10 FT on Friday, 2-3 FT nearshore /
3-5 FT offshore this weekend. However, fresh southerly winds
continue at 20-25 KT Friday before becoming SW 8-15 KT this weekend.
Scattered-numerous showers and storms with offshore-moving activity
expected.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  79  92  76  91 /  60  40  20  60
MCO  78  92  77  90 /  70  50  30  70
MLB  80  92  77  91 /  40  70  50  70
VRB  81  92  77  92 /  30  70  50  70
LEE  79  90  77  89 /  90  30  20  50
SFB  78  91  77  90 /  60  40  20  70
ORL  80  92  78  91 /  70  50  30  70
FPR  80  92  77  92 /  30  70  50  70

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...Tornado Watch until 6 AM EDT Friday for FLZ041-044>046-053-141-
     144-247-347-447-547-647-747.

     Tropical Storm Warning for FLZ041-044>046-053-058-141-144-154-
     159-164-247-254-259-264-347-447-547-647-747.

     Flood Watch until 8 AM EDT Friday for FLZ041-044>046-053-058-141-
     144-154-159-164-247-254-259-264-347-447-547-647-747.

     High Surf Advisory until 11 AM EDT Friday for FLZ141-154-159-164-
     347-447-647-747.

AM...Tornado Watch until 6 AM EDT Friday for AMZ550-552.

     Tropical Storm Warning for AMZ550-552-555-570-572-575.

&&

$$

UPDATE...Tollefsen
AVIATION...Schaper