326
FXUS62 KMFL 181348
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
948 AM EDT Wed Sep 18 2024

...New UPDATE...

.UPDATE...
Issued at 946 AM EDT Wed Sep 18 2024

Some morning convection in and around Naples lingers over the
coastal Gulf waters. Other than some minor tweaks to account for
that, the forecast is on track with no additional updates
ancitipated through midday. 12z MFL sounding shows some drier air
aloft which fits the bill for the thunderstorm concerns outlined
by the previous shift. Have a wonderful Wednesday!

&&

.SHORT TERM...
(Today through Thursday)
Issued at 249 AM EDT Wed Sep 18 2024

The mid-level low currently present over the southeastern United
States will gradually lift northeastward today which will veer
500mb flow across the region to a westerly direction. The
elongation of existing troughing over the eastern United States
will keep 500mb temperatures in the -6C to -7C range today with
forecasted daily afternoon lapse rates in the 5.5 to 6.0 C/km
range. At the surface, we will remain situated to the south of the
weak yet quite persistent stationary boundary still draped across
Central Florida. The CAMs (Convection Allowing Models) have been
fickle in this regime as they vastly under-modeled the amount of
mid-level dry air yesterday. While the spatial extent of
convection today may vary depending on what model solution you
take a look out, the presence of ample mid- level dry air presents
an interesting variable in the forecast. On one end, too much
mid-level dry air may mix down during the afternoon hours
suppressing widespread coverage. However, at the same time, mid-
level dry air could result in some robust wet microbursts with any
strong to severe storm that is able to develop. Forecasted DCAPE
values of 1000-1200 J/kg support the potential of isolated strong
to marginally severe if a tall enough storm is able to
materialize. The lack of wind-shear will once again set the stage
for multicellular clusters with boundary collisions zig-zagging
across portions of the area. The prevailing weak surface winds and
the 500mb westerly flow aloft will keep the highest changes of
afternoon storms favoring the eastern half of the region.

Westerly to north westerly mid-level flow on Thursday will once
again favor the greatest rain chances over the eastern half of
South Florida. Localized ascent along boundaries such as the sea-
breeze and outflow boundaries may result in some locally strong to
marginally severe storms. High temperatures today and on Thursday
will reach the upper 80s to low 90s across the region with cooler
temperatures realized in and around shower and thunderstorm
activity.

Temperatures today and tomorrow will reach the upper 80s to
low 90s across the region with heat indices once again in the
104-107 degree Fahrenheit range. With a potential delayed onset of
convection initiation due to mid-level dry air once again today,
a Heat Advisory will be in effect for Miami and Broward counties
from 10am to 6pm today.

&&

.LONG TERM...
(Thursday night through Tuesday)
Issued at 249 AM EDT Wed Sep 18 2024

By the end of the work week and into the upcoming weekend, upper
level troughing will continue to dig southward into the eastern
Gulf of Mexico and over South Florida, maintaining west-north
westerly flow over the region aloft. Meanwhile a persistent plume
of deep tropical moisture remains in place over the region as a
diffuse stationary frontal boundary meanders through this period.
The presence of cooler upper level temperatures (-6 to -7C @ 500
mb) and a pocket of divergence aloft may act to enhance convective
coverage and intensity at times, though most convective will be
driven by localized convergence maxima owing to mesoscale
processes (sea-breeze and outflow boundary collisions). Expect
bouts of periodic heavy rainfall to continue, particularly in the
afternoon when instability and low-level convergence is maximized.
Heavy rainfall that persists for a prolonged duration over urban
areas may result in the usual localized flooding concerns.

By Sunday and into early next week, a dominant/expansive ridge of
high pressure will emanate from the TX/Mexico region and increase
geopotential heights across South Florida. This may be
commensurate with a wedge of drier air advecting towards the
region through this same period (simultaneously), though there
exists uncertainty regarding the southward extent of this drier
air-mass. For now, it appears that strong upper ridging coupled
with a lack of moisture should allow for rainfall totals that are
below climatological norms through this period.

