Area Forecast Discussion
Issued by NWS Miami, FL

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804
FXUS62 KMFL 161724 AAC
AFDMFL

Area Forecast Discussion...UPDATED
National Weather Service Miami FL
124 PM EDT Fri Apr 16 2021

...18z Aviation Update...

.AVIATION(18Z TAFS)...
VFR conditions expected through the forecast cycle. Generally
south or southwesterly winds expected. Though right along the
Atlantic coast, the sea breeze may cause a southerly or even just
east of due southerly winds this afternoon. Otherwise, the only
concern would be the possibility of patchy fog overnight tonight
and early Saturday morning across the interior.

&&

.PREV DISCUSSION... (Issued 1011 AM EDT Fri Apr 16 2021)

UPDATE...
A quiet start weatherwise across South Florida today with most of
the convective activity forecast to remain north of the area
closer to the front in north and central Florida. Warm
temperatures and the light southwesterly to westerly flow could
allow for sea breezes to develop and keep the Atlantic sea breeze
pinned closer to the coast. The forecast captures the potential
for some showers and a few thunderstorms along the east coast this
afternoon due to this well. No major updates to the forecast are
planned through midday as the current forecast philosophy is on
track. Have a wonderful Friday morning!

PREV DISCUSSION... (Issued 341 AM EDT Fri Apr 16 2021)

DISCUSSION...

SHORT TERM (Through Saturday):

Models continue to depict a high pressure ridge centered to the SE
of the peninsula, with SoFlo under the influence of the NW
periphery of the high. This will result in mostly SW flow today
across much of the area, except near the Atlantic coastline where
sea breezes may result in periods of onshore flow this afternoon.

There might be more low level moisture available today as the
southwesterly flow brings some enhanced moisture advection from the
Caribbean/Gulf waters. In terms of the wind profile, if the
aforementioned onshore flow develops over the east coast, it could
result in confluent flow along the east coast areas, with potential
for a few showers or thunderstorms to form. Bulk shear and
instability parameters might be enough to actually have a quick
strong storm or two during the afternoon hours when daytime heating
peaks. Thus, POP/Wx grids will carry around 20%/slight chance of
thunderstorms for this afternoon across much of the Atlantic metro
areas.

Mainly benign conditions tonight with winds becoming light. Then for
Saturday, models suggest some erosion of the western periphery of
the ridge due to an approaching frontal boundary from the north.
This will also establish a more robust NW flow, which will likely
keep any potential convection over the Atlantic waters on Saturday
afternoon. Temperatures will continue on a warming trend under the
prevailing wind profile, with afternoon highs today in the upper 80s
to around 90, and mostly around 90 on Saturday.

Short term guidance and local models continue to suggest the
possibility of patchy fog overnight tonight into early Saturday
across portions of the interior and western sections of South FL.

LONG TERM (Saturday Night through Thursday):

Key Points:

* Medium-range model guidance is in good agreement -- depicting the
  potential for an active weather pattern to materialize across
  South Florida throughout much of the upcoming week.

* Present indications are that periods of locally heavy rainfall and
  perhaps instances of organized thunderstorm development will be
  possible from Monday through Thursday, as a quasi-stationary
  frontal boundary lingers to the north of South Florida amidst
  enhanced mid/upper-level west-southwesterly flow.

An initially split/unconsolidated mid/upper-level flow pattern will
gradually give way to a large-scale eastern CONUS trough, with a
belt of enhanced mid/upper-level west-southwesterly flow and
embedded cyclonic impulses grazing the South Florida CWA throughout
the week. At the surface, a quasi-stationary surface boundary will
linger over northern Florida -- where the bulk of heavy rain showers
and thunderstorms are presently forecast to develop in association
with DCVA/mid-level height-falls atop the quasi-stationary surface
boundary.

As a series of mid/upper-level cyclonic perturbations track east-
northeastward across the southeastern states from early Monday
through Thursday, increasing southerly moisture transport --
equatorward of the quasi-stationary surface boundary -- will foster
deep-layer moistening across South Florida amidst enhanced deep-
layer vertical wind shear (supporting periods of organized/heavy
rainfall-producing convection).

Heavy rainfall associated with multiple rounds of convection amidst
a WAA/isentropic ascent regime may result in an increasing flooding
threat beginning as early as overnight Sunday/Monday morning and
persisting through Thursday. There is plenty of uncertainty
regarding potential hazards at this time, so keep up with the latest
forecast information from NWS Miami.

MARINE...Mainly benign boating conditions will prevail through
Sunday, then a cold front approaching the area will introduce
showers and thunderstorms back into the forecast for much of next
week. Periodic cautionary conditions are possible in the Atlantic
waters at times into early next week.

BEACHES... A Moderate Risk of Rip Currents is in effect for
the Palm Beaches today. An enhanced risk may continue through the
weekend over the Atlantic beaches as some E/NE swell sticks around.

&&

.PRELIMINARY POINT TEMPS/POPS...
Miami            71  91  72  90 /  10  10   0  20
West Kendall     69  91  70  93 /  10  10   0  10
Opa-Locka        71  91  70  91 /  10  10   0  20
Homestead        70  89  70  90 /  10  10   0   0
Fort Lauderdale  71  91  72  90 /  10  10   0  20
N Ft Lauderdale  69  91  71  90 /  10  10   0  20
Pembroke Pines   70  91  71  91 /  10  10   0  20
West Palm Beach  67  92  69  90 /  10  10   0  20
Boca Raton       69  91  70  91 /  10  10   0  20
Naples           70  85  71  86 /  10  10   0  10

&&

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

$$

Update/Aviation...Frye/RAG
Today through Saturday and Marine...AR
Saturday Night through Thursday...Weinman

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