Port St. Lucie, Florida 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

342
FXUS62 KMLB 160605
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
205 AM EDT Mon Mar 16 2026

...New KEY MESSAGES, DISCUSSION, MARINE, AVIATION, FIRE WEATHER...

.KEY MESSAGES...
Issued at 205 AM EDT Mon Mar 16 2026

- Stay weather-aware today! There is a Slight Risk of strong to
  severe storms between 1 PM and 10 PM. The primary threats are
  damaging wind gusts over 60 mph and quarter-size hail. There is
  also a small chance of a couple of tornadoes.

- Windy and very warm ahead of the front through mid-afternoon.
  Southerly wind gusts will reach 25 to 30 mph outside of the
  storms. Poor to hazardous boating conditions are expected.

- Sharply colder by Tuesday. Expect wind chills in the mid to
  upper 30s northwest of I-4, and afternoon highs 20 to 25 degrees
  cooler than today. Gradual warming returns later this week.

&&

.DISCUSSION...
Issued at 205 AM EDT Mon Mar 16 2026

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

Early this morning, all eyes are on a powerful disturbance across
the Mississippi Valley that continues to carve out a sharp dip in
the polar jet stream. This feature will mature today, with surface
low pressure becoming vertically stacked beneath the core of the
upper-level trough across the Great Lakes. A strong cold front,
draped from its parent surface low down into the Gulf, is quickly
sweeping eastward toward Florida.

Locally, broad south to southwest flow is in place ahead of the
front this morning. At the base of the trough over AL/GA later
today, a 130+ kt jet streak at H5 will force ascent along and just
ahead of the cold front. By afternoon, the PBL mass response will
be characterized by 3 kft (H925) winds increasing to 25-35 kt,
further building to around 30-40 kt at 5 kft (H85). This results
in 25-30 kt of effective shear. Seasonably cool mid-level
temperatures, combined with unseasonably high surface moisture and
warmth, will yield 1,500-2,500 J/kg of SFC CAPE in the mostly
uncapped warm sector ahead of the front. Other favorable
convective parameters include STP values around 1, 150+ J/kg of
0-3km CAPE, and downdraft CAPE values approaching 1,000 J/kg.

Behind the front on Monday night, a shallow, yet stout, layer of
cold advection will rush southward, dropping 3kft temperatures
over northern portions of Central Florida from the 95th percentile
today (+19 to +20 deg C) down to near climatological minima (+1
to +3 deg C) by Tuesday afternoon! The anomalous subtropical
moisture will also be scoured out as PWs drop to 0.4 to 0.7 in
(near the 20th percentile).

Thereafter, confidence has begun to improve for the second half
of this forecast period. The 14/12Z grand ensemble still depicts
a fairly classic +PNA pattern with negligible high-latitude
blocking. The northern stream should relax and move poleward, but
a lingering trough will reside over the eastern U.S. downstream of
a record-shattering early-season heat ridge out West. Consensus is
growing that the nearby trough axis will be just progressive enough
to hold the deep moisture immediately southeast of Central Florida
late this week. A tightening pressure gradient is anticipated over
the peninsula, freshening onshore flow and gradually eroding the
cool, continental air mass.

By the weekend, another disturbance in the polar jet
across the Northeast U.S. should continue to push the trough
seaward. Quasi-zonal flow aloft will act to pull downslope-warmed
air off the Rockies toward the Deep South. Confidence trails off in
about a week. By next Monday, a majority of the membership keeps any
fronts north of Florida. However, around a third of the members
dig a deeper trough into the Northeast U.S., sending a backdoor
cold front toward the state.


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

Today...

...A Few Strong To Severe Storms This Afternoon and Evening...

The morning should start off on a quiet note, with hi-res guidance
suggesting breaks of sunshine and quickly-warming temperatures
through midday. As the low-level jet cranks up, the initial
mix-out late in the morning could deliver southerly wind gusts up
to around 30 mph. Windy conditions will then persist as we move
into the afternoon.

Similar to what happened yesterday, we expect conditions to go
downhill as we push into the afternoon and evening. You`ll want to
have multiple ways of receiving weather warnings. Consider checking
the Wireless Emergency Alert feature in your phone`s settings,
and make sure weather alerts are enabled.

Proximity soundings look uncapped by early afternoon, with
convective temps in the low-mid 80s. A couple of rounds
of storms are on the table. First, we cannot rule out some
discrete storms firing off in the open warm sector by early-mid
afternoon. This activity will be moving northeastward, and the
environment raises some concern that a couple of supercells may
develop. Convective-allowing models favor development from Melbourne
to Okeechobee and east to the coast. Damaging wind gusts and large
hail would be the primary threats, with a limited tornado threat
existing, especially along the coast.

Then, as the cold front arrives northwest of Orlando by 2-4
PM, a broken line of showers and storms should push into the
district. This activity may arrive either just before or during
the I-4 evening rush. These broken line segments will be moving
southeastward, reaching the Treasure Coast between 6 and 10 PM
before exiting the area to the south. Shear vectors parallel to
the line segments may limit severe potential. However, any bowing
segments that allow the 0-3km vector to become at least somewhat
perpendicular to the line would be capable of producing damaging
wind gusts and a brief tornado.

