392
FXUS62 KMLB 231853
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
253 PM EDT Mon Sep 23 2024

...New DISCUSSION, MARINE, HYDROLOGY...

.DISCUSSION...
Issued at 202 PM EDT Mon Sep 23 2024

...Potential Tropical Cyclone 9 over the NW Caribbean has a high
chance for further tropical development as it lifts north into the
eastern Gulf of Mexico this week and strengthens...

...While it is too early to describe exact impacts to east central
Florida, heavy rain and increasing winds are becoming an increasing
concern, as well as an isolated tornado threat...

...A plume of deep moisture may remain behind and keep a threat for
heavy rainfall into the weekend...

Current-Tonight-Tue-Tue Night...A tight moisture gradient in place
keeping ISOLD-SCT showers (20-40pct) (ISOLD lightning storm) mainly
near Orlando southward, and 10pct threat further northward.
Otherwise warm & humid conditions with highs in the U80s (coast)
and near 90F to L90s inland. Conditions remain very warm aloft
(-3C to -4C) limiting instability as subsidence is the main
feature here with mid-level ridging spreading across the Gulf and
FL peninsula. Any convective activity is expected to diminish or
push into WCFL by early evening. We do maintain a small PoP
(20pct) for southeast St. Lucie and Martin counties overnight.

Weak surface high pressure northward has pushed off of the
Carolinas into the western Atlc and will continue to weaken and
drift seaward. ENE/E winds 10-15 mph (15-20 mph along coast) with
higher gusts will diminish this evening and overnight becoming
light and veering slightly to E/ESE, but may still stay up around
5-10 mph along the immediate coast. Overnight mins in the L-M70s,
with U70s along the immediate Space/Treasure coasts and conditions
remaining muggy for both tonight and Tue night. Highs Tue should
mirror those of today (Mon). Will also keep a small PoP (20pct)
across the Treasure Coast and southern Osceola/Okeechobee counties
for Tue. Slightly higher wind speeds for Tue, only with a slight
veering to E/ESE.

.Previous Extended Forecast Discussion Modified...

Wed-Sun...Increasing consistent model guidance continues to forecast
a tropical cyclone developing in the NW Caribbean and lifting north
into the SE Gulf of Mexico while strengthening Wed-Thu. Confidence
on size, intensity and forecast track remains low but is gradually
increasing. The NHC has begun initiating PTC9 (Potential Tropical
Cyclone Nine) advisories. NHC has also scheduled an Air Force
recon mission to investigate the disturbance at this (Mon) afternoon.

The GFS and ECMWF ensembles remain consistent showing an upper
ridge over the SW Atlc and a developing cut-off low over MO/AR
that steers this system north to north northeast up thru the
eastern Gulf of Mexico and across the NE gulf coast later this
week. While it is too early to describe specific impacts for EC
FL, heavy rainfall and increasing winds are becoming an increasing
concern. Other hazards such as isolated tornadoes may also come
into play.

Models show a brief dry slot across the area Thu night/early Fri
then a plume of deep moisture redevelops over the FL peninsula
late Fri into the weekend long after the tropical system has
departed. This would produce high rain chances and a continued
threat for heavy rainfall, on ground that may be largely
saturated.

We are in peak hurricane season. Check weather.gov/mlb and hurricanes.gov
for the latest updates, and take the time to check on your hurricane
preparedness kits and plans.

&&

.MARINE...
Issued at 202 PM EDT Mon Sep 23 2024

Afternoon-Tue Night...Weak surface high pressure continues to drift
further into the western Atlc. Moderate E/ESE flow will continue
during this time with winds increasing further Tue night 13-18 kts.
Scattered showers and isolated lightning storms will occur this
afternoon from the Cape southward with lower coverage on Tue as
drier air filters down from the north. Seas 3-4 feet today-tonight
building 4-5 ft Tue and up to 6 ft Tue night in the Gulf Stream
Cape southward.

.Previous Extended Marine Forecast Discussion Modified...

Wed-Fri...Potential Tropical Cyclone Nine is forecast to continue
to develop and strengthen over the northwest Caribbean in the
next 48 hours, moving north into the eastern Gulf of Mexico mid
week. Boating conditions are forecast to deteriorate further Wed
into Thu as southeast winds increase 20 kts Wed and 25+ kts Wed
overnight into Thu with seas building 7-9 ft (perhaps 10 ft north
of the Cape during Thu). Small Craft Advisories look likely by
Wed aftn. Deep moisture lifting northward will support a high
coverage of showers and storms beginning late Wed into Fri. Winds
will become S/SW Fri and decrease 15-20 kts with seas subsiding
below 5 ft along the coast due to the offshore component but
remaining 6-7 ft offshore.

&&

.HYDROLOGY...
Issued at 202 PM EDT Mon Sep 23 2024

The Saint Johns River at Astor is forecast to remain in Moderate
Flood Stage through at least Friday before falling into Minor
Flood Stage on Saturday. However, any additional heavy rainfall
later this week and into the weekend will have the potential to
delay the decline further and may cause additional rises.

&&

.AVIATION...
(18Z TAFs)
Issued at 144 PM EDT Mon Sep 23 2024

VFR forecast through the period. VCSH continues from MLB southward
for isolated onshore moving showers. East winds increase to 10-12
kts with occasional gusts between 15-18 kts. Winds diminish to
around 5-8 kts overnight.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  74  89  76  89 /   0   0   0  30
MCO  74  91  76  90 /   0   0   0  50
MLB  77  89  79  89 /   0   0  10  40
VRB  76  89  78  89 /   0  10  20  50
LEE  73  92  76  90 /   0   0   0  40
SFB  73  91  75  89 /   0   0   0  40
ORL  74  92  76  90 /   0   0   0  50
FPR  75  89  78  89 /  10  10  20  60

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&

$$

DISCUSSION...Sedlock
AVIATION...Law