Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 111456

Area Forecast Discussion
National Weather Service Melbourne FL
955 AM EST Mon Dec 11 2017


...Temperatures rising after a cool, frost start to the day...

...Patchy frost possible again tonight across the interior south...

Current...Pre-sunrise lows were in the M-U30s over the interior and
north and L40s for metro Orlando and the Space and Treasure Coast
barrier islands.

Cold high pressure ridge continues to extend SE from the Rockies
across AZ/NM/TX, then eastward from south TX across the Gulf Coast
region, GOMEX and Florida. The mid to upper level flow pattern
remains broadly cyclonic overhead with an elongated E-W H50 vort
axis stretching from the GOMEX across central Florida and into the
Atlantic. No surprise at all to the aridity in the morning RAOBs,
which show PWAT values in the 0.25" to 0.35" range. RAOBs and CCAFS
DRWP data also show slackening low to mid level NW flow which backs
to westerly near or a little above H70.

Remainder of big surprise. Full sun and cool temps, with
maxes in the L60s north-central and M60s south. NW winds of 5-10 MPH
will back slightly to W-WNW by late afternoon as the surface ridge
axis currently overhead begins to sag southward.

Tonight...GFS shows very dry air across the southern CWA as the
ridge settles south, with return westerly flow developing to the
north. This portends colder temperatures (U30s), and potential for
another night with patchy frost inland from the coast and south of
Lake Kissimmee-Melbourne. Expect L-M40s across the north, and along
the immediate SE coast,




.MARINE...Current buoy and C-MAN data indicate that NW-N winds have
decreased to about 10-12KT with 2FT seas near the coast and 3 to
possibly 4FT in the Gulf Stream south of SIPF1. Winds and seas
figure to slacken further per model guidance this afternoon/evening
so plan to cap off at 3FT through tonight.




.PREV DISCUSSION... /issued 232 AM EST Mon Dec 11 2017/

Tuesday...A longwave trough extending from the Great Lakes to the
Southeast states on Tue will allow a reinforcing dry cold front to
reach east central Florida by Tue evening. Ahead of the front
westerly low level flow will become breezy by afternoon with
afternoon high temps warming into the lower 70s.

Tue Night...Low level flow will become northwest to around 10 mph
overnight with a dry dry NW flow through a deep layer behind the
cold front. Low temperatures will drop into the lower 40s for much
of east central Florida but some colder readings in the upper 30s
will affect portions of Volusia and Lake county.

Wed...Dry, sunny and cool weather is expected on Wednesday with low
level northwest flow as high pressure slides east along the northern
Gulf coast. Highs are expected in the upper 50s north to lower to
mid 60s srn sections.

Thu-Mon...Forecast challenge for the extended range will be exact
timing of next trough that will bring a chance of showers for late
week. Both the GFS and ECMWF keep Thursday dry as high pressure
moves eastward into the Atlantic and low level westerly flow
develops by afternoon. The ECMWF continues its trend of a deeper and
slightly slower shortwave trough with the bulk of the shower
activity moving through Friday night while the GFS has the timing
about 12 hours faster. For now will keep shower chances in both the
Friday/Fri Night periods before the shortwave moves east of the
state into Saturday afternoon. High pressure should be near the
peninsula in the wake of the aforementioned trough by late Saturday
into Sunday.  Generally mild temps are expected behind the next
system with rising 500 mb heights across central Florida. This will
allow for high temps in the 70s for Sunday and Monday and lows
mainly in the 50s.


.AVIATION...Continued VFR/SKC.


Today-Tonight...Weak high pressure ridging will reside over the
coastal waters for this period. Confident we can drop any remaining
cautionary statements for the Gulf Stream with next coastal waters
forecast issuance. Seas continue to subside with 2-3 ft seas very
near shore and generally 3-4 ft seas over the Gulf Stream, outside
of a few 5 ft wave sets early this morning south of the Cape. NW
winds 10-14 kts over the open Atlc early on will fall to AOB 10 kts
areawide this afternoon as winds become more WNW/WRLY. Wind speeds
will pick up a bit again this evening to 10-15 kts over the open
Altc, perhaps up around 15 kts well offshore the Volusia coast late.

Tuesday...Westerly winds will increase to around 15-20 knots near
shore and up to 20 knots offshore into late afternoon ahead of the
next dry cold front. Seas will build to 4-6 ft offshore.

Tue Night...NW winds will increase to near 20 knots near shore and
up to 20-25 knots offshore. Small craft advisories will likely be
required with seas building up to 7-9 ft well offshore late.

Wed...NW winds to 15-20 knots in the morning will decrease into the
afternoon but seas will remain at hazardous levels in the gulf
stream into the afternoon hours.

Thu-Fri...Westerly winds are expected to decrease Thu to around 10
knots allowing seas to subside. An increase in southwest winds is
expected Friday to 15-20 knots ahead of the next front.


Today...Outside of unseasonably cold temperatures early this
morning, we may also realize some patchy frost early on. Weak
pressure gradient over the area today with a continued very dry
airmass in place. Weak high pressure ridging resides over the area
with 20FT winds generally NW or WNW 3-7 mph promoting poor to fair
dispersion at best. Lowest afternoon RH values will fall into the M-
U20s/L30s interior and around 35pct closer towards the east coast.

Tuesday...Westerly low level winds will increase into the afternoon
and become breezy in some locations. High temps will warm into the
lower 70s in the afternoon allowing afternoon Min RHs to drop to
between 35 to 40 percent.

Wednesday...Drier and cooler weather is expected with Min RHs
dropping to around 30 percent across the nrn interior behind the
next dry front. NW winds expected up to 10-15 mph.


DAB  61  43  73  39 /   0   0   0   0
MCO  63  43  73  43 /   0   0  10   0
MLB  64  42  73  43 /   0   0   0   0
VRB  64  40  73  43 /   0   0   0   0
LEE  63  45  72  43 /   0   0   0   0
SFB  62  43  73  42 /   0   0  10   0
ORL  62  45  73  44 /   0   0  10   0
FPR  64  39  73  41 /   0   0   0   0



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