Okeechobee, Florida Weather Forecast Discussion

659
FXUS62 KMLB 112001
AFDMLB
Area Forecast Discussion
National Weather Service Melbourne FL
401 PM EDT Thu Sep 11 2025
...New KEY MESSAGES, DISCUSSION, MARINE...
.KEY MESSAGES...
Issued at 347 PM EDT Thu Sep 11 2025
- Bands of onshore moving showers will continue to pose a risk for
  heavy rainfall and minor flooding from the Treasure Coast to
  near Lake Okeechobee through the rest of evening.
- There is potential for bands of onshore moving showers to set up
  along the coast through the overnight period.
- While drier air lowers rain chances going towards the weekend,
  the risk for minor flooding will linger.
&&
.DISCUSSION...
Issued at 347 PM EDT Thu Sep 11 2025
Currently...A somewhat amorphous front sits near to just south of
the Treasure Coast and Lake Okeechobee. Breezy and gusty
conditions have developed along portions of the coast behind the
front as the east coast sea breeze enhances onshore
(northeasterly) flow. Drier air filtering in from the north is
causing a noteworthy moisture gradient across the area, with PWATs
as low as 1.7" north of I-4 increasing to +2.2" down south closer
to the front. Bands of showers have developed along the Treasure
Coast in this higher moisture with the onshore flow, and will be
the primary focus for heavy rainfall across the southern counties
that could lead to minor flooding.
Rest of Today...Minor flooding from heavy rainfall will once
again be the primary storm threat. Through the afternoon and
evening the highest chances are from the Treasure Coast counties
inland to Okeechobee county, in an area of anomalously high
moisture with PWATs well above the 90th percentile associated with
a frontal boundary departing into South Florida. Moderate onshore
(northeasterly) flow at the surface behind the front and
increasing southwesterly flow in the levels above the surface are
producing bulk shear values of 30-40 kts, enhancing
banding/training of showers and storms as they push onshore and
inland, and could cause convection to become slower moving as
winds aloft increase. CAMs want to push this current activity
inland fairly quickly, and so far that is playing out, but their
performance has been mediocre at best over the last 18 hours, and
the official forecast calls for rain chances up to around 70%
here in the afternoon to gradually decrease through the late
evening. Primary storm threats will be heavy rainfall
accumulations of 2-4" with locally higher amounts possible where
banding of showers sets up, occasional to frequent cloud to ground
lightning, and gusty winds to around 45 mph. Given the high shear
and copious moisture, there is also a very low chance for a
couple funnel clouds. There is Slight Risk (level 2 of 4) for
excessive rainfall from the Treasure Coast to near Lake
Okeechobee, and a Marginal Risk (level 1 of 4) just to the north
across the southern portions of Brevard and Osceola, and including
portions of Indian River and Okeechobee counties not in the
Slight risk.
Go north to and past Osceola and Brevard counties and it`s a
whole different story for the afternoon and evening. Drier air
filtering in from the north, especially in the 850-700mb layer
crucial for updraft development, has led to mostly dry conditions
across the rest of the area. Forecast carries a 20-50% chance of
showers here, and it`s very possible these are going to be well
overcooked. That said, the cu field from daytime heating is fairly
healthy and PWATs still range from 1.9-2.2" south of I-4, so
don`t want to get too crazy with the PoP hammer and will let them
ride for now. Generally expect showers at best here, but can`t
rule out a lightning storm that manages to punch through.
Tonight...Can`t quite close the book on the heavy rainfall threat
as some upper-level energy swings through and the front/moisture
takes it`s time pushing south. Highest rain chances shift
offshore, but with the continued northeasterly flow at the
surface, could see additional bands of showers develop and move
onshore through the night. There is potential for these bands to
become nearly stationary as southwesterly flow above the surface
continues to increase (and any land breeze that attempts to
develop won`t help), continuing the risk for rainfall
accumulations of 2-4" with locally higher amounts possible where
bands set up, especially if they become slow moving. Other storm
threats remain occasional cloud to ground lightning, gusty winds
to 45 mph, and can`t rule out funnel clouds given the amount of
shear.