SPC has placed most of the area in a Slight / 15% severe wind risk
today. This matches well with the latest AI/ML guidance.

Storms should be moving quickly enough to limit the risk for
excessive rainfall. There is a low chance (10%) of picking up 2-3"
if your location sees multiple rounds of storms today.

High temps will reach the 80s today, the warmest from Orlando
southward, where some upper 80s are expected. A few spots may
reach 90 deg F, particularly close to Lake O.

Tonight - Tuesday Night...

Don`t put away the socks, jackets and Q-zips just yet. Lingering
showers should exit the Treasure Coast by around midnight, paving
the way for colder air to rush down the peninsula. Wind chills in
the mid- upper 30s should be expected northwest of I-4 on Tuesday
morning. Highs on Tuesday will be well below normal, from near 60
over Volusia County to the upper 60s south of St Lucie Inlet.
Throw in a thickening cirrus deck and a pesky northerly breeze,
and you have the recipe for a chilly Florida afternoon.

Cold March temperatures will persist into Tuesday night. Low temps
should fall well into the 40s over the interior and Volusia County,
with low 50s along the immediate coast south of the Cape.

Wednesday - Next Weekend...

Due to some discrepancies in the guidance, we will continue to
carry low (< 30%) rain chances over the Treasure Coast on
Wednesday, perhaps lingering along the coast south of the Cape
into Thursday and Friday as well. However, recent trends have been
drier.

Florida will be stuck between strong high pressure to the north and
an old surface trough from the Bahamas to the NW Caribbean Sea. This
will cause winds to turn northeasterly, ending the cold advection
and slowly warming our temperatures in time. Temperatures return
closer to normal by Friday, then jump further as we move into
the weekend. There is now a 70-80% chance of reaching 80 deg F +
by Saturday and Sunday under plentiful sunshine.

&&

.MARINE...
Issued at 205 AM EDT Mon Mar 16 2026

Boating conditions worsen and become hazardous over the
next day or so as a strong cold front approaches the local
Atlantic. Offshore-moving showers and storms will have the potential
to produce gusty winds this afternoon and evening as the front
passes. South-southwest winds turn northwesterly and freshen
tonight. The cold front stalls in the southern Bahamas by mid-week
as high pressure moves over the Mid-Atlantic states. Moderate to
fresh onshore winds will result, building seas once again later
in the week.

Small Craft Advisories will go into effect today, first for the
Gulf Stream this morning, then for the nearshore zones by
afternoon. Seas 3-6 ft today, building to 6-9 ft by early Tuesday
in the Gulf Stream. Seas diminish to 4-6 ft on Wednesday, but some
7 ft seas return to the Gulf Stream on Thursday as onshore winds
increase.

&&

.AVIATION...
(06Z TAFs)
Issued at 205 AM EDT Mon Mar 16 2026

S/SW winds increase through sunrise just above the boundary layer
reaching 30-35 kt around 2k ft across northern terminals. There will
be a corresponding increase in the southerly sfc wind of 8-10 knots
so have held off on LLWS in the TAFs. After sunrise, daytime heating
will quickly mix down those gusty S/SW winds reaching 24-28 kts. A
squall line will approach northern terminals ahead of a strong cold
front btwn 19Z-23Z. Ahead of the main band, discrete convection
should develop south of MCO and affect MLB-SUA btwn 19Z-22Z. This
may be followed by another round of storms there with the squall
line itself closer to 00Z-02Z though some weakening should occur.
TEMPO groups are in place for all terminals for CIG/VSBY
restrictions in TSRA btwn 19Z-23Z along with gusty winds around 30
knots. There is potential for convective wind gusts greater than 35
knots at several terminals. A NW wind shift will occur from north to
south Mon night behind the front with 15kts G20-24kts.

&&

.FIRE WEATHER...
Issued at 205 AM EDT Mon Mar 16 2026

Numerous showers with scattered storms are forecast this
afternoon and evening ahead of a cold front. While wetting rains
are forecast for many places, lightning may spark new fires.

Much cooler and drier air filters over the district on Tuesday. RH
minima on Tuesday fall to 30-40% near and northwest of I-4. North
winds around 10-12 mph will combine with the dry air to produce
fire-sensitive conditions. RH values recover slightly on Wednesday
and Thursday, then fall into the 35-40% range again on Friday over
the interior.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  83  45  59  45 /  80  30   0   0
MCO  85  49  61  47 /  80  30   0   0
MLB  86  52  63  50 /  80  50  10  10
VRB  87  56  65  53 /  80  60  10  10
LEE  81  45  61  43 /  80  20   0   0
SFB  83  48  61  45 /  80  30   0   0
ORL  84  49  61  47 /  80  30   0   0
FPR  87  56  65  53 /  80  60  10  10

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory from 2 PM this afternoon to 11 AM EDT
     Tuesday for AMZ550-552.

     Small Craft Advisory from 2 PM this afternoon to 2 AM EDT
     Wednesday for AMZ555.

     Small Craft Advisory until 2 AM EDT Wednesday for AMZ570-572-575.

&&

$$

DISCUSSION...Heil
AVIATION...Kelly