Mount Plymouth, Florida Weather Forecast Discussion

776
FXUS62 KMLB 181744
AFDMLB
Area Forecast Discussion
National Weather Service Melbourne FL
144 PM EDT Thu Sep 18 2025
...New AVIATION...
.KEY MESSAGES...
Issued at 315 AM EDT Thu Sep 18 2025
- A high risk of rip currents exists at St. Lucie and Martin
  county beaches today, with a moderate risk at Volusia, Brevard,
  and Indian River county beaches.
- Coverage of rain and lightning storms will gradually increase
  from south to north through late week; locally heavy rainfall
  possible across the Treasure Coast today. A Marginal Risk of
  Excessive Rainfall exists over portions of the Treasure Coast,
  Okeechobee, and Brevard Counties today.
- Temperatures remain near to slightly below normal this week and
  into early next week, especially across the south, where higher
  coverage of clouds and rain are forecast.
&&
.DISCUSSION...
Issued at 315 AM EDT Thu Sep 18 2025
Today-Tonight... The mid to upper level trough across the eastern US
will slowly shift eastward and out into the Atlantic into tonight.
The surface low pressure over NC/VA will gradually move northeast
off of the New England coast and open into a trough. Locally, deep
moisture will continue to build northward across the Florida
peninsula through the day, with forecast PW values increasing to 1.8-
2.0" from around Melbourne southward, with comparably drier air ( PW
values of 1.5"-1.7") farther inland and northwest. This will result
in greater rain chances across the area today. There is a medium (50-
70 percent) chance of rain and lightning storms from Brevard to
Orange Counties southward this afternoon and early evening, with 30-
40 percent north and west of there. The main storm hazards will be
frequent lightning strikes, gusty winds of 40-50 mph, and locally
heavy downpours. There is a Marginal Risk for excessive rainfall for
portions of the Treasure Coast, Okeechobee, and Brevard Counties
today. Weak steering flow aloft combined with the higher moisture
may support training activity and/or multiple rounds of slow-moving
showers, which in turn, may lead to minor flooding. Much like this
last night, scattered onshore moving showers will continue to be
possible overnight. The greatest potential for these onshore moving
showers will be along the coast from around Melbourne southward.
Lightning storm activity overnight looks to remain limited, however,
an isolated storm or two can not be ruled out.
Outside of convection, northeast winds of 5-10 mph will prevail
today before turning easterly and increasing to 10-15 mph (with
gusts to around 20 mph along the coast) in the afternoon behind the
sea breeze. Onshore flow and high cloud cover will help keep
temperatures norm to slightly below normal today. Afternoon highs
will be in the mid to upper 80s, with some locations around the
Greater Orlando area forecast to reach 90 degrees. Overnight lows
will remain in the low to mid 70s.
Friday-Sunday... The mid to upper level trough will continue to
shift eastward across the Atlantic through the period, with quasi-
zonal flow developing aloft through early weekend. Flow is forecast
to then become more meridional into late weekend as another trough
aloft begins to build towards the area. At the same time, a mid to
upper level trough will shift eastward across Canada and towards the
Great Lakes. At the surface, a boundary will reestablish itself
across South Florida to just offshore of South Florida this weekend
and will begin to slowly shift northward late weekend. Locally,
deeper moisture will continue to build northward across the local
area through early weekend. This will result in greater rain chances
across east central Florida through the time period, with a low to
medium (30 to 70 percent) chance for rain and lightning storms each
day, with Sunday having the lowest rain chances (PoPs 30-50
percent). The greatest rain chances are focused across southern
portions of the forecast area each day, where PWATs are anticipated
to be highest (1.8 to 2.0"). The main storm hazards will be frequent
lightning strikes, gusty winds of 40-50 mph, and locally heavy
downpours. Locally heavy rainfall will continue to be a concern as
weak steering flow aloft combined with the higher moisture may
support training activity and/or multiple rounds of slow-moving
showers which could lead to minor flooding. Any lingering activity
is forecast to diminish late each evening across the peninsula, with
scattered showers and storms remaining possible across the Atlantic
waters overnight.
Northeast winds will continue to prevail with speeds generally 5-10
mph. The east coast sea breeze is forecast to form each afternoon,
veering the winds more easterly and increasing the winds to 10-15
mph. Breezy conditions along the coast, with gusts up to 20 mph,
will continue to be possible in the afternoon behind the sea breeze.
The onshore flow coupled with some high cloud cover will help keep
temperatures near normal to slightly below normal. Afternoon highs
will be in the mid to upper 80s on Friday, and then upper 80s to low
90s Saturday and Sunday. Overnight lows will be in the low to mid
70s.
Monday-Thursday... The aforementioned mid-upper level trough near
the Great Lakes will slowly shift eastward as a mid to upper level
cutoff low develops across the Central US into mid week. This cutoff
low will slowly drift eastward towards the Great Lakes into mid to
late week. This will result in mid level ridging developing over the
Florida peninsula mid week. At the surface, the boundary across
South Florida will continue to shift northward to near to just south
of the local area by early week and will remain through mid to late
week while slowly drifting eastward and diminishing. Locally,
northeast to east winds at 10-15 mph will persist through the period
with the east coast sea breeze forecast to form each afternoon.
Global models continue to slightly disagree on moisture for next
week. So have decided to continue to go with NBM for rain chances
(30-50 percent). Scattered daily storms are also forecast, with with
lightning strikes and gusty winds the main concerns aside from heavy
rainfall and flooding. Any lingering activity is forecast to
diminish late each evening across the peninsula, with scattered
showers and storms remaining possible across the Atlantic waters
overnight.
Temperatures will be near normal for this time of year as onshore
flow persist. Afternoon highs will be in the  upper 80s to low 90s.
Overnight lows wil continue to be low to mid 70s.
&&
.MARINE...
Issued at 315 AM EDT Thu Sep 18 2025
Today-Monday... Favorable boating conditions forecast into the next
week. Northeast winds will become more easterly into late week with
speeds around 12 KT today. Wind speeds will increase to 10-15 KT
late week and into the weekend, and remain into early next week, as
a surface boundary reestablishes itself near to just south of the
local waters. Seas 3-5 ft prevailing through the time period.
Isolated showers and storms will largely be confined to the Gulf
Stream and southern Treasure Coast waters through today, until
deeper moisture brings higher rain and lightning storm chances late
week and into the weekend before rain and storm chances decrease
slightly into next week.
&&
.AVIATION...
(18Z TAFs)
Issued at 144 PM EDT Thu Sep 18 2025
Coverage of showers and isolated storms is forecast to increase
through the afternoon. VCSH included along the coast from TIX
southward and at LEE. There is a low chance for lightning across
the interior and have opted to keep a mention of VCTS at
MCO/ISM/SFB after 19Z. Showers and storms mostly diminish by 00Z.
However, isolated showers remain possible along the coast from
Cape Canaveral southward overnight and have kept VCSH for most
coastal terminals. East-northeast winds increase to around 10 kts
today, becoming light and variable tonight. Northeast winds
increase tomorrow with gusts around 20 kts across the north.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB  73  86  74  86 /  20  20  20  30
MCO  73  89  73  89 /  20  30  10  30
MLB  74  87  76  87 /  40  40  30  40
VRB  73  87  75  88 /  40  40  40  40
LEE  71  89  72  89 /  10  20   0  20
SFB  72  88  73  88 /  10  30  10  30
ORL  73  89  74  89 /  20  30  10  30
FPR  73  87  73  88 /  40  40  30  50
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
DISCUSSION...Watson
AVIATION...Law

NWS MLB Office Area Forecast Discussion