440
FXUS62 KMLB 251105
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
705 AM EDT Wed Sep 25 2024

...New AVIATION...

.AVIATION...
(12Z TAFs)
Issued at 705 AM EDT Wed Sep 25 2024

MCO IMPACTS:
- Gusty crosswinds for N/S ops (ESE G20-25 KT) starting this
  morning.
- 60% chance of showers/storms after 25/18Z with occasional
  IFR/MVFR restrictions.
- Helene to bring significant aviation impacts on Thursday.

Forecast appears on track, except timing of showers has moved up a
bit. For MCO and Orlando area, showers begin mid/late morning,
eventually with TS mention this afternoon. Timing is somewhat
later for DAB. From MLB south to SUA, showers have already been
arriving from the SE with TS potential increasing after 14Z. Dips
to MVFR/IFR expected in/near rain and storm areas.

ESE winds will ramp up to 10-20 KT G20-25 KT from late morning
onward. Gusts will continue along the coast into tonight. Winds
will continue to strengthen into Thursday as Helene moves through
the NE Gulf, along with periods of rain/storms.

&&

.PREVIOUS DISCUSSION...
Issued at 455 AM EDT Wed Sep 25 2024

Key Messages:

-Tropical Cyclone Helene will lift north into the eastern Gulf of
 Mexico next 48 hours and produce heavy rain, strong winds and
 possible tornadoes. Rough, battering surf will produce dangerous
 conditions at the beaches.

-Hot and humid late week behind "Helene" as plume of deep moisture
 returns and keeps a threat for heavy rain this weekend.

Today...Considerable high cloudiness spiraling anticyclonically
outward from TC Helene will continue to spread north across cent
FL. "Helene" is currently located in the far NW Caribbean near
the Yucatan channel early this morning. As "Helene" continues to
intensify and begins to lift northward into the eastern Gulf later
today, the SE pressure gradient across our area will tighten and
produce a balmy, breezy day. Meanwhile, deep moisture is surging
northward which will support a higher coverage of showers and
storms with banding setting up near the east coast and spreading
inland. These bands will not be directly connected to Helene yet
but may be described as detached outer rainbands. Locally heavy
rain will accompany these bands and training of cells is possible
which would create a localized flood threat, esp where recent
heavy rains have occurred. For this evening and tonight, low level
shear/helicity will begin to increase and present a TC tornado
threat within rainbands but decreasing instability with loss of
heating calls into question the coverage and intensity of
convection after sunset.

Thu...As "Helene" lifts N/NE across the eastern Gulf of Mexico and
makes its closest approach to EC FL, the tornado threat will
increase as STP parameter maximizes (greater than 1) during the
aftn/eve. So a tornado watch is a possibility for at least parts
of central FL. The large envelope of winds esp on the east side of
this system will produce frequent gusts to tropical storm force
(39mph+) esp in passing rainbands. With 925 mb winds around 50
knots, wind gusts up to 60 mph will be possible.

Fri-Tue...Models show a dry slot moving into the area from the SW
on the backside of "Helene" as it lifts northward into GA then
the TN Valley Thu night/early Fri. But a plume of deep moisture
will remain across south FL and return northward over central FL
late Fri into the weekend. Hot, breezy SW flow on Fri-Sat will
produce max temps in the lower 90s even at the coast. Combined
with high humidity, peak heat indices will climb to 104-108. Storm
coverage looks higher on Sat when the deep moisture is squarely
over the area so have drawn 60 PoP areawide. Then decreasing rain
chances Sun (50 percent) and Mon/Tue (40 percent).

&&

.MARINE...
Issued at 455 AM EDT Wed Sep 25 2024

Tropical Storm Warnings are in effect for the adjacent Atlantic
waters out to 60 nm. Tropical Storm Helene is forecast to
continue to strengthen over the northwest Caribbean, moving north
into the eastern Gulf of Mexico later today and accelerate into
the FL Big Bend late Thursday. Boating conditions are
deteriorating today as southeast winds increase 20 kts, then
strengthening 30-40kts during Thu. Seas building 7-10 ft peaking
at 13 ft offshore Volusia and Brevard Thu aftn/night. Deep
moisture lifting northward will support a high coverage of showers
and storms thru Thu. Winds will become SW Fri and gradually
decrease near 15 knots Fri night with seas subsiding below 5 ft
along the coast due to the offshore component but remaining 6-7 ft
offshore. Flow remains offshore (W to SW) Sat-Sun up to 15 knots
with seas subsiding 3-4 Sat and 2-3 ft Sun. There will be
scattered to numerous storms pushing offshore esp Sat.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  89  77  89  78 /  50  70  90  60
MCO  90  77  89  79 /  60  70  90  60
MLB  88  79  90  79 /  60  70  80  70
VRB  88  78  91  78 /  70  70  80  70
LEE  90  77  87  78 /  60  70  90  60
SFB  89  77  88  79 /  60  70  90  60
ORL  90  78  89  80 /  60  70  90  60
FPR  88  78  90  78 /  60  70  70  70

&&

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

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

&&

$$

DISCUSSION...Kelly
AVIATION...Heil