Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 201506
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
1006 AM EST Mon Feb 20 2017

.UPDATE...
An amplifying ridge of high pressure will bring dry and warming
conditions through this afternoon. As the lower level flow
continues to turn more northeasterly, few/sct low clouds will be
advected over the east coast metro. For the morning update,
adjusted sky cover downward over the interior and Gulf Coast to
account for this trend. Mostly clear skies, along with light
northeast surface winds, will allow for the warmest temperatures
to occur along the western half of the peninsula this afternoon.
Late tonight into early Tuesday morning, good radiational cooling
over the northern interior, combined with light and variable
surface winds, will increase the chance of fog. Added patchy fog
to the region north and west of Lake Okeechobee, where the SREF
model indicated the highest probability of occurrence. Otherwise,
the forecast appeared on track.

&&

.PREV DISCUSSION... /issued 555 AM EST Mon Feb 20 2017/

AVIATION...

Thus far areas of dense fog in the interior has not impacted any
of the South Florida terminals, but terminals KTMB and KAPF might
have very brief MVFR conditions around 12-13z if mist/fog occurs.
Not mentioned in TAF and will amend if necessary. Otherwise,
stable weather and VFR conditions expected by mid-morning and
through the afternoon, with the Atlantic and Gulf coast sea
breezes expected by late morning to early afternoon. On the
synoptic scale northeasterly winds expected to prevail.

PREV DISCUSSION... /issued 305 AM EST Mon Feb 20 2017/

.Warm, generally dry Washington`s Birthday holiday expected...

DISCUSSION...
High pressure has established itself over the region on this
holiday Monday. Surface moisture remains healthy enough to promote
some fog development this morning, which could necessitate a Dense
Fog Advisory at some point in the next few hours. Easterly to
northeasterly flow today will allow many inland portions of South
Florida to warm up and warmer guidance was favored for the
forecast while the easterly pattern remains. Would not be
surprised to see Atlantic and Gulf sea breeze circulations develop
today and push towards the east coast and Naples metro areas,
respectively. The high pressure over the region should act to
suppress convection. To the west, a potent system is pushing
through Texas and the southern plains early this morning. While
our weather will remain warm, generally dry, and filled with
plenty of sun today and on Tuesday, things will begin to shift by
mid-week as this system evolves and approaches the region.

Both the 00z GFS and ECMWF are showing a cut off low developing at
the mid-levels late Tuesday as the system is over Louisiana. By
then, the system will have what could potentially be a potent line
of storms over the waters of the Gulf of Mexico. These storms will
push eastward as the parent low shifts south and east towards
Florida. The system will be knocking on our door early on
Wednesday, with the low hanging around creating unsettled
conditions until possibly as late as Friday.

Let`s point out a few things about this system and its forecast
trends as of late:
* Model guidance has shown some inconsistency over the last few
  days
* The 00z GFS, which this time yesterday has more of mid-level
  trough than a well-defined cut off low, is now trying to
  produce a pretty ferocious system that takes a more northerly
  path than previous runs
* The 00z ECMWF continues to show a cut off low, bringing
  consistency for several days on that front, but has also started
  to favor a more northerly path over the southern tip of the
  peninsula of Florida

Based off this, the uncertainty remains fairly high with the
evolution of this system and how it will affect our region over
the coming week. The potential outcomes range from a strong to
severe weather threat from a squall line to a weakening system
that will struggle to produce thunderstorms. At this point, will
continue with the forecast trend we have carried over the last
several days which is to include thunderstorm mentions in the
forecast with healthy rain chances. The swings in solutions
between model runs will mean that it is *crucial* to continue
monitoring the forecast evolution of this system as it could pose
a potential threat to South Florida later this week.

As the mid-level low is absorbed back into the parent trough
Friday into Saturday, it will depart our region into the Atlantic.
Our area will see a general drying trend, though a weak frontal
boundary associated with a system over the Great Lakes could bring
some low end rain chances on Saturday into Sunday.

MARINE...
Conditions will remain benign through mid-week when the next
system approaches from the west. Deteriorating conditions could be
seen over the Gulf waters as early as late Tuesday spreading
across the region to end the week. Showers and storms are expected
between late Tuesday/early Wednesday and Friday. Mariners should
remain aware of the latest forecast as details could change
rapidly between updates.

&&

.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach  82  65  80  66 /   0   0  10  20
Fort Lauderdale  81  68  80  69 /   0   0  10  20
Miami            82  67  80  68 /   0   0  10  20
Naples           84  63  82  64 /   0   0   0   0

&&

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

UPDATE...27/JT
DISCUSSION...02/RAG
MARINE...02/RAG
AVIATION...60/BD






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