Area Forecast Discussion
Issued by NWS Melbourne, FL

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490
FXUS62 KMLB 151909
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
209 PM EST Fri Dec 15 2017

.DISCUSSION...

TONIGHT/SAT...Satellite reveals meager multi-deck cloudiness
ahead of an approaching/weakening frontal boundary across the
forecast area. The pre-frontal environment has been less than
dramatic and minimally productive, even regarding cloud cover.
Expect the front to transition south through Central FL overnight
with PoPs too low to mention. Winds will turn out of the north
behind the boundary, but without a big post-frontal rush. Min
Temps will generally be in the 50s. By Sat, strong high pressure
will build over the Deep South to futher facilitate a veering of
the surface winds out of the northeast, even as the high pressure
center slides seaward off the Carolina coast. Thus, only slightly
cooler with Max Temps in the U60s/M70s distributed N-S.

SAT NIGHT-SUN NIGHT...Surface high pressure will push off of the
Southeast U.S. coast and into the Western Atlc. The associated
east-west oriented ridge axis will drop into North FL by daybreak
Mon morning. Initial ENE/NE flow will veer to E early on Sun,
then southeast by late afternoon/Sun evening. Wind speeds
generally light as a weak pressure gradient will be in place.
Conditions expected to remain dry. PWAT values will flirt on
either side of one inch with deepest moisture northward as a weak
low pressure system tries to organize across the Gulf Coast
States. Further aloft the flow remains mainly zonal as mid-level
high pressure ridging remains in control, centered near the
Bahamas. All short-wave troughing or decent energy impulses remain
north of the region.

Lows Sun will be in the 50s, except low to mid 60s immediate
Treasure Coast. Highs Sun will warm into the upper 70s, except mid
70s Volusia coast. Lows Sun overnight into Mon morning will be mild
and in the U50s/L60s, except M60s immediate Space/Treasure coasts.

MON-FRI...(From Previous Discussion) 00Z GFS/ECMWF are in
reasonable agreement early next week showing mid level ridge over
FL straits/Cuba. This will keep warm/dry conditions across the
forecast area through Tue as deeper moisture gets steered around
the ridge to the north of the area. Above normal high temps
expected to reach the lower 80s both days. Then model solutions
diverge mid week when the GFS shows the next front reaching
central FL Wed while the ECMWF keeps the front to our north and
continues the warm/dry weather thru Thu. The difference is
attributed to how each model ejects an upper low over the desert
SW across the southern US. The GFS is more potent with the short
wave, weakening the ridge aloft which allows the front to make
more of a southward push. Using a model blend produces token 20
PoPs for Wed- Thu. Since the model guidance is not in agreement
here, there is considerable uncertainty in the forecast but
confidence should increase in the next couple days.


&&

.AVIATION...VFR with SW/WSW winds around 10 kt gradually becoming
light and more westerly/northwesterly late this evening and
eventually northerly overnight tonight.  Winds will continue to veer
to the NNE/NE Saturday morning into the afternoon.

&&

.MARINE...
TONIGHT-SAT...Offshore flow around 10 knots (10-15 knots well-
offshore) will continue through sunset ahead of an approaching/
weakening frontal boundary currently over North FL which is slowly
making southward progress. As this boundary transitions southward
over the forecast waters, a brief passing shower may occur. Then
overnight winds will turn out of the north behind the front,
remaining 15 knots or less. Seas will range from 1-3 feet, but an
area of 3 foot seas will expand particularly over the Gulf Stream.
Local winds will veer to the northeast for Sat. Seas will be 15
knots or less and seas 2-3 feet.

SAT NIGHT-WED...Surface high pressure will move off of the
Southeast U.S. coast and into the Western Atlc as northeast winds
veer to the east by early Sun, then southeast by late Sun
afternoon/night, southerly by Mon evening, finally SSW on Tue as
an east-west ridge axis lies across the central peninsula. A cold
front approaches from the north on Wed, but there remains
disagreement between medium range models on just when it will move
south from north FL. Wind speeds generally 6-12 kts. Seas 2-3
feet favoring comfortable small craft boating conditions.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  53  65  55  74 /   0   0   0   0
MCO  53  71  54  79 /   0   0   0   0
MLB  57  71  60  77 /   0   0   0   0
VRB  57  73  61  78 /   0   0   0   0
LEE  51  69  52  77 /   0   0   0   0
SFB  52  69  54  77 /   0   0   0   0
ORL  53  70  54  78 /   0   0   0   0
FPR  57  74  62  78 /   0   0   0   0

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&

$$

SHORT TERM...DS
LONG TERM....TS
AVIATION...JC



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