Sunny Isles, Florida Weather Forecast Discussion

657
FXUS62 KMFL 162257
AFDMFL
Area Forecast Discussion
National Weather Service Miami FL
657 PM EDT Tue Sep 16 2025
...New AVIATION...
.UPDATE...
Issued at 137 PM EDT Tue Sep 16 2025
No major changes to the forecast with the afternoon package. PWAT
observations from ACARS at MIA/FLL/PBI are running a little behind
the originally forecast values (1.6-1.7 inches versus the
forecast 1.9-2.0 inches), but satellite imagery shows a moister
airmass gradually progressing northward over the region, which
will enable the development of afternoon showers and
thunderstorms. Conditions will improve shortly after nightfall.
&&
.SHORT TERM...
(Today through Wednesday)
Issued at 117 AM EDT Tue Sep 16 2025
A pattern change is ahead for South Florida, and today will serve as
the bridge between the brief respite of dry weather we have
experienced over the last two days and a wetter, more impactful
pattern during the second half of the work week. All things must
come to an end, and the drier air aloft that has suppressed
convective activity will wane in influence and scope across the
our area starting today. Zooming out and taking a big picture
look at the synoptic features in play, an expansive sprawling cut-
off low currently over the southeastern United States will remain
stationary today, effectively blocked by persistent mid-level
ridging to the east over the western Atlantic waters. An
associated weak surface low just to the east of the mid-level cut
off low is forecast to gradually move onshore across coastal North
Carolina later today. This distant surface low is worth
mentioning as it still remains attached to a weak stalled out
frontal boundary that we dealt with last week, with the boundary
still remaining elongated from the far offshore western Atlantic
waters into the Florida Straits early this morning.
While South Florida will still remain to the north of the stalled
frontal boundary over the Florida Straits, the uptick in atmospheric
moisture across the region should correlate with higher spatial and
temporal coverage of showers and storms during the afternoon hours
today (40-60%) as opposed to the more sparse coverage experienced
yesterday. Area-wide precipitable water values will increase back
into the 1.9 to 2.1 range by this afternoon which is above
climatological norms and near the 90th percentile for the date.
Even with moisture return in the mid-levels of the atmosphere
today, there will still be enough residual mid-level dry air to
support the potential of an isolated strong to severe thunderstorm
during the afternoon and early evening storms. The main threat
will once again be the potential of an isolated strong (45 to 55
mph) to marginally severe wind gust. The greatest coverage of
showers and storms is once again expected across inland areas as
that is where sea-breeze and outflow boundaries are forecast to
converge during the mid to late afternoon hour. High temperatures
will once again reach the upper 80s to low 90s with sharp
temperature fluctuations possible in and around shower and
thunderstorm activity.
By Wednesday, the aforementioned cut-off low will begin a slow
acceleration to the northeast out ahead of the next longwave trough
pushing eastward across the central United States. At the same time,
an upper level jet streak will develop across the southeastern
United States (including northern Florida and the Gulf) which will
place South Florida in an area of enhanced low-level convergence
(right entrance region). This synoptic boost of ascent will combine
with deeper moisture across the region and kick off the beginning of
an active period for our area. The surface low meandering across
coastal North Carolina will gradually lift northwestward, dragging
that pesky frontal boundary over the Florida Straits back northwards
(pseudo warm front?) into our area. As the front arrives back over
South Florida, even deeper moisture and low level ascent is forecast
to make a return to the region with the continuance of an increasing
trend in precipitable water values. Maximum daily rain chances
increase to the 60-80% range Wednesday. Forecast model guidance once
again depicts the potential of a saturated atmosphere over South
Florida with precipitable water values in the 2.1 to 2.3 inch range
(now over the the 90th percentile for September 17th). A
saturated atmosphere brings an increased threat of heavy rainfall
that could result in accumulations adding up over a short period
of time. The Weather Prediction Center (WPC) has placed the east
coast metro areas of South Florida in a Marginal Risk (level 1 of
4) of excessive flooding on Wednesday. This means that there is a
5-15% chance of excessive rainfall that may lead to flash flooding
within a 25 mile radius of a location.
High temperatures will trend lower on Wednesday due to abundant
cloud cover and the cooling influences of showers and storms,
forecasted highs area-wide will be in the middle to upper 80s.
&&
.LONG TERM...