Temperatures through this period will hover around seasonal norms
through this period. Afternoon high temperatures should reach the
upper 80s to low 90, while dew points reach the mid to upper 70s
through the early part of the weekend. Heat Advisories may be
necessary during portions of this period, although that will be
contingent on the rainfall and cloud coverage for any given
afternoon. Towards the end of the weekend and into early next
week, dew-points may drop a few degrees, although less cloud
coverage and rainfall could allow for more oppressive temperatures
through this period.

As of the 2am Tropical Weather Outlook, the National Hurricane
Center now identifies an area of low pressure in the western
Caribbean Sea with a 20% chance of tropical development over the
next seven days. Readers are reminded that a lot can change in the
7-10 day time-frame, especially with the genesis and evolution of
tropical systems. While the general pattern for tropical
development appears to be favorable, it remains far too early to
identify a potential track. In simplest terms, while deterministic
model solutions will vary from run to run, it is very important
to take them with several grains of salt. Ensemble model plots
(EPS and GEFS) may provide a slightly clearer picture of what may
unfold, however it is still quite early. Regardless of what
transpires, this is an important reminder that we are in the midst
of the peak of hurricane season. Although the climatological peak
of the Atlantic hurricane season is on September 10th, the
stretch of late September into the first half of October is the
climatological peak for hurricane landfalls in South Florida.
Remain weather aware, check hurricane supplies, and most
importantly, be sure to receive information from reliable sources
such as the National Hurricane Center, NWS Miami, and local and
national broadcast media sources.

&&

.AVIATION...
(12Z TAFS)
Issued at 757 AM EDT Wed Sep 18 2024

Light winds will increase out of the SE early this afternoon
across the east coast terminals. Scattered to numerous showers and
storms will develop as the day progresses. These storms could
bring sub-VFR conditions to the east coast terminals, mainly
during the afternoon/early evening, and short fused AMDs will be
likely. At KAPF, morning convection lingers and winds will
increase out of the SW this afternoon as a Gulf breeze develops.

&&

.MARINE...
Issued at 249 AM EDT Wed Sep 18 2024

Generally light winds will prevail across the area through most
of this week as a weak surface boundary remains just to the north
of the area. Scattered showers and thunderstorms will be possible
each day through the period and could lead to locally higher
winds and seas.

&&

.BEACHES...
Issued at 249 AM EDT Wed Sep 18 2024

Minor to moderate coastal flooding will continue during periods
of high tide due to astronomically higher tides associated with
the full moon phase. Elevated tides will continue on both coasts
of South Florida through the end of the work-week.

Upcoming High Tide Times:

Naples: 1:46 PM Wed, 1:52 AM Thu, 2:38 PM Thu
Lake Worth: 8:38 AM Wed, 9:01 PM Wed, 9:31 AM Thu
Port Everglades: 8:58 AM Wed, 9:19 PM Wed, 9:50 AM Thu
Virginia Key:  9:45 AM Wed, 10:04 PM Wed, 10:36 AM Thu

Decreasing northerly swell will result in a high risk of rip
currents for the Palm Beaches coast once again today with a
moderate risk of rip currents elsewhere on the east coast of South
Florida.

&&

.PRELIMINARY POINT TEMPS/POPS...
Miami            93  77  92  75 /  60  50  70  60
West Kendall     92  75  90  73 /  70  50  70  50
Opa-Locka        93  76  92  75 /  70  50  70  50
Homestead        91  75  89  75 /  60  50  70  60
Fort Lauderdale  92  76  91  75 /  60  50  70  60
N Ft Lauderdale  92  76  92  75 /  70  50  70  60
Pembroke Pines   93  76  92  75 /  60  50  70  50
West Palm Beach  92  75  91  75 /  60  50  70  50
Boca Raton       92  75  90  75 /  60  50  70  60
Naples           91  77  90  76 /  50  40  50  30

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Advisory until 2 PM EDT Friday for FLZ069-075-168-
     172>174.

     Heat Advisory until 6 PM EDT this evening for FLZ071>074-172>174.

     High Rip Current Risk until 8 PM EDT this evening for FLZ168.

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

$$

SHORT TERM...Hadi
LONG TERM....Hadi
AVIATION...RAG