285
FXUS62 KMFL 151225
AFDMFL
Area Forecast Discussion
National Weather Service Miami FL
825 AM EDT Tue Sep 15 2026
...New AVIATION...
.KEY MESSAGES...
Updated at 821 AM EDT Tue Sep 15 2026
- Scattered showers and thunderstorms focus mainly across
Southwest Florida today. Frequent lightning, heavy rain and
gusty winds will be possible with any storms.
- An approaching upper-level low is expected to bring
increasingly unsettled weather for the middle to end of this
week.
- High temperatures remain in the low to mid 90s across South FL
each day, resulting in widespread Moderate HeatRisk.
&&
.SHORT TERM...
(Today through Wednesday)
Issued at 235 AM EDT Tue Sep 15 2026
The mid-week period consists of the formation of a Rex Block
ridge that covers most of the central and eastern CONUS. In the
western Atlantic, an upper-level low will be strengthening and
advecting southwestwards underneath this ridge, which will
effectively pull the low directly towards the Florida Peninsula
given the where the ridge is located. While this upper-level low
is not likely to reach our region until Wednesday night, we will
still see the effects of it for this mid- week period.
Firstly, the pressure gradient will enhance as the low approaches in
conjunction with the ridge strengthening. Latest HREF/LREF and other
ensemble data suggests around a 70-80% chance that H500 heights will
reach 600 decameters as a result of the amplifying ridge over the
eastern U.S., which would be above the 90th percentile for
heights. As a result, the pressure gradient will strengthen and
lead to a period of breezier easterly to northeasterly winds
beginning as soon as later this afternoon, but definitely for
tomorrow. With the lack of a surface low forming, not expecting
these winds to be overly strong, but they will be above average in
breeziness. Secondly, forcing for ascent will increase via
positive vorticity advection occurring towards South Florida,
which will provide energy for the production of widespread showers
and thunderstorms. Given the increase in northeasterly flow, we
should see the brunt of activity focusing in SW Florida, but speed
convergence and early diurnal processes is expected to result in
some scattered showers and thunderstorms in SE Florida as well for
today and tomorrow.
Overall, given the increasing amount of showers and storms that are
expected to form across the region over the next several days, the
primary concern will be for excessive rainfall flooding although the
risk for this also doesn`t seem that high. HREF LPMM generally
highlights a high-end scenario around 4-5" in a short time frame (~2
hours) with 90th percentile QPF (a reasonable high-end) of 2-4"
total over the next few days combined. Additionally, severe
parameters (lapse rates, CAPE/DCAPE, shear, etc.) are relatively
benign, although of course an isolated strong core remains possible
to occur via max convergence of low level boundaries that are able
to spark a more robust updraft. Nevertheless, this has a very low
chance of occurrence so not expecting much of a severe threat here
through the period.
High temperatures across the region will generally reach the low 90s
still through mid-week, with some areas seeing max temps in the
upper 80s. Overnight lows for Tuesday night will range from the low
to mid 70s across SW Florida to the upper 70s and low 80s for the
east coast metro areas.
&&
.LONG TERM...
(Wednesday night through Monday)
Issued at 235 AM EDT Tue Sep 15 2026
The stout 600 decameter H5 heat dome will finally begin to weaken
and shift west for the latter half of the week. The main high
pressure center will move west of the Mississippi by Thursday, with
mid-level height falls occurring across Florida as and inverted
trough begins to push west across the Gulf Stream. There is very
good agreement amongst both ensemble and deterministic guidance that
a cut-off upper low will develop on the southeast side of the ridge.
This will occur as part of the upper level jet detaches from the
main flow over the Great Lakes, creating a Rex Block pattern across
the southeast, with deepening low pressure over Florida and
persistent ridging over the Deep South. This shift in the upper
level pattern will create much more unsettled weather across South
Florida, with PoPs climbing above 80% each day through the end of
the week.
