Area Forecast Discussion
Issued by NWS Miami, FL

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383
FXUS62 KMFL 160701
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
301 AM EDT Wed Oct 16 2019

.Short Term...

Today through Thursday Night...

Wednesday is a day of transition as surface high pressure gives way
to an approaching cold front. Ahead of the front, the wind will back
from the southeast to the south and eventually become southwesterly
later today. Increasing moisture today will allow for an increase in
shower activity, and a non-zero chance of thunderstorms, this
afternoon. The focus for convection will be along the Atlantic
coast, where the southwesterly flow will pin any attempt at the east
coast sea breeze. Warm temperatures in the lower 90s could again
flirt with records if temperatures were to be a few degrees warmer
than forecast today.

Diurnally driven convection should diminish after sunset but the
increasing surface moisture will lead to the potential of fog on
Wednesday night into Thursday morning. With the front remaining
around or just north of the region, additional Gulf moisture surges
on Thursday could lead to increased shower and thunderstorm coverage
over a good portion of the day. Peak convective activity is still
expected in the late morning into the evening hours. Maximum
temperatures will be in the upper 80s to lower 90s on Thursday,
which should be a few degrees cooler in most areas compared to
Wednesday. The threat of fog returns for Thursday night/Friday
morning as sufficient surface moisture, light wind flow, and drier
air aloft could once again provide for efficient radiational
cooling.

.Long Term...

Friday through Wednesday...

The aforementioned frontal boundary will sag southward over South
Florida Friday before stalling just north of the Florida Keys as
ridging aloft elongates east to west and tightens. By Saturday,
this boundary lifts back north as a warm front, keeping southerly
to southwesterly wind flow and ample moisture across the region. A
couple of weak impulses meandering through the zonal flow will
swiftly cross the CWA over the course of the weekend. This in
combination with increasing moisture will keep scattered to
numerous showers with isolated thunderstorms in the forecast
throughout the weekend.

There are a few things to note with the forecast this weekend...

1. With a prevailing S flow, if the east coast sea breeze does
develop, then it will likely get pinned across the east coast.
This means that localized flooding will be possible, especially
with heavy rainfall rates, previous rainfall, and widespread
coverage.

2. GFS is suggesting Storm Relative Helicity (SRH) values creep
towards 300 m2/s2 Saturday afternoon. With additional areas of
localized convergence and lift, ie boundary collisions, wouldn`t
be surprised for brief bouts of weak rotation.

3. Forecast derived PW`s will also be on the rise due to the
shortwaves passing through and the S/SW flow. Forecast soundings
represent a sufficiently moist profile further indicating the
potential for heavy rainfall and localized flooding.

Now, a lot of this is dependent on a rather energetic low pressure
system and its development/track across the Gulf of Mexico. The
GFS and ECMWF continue to disagree on both intensity of the system
and path. The GFS takes the low toward the Florida Panhandle late
weekend while the ECMWF weakens the low and takes it toward the
Gulf Coast States. If the GFS solution prevails, then the forecast
will be a lot soggier this weekend as opposed to the ECMWF. As of
0200 AM EDT, the National Hurricane Center (NHC) is giving the low
pressure a 40 percent chance of formation in the next 5 days.

By early next week, a brief drying trend looks to occur across the
region, however by mid-week, a cold front tries to cut through the
state and PoPs once again increase.

&&

.Marine...
Predominantly easterly winds will shift from the south throughout
the day today with speeds of around 10 to 15 kt. By Friday, winds
look to be light and variable due to a stationary frontal boundary
though this is short lived and winds are forecast to pick back up
from the SE at 10 to 15 kt Saturday before shifting from the S
Sunday.

Lingering NE swells of 1 foot or less in the Atlantic waters
offshore Palm Beach County today before subsiding overnight. By
this weekend, a low pressure system in the Gulf will deliver
higher seas of 4 to 6 feet and a W/SW swell of 1 to 2 feet in the
Gulf waters. Both seas and swells diminish throughout the
beginning of next week.

Increasing shower and thunderstorm chances over the local waters
especially late this week.

&&

.Aviation...
VFR generally expected through the period, though some showers are
possible Wednesday afternoon and fog is possible late in the
forecast period. Wind should generally remain light through the
period. Focus for convection will be along the east coast
terminals this afternoon but chances are still too low to include
any restrictions with this TAF package.

&&

.Beach Forecast...
A Coastal Flood Statement is in effect for the east coast today
for possible flooding during times of high tide. With a decrease
in northeasterly swell, the threat for rip currents decreased,
though a Slight Risk for rip currents is possible for all South
Florida beaches today. As winds shift from the south/southwest
towards the end of the work week, the threat for rip currents
along the east coast beaches should stay on the Slight end though
may increase for the Gulf Coast beaches.

&&

.Preliminary Point Temps/PoPs...
West Palm Beach  90  74  88  74 /  20  20  50  20
Fort Lauderdale  89  76  88  76 /  20  10  50  20
Miami            89  76  89  75 /  20  10  40  10
Naples           88  76  87  73 /  20  20  30  10

&&

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


Marine...03/Fell
Aviation...02/RAG
Beach Forecast...03/Fell
Short Term...02/RAG
Long Term...03/Fell



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