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fxus62 kmfl 231221 
afdmfl

Area forecast discussion
National Weather Service Miami Florida
821 am EDT Thu Mar 23 2017

Aviation...
a cold front dropping southward across the region through this
afternoon will bring increasing clouds with a chance of showers
and thunderstorms. Between 23/1500z-1800z, thunderstorms in the vicinity conds may develop
with sct025 and bkn050, then expect decreasing convective
activity by late evening. Small hail and gusty/erratic winds will
be possible the storms as they move southward along the peninsula.
Behind the front, east northeast winds will increase to around
15-17 knots with occasional higher gusts. At kapf, east-northeast winds will
be weaker, only around 12 knots. Breezy conditions should continue
through the night along the East Coast taf sites with vcsh.

&&

Previous discussion... /issued 411 am EDT Thu Mar 23 2017/

Discussion...

Today-tonight: weakening frontal boundary making it's way south and
west across central Florida early this morning, generating a few
showers and storms, mainly across the waters. Analysis shows that
the deeper moisture associated with the boundary is lagging
behind slightly, and while the boundary and wind shift are likely
to arrive into South Florida early morning, the deeper moisture
may lag more towards this afternoon.

Despite this, enough low-level moisture, along with weak
overrunning/isentropic lift will allow scattered showers to spread
from northeast to southwest across the region through the morning
hours. The best rain chances will be late morning into this
afternoon, when the deeper moisture and best lift combine.

Upper level vort maxes crossing the peninsula this morning have
brought in much colder temperatures aloft, with RUC analysis showing
500mb temps around -14 to -16c. With another vort Max expected to
cool temps a degree or two, and daytime temperatures still expected
to climb into the upper 70s and low 80s, mid level lapse rates will
be quite steep today. This instability means that a few storms can't
be ruled out, especially along the East Coast and Lake Okeechobee
region. It also sets up a favorable environment for a few strong
storms with hail, and Storm Prediction Center has placed most of South Florida under a
marginal risk for today. Overall rainfall amounts are expected to
generally be light, but a few areas could see a nice soaking
rainfall of around a half an inch, helping the ongoing drought
situation.

Conditions to become breezy to windy late in the day as east-
northeast wind surge arrives behind the boundary, with the
strongest winds along the East Coast. Overnight lows will be in
the around 60 over the interior and Gulf Coast and mid-upper 60s
for the East Coast.

Friday: boundary moves south of the region and washes out as strong
high pressure builds to the north. The tight pressure gradient will
lead to an breezy to windy day, with wind gusts of 20-30 mph common
at times. Lingering showers along the East Coast will also
continue.

Highs on Friday behind the front will be slightly cooler, ranging
from the mid 70s to around 80. Low temperatures will generally be in
the 60s, with a few upper 50s readings in the interior.

Saturday-wednesday: models have shifted westwards with the cut-off
low that had been forecast to meander well east of the Bahamas. This
results in a weaker and shorter lived upper level ridge moving
across the Florida Peninsula on Saturday. The weaker ridge in turn allows
the next system moving across the Tennessee/MS valley to dig a little
further south before the ridge rebuilds Monday and Tuesday.

Generally easterly flow will prevail through the period, remaining
breezy on Saturday before the surface gradient weakens Sunday and
Monday. Periodic showers are expected through the period off the
Atlantic as easterly flow continues to bring in low level
moisture. Some enhancement in coverage is possible during the
weekend as vort maxes rotate through the region, and again on
Tuesday as another weak front approaches.

Temperatures will be near to slightly above normal for the long term
period.

Marine...boating conditions will begin deteriorating late this
morning over the Atlantic waters, and into this evening over the
Gulf as a weak frontal boundary moves across the region. The
boundary will also bring scattered to numerous showers, with the
potential for a few storms, especially over the local Atlantic
waters.

Expect east-northeast winds 20-25kts over much of the local waters,
including Biscayne Bay, through the overnight hours with seas
building to 9-11ft in the Gulf Stream. Winds diminish into Friday,
but hazardous marine conditions for the Atlantic waters are
expected to continue through Saturday. A Small Craft Advisory is
currently in effect for the Atlantic waters from midday, and the
Gulf waters starting this evening.

Aviation...generally VFR conditions should prevail, though sub-
VFR conditions are possible with overnight fog possible at apf.
Showers and thunderstorms will be possible today, with a focus on
the East Coast during the afternoon and evening.

Beach forecast...east-northeasterly wind surge arrives early this
afternoon with frontal boundary, leading to a rapid increase in the
rip current threat along all the Atlantic beaches. There is a high
risk of rip currents for all the East Coast beaches today and into
the weekend.

Fire weather...light to moderate showers are expected to overspread
much of the region through the day with a frontal boundary, along
with a threat for isolated thunderstorms. A few showers may also
linger along the East Coast into Friday, with relative humidity
values expected to remain above critical levels through Saturday.
Gusty east-northeast winds will also arrive with the boundary late
today, leading to very good to excellent dispersions across much of
the region into Saturday.
&&

Preliminary point temps/pops...
West Palm Beach 78 69 78 68 / 60 40 20 10
Fort Lauderdale 79 69 78 70 / 60 50 30 20
Miami 81 68 79 69 / 50 40 40 20
Naples 80 62 82 62 / 40 20 10 0

&&

Mfl watches/warnings/advisories...
Florida...high rip current risk through Friday evening for flz168-172-173.

Am...Small Craft Advisory from noon today to 8 am EDT Saturday for
amz630-650-651-670-671.

GM...Small Craft Advisory from 8 PM this evening to 11 am EDT Friday
for gmz656-657-676.

&&

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