(Wednesday night through Monday)
Issued at 117 AM EDT Tue Sep 16 2025
With the background environment conducive for heavy rainfall, the
main driving force behind rainfall accumulations will be the
coverage and storm motion of showers and storms across the region
during the second half of the week. Overnight model guidance
continues to hone in on Thursday being the day with the greatest
potential of seeing higher end QPF values as the aforementioned jet-
streak nearby and the stalled boundary directly overhead act to
provide favorable conditions for numerous showers and storms. The
deterministic GFS and Euro continue to hint at a lobe of mid-level
vorticity pivoting across South Florida on Thursday with forecasted
precipitable water values potentially increasing to the 2.2 to 2.4
range which would be very close to the daily max value for the date.
Forecast model soundings during this time frame continue to depict a
classic skinny CAPE profile that points to the potential of
efficient rainfall rates that could lead to localized flooding
concerns over urban metro areas. ECENS and GEFS ensemble guidance
suites depict a higher QPF signal across the east half of the region
on Thursday which coincides with the return and stall of the frontal
boundary. WPC cluster analysis also highlights a heavy rainfall
threat across the eastern half of the region during this time frame.
The Weather Prediction Center also maintains a marginal risk of
excessive rainfall for the east coast of South Florida on Thursday.
With the abundance of convective activity and resultant cloud
debris, high temperatures may be held in check once again on
Thursday with forecast highs in the low to mid 80s.
Forecast guidance keeps the stalled frontal boundary in place over
South Florida Friday which will result in scattered to numerous
showers and storms during the afternoon and evening hours. However
by the weekend, a notable shift on the latest forecast models has
occurred as they now depict the potential of an area of low pressure
developing along the boundary in the western Atlantic. Cyclonic flow
around this developing feature may result in the potential of drier
air moving southward across the peninsula which may limit rain
chances during the weekend as opposed to the mid to late work week.
Uncertainty remains regarding this solution however, and forecast
rainfall totals on Saturday and Sunday currently remain near
climatological norms in the 50-60% range. The lessening of mid-level
flow aloft will once again result in sea-breeze circulations
remaining the main foci of diurnal convection each afternoon and
evening which will likely focus the greatest convective chances
across interior areas each afternoon during the weekend. High
temperatures on Friday through early next week will reach the upper
80s to low 90s area-wide.
&&
.AVIATION...
(00Z TAFS)
Issued at 656 PM EDT Tue Sep 16 2025
Generally VFR for the start of this cycle, with winds becoming
light and variable. There is a slight chance for showers
developing between 06-09z, so made mention of VCSH, but overall
coverage and impacts should remain low. Another round of SHRA/TSRA
tomorrow could lead to reduced cigs/vis in the afternoon.
Generally easterly winds will prevail.
&&
.MARINE...
Issued at 117 AM EDT Tue Sep 16 2025
A moderate easterly breeze will enhance later today and continue
into the mid week period. Seas across the Atlantic waters will
generally remain between 2 to 5 feet through Thursday morning while
seas across the Gulf waters remain at 1 to 2 feet. Periods of rough
seas and gusty winds will be possible each day near the most robust
shower and thunderstorm activity.
&&
.BEACHES...
Issued at 117 AM EDT Tue Sep 16 2025
A high risk of rip currents will continue along the Palm Beach County
beaches today as onshore flow enhances this afternoon and a
northeasterly swell in the Atlantic waters lingers. The high risk of
rip current risk will continue and potentially expand further south
across the east coast by mid-week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Miami            77  87  76  85 /  50  70  70  80
West Kendall     76  87  75  85 /  50  70  70  80
Opa-Locka        77  88  76  87 /  50  70  70  80
Homestead        76  86  75  85 /  50  70  70  80
Fort Lauderdale  77  86  75  85 /  50  70  70  80
N Ft Lauderdale  77  86  77  85 /  50  70  70  80
Pembroke Pines   77  89  76  88 /  50  70  70  80
West Palm Beach  77  86  75  84 /  50  70  60  70
Boca Raton       76  88  75  87 /  50  70  70  70
Naples           76  88  74  87 /  40  70  40  70
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Wednesday evening for FLZ168.
AM...None.
GM...None.
&&
$$
SHORT TERM...Hadi
LONG TERM....Hadi
AVIATION...ATV

NWS MFL Office Area Forecast Discussion