376
FXUS62 KMLB 201126
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
726 AM EDT Fri Sep 20 2024

...New AVIATION...

.AVIATION...
(12Z TAFs)
Issued at 629 AM EDT Fri Sep 20 2024

Patchy fog this morning affecting LEE and OBE. Expect reductions
to clear through around 13Z. Then, VFR conditions prevailing.
Scattered showers and storms this afternoon, mainly along and
inland from the Treasure Coast. VCSH developing around 20Z from
MCO southward, with VCTS possible at FPR and SUA. Convection will
move inland through the afternoon, clearing around sunset. Then,
models suggest showers along the coast overnight (after around
5Z), pushing onshore due to NNE/NE flow. Winds around 10kts or
less through the period.

&&

.PREVIOUS DISCUSSION...
Issued at 227 AM EDT Fri Sep 20 2024

KEY MESSAGES:

- The best chance (30-50%) for a few lightning storms today
  resides closer to the Treasure Coast. This weekend, 30-40%
  shower/storm chances continue.

- Minor coastal flooding remains possible, particularly during
  the late morning high tides through the upcoming weekend. Low-
  lying streets, yards, and docks along the barrier islands and
  Intracoastal may experience minor flooding.

- There is a medium chance (40%) for tropical development in the
  northwest Caribbean or southern Gulf of Mexico next week. It is
  too early to determine what, if any, impacts this would bring to
  East Central Florida. Continue to monitor the forecast for
  updates.

              ----------Synoptic Overview----------

This morning, a weak trough extends down the U.S. East Coast. To the
west, upper high pressure resides over Texas, out ahead of deep low
pressure over California. Florida will remain influenced by the
trough through Saturday before the upper high migrates eastward
early next week. By Tuesday or Wednesday, ensemble guidance suggests
ridging will become anchored near Florida as a trough pushes
across the Upper Mississippi River Valley.

At the surface, weak high pressure will slowly settle across the
Appalachians through this weekend. Northeasterly boundary layer flow
will result, and moisture values will remain near to somewhat below
normal for mid/late September.

The Central American Gyre is still forecast to become active over
the NW Caribbean by early next week. A propensity of ensemble
members eventually develops negative pressure anomalies near the
Yucatan Channel. There is a medium chance of eventual tropical
development from this feature. However, it`s too early to
determine whether impacts will occur locally.

             -------Sensible Weather & Impacts-------

Today & Tonight...

We should start our day off fairly quietly. Some patchy fog is
possible around dawn. Boundary-layer flow turns onshore today, with
a few gusts to around 20 mph especially north of Cape Canaveral.
Weak cyclonic flow and associated vorticity remain overhead, but
moisture is limited above H7. This supports only 20-30% shower/storm
chances near I-4 and the Space Coast and 40-50% chances for the
Treasure Coast. Any stronger storms would have the potential to
produce occasional lightning strikes, gusty winds 40-45 mph, and
brief torrential rain which could cause minor flooding. Highs should
reach the upper 80s to around 90F. Later tonight, a few showers may
try to skirt the coast in the increasing NE flow. Lows 70-77F,
warmest beachside.

Minor coastal flooding is anticipated at high tide today, with water
levels likely at their peak between 8 AM and noon.

This Weekend...

Northeast surface flow becomes well-established across the Sunshine
State as high pressure nestles over the Appalachians. Ripples of
moisture in the boundary layer, and lingering mid-level vorticity,
lend to broad 30-40% chances for showers and a few storms. Some
of this activity will extend into the overnight hours,
particularly along the coast.

It will be breezy at times, with a few gusts up to 20 mph each day.
Highs will again range from the upper 80s to the low 90s, with lows
in the low/mid 70s.

A minor coastal flooding threat persists during high tide cycles
through at least Sunday. The highest water levels are forecast in
the late morning hours with a lesser peak in the late evening.
Beach-goers should be mindful that surf will be slowly building
and the rip current risk will be at least moderate, and
potentially even high!

Monday-Wednesday...

Ensembles strongly indicate that upper ridging becomes entrenched
over Florida. With increased subsidence and a further diminution of
available moisture, rain/storm coverage still looks below normal for
late September. At the surface, east winds will remain breezy at
times, which could push a few low-topped showers onshore. We are
currently carrying 10-30% measurable rain chances each day, except
20-40% for the Treasure Coast. Steady-state temperature trends are
in order, with each day ranging from the upper 80s to the low 90s.

Later Next Week...

All eyes remain on the extended forecast as most ensemble members
and their respective means congeal deep tropical moisture and lower
surface pressures over the NW Caribbean or southern Gulf of Mexico.
Unfortunately, that`s about where the agreement stops. The National
Hurricane Center still highlights a 40% chance of tropical
development with this disturbance. At this time, however, there is
currently no well-defined system for models to track. Furthermore,
the mid-latitude longwave pattern will be in the process of
realignment. A weak trough is expected to push into the Midwest as
ridging builds over the West ahead of an enhanced Pacific jet.
There is a significant spread in the depth and timing of the
Midwestern trough and its embedded vort maxima. All told, one
should not expect a lot of clarity on this setup for 2-3 more days
at least.

It`s still way too early to determine whether any local impacts from
this potential disturbance will occur. For now, we are showing a
gradual uptick in shower/storm chances late next week. Keep checking
weather.gov/mlb for updates over the next few days.

&&

.MARINE...
Issued at 227 AM EDT Fri Sep 20 2024

Boating conditions slowly become poorer over the next few days as
onshore winds increase. As high pressure settles into the
Appalachians, northeast winds freshen to 8-13 KT today through the
weekend. There is a low to medium chance for showers and a few
storms, though offshore-moving storms look less likely. By early
next week, winds turn more easterly at 10-15 KT. Seas 2-4 FT through
Saturday before building to 3-5 FT Sunday-Tuesday, largely driven by
a northeast swell at 9-11 sec.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  88  74  87  75 /  20  20  40  20
MCO  90  74  90  73 /  30  10  40   0
MLB  88  75  88  76 /  30  20  40  20
VRB  88  73  89  74 /  40  20  40  20
LEE  90  73  90  73 /  20   0  30   0
SFB  89  73  88  73 /  30  10  40  10
ORL  90  74  90  75 /  30  10  40   0
FPR  88  73  88  73 /  40  20  40  20

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Advisory until 2 PM EDT Sunday for FLZ141-154-159-
     164-347-447-647-747.

AM...None.
&&

$$

DISCUSSION...Heil
AVIATION...Leahy