604
FXUS62 KMFL 080532
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
132 AM EDT Tue Sep 8 2026

...New SHORT TERM, LONG TERM, AVIATION, MARINE, BEACHES...

.KEY MESSAGES...
Updated at 125 AM EDT Tue Sep 8 2026

 - Numerous showers and thunderstorms will develop today,
   primarily across inland areas between 2-8 PM. Gusty winds and
   dangerous cloud to ground lightning is possible with any storm.

 - Slow moving storms will increase the risk for localized
   flooding especially if rainfall occurs in a short period of
   time over an urban area.

 - High temperatures will generally rise into the lower 90s across
   most of South Florida through this week, creating widespread
   Moderate HeatRisk each day.

&&

.SHORT TERM...
(Today through Wednesday)
Issued at 125 AM EDT Tue Sep 8 2026

05z Mesoanalysis depicts quite the saturated boundary layer across
South Florida early this morning, as the combination of decaying
cold pools and a land breeze has resulted in a classic peninsular
drainage flow pattern. The 00z MFL RAOB (Rawinsonde Observation/
Upper Air Sounding) in tandem with recent ACARS data from SoFlo
airports depicts ample convective inhibition within much of the
vertical column (500-1000mb) and a stout near surface inversion. For
the remainder of the overnight hours through daybreak this pattern
will act to focus shower and thunderstorm activity offshore
(nearshore Atlantic & Gulf waters) where instability is maximized
and aided by the diurnal cycle of atmospheric convection (oceanic
convection peaks in intensity and coverage during the early morning
hours). Some of this shower and thunderstorm activity may make it
close to the coast (especially along the east coast of South
Florida) prior to or around daybreak but should remain maximized
where instability is greatest. Back onshore, ample moisture trapped
underneath the near surface inversion may set the stage for pockets
of localized dense fog across inland areas where winds decouple
under clearing skies. HREF probabilities for visibility values below
a half a mile remain low in the 10-20% range with a maxima in these
values near Lake Okeechobee. Even with low confidence on more
significant fog impacts, patchy fog could still prove to be
impactful along Alligator Alley, SR-80, and US-27. Any isolated fog
that does develop will gradually mix out and dissipate as sunshine
erodes the near surface inversion and diurnal atmospheric mixing
begins. Wakeup temperatures will range from the low 70s near Lake
Okeechobee to temperatures in the mid to upper 70s along the coast.

South Florida will remain to the south of a frontolytic frontal
boundary currently draped across the northern half of the Florida
peninsula today. As is such the case this time of year (for better
or worse), no discernible temperature gradient exists across the
aforementioned frontal boundary. What does exist however is a
notable moisture gradient from north to south and that will continue
to have direct implications on our weather regime and convective
coverage here in South Florida. While the use of precipitable water
values (averaged out for the entire vertical column) has it`s
caveats, 05z RTMA analysis as well as forecast soundings (RAP, HRRR,
etc) for this afternoon depict precipitable water values across
South Florida remaining in the 2.0 to 2.1 inch range. According to
SPC`s Sounding Climatology interface, these values will be between
the 75th to 90th percentile for today`s date, a factoid that
highlights that the atmosphere remains moist and with enough diurnal
heating, unstable. Aloft, orphaned lobes of mid-level vorticity
remain just to the north of our region as the waning influence of
"parent" mid level troughing has long departed and 500mb heights and
temperatures have begun to increase across most of the southern
United States as a developing mid level ridge slides eastward.

