Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 201428
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
928 AM EST Mon Jan 20 2020


.Update...
Cold front moved across soFlo a little faster than anticipated
with the pre-frontal convection ahead of the main boundary already
past the Florida Keys. Radar was showing a few small showers
lingering over the Atlantic coastal waters, but these should also
push further southeastward through the rest of the morning hours.

The 12Z MFL sounding came out fairly dry, with PWATS around 0.9
inches, and this was ahead of the FROPA. Thus, with the main
boundary already pushing south of the Miami metro area, as
suggested by the northward shift in winds and dropping dew points,
will go ahead and remove all mention of showers for the rest of
today and through Tuesday.

Models also backed down from bringing the surge of northerly winds
in the wake of the FROPA for today or tonight, and the
breezy/gusty conditions are not expected until late Tuesday when
more robust cold/dry air advection establishes. Therefore, expect
moderate northerly flow through Tuesday morning, with temperatures
tonight dropping into the low-mid 40s inland and mid-upper 50s
near the coast.

&&


.Prev Discussion... /issued 629 AM EST Mon Jan 20 2020/


.Cold front moving through South Florida this morning...

Short Term (Today and Tonight)...
Some showers have developed ahead of the cold front this morning,
with a focus over the local waters where more ample moisture
exists to support convection. In general, activity early today
should remain shallow showers with spartan coverage. As the front
pushes through the area this morning, a general drying trend is
expected from northwest to southeast throughout the day. Gusty
northwesterly to northerly winds will last overnight with
temperatures falling into the lower 40s over Glades and Hendry
Counties, 40s across the rest of Southwest Florida and inland
Southeast Florida, and mid to upper 50s along the Atlantic coast.
Due to the Atlantic moisture, cannot rule out some shallow showers
over the Atlantic waters which could push near the coast but
things should generally remain dry after the main front pushes
through.

Long Term (Tuesday through Sunday)...
A shortwave trough will continue to swing southeastward across the
SE CONUS and out over the Atlantic on Tuesday/Tuesday night, helping
induce the formation of a surface low off the Carolina coast. This
developing low will keep the gradient tight and breezy northerly
winds in place over South Florida into Wednesday, when the surface
low finally pushes off further into the Atlantic. This prolonged
period in breezy northerly winds will leave more time for cooler and
drier air to filter in across the area, making Tuesday night into
Wednesday morning the coldest of the period with low temperatures
ranging from the mid 30s west of the Lake/interior SW Florida to the
upper 40s right along the East Coast. While frost is not expected to
be a concern since winds should stay around 10mph or more overnight,
a wind chill advisory (wind chill of 35 degrees or less and winds
over 5 mph for 3+ hours) will be possible for some of the interior
portions of the area.

Wednesday will remain cool under northerly winds with high
temperatures in the 60s. Winds become more easterly Wednesday night
as the surface low to the northwest moves further away, kicking off
a gradual warming and moistening trend stretching into the weekend.
In the meantime, another shortwave trough swinging across Texas will
help induce a surface low over the northwestern Gulf on Thursday.
The shortwave trough begins to phase with the longwave trough as it
rounds the base of it, helping drag the surface low to the northeast
across the Southeast CONUS on Friday. This system should ultimately
drag another cold front through South Florida on Saturday, but with
the loss of upper level support by this time not much convection is
expected. This second front cools things off again but not nearly as
cold as the first front, with low temperatures only expected to dip
into the upper 40s west of the Lake to the upper 50s/near 60 along
the East Coast Sunday night.

Marine...
Stiff northerly to northwesterly flow behind today`s cold front
will allow for hazardous conditions to develop in the Gulf and
Atlantic waters. There will be some brief improvement for the Gulf
but the Atlantic waters could see the hazardous conditions linger
through a good portion of the week. Some initial Small Craft
Advisory issuances will go out with this forecast package but
mariners are advised to stay aware of the latest forecast as
these advisories will likely change in time and require extensions
into the late parts of the week.

Beach Forecast...
An elevated risk of rip currents will remain along the Atlantic
beaches on this Martin Luther King, Jr. Day with a high rip
current risk remaining along the Palm Beaches again today. The
Gulf beaches will see an elevated rip current risk develop behind
the cold front that may linger through mid-week. Meanwhile on the
Atlantic beaches, the elevated rip current risk will remain
through the week with some of the Palm Beaches maintaining the
risk into the weekend potentially.

Prev Discussion... /issued 1238 AM EST Mon Jan 20 2020/

Aviation...
Some bouts of sub-VFR cigs (and possibly vsbys) overnight into
the morning hours as showers ahead of a cold front push across
South Florida. Lingering low cigs in the morning should improve by
midday. Gusty northwesterly to northerly flow by afternoon which
should become a tad lighter overnight Monday into Tuesday to close
out the forecast period.
&&

.Preliminary Point Temps/PoPs...
West Palm Beach  71  54  66  46 /  20  20  10  10
Fort Lauderdale  73  56  68  47 /  40  20  10   0
Miami            75  54  69  45 /  30  10  10   0
Naples           71  47  63  41 /  10   0   0   0

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk until 7 PM EST this evening for FLZ168.

AM...Small Craft Advisory from 4 AM to 8 PM EST Tuesday for AMZ651-
     671.

     Small Craft Advisory until 8 PM EST Tuesday for AMZ650-670.

GM...Small Craft Advisory until 4 AM EST Tuesday for GMZ656-657-676.

&&

Update...17/AR








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