Area Forecast Discussion
Issued by NWS Miami, FL

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247
FXUS62 KMFL 191744
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
1244 PM EST Mon Nov 19 2018

.AVIATION...

Prevailing VFR through the TAF period, with VCSH possible from
20-01z this evening. Otherwise E to SE winds are anticipated
through early evening, becoming light and variable tonight. The
exception is at Naples, where a gulf coast seabreeze will develop
shifting winds to the west southwest into this evening.

.PREV DISCUSSION... /issued 1041 AM EST Mon Nov 19 2018/

DISCUSSION...

Modest westerly flow prevails aloft, with low-level winds turning
east-southeast. Column integrated precipitable water from the 19.12z
MFL sounding was 1.30, with satellite analysis and model forecast
time-height plots indicating this moisture should remain in place
today at and below 10 kft, with a pronounced dry layer above this.
Surface analysis reveals troughing both along the Atlantic coast and
in the southeast Gulf of Mexico, and these boundaries will serve as
foci for isolated to scattered shower development today. Easterly
flow will then carry these showers into interior South Florida this
afternoon. Modifying the sounding for heating/mixing this afternoon
generates a meager 650 J/kg of SBCAPE, and combining this with weak
lapse rates and limited forcing, suggests keeping thunder out of the
forecast for today. The going forecast remains in good shape, and
only minor changes were made to PoPs/sky to account for trends, and
to increase wind speeds slightly across the Atlantic/Gulf waters and
along the coastal interface.

BEACH FORECAST...

Increased today`s rip current risk to moderate for Palm Beach
County beaches, where recent wind/wave data suggest that swimming
conditions may become more hazardous for today. This elevated
risk may persist for Palm Beach County this week, while increasing
for Broward and Miami-Dade County beaches late in the week.

PREV DISCUSSION... /issued 652 AM EST Mon Nov 19 2018/

AVIATION...

VFR conditions will prevail throughout the forecast period. Winds
will generally remain light and variable through the overnight
hours. These winds will gradually increase out of the east
southeast by the middle of Monday morning to 5 to 10 knots. There
could be some isolated to scattered showers through the overnight
hours mainly at KPBI. At KAPF, a gulf coast seabreeze will
develop shifting the winds to the west southwest Monday afternoon.

PREV DISCUSSION... /issued 233 AM EST Mon Nov 19 2018/

DISCUSSION...
Somewhat warmer and more active weather is in store for the week.

Models are in pretty good agreement for at least most of the week
with the pattern. Cyclogenesis is forecast off the mid-Atlantic
coast over the next 24 hours. This low will have an associated
cold front, which should extend into the Gulf of Mexico. Models
are indicating the front will be fairly weak, and no significant
temperature or dew point changes. It is more like a weak boundary
moving through. however, it may be enough to initiate some shower
activity over the next couple of days.

The models do show the front sneaking across the area on Tuesday.
This can be seen by the 1000-500 mb thickness decrease on Tuesday.
The front will not have a good push behind it and there is
uncertainty as to how far south it will make it. However, both the
ECMWF and the GFS are hinting it may make it into the Florida
Straits by Tuesday afternoon.

Behind the front, high pressure builds to the north. However, the
surface wind never really turn to the east, but maintains a
fairly dominate northerly component. The high does seem to quell
shower activity for Wednesday and Wednesday night.

By Thursday, Thanksgiving day, a 500mb short wave approaches the
area, bringing some instability to the area. PWATs are not very
impressive, with the GFS showing around a half of an inch. GFS
does also show some weak CAPE for the area, generally around 700
J/KG or less across South Florida. The higher CAPE tends to stay
off shore, according to the model. However, the both the ECMWF and
the GFS are indicating another round of cyclogenesis, this time
over the western Gulf of Mexico. This looks to be a slow process,
as it takes a couple of days before it becomes a closed low,
somewhere near the Louisiana coast. However, it does attach
itself to the boundary that stalled in the Florida Straits, giving
it a push northward, as weak warm front. This will mainly aid in
initiating shower activity for Thanksgiving day for a good
portion of South Florida. Friday looks to be in about the same
pattern and therefore showers are still possible for much of South
Florida.

By the weekend, a strong low develops as a lee side low over the
Plains. This low will quickly move eastward, absorbing the Gulf
low, and push a cold front into the Florida peninsula over the
weekend. But alas, it looks like an Okeechobee teaser, basically a
cold front stalling out in the lake region, and never making it
quite into South Florida. But it will be enough to keep showers in
the forecast through the beginning of next week.

So, overall, the week will see a slight chance to a chance of
showers for South Florida. the Atlantic waters may see a few
thunderstorms later this week. There does not seem to be any
significant change to the temperatures through the week, with
highs generally in the 80s, and lows in the 60s and 70s. The weak
cold front could bring some upper 50s into the western Lake
region by Wednesday morning, and for the remainder of the week.

MARINE...
The weather for the next week will see showers in the forecast
each day, with a weak cold front slightly enhancing shower
coverage Tuesday. The front move back to the north for the second
half of the week, which may initiate some thunderstorms over the
Atlantic waters Wednesday, and again for the weekend. Seas for the
next couple of days should run up to a foot in the Gulf and 1 to 2
feet in the Atlantic. The wind is forecast to increase for the
middle of the week, out of the northeast. This would cause seas to
build slightly, up to around 3 feet on Wednesday for both the
Atlantic and the off shore Gulf waters.

AVIATION...
VFR conditions will prevail throughout the forecast period. Winds
will generally remain light and variable through the overnight
hours. These winds will gradually increase out of the east
southeast by the middle of Monday morning to 5 to 10 knots. There
could be some isolated to scattered showers through the overnight
hours mainly at KPBI. At KAPF, a gulf coast seabreeze will
develop shifting the winds to the west southwest Monday afternoon.
&&

.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach  67  83  63  81 /  30  30  30  30
Fort Lauderdale  73  84  71  82 /  20  30  30  30
Miami            72  83  70  82 /  20  30  30  30
Naples           70  84  69  83 /  20  20  10  10

&&

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

UPDATE...34/SPM
DISCUSSION...13
MARINE...13
AVIATION...34/SPM
BEACH FORECAST...34/SPM






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