Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 201935
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
335 PM EDT Sun May 20 2018

.DISCUSSION...

Tonight-Monday...The GFS nudges some mid level drying in from the
east early so this points to lowered rain chances areawide through
this evening.  The waters to our east have not had many showers
today, so the GFS trend looks reasonable.  The model shows a bit of
a southeast low level wind surge with increasing moisture after
midnight across our southern waters. MOS paints likely PoPs from
Melbourne to Stuart and Okeechobee with increasing chances after
midnight. Will follow that guidance and have PoPs of 40 percent
elsewhere.

The models show mid/upper trough over the eastern Gulf of Mexico
weakening on Mon but a plume of high moisture is forecast to extend
from the Caribbean into the Florida peninsula.  MOS has very high
PoPs areawide (~80%).  Did not go that high, but trended upward to
70% due to continued high moisture, breezy southeast winds providing
some low level convergence and divergence aloft in association with
the weak trough in the Gulf. Clouds and showery weather will once
again limit high temps and have gone with lower 80s across the area.

Previous Discussion...

Tue-Sun...The Atlantic ridge axis will remain the dominant weather
feature with a moist south to southeast flow keeping rain chances
above normal (50 to 60 percent) most days supporting mainly daytime
showers and storms. The ridge axis is forecast to gradually shift
southward and weaken during mid to late week as a trough develops
over the Southeast US. A slight reduction in the deep moisture by
Wed will allow rain chances to decrease to 30-40 percent for most
areas. It will remain humid with max temps in the mid 80s.

Both GFS and ECMWF show a mid level trough developing over the
Gulf of Mexico late in the week. The GFS retrogrades a piece of
energy SW from the base of a departing shortwave trough off the US
east coast. The real difference is how each model handles lower
pressure at the surface. The ECMWF continues to show low pressure
developing directly underneath the upper low over the central Gulf
on Fri. This looks suspect as the best support for sfc low
pressure would be to the ascending (east) side of the upper low,
closer to the GFS solution. But both models show deep tropical
moisture overspreading the FL peninsula during the first part of
the upcoming holiday weekend which will prompt high rain chances
with a threat for heavy rain and localized flooding due to already
wet conditions.

&&

.AVIATION...Light showers will continue across most of the area
through at least 20/24Z. Lower CIGs have been hovering between
020-030 this afternoon, with terminals periodically falling into
MVFR conditions with BKN025-030 decks. As of 3PM, already seeing
moderate to heavy showers develop across the interior along the
sea breeze. These showers may cause periodic reduced visibilities
and IFR CIGs of BKN010-015, thus I have updated the
KMCO/KSFB/KISM/KLEE TAFs to account for this through 20/21Z.
Forecasting mainly VFR conditions after 20/24Z. Winds will
increase after 21/14Z with all terminals likely to see sustained
winds of 12-15 knots and gusts around 20 knots. Showers are likely
Monday afternoon, thus have included VCSH for all terminals,
although some showers may develop along the coast earlier than
21/14Z.

&&

.MARINE...
Tonight-Monday...Conditions for small craft operation will remain
poor.  Southeast winds 15-20 knots are forecast over the offshore
waters with 15 knot speeds closer to shore.  Seas 3-5 feet close to
the coast and 4-6 feet offshore.  There will be a bit of a lull in
showers/isolated storms through late evening, but moisture surging
back northward overnight and early Mon should result in likely rain
chances south of Cape Canaveral, then across the remainder of the
nearshore waters Mon morning. With a little mid level dry air,
some of the showers/storms are expected to produce stronger wind
gusts to near 35 knots.

Tuesday-Friday...The axis of the Atlantic ridge is forecast to
settle close to the waters on Wed and produce a day or two of
reduced southeast flow. However, Tue still looks to have poor
conditions as southeast winds will be close to 15 knots and
offshore seas up to 6 feet. There is also uncertainty if a low
pressure system may form in the northwest Caribbean or eastern
Gulf, which could lead to substantial deterioration of boating
conditions late in the week.


&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  72  80  70  82 /  40  60  30  50
MCO  70  82  71  85 /  40  70  20  50
MLB  73  81  74  82 /  60  70  30  50
VRB  73  80  72  83 /  60  70  30  40
LEE  70  83  70  86 /  40  70  20  50
SFB  70  81  70  84 /  40  70  20  50
ORL  70  81  70  83 /  40  70  20  50
FPR  72  80  72  83 /  60  70  30  40

&&

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

$$

SHORT TERM/LONG TERM...Lascody
IMPACT WX....Spratt
AVIATION...Rodriguez


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