528
FXUS62 KMFL 171822
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
222 PM EDT Thu Jul 17 2025

...New UPDATE, AVIATION, BEACHES...

.KEY MESSAGES...
Updated at 222 PM EDT Thu Jul 17 2025

 - One more day of scattered to numerous showers and storms.

 - Dangerous heat indices begin Friday and last through the
   weekend.

 - Lower rain chances Friday through the weekend.

&&

.UPDATE...
Issued at 222 PM EDT Thu Jul 17 2025

Last of the low/mid level impulses embedded in broadly cyclonic
S/SE winds on the back side of the low pressure over the northern
Gulf is moving through South Florida this afternoon. This is
leading to the last in a period of scattered to numerous showers
and thunderstorms over interior and western sections of South
Florida. Residual cold air aloft (characterized by 500 mb temps in
the -8C to -9C range) will aid in the development of a few strong
to even marginally severe storms. Strong/gusty winds and frequent
lightning are the main threats, with hail a secondary threat.
Most of the showers and thunderstorms should dissipate by 8-10 PM
tonight. East coast areas will stay mainly dry this afternoon and
tonight, outside of a few showers which could briefly move
onshore.

Friday-Saturday: strong and deep-layered high pressure east of
the Bahamas today will move west and dominate the local weather
regime Friday through the weekend. A consensus of the models
continue to indicate 500 mb heights at or near record-high levels
for the date (595-597 dm) over South and Central Florida Friday
and Saturday, along with 850-700 mb temperatures well above the
90th percentile of climatology. The end result is decreasing
convection and rain chances below climatological normals for mid-
July. Interior and SW Florida PoPs are mostly in the 30-35% range,
and 20% or less SE Florida metro with lower PoPs Saturday vs
Friday as the high center moves over the peninsula.

Main concern for Friday and Saturday continues to be higher heat
index values potentially meeting Heat Advisory criteria. The
synoptic pattern and temperature profile described above is
conducive for higher than normal temperatures along with
seasonably high dewpoints. Adjusted high temperatures slightly
higher than the NBM mean on Friday, closer to the 75th percentile
which may still be rather conservative in some areas.

Details on expected/potential range of temperatures - and other
sensible weather for the next several days - is included in this
morning`s Short Term/Long Term sections which are included below
and remain valid based on latest analysis and trends.

&&

.SHORT TERM...
(Today through Friday)
Issued at 335 AM EDT Thu Jul 17 2025

An upper low will move from the western Atlantic over the
Peninsula by tonight. Under the diffluent upper flow and with
deep layer moisture ahead of it, expect scattered to numerous
showers and storms to develop. Forcing from the surface level will
likely be a combination of coastal convergence from the
background winds on the western periphery of the building
subtropical ridge, outflow from convection over the Bahamas this
morning, and a little bit of seabreeze influence. While maybe a
little more active than a typical seabreeze type day, the
evolution will be similar. Expect east coast showers this morning
to spread inland through mid-morning, with more robust storm
development by the early afternoon. Storms will spread west and
become more numerous through the afternoon.

On Friday, the strong mid-level ridge that developed under the
upper-level +PV anomaly will shift overhead. Ensembles continue to
show the strength of the ridge at the top end of climatology for
this time of year, with accompanying mid-level dry air. The low-
level ridging is also quite impressive, with heights in the 90th
percentile vs climo. This also means that lower tropospheric
temperatures will be well above average and in similar percentile
ranges vs climo. And while the mid-level dry air will keep
thunderstorm development severely limited, the plentiful low-level
moisture from the near surface SE flow will keep dewpoints, RH,
and subsequently heat indices quite high. Under the easterly flow
regime, the western half of south Florida winds up being the
warmest, with highs in the mid 90s and the potential for isolated
locations to experience heat indices in excess of 110. Along the
east coast, low-to mid 90s will be more likely with scattered
locations heat indices exceeding 105.

&&

.LONG TERM...
(Friday night through Wednesday)
Issued at 335 AM EDT Thu Jul 17 2025

The strong low/mid-level ridging and drier mid-level air will
persist through the weekend and so will the lower rain chances and
high temps/heat indices. WPC guidance based on forecast highs and
ensemble spread indicates a greater than 50% chance that max heat
indices will exceed 110 across the western half of south Florida
and exceed 105 across the eastern half each day. By next week, the
dry mid-level air will shift west of south Florida and rain
chances will start to increase once again to seasonable levels.
With deep layer ridging prevailing, expect the primary forcing
mechanism for convection to be the seabreeze. There are some
indications that a surface low resultant from Lee Cyclogenesis
near the Mid-Atlantic will advect SW across the northern part of
Florida early to mid-week. While this most likely won`t directly
impact south Florida, it could disrupt the easterly flow regime
and result in convection across a larger portion of the region
rather than mostly across the western half.

&&

.AVIATION...
(18Z TAFS)
Issued at 222 PM EDT Thu Jul 17 2025

Most SHRA/TSRA will affect interior and western sections of South
Florida through about 00z, primarily affecting sites along the
Gulf coast (APF) and over the Everglades with TEMPO TS and MVFR
conditions. Elsewhere, SHRA/TSRA will be much more limited in
coverage with minor impacts at the east coast terminal sites
through the forecast period. Wind 120-140 degrees gusting to
around 20 knots at the east coast sites during the 14z-00z time
frame, except a weak seabreeze at the Gulf coast/APF through 00z.

&&

.MARINE...
Issued at 335 AM EDT Thu Jul 17 2025

Cautionary level winds will be possible over Atlantic waters
through the first half of the day today. As the calmer center of the
subtropical ridge draws nearer winds will subside below headline
levels once again. Showers and thunderstorms remain likely again
today but a period of drier conditions is expected beginning
tomorrow and lasting into the weekend.

&&

.BEACHES...
Issued at 222 PM EDT Thu Jul 17 2025

The rip current risk will continue to increase at the Atlantic
beaches over the next couple of days with the moderate to fresh
onshore winds. As a result, a high risk of rip currents is
becoming more likely for Friday and remain elevated through
Saturday before decreasing Sunday and early next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Miami            81  92  80  91 /  10  20  10  10
West Kendall     78  92  78  92 /  10  20  10  10
Opa-Locka        81  94  80  93 /  20  20  10  10
Homestead        81  91  81  90 /  10  20  20  10
Fort Lauderdale  81  91  80  90 /  20  10  10  10
N Ft Lauderdale  81  92  80  91 /  30  10  10  10
Pembroke Pines   83  95  82  95 /  20  20  10  10
West Palm Beach  80  92  78  91 /  30  10   0  10
Boca Raton       80  93  79  92 /  30  10  10  10
Naples           78  95  77  94 /  50  40  10  30

&&

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

$$

UPDATE...Molleda
SHORT TERM...Harrigan
LONG TERM....Harrigan
AVIATION...Molleda