The nearby boundary and the onset of a strengthening mid-level ridge
across the southern United States will also result in light winds
(below 5-10 knots) throughout much of the atmospheric column today.
As is standard fare and a common occurrence in this type of flow
regime, each mesoscale model this morning has a different evolution
for what may transpire across South Florida this afternoon and
evening. The 00z HRRR depicts convection initiating on the Gulf sea-
breeze and advecting to the northwest as the day progresses whereas
the 00z RRFS and HiResW show an inverse convective evolution playing
out. Rather than just guessing which model solution is correct
(lukewarm odds for verifying), we can use forecast analysis and
climatology to get a better idea of how things will play out. NWS
Tampa Bay produced a comprehensive study a few years back on
thunderstorm climatology for the Florida Peninsula that takes into
account average mean flow between the 1000mb, 925mb, 850mb, and
700mb layers. When mean flow across these various layers is below 5
knots, convection can propagate (albeit slowly) in any direction.
With the onset of diurnal heating, winds will veer onshore along
both coasts during the late morning/early afternoon hours as
differential heating gets the diurnal sea-breeze circulation going.
It`ll take some time to fully erode any residual convection
inhibition, that stout near surface inversion, and stratified
atmosphere at daybreak. Hence inland areas will be the foci for the
bulk of convective activity today as both the Atlantic and Gulf sea-
breezes gradually push inland and away from the coast as the
afternoon progresses.

As convection evolves from initial discrete cores into congealing
multicellular clusters, outflow dominant cold pools may result in
decaying convection pushing back towards the coast during the late
afternoon and early evening hours. 500mb temperatures will remain
quite warm today between the 75th and 90th percentile at -5C to -6C
with consequently equally meager mid-level lapse rates. While ample
instability (forecasted CAPE of 3000-4000+ J/kg) and moisture will
lead to numerous shower and thunderstorms this afternoon, the threat
of severe convection remains minimal. Frequent lightning, gusty sub-
severe winds, and heavy rainfall remains the primary hazard with
showers and thunderstorms today. With a saturated environment and
variable flow (Corfidi upshear and downshear vectors below 10 knots)
in the vertical column, pockets of heavy rainfall are once again
possible today, especially when convection is pinned along boundary
collisions. HREF`s LPMM depicts isolated pockets of 2-3" of rainfall
across primarily inland locales through 00z (8pm) this evening.
Model guidance can be fickle in the exact placement of these higher
pockets of QPF, so some potential remains for inland suburbs to see
heavy rainfall and localized urban flooding, although the threat
will remain fairly marginal in nature. While convective timing can
be hard to nail down, model guidance and environment analysis depict
the bulk of diurnal convection across South Florida occurring
between 2pm to 8pm. High temperatures are forecast to peak in the
low 90s this afternoon before overspreading convection (and
resultant cloud debris) act to cool temperatures down. Before any
relief from the heat, ample humidity and sunshine will result in
apparent temperatures in the 100F to 105F degree range across most
of the region. NWS`s Probabilistic HeatRisk has high probabilities
(70-90%) of Moderate HeatRisk for most of South Florida today. Be
sure to take necessary heat precautions today if you or your loved
ones are sensitive to heat.

As mid-level ridging continues to build across the southeastern
United States, a large and expansive area of surface ridging will
also begin to build across the western Atlantic waters tonight into
Wednesday. Anticyclonic surface flow around this feature will
enhance in tandem which will result in background winds shifting to
a southeasterly direction by tonight. Although the diffuse boundary
to our north is forecast to dissipate during this time frame, deep
moisture will remain in place across our region. The confluence of a
land breeze from earlier diurnal convection and light southeasterly
flow over the nearshore Atlantic waters may set the stage once again
for early morning shower and thunderstorm activity across the
Gulfstream waters tonight through daybreak on Wednesday. With a
southeasterly wind component now in play, early morning showers and
thunderstorms may move onshore along the east coast of South Florida
before a stable atmosphere results in the waning and dissipation of
activity. The subtle shift in surface winds will focus afternoon
convection across inland and coastal southwestern Florida on
Wednesday afternoon as a pinned Gulf breeze will be prevented from
making much headway inland. Convective hazards remain similar to
what will transpire today (gusty sub-severe winds, frequent cloud to
ground lightning, and heavy rain) with the caveat that heavy
rainfall on Wednesday afternoon/evening may fall directly over
portions of the Naples metro which could cause isolated urban
flooding. High temperatures on Wednesday afternoon are forecast to
reach the low to mid 90s before the cooling influence of convection
and cloud cover act to reduce temperatures once again.

