Port St. Lucie, Florida 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

409
FXUS62 KMLB 191910
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
310 PM EDT Sat Jul 19 2025

...New KEY MESSAGES, DISCUSSION, MARINE...

.KEY MESSAGES...
Issued at 304 PM EDT Sat Jul 19 2025

- A Heat Advisory remains in effect for Brevard, Lake, Orange,
  Osceola, Seminole, and Volusia counties until 6 PM for peak heat
  indices of 108 to 110 degrees.

- Very warm and humid conditions with peak afternoon heat indices
  up to 110 and Moderate to Major HeatRisk impacts continue
  across portions of east central Florida through early next week.

- Rain and lightning storm chances remain below normal through
  this weekend, with chances increasing once again next week as a
  weakening front and high moisture approach from the north.

&&

.DISCUSSION...
Issued at 304 PM EDT Sat Jul 19 2025

Currently...Wasn`t hard to find the ridge axis from the Atlantic
surface high in this morning`s cu-field, extending west-southwest
from near Sebastian/Vero Beach inland. A decent amount of moisture
remains near the surface, contributing to the oppressive heat,
while at the same time very dry conditions in the low-mid levels
have been hostile to deep convection. GOES PWATs range from 1.4"
along the coast behind the sea breeze, to around 1.6" across most
of East Central Florida, peaking around 1.8" north of I-4 where a
few showers and lightning storms have managed to develop on the
east coast sea breeze and lake breeze boundaries.

Rest of Today...Subsidence from mid-level ridging directly over
central Florida and southerly flow around the ridge axis will push
afternoon temperatures into the L-M90s, which combined with
humidity will produce peak heat indices between 102-110, higher to
north where it`s a little warmer. A Heat Advisory remains in
effect for Brevard, Lake, Orange, Osceola, Seminole, and Volusia
counties until 6 PM. This level of heat can impact most people
spending extended periods of time outdoors, putting everyone at a
greater risk for heat stress. If spending long durations outside
today, be sure to remain adequately hydrated, take frequent breaks
in the shade or air conditioning, wear lightweight, lightly
colored clothing, and if possible, shift activities away from the
peak heating hours of the day.

Expect little to no relief from rain (in fact rain might actually
make things work by spiking humidity), as entrainment and
subsidence continue to be significant hurdles to deep convection.
There`s a 10-20% chance of showers and lightning storms popping up
on boundaries and the sea breeze through the rest of the
afternoon, increasing to all of 20-40% along and north of the I-4
corridor in the evening with the sea breeze collision and higher
moisture. That said, any storms that manage to develop will be
capable of producing frequent lightning strikes, wind gusts to 45
mph, and brief heavy downpours thanks to T500 remaining around -8C
and downdraft enhancement from the dry air.

Sunday-Monday...The mid-level ridge shifts westward, reducing the
effect of subsidence warming some, but low-level flow becoming
more southerly to southwesterly as the ridge axis shifts further
south makes up the difference and then some, helping to push high
temperatures closer to the M-U90s, especially Monday. While
forecast dewpoint temperatures have dropped a degree or two since
the previous package, these hot temperatures combined with
humidity are still expected to produce peak afternoon heat
indices of 102-110, especially from Osceola and Brevard counties
north where the effect of the southerly to southwesterly flow will
have the greatest impact (i.e. it`ll be hot), and additional Heat
Advisories remain on the table. Rain and storm chances remain
dismal Sunday at just 20-30% inland (well inland to the south),
but begin to improve Monday increasing to 20-50% across the area
as the high aloft departs westward and low-mid level moisture
increases ahead of an approaching weakening front. Any storms
that manage to develop remain capable of producing frequent
lightning strikes, gusty winds, and heavy downpours, with higher
chances of seeing these stronger storms Monday as the environment
becomes more favorable and overall coverage increases. Showers
and storms continue to follow the usual afternoon timing pattern,
diminishing into the late evening and early overnight, but chances
for convection lingering late across the local Atlantic waters
increases Monday night.

Tuesday-Friday...(Modified Previous Discussion) By Tuesday, the
mid-level ridge weakens across the Gulf, allowing a weakening
front to approach Florida. The front is forecast to stall just
north of the area, with the potential for a low to develop along
the boundary and shift westward towards the Gulf. This is forecast
to result in increasing moisture across east central Florida,
with PWATs surging above 2 inches once again. Rain and storm
chances increase through the remainder of the work week, with PoPs
capped at 70 percent through the extended period at this time.
While it is still too early to determine exact storm threats,
lightning, gusty winds, and heavy downpours will all be possible
given the current model guidance.

Heat will continue to be a concern through next week, though
highs fall slightly into the upper 80s to low 90s thanks to the
greater rain and storm chances helping to limit daytime heating.
However, conditions remain muggy, with peak heat indices still
forecast to reach 102 to 107 across much of east central Florida.
Some areas may exceed advisory thresholds, but confidence in this
does remain lower this far out. Lows remains seasonable in the low
to mid 70s overnight, with muggy conditions persisting.

&&

.MARINE...
Issued at 304 PM EDT Sat Jul 19 2025

Generally favorable albeit hot boating conditions continue through
the weekend and early next week. The ridge axis of the Atlantic
high will slowly drop from Central Florida today to South Florida
by Monday, as a front and associated higher moisture moves into
the Deep South. Mostly dry conditions expected through Sunday,
then rain chances increase again Monday. The high further weakens
going towards mid-week, allowing the weakening frontal boundary to
drop closer to Florida. High rain chances return as moisture
surges across the area, and there is potential for a low pressure
system to develop along this boundary, causing winds and seas to
deteriorate. Mainly southerly winds backing to the southeast to
east in the afternoon with the sea breeze today and Sunday become
more southwesterly, backing to the south to southeast with the sea
breeze Monday onward. Seas 1-3 ft through Tuesday could increase
Wednesday and Thursday.

&&

.AVIATION...
(18Z TAFs)
Issued at 135 PM EDT Sat Jul 19 2025

Mostly VFR. Drier airmass and ridge aloft will continue to keep
lower shower/storm coverage in the forecast, with rain chances
only around 20-40% near to NW of I-4. Have added VCSH for
KSFB/KMCO/KISM for 21-01Z, and kept VCTS at KLEE for 22-01Z where
thunder chances will be slightly higher closer to where late day
sea breeze collisions are expected. For now have kept any tempo
groups out of these inland TAF sites due to the lower rain
chances, but will continue to monitor for any needed amendments.
Shower/storm chances remains low into Sunday, and any convective
development looks to be very late in the day near to west of
Orlando from 23-01Z, so even for KMCO have left out any mention of
VCSH/VCTS for Sunday.

Winds will be light and variable, except behind the inland moving
east coast sea breeze this afternoon where winds will be out of
the E/SE around 10 knots.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  75  94  76  94 /  10  20  10  40
MCO  76  97  77  97 /  10  30  10  40
MLB  76  92  76  94 /   0  10  10  30
VRB  74  92  73  93 /   0  10   0  20
LEE  77  95  77  94 /  20  20  10  40
SFB  76  97  77  97 /  10  20  10  40
ORL  77  97  77  97 /  10  30  10  40
FPR  74  92  73  93 /   0  10   0  20

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...Heat Advisory until 6 PM EDT this evening for FLZ041-044>046-053-
     141-144-247-347-447-547-647-747.

AM...None.
&&

$$

DISCUSSION...Haley
AVIATION...Weitlich