Friday-Saturday...Troughing over the eastern US digs down to the
Atlantic seaboard Friday and sweeps across Florida Saturday,
helping to slowly usher the front over South Florida further south
and drier air into East Central Florida. However, much of this
drier air will be in the mid to upper levels, while onshore flow
continues to provide a decent source of moisture at the surface
and lower levels, and higher moisture to the south is slow to
scour out. As a result, rain chances have come up a few notches
since the previous forecast, to 40-60% in the afternoons and a
lingering 30-50% along the coastal corridors during the
overnights, both higher to the south. Given the very dry air aloft
and middling instability most of this activity looks to be low-
topped showers, which is consistent with a moderate onshore flow
regime, but any deeper convection that manages to develop could
see downdraft enhancement leading to strong wind gusts, frequent
cloud to ground lightning, and locally heavy rainfall. We continue
to carry a Marginal Risk for excessive rainfall across most of
ECFL Friday and portions Saturday, and a lingering Slight Risk to
the south both days as moisture lingers well to the south.
Temperatures below normal with afternoon highs below in the
M-U80s, and morning lows in the L70s, flirting with the U60s in
the cooler rural spots.
High astronomical tides will continue to cause wave runup to near
the dune line during the early afternoon high tides, and a
Moderate to High Risk of life-threatening rip currents will also
continue.
Sunday-Thursday...Not thrilled with model consistency in the
extended term of the forecast. Global models are back to
developing cutoff mid-level lows and attendant surface lows
somewhere off the Atlantic seaboard, with locations of theses
features ranging from just offshore East Central Florida in the
ECM to the Mid-Atlantic in the GFS and CMC. Official forecast
leans towards the latter two since they`re more in line with
previous runs (including the ECM), ensemble means, and more
consistent with the previous forecast. Hence, the official
forecast continues to call for drier than normal air to continue
filtering in from the north, knocking rain chances down below
normal. Temperatures also remain below normal in this northerly
flow.
&&
.MARINE...
Issued at 347 PM EDT Thu Sep 11 2025
Rest of Today-Tonight...The frontal boundary will continue to
press slowly southward out of the Treasure Coast tonight. Winds
NNE-NE 10-15 kts from sea breeze enhancement this afternoon settle
to around 10 kts late tonight. There will still be periods of
moderate to heavy rainfall, with greatest coverage generally Cape
southward. Seas typically 3-5 ft.
Friday-Monday (Modified Previous Discussion) The boundary will
finally push into south FL and remain south of the local waters
thru the remainder of the extended, though moisture is slow to
scour out - esp south of the Cape. Wind directional component will
continue to be mainly NNE/NE thru the period, increasing to 10-15
kts from the afternoon and early overnight from sea breeze
enhancement, and settling to 5-10 kts in the late overnight and
early morning. Winds could increase to 15-20 kts at times in the
Volusia waters, mainly Saturday and Sunday. Seas 3-5 ft, up to 6
ft in portions of the Gulf Stream over the weekend. Confidence in
the forecast decreases Sunday and Monday, due to uncertainty in
the development of a low pressure system somewhere along the
Atlantic Seaboard, from possibly in or near the local Atlantic
waters all the way up to the Mid-Atlantic.
&&
.AVIATION...
(18Z TAFs)
Issued at 155 PM EDT Thu Sep 11 2025
Onshore-moving showers continue along the Treasure Coast, with the
possibility of a few embedded thunderstorms this afternoon. TEMPOs
have been included for brief VIS/CIG reductions in heavier
storms. To the north, chances for SH appear limited due to the
current CAMs and CU field presentation. Thus, have removed mention
of VCSH for all but MLB. However, showers are expected to build
northward along the coast overnight, possibly stretching as far
inland as SFB this evening. So, have included VCSH for much of the
period along the coast after 0Z. Higher coverage of showers is
forecast Friday, with VCSH after 18Z over the interior. VFR
conditions look to prevail, but periods of MVFR CIGs cannot be
ruled out, especially overnight.
N/NNE flow will remain breezy this afternoon and into this
evening, especially along the coast. Winds 10-15 kts, with gusts
to around 20-25 kts are expected to slacken after sunset. Then,
winds will become breezy again through the morning Friday.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB  74  85  73  84 /  30  50  30  50
MCO  73  87  72  87 /  20  50  20  50
MLB  76  86  74  86 /  40  60  40  50
VRB  75  87  73  86 /  40  60  40  50
LEE  72  87  71  87 /  10  30  10  40
SFB  73  87  72  86 /  20  40  20  50
ORL  74  87  72  86 /  20  50  20  50
FPR  74  87  73  87 /  50  60  40  50
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
DISCUSSION...Haley
AVIATION...Leahy

NWS MLB Office Area Forecast Discussion