Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 070835
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
335 AM EST Thu Dec 7 2017

.DISCUSSION...

Current...A cool but shallow air mass is oozing south over the area,
denoted by a northerly wind shift and low stratus between 400 to 800
feet above ground level. Low level profilers at the Cape reveal its
limited depth, with northerly flow present up to about 1000-1500
feet and southwest winds directly above that. Weak cool air
advection behind the boundary has dropped temperatures into the low
60s across the I-4 corridor, while upper 60s remain across the Space
and Treasure Coasts. The real change in air mass resides to our
north, where temps range from the low 40s over the Panhandle to low
50s across the northern peninsula.

Today/Tonight...The aforementioned front will continue to ooze south
this morning before stalling and losing its definition across the
Treasure Coast and Okeechobee County. Expect a north to south
gradient in both clouds and temperatures today as strong surface
heating mixes out the post-frontal airmass from south to north.
Expect clouds to persist north and west of the Interstate 4
corridor, with some sun expected south of there. Where the sun
doesn`t make an appearance today temps will struggle to reach 70,
while 80 appears likely south of the Beachline (528). Chances for
precipitation appear quite slim and more a result of daytime
heating, so central and southern areas would be favored for seeing
isolated/brief popup showers.

The cool/shallow airmass will likely sag back south after sunset
with the loss of daytime heating. Models indicate this along the I-4
corridor and points to the north. Elsewhere, low clouds/stratus
should result from strengthening southwest flow aloft. Precip
chances look low (20%) as the bulk of the shower activity remains to
our north. Overnight temps will range from the upper 50s across
Lake/Volusia counties to the upper 60s over the Treasure Coast.

Fri-Sat...The 00z models show little change from previous runs with
a nearly stationary front across the central peninsula early Friday
and a weak frontal wave approaching from the Gulf of Mexico. This
weak low will lift northeast into the Atlantic late Fri night and
early Sat, causing the front to drop southeast of the area Sat
morning.

The main concern with this frontal passage will be a chance for
storms along and ahead of the front. Some local heavy rain to
around 2 inches is also possible. Daytime heating into the lower
80s Fri across southern sections may generate isolated storms, but
the highest moisture and increased jet dynamics will arrive Fri
night ahead of a shortwave trough. The GFS and ECMWF continue to
generate the most precip from Fri night into Sat morning across
areas between Cape Canaveral, Lake Okeechobee and the Treasure
Coast. Low level winds are progged to be unidirectional but 850mb
speeds look to be 30-35 knots, so a few strong storms are also
possible in that area.

MOS PoPs are 90 percent or greater Fri night across the area and
in the south early Sat. The ECMWF is slightly slower than the
GFS, so categorical values should continue into Sat from the Space
and Treasure Coast to Okeechobee. Shower chances will linger well
behind the front Saturday morning across the north and into early
afternoon in the south.

High temperatures Fri will show a rather large range from the mid-upper
60s in the north to the lower 80s in the south. Cold advection
kicking in early Sat behind the front, and lingering showers with
extensive cloudiness will allow for very little temperature rise
during the day. In fact, some high temperatures for Sat may occur
before sunrise.

Steady cold advection will drive low temperatures Sat night into the
upper 30s to lower 40s. Wind chill values early Sun morning are
forecast to drop into the lower-mid 30s.

Sun-Thu...Cool high pressure ridge over the deep south will sag
south early in the week as the next cold front drops out of the
mid section of the country and reaches the local area on Tue.
There will be little moisture for this front to work with so rain
chances will be low.

It will be cool and dry Sun-Mon with highs in the lower-mid 60s.
Mon morning might be the coolest as the high pressure ridge axis
drops into north Florida and decreases winds. Some mid 30s are
possible in the north. Temperatures look cooler than normal Wed
behind the next front, then close to normal on Thu.

&&

.AVIATION...
A cool but shallow air mass oozing down the central Peninsula is
generating LIFR/IFR CIGS and some reduced visibilities from KMLB-
KISM north. Expect ceilings to slowly climb to MVFR by the afternoon,
with more breaks in cloud cover expected further south. The
cool/shallow airmass should remain north of the Treasure Coast
terminals leading to mainly VFR conditions outside of some light
fog and scattered low clouds this morning. Ceilings will lower
again tonight as stratus redevelops/thickens.

&&

.MARINE...
Today/Tonight...A weak front will sag south through the waters and
stall over the Treasure Coast. Winds will vary from light/variable
along the front itself, north at 10-15 knots behind the boundary,
and south up to 10 knots ahead of the boundary. Seas 3-4 feet
nearshore and up to 5 feet offshore.

Fri-Sat...Nearly stationary front is forecast to cut across the
central peninsula through Fri, with north winds up to 10-15 knots
behind it. The front will start to sag south Fri night and
northwest/north winds will pick up to around 20 knots late in the
north. These winds will encompass all of the waters on Sat. In
addition to hazardous wind/sea conditions, extensive cloudiness
and showers will persist across the waters well into Sat.

Sun-Mon...A post-frontal high pressure ridge will extend over the
deep south on Sun, then the axis will sag into the local waters on
Mon.  Northwest/north winds will likely continue to produce poor to
hazardous boating conditions on Sun, especially in the Gulf Stream.
Decreasing winds/seas will occur Mon.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  68  59  70  50 /  30  40  50  80
MCO  76  62  77  55 /  20  20  50  80
MLB  78  65  82  59 /  20  20  50  80
VRB  80  66  82  61 /  20  20  40  80
LEE  71  58  71  51 /  30  30  60  80
SFB  73  60  74  52 /  20  30  50  80
ORL  75  62  76  54 /  20  20  50  80
FPR  80  66  82  62 /  20  20  40  80

&&

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

$$

SHORT TERM...Ulrich
LONG TERM....Lascody



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