&&

.LONG TERM...
(Wednesday night through Monday)
Issued at 125 AM EDT Tue Sep 8 2026

Upper-level ridging over the eastern CONUS will gradually push
eastward into the Atlantic as it becomes flattened by an upper-level
trough during the second half of the week. At the surface, high
pressure situated over the western Atlantic is expected to maintain
a general easterly flow across South Florida through the weekend.
Under this regime, isolated to scattered showers and thunderstorms
migrating onshore from the Atlantic waters will be possible along
the East Coast each morning. As daytime heating ramps up and sea
breezes push inland, the primary focus for convection will shift
toward the interior and SW Florida, where activity will be maximized
during the afternoon and early evening hours each day.

Current LREF ensemble mean guidance indicates that atmospheric
moisture content will remain slightly above normal through the
period, with PWATs generally in the 1.9-2.1 inch range. However,
global models continue to show a Saharan dust plume approaching the
region this weekend into early next week. While the highest dust
concentrations should remain well to the south of the peninsula, any
mid-level dry air intrusion could potentially enhance mid-level
lapse rates and DCAPE, thereby increasing the potential for
localized severe winds in robust afternoon convection. Confidence in
this scenario remains low at this time, given uncertainty regarding
the timing and extent of the dry air intrusion. Otherwise, the
potential for severe weather is expected to remain fairly limited,
with wind shear staying weak and 500 mb temperatures forecast to
remain near to slightly warmer than climatology through the period.

High temperatures will rise into the lower 90s across most areas
through early next week, reaching the mid 90s over interior SW
Florida. Overnight lows will range from the low 70s across the
interior to the low 80s along the coasts. Major HeatRisk
probabilities will gradually increase across coastal and metro areas
into the weekend as persistent onshore flow keeps heat indices
elevated and limits overnight cooling.

&&

.AVIATION...
(06Z TAFS)
Issued at 125 AM EDT Tue Sep 8 2026

VFR conditions are expected to prevail through the period. L/V winds
will increase to 5-7 kts after 16Z with scattered convective
activity developing again after 17-18Z. Confidence is too low to
include TEMPOs at this time, as there is a chance most of this
activity stays away from the terminals. KAPF will see SW winds again
in the afternoon today.

&&

.MARINE...
Issued at 125 AM EDT Tue Sep 8 2026

Light to gentle southerly winds will prevail today before shifting
southeasterly tonight into Wednesday. Afternoon sea breezes will
produce localized wind shifts once again today, turning winds
southeasterly over the Atlantic waters and southwesterly over the
Gulf waters today. Winds across all waters will veer to a
southeasterly direction tonight into Wednesday, with the exception
of a brief period of onshore wind flow across the nearshore Gulf
waters each afternoon through the remainder of the work week.
Scattered to numerous showers and thunderstorms will develop over
the local waters each day. Gusty and erratic winds, along with brief
periods of rough seas, will be possible in and around thunderstorms.
Seas across the Atlantic and Gulf waters will generally remain at 2
feet or less through tonight, before wave heights enhance to 3-4
feet across the Atlantic waters on Wednesday in response to
increasing northeasterly swell.

&&

.BEACHES...
Issued at 125 AM EDT Tue Sep 8 2026

The combination of increasing northeasterly swell and onshore
surface winds may result in an elevated rip current risk at Palm
Beach County beaches beginning on Wednesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Miami            90  79  90  80 /  40  30  40  30
West Kendall     90  78  90  79 /  50  30  40  30
Opa-Locka        91  80  91  81 /  40  30  40  30
Homestead        91  78  91  79 /  50  30  30  40
Fort Lauderdale  90  79  90  80 /  40  40  40  30
N Ft Lauderdale  91  80  91  81 /  40  30  50  30
Pembroke Pines   90  79  90  81 /  50  30  40  30
West Palm Beach  92  78  92  79 /  40  30  60  20
Boca Raton       90  79  90  79 /  40  40  50  20
Naples           91  77  92  77 /  40  50  80  40

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
GM...None.
&&

$$

SHORT TERM...Hadi
LONG TERM....DPB
AVIATION...DPB