Continued deep moisture (with PWATs above 2 inches) and increased
forcing aloft should allow for scattered to numerous storms to
develop across the region. While there is still some spread in the
guidance, most ensemble QPF clusters are only showing about 1.5 to
2.5 inches of rainfall for the Thursday through Friday period. These
amounts shouldn`t result in anything more than a few isolated urban
flooding impacts for low lying and poor drainage locations. At the
surface, pressure gradients will relax across the region after
Wednesday, knocking down ENE winds back to around ten knots. This
should result in slower and more erratic storm motions, with
development following outflow and boundary collisions. But with the
upper low moving overhead, increased forcing may allow for a few
training storms to hit the same area multiple times. As the low
crosses into the Gulf over the weekend, there is also an indication
that there could be some coastal convergence and pinned coastal
storms. While not quite perpendicular to each other, winds at 500
and 700 mbs will be out of the SW, while winds at the surface will
be out of the E to NE. This may lead to slow moving storms and
enhanced moisture convergence along the Paradise Coast, which also
happens to be where most ensemble QPF clusters show the highest
rainfall amounts to be (although mostly offshore).
While more uncertain, there will also be an isolated threat of
severe weather as the disturbance crosses the region. Some models
are showing that 500 mb temperatures may drop into the -8 to -9 C
range, within the 25th percentile for this time of year. This could
result in some steeper lapse rates, allowing for some stronger cores
to develop and for a low chance of hail and strong downburst winds.
However, increased cloud cover may inhibit the amount of diurnal
heating and instability that accumulates throughout the day, keeping
the threat of strong storms more conditional and low confidence.
Overall, highs will remain in the upper 80s to low 90s across SoFlo,
with lows in the 70s. Once the upper low ejects out to the west on
Sunday, we should return to our more typical sea-breeze dominated
wind regime, with scattered afternoon storms.
&&
.AVIATION...
(12Z TAFS)
Issued at 821 AM EDT Tue Sep 15 2026
VFR conditions should generally prevail today, with brief periods
of sub-VFR conditions possible due to SHRA/TSRA starting late
morning today. Confidence remains generally low regarding timing,
so went without significant mention on the TAFs for this cycle.
Light easterly flow should prevail through the period.
&&
.MARINE...
Issued at 235 AM EDT Tue Sep 15 2026
Benign conditions continue today, but increasing winds and seas are
expected to arrive Wednesday towards the end of the week as a
disturbance approaches from the western Atlantic. For today, a
gentle northeasterly flow is expected across the Atlantic waters
with light to gentle winds in the Gulf shifting to the SW in the
afternoon. Seas remain at 2 feet or less for today. For Wednesday,
northeast winds will increase, becoming moderate to fresh over the
Atlantic waters and fresh to strong for the Gulf waters.
Additionally, seas are expected to rise to 5-8 feet in the
Atlantic by late Wednesday with Gulf seas at 3-5 feet. Therefore,
increasingly hazardous conditions for small craft will be
developing over the next several days and may require an advisory.
Other than winds and seas, an increased number of shower and
thunderstorms are also expected.
&&
.BEACHES...
Issued at 235 AM EDT Tue Sep 15 2026
The risk for rip currents will rise beginning on Wednesday and into
the late week period as increased onshore winds and swell arrive due
to a disturbance approaching from the western Atlantic. This risk
is expected to remain elevated for several days.
&&
.PRELIMINARY POINT TEMPS/POPS...
Miami 90 79 89 77 / 40 50 70 60
West Kendall 90 77 89 75 / 40 40 60 40
Opa-Locka 90 78 90 79 / 40 50 70 60
Homestead 91 78 90 79 / 40 50 60 60
Fort Lauderdale 89 80 88 79 / 40 60 70 70
N Ft Lauderdale 90 79 89 78 / 50 60 70 70
Pembroke Pines 90 78 89 77 / 40 50 70 60
West Palm Beach 90 79 90 78 / 60 60 70 70
Boca Raton 89 80 88 78 / 60 60 70 80
Naples 92 76 92 75 / 70 30 80 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
GM...None.
&&
$$
SHORT TERM...Redman
LONG TERM....NMP
AVIATION...ATV
NWS MFL Office Area Forecast Discussion