439
FXUS62 KMFL 250707
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
307 AM EDT Wed Sep 25 2024

...New SHORT TERM, LONG TERM, MARINE, BEACHES...

.SHORT TERM...
(Today through Thursday)
Issued at 302 AM EDT Wed Sep 25 2024

*** KEY POINTS FOR TROPICAL STORM/HURRICANE HELENE ***

Impacts for South Florida: Helene, soon to be a hurricane, will
bring about heavy rain, gusty winds, storm surge (Gulf Coast), and
increased flooding potential as its outer bands move across the
region. A Tropical Storm Warning is in effect for Collier, Glades,
Hendry, and Mainland Monroe counties.

Flood Watch Issued: A Flood Watch is in effect for all of South
Florida, as rainfall amounts of 2-6 inches are possible across
inland and metro areas.

Storm Surge Risk: 2-4 feet of storm surge is expected along the Gulf
Coast from Bonita Beach to Flamingo due to Helene`s size and the
shallow Florida shelf. Values as high as 5 feet may be observed. A
Storm Surge Warning is in effect for these coastal areas.

Limited Tornado Threat: Tropical tornado risk is limited but a few
tornadoes may spawn Wednesday night into early Thursday, especially
along the southwest Florida and the Lake Okeechobee region.

The focus remains on Tropical Storm Helene, which is expected to
strengthen into a hurricane as it moves over the northwestern
Caribbean Sea, just offshore from the Yucatan Peninsula. South
Florida is already experiencing the effects of the storm, as
evidenced by high precipitable water (PWAT) values exceeding 2.2
inches, dew points in the upper 70s, and warm air aloft. Outer bands
from Helene are expected to move northward across the region today,
bringing periodic heavy rain with intervals of sunshine. Winds from
the southeast will strengthen throughout the day, with gusts
exceeding 30 mph, especially along the coasts.

The primary impacts from Helene will arrive late Wednesday as the
storm center progresses northward through the Gulf of Mexico. A
significant moisture envelope will move into the region during this
time, with PWAT values forecasted between 2.3 to 2.5 inches - nearing
climatological highs for late September. Models also indicate a long,
skinny CAPE profile, supportive of warm cloud processes and heavy
rainfall. Given these parameters, there is potential for heavy rain
and localized flooding across the area. A Flood Watch is in effect
for Collier, Glades, and Hendry counties from Wednesday morning
through Friday, with the possibility of extending eastward depending
on rainfall accumulation earlier today.

Rainfall amounts between late Wednesday and Friday evening are
expected to range from 2 to 4 inches inland, with metro areas
potentially seeing 3 to 6 inches. Several advisories remain in
effect for the Gulf Coast, including a Tropical Storm Warning and a
Storm Surge Warning from Bonita Beach to Flamingo. Storm surge may
reach 2-4 feet, with some vulnerable coastal areas possibly seeing
up to 5 feet due to the large size of Helene and the shallow nature
of the Florida shelf. Dangerous marine and boating conditions will
prevail across the entire region, with the most significant impacts
felt in the Gulf waters. As Helene`s outer feeder bands move across
the region, tropical storm-force wind gusts are possible throughout
South Florida.

Aside from the risks of storm surge, flooding rains, and wind, the
threat of tropical tornadoes appears limited. South Floridas
residence time within the northeast quadrant of the system could
reduce the window for tornadic activity, with the peak risk for
tornadoes between 18Z-00Z due to dry air mixing and diurnal heating.
Tornado potential may be confined to coastal areas of Collier,
depending on the storm`s track. A second window for possible
tornadogenesis may open in the Lake Okeechobee region Thursday
afternoon as Helene moves further north in the Gulf of Mexico.
Temperatures will remain near climatological norms, as cloud cover
and widespread rain keep highs in check. Rainbands will bring gusty
winds, intense rainfall, and localized urban flooding throughout the
day. The brunt of the storm`s impacts will begin this afternoon and
continue through the night, with rainbands lingering through
Thursday as the system`s trailing edge moves through the area.

