330
FXUS62 KMFL 191844
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
244 PM EDT Thu Sep 19 2024

...New LONG TERM...

.SHORT TERM...
(Rest of today through Friday)
Issued at 120 PM EDT Thu Sep 19 2024

Scattered to numerous showers will be likely across portions of
South Florida this afternoon as as troughing prevails aloft and a
front remains stalled over northern Florida. This is helping pool
moisture over the region as evidenced by MLF`s 12Z sounding which
showed PWATs of 2.02 inches, well above average for this time of
year. The sounding also showed light sfc-3km westerly flow and ample
instability (SBCAPE >2000 J/kg), along with light WSW flow aloft.
Given this setup, expect afternoon sea breeze and outflow boundaries
to become the focal points for deeper confection. The main concern
for today remains heavy rainfall with slow moving storms which could
lead to localized flooding for portions of South Florida. In fact,
the HREF LPMM shows isolated areas along the East Coast metro
possibly getting 4-6 inches of rain, and there are areas that have
already received 2-4 inches of rain over the past couple of days,
which has made for waterlogged soils. To that effect, WPC has
placed most of the East Coast metro under a marginal (1/5) risk
for excessive rainfall this afternoon.

The frontal boundary will slowly drift southward across our region
tomorrow, ushering in some slightly drier mid-level air over the
area. This drier air mass could help limit shower and storm coverage
tomorrow. However, with troughing lingering over the peninsula and
light low level flow, there is still a chance for sea breeze driven
convection to pick up tomorrow afternoon. We kept PoPs in the 40-50%
range.

Although temperatures and heat indices will remain above normal,
convection and cloud coverage should help keep them below advisory
criteria through the period.

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 209 PM EDT Thu Sep 19 2024

The mid-lvl trough axis will push through the area on Saturday,
with low-lvl easterly flow becoming more established as sfc high
pressure builds over the SE US. Although drier mid-lvl air behind
the late week frontal passage will contribute to PWATs dipping
near to just below climo (mostly 1.7 to 1.8 inches), seasonably
cool temperatures aloft (around -7C at 500mb), combined with
residual low-lvl moisture will support scattered showers and
storms. The highest rain chances look to be over SW Florida given
both the prevailing easterly flow and N-S moisture gradient.

Mid-lvl ridging will then build into the SE US Sunday through
early next week, with dry mid-lvl air, warm temperatures aloft,
and general synoptic subsidence prevailing over SFL through at
least Tuesday. Although the mid- lvl drying is quite evident, with PWATs
dipping down into the 1.5-1.6 inch range over portions of the
area, enough moisture remains in the low-lvls to support
scattered showers and storms through the period. The highest rain
chances, given the persistent easterly flow, would be over
western portions of the Peninsula, and given the relatively
stable airmass, deep convection may largely be limited to the
southern third or so of the Peninsula (where instability is
maximized).

Towards the latter part of the upcoming workweek, forecast
uncertainty increases as a portion of the Central American Gyre
may consolidate into a more defined area of surface low pressure
over the northern Caribbean or southern GOM. If this low
consolidates further north or east it would (at the very least) likely
draw deeper moisture towards the area which would naturally lead
to higher rain chances. Conversely if the surface low forms over
the Yucatan or SW Gulf (or doesn`t form at all), the drier ridge-
dominated synoptic pattern would likely persist. It is important
to note that these gyre setups in which there isn`t an extant
disturbance are notoriously challenging to forecast.
Consequently, particularly at these forecast lead times, the
global ensembles provide a more complete picture of possible
solutions compared to individual deterministic model runs, which
will often display poor run to run consistency.

Temperatures will likely remain just above seasonal normals with
forecast highs in the upper 80s and lower 90s through the period.
Although peak heat indices will likely reach the triple digits,
somewhat lower dewpoints (mostly low to mid 70s) should preclude
the issuance of heat advisories.

&&

.AVIATION...
(18Z TAFS)
Issued at 120 PM EDT Thu Sep 19 2024

Brief periods of MVFR/IFR conditions could be likely for all sites
as slow moving SHRA/TSRA begin to develop. The sea breeze will
begin to work in over the sites around 18Z, and winds could become
gusty within storms and outflow boundaries. Conditions should
begin to improve shortly after sunset, but some stratiform rain
coverage could linger for a few hours after 00Z.

&&

.MARINE...
Issued at 120 PM EDT Thu Sep 19 2024

Winds remain generally light across the coastal waters today as a
weak surface boundary remains just to the north of the area, with
continuing scattered to numerous showers and thunderstorms possible
each day. The boundary reaches the area on Friday, bringing a
decrease in thunderstorm activity through the weekend and into early
next week. However, periods of locally higher seas and gusty winds
may accompany any thunderstorm that forms.

&&

.BEACHES...
Issued at 120 PM EDT Thu Sep 19 2024

Expect minor to moderate coastal flooding to continue during periods
of high tide. These elevated tides will continue to affect all
coastal areas of South Florida through Friday morning, for which a
coastal flood advisory remains in effect. For the upcoming weekend,
a decrease in northerly swell should help reduce the risk for
moderate flooding, but some minor flooding could still be possible.
Additionally, an elevated risk of rip currents could continue for
the Palm Beaches during the next several days.

NAPLES HIGH TIDE TIMES... 1:56 PM today, 1:44 AM tomorrow morning, 2:57PM
tomorrow afternoon

LAKE WORTH HIGH TIDE TIMES...949 PM tonight, 10:24 AM tomorrow morning

&&

.PRELIMINARY POINT TEMPS/POPS...
Miami            76  89  76  90 /  50  60  40  40
West Kendall     74  90  74  91 /  50  60  40  50
Opa-Locka        75  90  75  91 /  50  50  40  40
Homestead        75  89  75  90 /  50  60  40  50
Fort Lauderdale  75  88  76  88 /  50  60  40  40
N Ft Lauderdale  75  89  77  90 /  50  60  40  40
Pembroke Pines   75  91  77  92 /  50  50  30  40
West Palm Beach  75  89  76  90 /  50  50  30  30
Boca Raton       75  90  76  90 /  50  60  30  40
Naples           77  90  75  92 /  40  40  20  30

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Advisory until 5 PM EDT Friday for FLZ069-075-168-
     172>174.

AM...None.
GM...None.
&&

$$

SHORT TERM...ATV
LONG TERM....Carr
AVIATION...ATV