344
FXUS62 KMFL 201918
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
318 PM EDT Thu Jun 20 2024

...New LONG TERM...

.SHORT TERM...
(Rest of today through Friday)
Issued at 147 PM EDT Thu Jun 20 2024

Typical summertime conditions will be on tap for South Florida
today, with chances for scattered showers and a few thunderstorms
across the interior and southwest Florida coastline. Sounding date
from the 12Z MFL launch and ACARS flights show moderate instability
and lapse rates in place across the area, with dry air in the mid-
levels with near climo moisture near the surface. The combination of
these factors has allowed for a few isolated low-topped showers
along the East Coast earlier today, but the dry air aloft has helped
limit ascent and further vertical development. Activity will
continue through the afternoon, mainly over the interior and Gulf
Coast as the dominant easterlies quickly push the East coast sea
breeze further inland.

On Friday, models show a large area of enhanced moisture associated
with a weak surface trough over the southwest Atlantic gradually
migrating towards the region. Some of these models show dry air
potentially wrapping around the southwestern side of the trough and
over our region, which could help limit widespread rainfall across
South FL. Winds will veer slightly from the southeast, which will
help in concentrating scattered showers and thunderstorm activity
towards the Lake region in the afternoon hours.

Temperatures across the East Coast today will benefit from the
breezy easterly flow, with highs topping off in the upper 80s.
Interior and southwest FL will see further warming throughout the
day, with highs in the low 90s. Conditions on Friday could get
slightly warmer, with temperatures along the East Coast potentially
reaching the 90s. Temperatures indexes will hit triple digits each
afternoon but should remain below advisory criteria.

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 318 PM EDT Thu Jun 20 2024

Expansive mid-level ridging across the southeastern United States
will continue to remain in firm control of our prevailing weather
pattern as we enter the upcoming weekend. At the surface, the long-
persistent surface ridging in place across the western Atlantic
waters will prevail easterly to southeasterly flow across the region
on Saturday. Peripheral moisture from a large and expansive Central
American Gyre (C.A.G.) will begin to filter into the region on
Saturday with notably higher precipitable water values in the 2.0-
2.4 inch range. This moistening in the vertical column will allow
for a greater abundance of convection, albeit with still relatively
warm 500mb temperatures as mid-level ridging remains in place aloft.
Given the prevailing easterly flow, convection will favor the east
coast metro areas in the morning with a increase in shower and
thunderstorm activity across inland areas and southwestern Florida
during the afternoon hours in conjunction with peak diurnal heating.
Given the relatively weak/light 500mb flow during this time frame
and moist forecast soundings, cannot rule out localized flooding
along the Gulf coast metro areas on Saturday afternoon. The
formation of a gulf breeze due to the weakening influence of the
surface ridge could also aid in thunderstorm development along the
gulf breeze during the afternoon hours. Although synoptic parameters
don`t appear very conducive for strong storms, mesoscale ascent
could aid the development of a few strong multi-cellular pulse
storms before they move off of the boundary and into
unfavorable residual cold pools.

As a mid-level trough dips southward across the Great Lakes on
Sunday, the aforementioned mid-level ridging will begin to break down
and weaken in spatial extent. Easterly surface flow will begin to
weaken as the previously expansive surface ridging over the western
Atlantic waters begins to weaken and retreat out of the region.
There will still be just enough of an easterly component to see a
foci of convection across the western half of South Florida, with a
gulf breeze once again providing convergence of convective
development and potential localized flooding concerns given the
light 500mb flow. By Monday, surface flow will become more southerly
in nature as the influence of the surface ridge of high pressure
continues to wane. This will act to focus the bulk of convection
during the start of the work-week across inland areas which would
favor Lake Okeechobee and other inland locales as boundary
collisions occur inland and away from the coast. Throughout this
time period, pockets of deeper tropical moisture associated with the
periphery of the ongoing Central American Gyre (C.A.G.) will rotate
into South Florida which will keep rain chances in the 50-60% chance
each afternoon.

As mid-level troughing finally settles into place across the eastern
United States on Tuesday, an associated surface frontal boundary
will be displaced across the southeastern United States. Our
prevailing surface winds will respond to this feature as background
winds begin to veer to a more southwesterly direction. This slight
detail will mar a notable change in our prevailing weather pattern
beginning on Tuesday. Southwesterly flow will aid with the inland
propagation of the gulf sea-breeze and act to pin the Atlantic sea-
breeze along the east coast. If forecast trends were to continue,
this would act to forecast the highest concentration of convection
along the east coast metros each afternoon beginning on
Tuesday/Wednesday. With precipitable water values still in the 1.8
to 2.2 range throughout the work week and relatively light 500mb
flow still in place, localized flooding could be in the cards once
again... especially in urban areas. While the most favorable
kinematics stay to the north of the region from a synoptic forcing
perspective, once again cannot rule out some strong pulse storms
along boundary collisions.

To summarize the analysis above, the extended period features a
transition between mid-level ridging and the arrival of a mid-level
trough. We remain on the periphery of a deep plume of tropical
moisture associated with a large and expansive Central American Gyre
(C.A.G.) which will at times advect deeper moisture into our area.
The combination of a decrease in surface winds and a lack of
synoptic flow across the region could result in slow-moving
convection this upcoming weekend and into next week. This could
result in localized flooding concerns as storms generally drift/move
along boundary collisions. Temperatures will remain near norms with
highs in the upper 80s to mid 90s, largely dictated by convective
trends as well as anvil cloud debris. With the abundance of moisture
in the vertical column, it will certainly feel quite muggy out there
with heat indices in the 100`s.

&&

.AVIATION...
(18Z TAFS)
Issued at 147 PM EDT Thu Jun 20 2024

Generally VFR through the period. KAPF could see brief periods of
MVFR conditions later today as SHRA/TSRA develop along the Gulf
Coast, which could prompt short-fuse amendments. Gusty easterly
flow prevails through the evening, with wind speeds decreasing
overnight and into tomorrow, when flow veer from the southeast.

&&

.MARINE...
Issued at 147 PM EDT Thu Jun 20 2024

Winds begin relaxing a little with both wind speeds and seas
gradually dropping to below advisory criteria on both sides of the
peninsula later today. The SCA will expire this morning for the
Gulf, and in the early afternoon for the Atlantic waters. Moderate
E/ESE winds will prevail through the end of the work week, but
brief periods of rough seas and gusty winds will accompany any
thunderstorm that forms.

&&

.BEACHES...
Issued at 147 PM EDT Thu Jun 20 2024

Persisting robust coastal easterly winds will keep a high risk of
rip currents across all the Atlantic beaches through Friday, then
relaxing enough for risk level to drop to moderate during the
weekend. Surf should also gradually decrease today and tomorrow.

&&

.PRELIMINARY POINT TEMPS/POPS...
Miami            78  89  81  90 /  10  40  30  40
West Kendall     76  91  79  90 /  10  50  30  50
Opa-Locka        77  91  81  91 /  10  40  30  40
Homestead        78  89  80  89 /  10  40  40  50
Fort Lauderdale  78  88  81  88 /  10  40  30  40
N Ft Lauderdale  77  89  81  89 /  10  40  30  40
Pembroke Pines   79  92  81  92 /  10  40  30  40
West Palm Beach  75  90  79  90 /  10  30  30  40
Boca Raton       77  90  81  90 /  10  30  30  40
Naples           75  92  78  92 /  20  50  30  50

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Friday evening for FLZ168-172-173.

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

$$

SHORT TERM...ATV
LONG TERM....Hadi
AVIATION...ATV