&&

.LONG TERM...
(Thursday night through Tuesday)
Issued at 302 AM EDT Wed Sep 25 2024

Helene will have made landfall along the Big Bend/Gulf Coast region
of Florida by late Thursday, and its direct impacts will be distant
from South Florida. However, a stream of elevated moisture,
characterized by PWAT values of 2.3-2.5 inches, will continue to
drape over the region as breezy southwesterly flow persists. This
southwest flow, associated with Helene`s extratropical transition,
could enhance low-level convergence, further elevating hydrologic
concerns, especially in areas prone to poor drainage. The moisture
fetch will likely linger into the weekend, keeping humidity levels
high across South Florida.

Through the weekend, South Florida will experience a transitioning
weather regime. Initially, low-level steering flow will come from
the south and southwest, but it is expected to gradually shift to
the west and northwest over time. The stream of moisture will become
more diffuse, but enough will remain to produce scattered showers
and thunderstorms. Localized flooding may occur, but overall impacts
should be minimal.

Looking beyond the weekend, some long-range models suggest the
potential for a weak frontal passage, bringing a light northwesterly
flow. However, it is too early to confirm this, and the event
remains uncertain given its distance in time.

&&

.AVIATION...
(06Z TAFS)
Issued at 100 AM EDT Wed Sep 25 2024

SCT showers and thunderstorms early this morning will increase in
coverage as the day goes on as Tropical Storm Helene enters the SE
Gulf of Mexico. E/SE winds around 10 kts early this morning will
increase to 15-20 kts with gusts of 25-30 kts by this afternoon
and continue through the remainder of the period. Brief flight
restrictions are likely during periods of heavy rain today and
tonight.

&&

.MARINE...
Issued at 302 AM EDT Wed Sep 25 2024

Moderate easterly winds will gradually increase in magnitude as
Tropical Storm (soon to be Hurricane) Helene approaches the Gulf
waters. Winds and seas will become dangerous across the local waters
as the system intensifies and moves northward. Tropical Storm
conditions are likely across all the local waters, and the most
dangerous conditions will occur across the Gulf waters. Numerous
to widespread showers and thunderstorms will generally be observed
by midday today into Thursday.

&&

.BEACHES...
Issued at 302 AM EDT Wed Sep 25 2024

Moderate to major coastal flooding can be expected over the Gulf
coast late Wednesday into Thursday as Tropical Storm Helene
strengthens and tracks through the SE Gulf of Mexico.

Strengthening onshore flow will result in an extended period of high
rip current risk over the east coast (likely through the work week),
with potentially hazardous surf developing over the Palm Beaches in
the mid-week period. Additionally hazardous beach conditions look
likely over the Gulf coast beaches starting Thursday as surf
increases in association with Tropical Storm Helene.

&&

.PRELIMINARY POINT TEMPS/POPS...
Miami            89  79  89  80 /  70  70  70  70
West Kendall     89  79  89  80 /  70  70  70  70
Opa-Locka        90  79  89  80 /  70  70  70  70
Homestead        88  79  88  80 /  70  80  70  70
Fort Lauderdale  88  79  89  80 /  70  70  70  70
N Ft Lauderdale  89  79  90  80 /  70  70  70  70
Pembroke Pines   91  80  90  82 /  70  70  70  70
West Palm Beach  89  79  90  80 /  70  70  70  60
Boca Raton       90  79  90  80 /  70  70  70  70
Naples           91  79  87  81 /  80  80  90  80

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...Tropical Storm Warning for FLZ063-066-069-070-075.

     Flood Watch from 8 AM EDT this morning through Friday morning
     for FLZ063-066>075-168-172>174.

     Storm Surge Warning for FLZ069-075.

     High Rip Current Risk through Thursday evening for FLZ168-172-
     173.

AM...Tropical Storm Warning for AMZ610.

     Small Craft Advisory until 6 PM EDT Thursday for AMZ630-650-651-
     670-671.

GM...Tropical Storm Warning for GMZ656-657-676.

&&

$$

SHORT TERM...Bhatti
LONG TERM....Bhatti
AVIATION...CMF