Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 230140
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
940 PM EDT Tue May 22 2018

.UPDATE...

Current...ECFL remains in a stagnant pattern of SE to SSE surface
and low level flow on the SW flank of a strong western Atlantic high
pressure ridge. Subtle changes in the pattern aloft as the upper
trough just to our west has deformed/fractured, with the main piece
retrograding westward into the central GOMEX while a smaller piece
drifts east across north-central Florida. The mid level reflection
is a little farther SE, offshore the central peninsula. Mid level
winds have responded by becoming quite light, while the upper flow
has veered more to SW-W. Local RAOBs show PWATs remain rather moist
(1.7-1.8") but down a couple tenths from recent evenings.

Local doppler radars show just about all the precip over central
Florida has dissipated, and activity upstream over the Atlantic is
pretty minimal.

Remainder of tonight...Expect another warm/humid and mostly cloudy
night. Local air mass is not quite as moist this evening compared to
recent days and upper pattern doesn`t appear to support another late
night bout of heavy rain over the Treasure Coast counties, in spite
of the late night deluges there several of the past mornings. Will
still keep a small coastal POP going overnight. Evening update will
refresh wording.

&&

.AVIATION...Mainly VFR. Small threat for MVFR near 3SM/BKN025 in
coastal showers along the DAB-SUA coastal corridor.

&&

.MARINE...Moderate SE winds up to 15KT with seas 2-3FT near shore
and 4FT well offshore, mainly south of Cape Canaveral

&&

UPDATE/AVIATION...Cristaldi
IMPACT WX...Weitlich

&&

.PREV DISCUSSION... /issued 343 PM EDT Tue May 22 2018/

...More Heavy Rain on Tap for Late in the Week...

Wed-Thu...The Atlantic surface ridge axis is forecast to slide
slowly southward closer toward the local area. The low-level flow
looks to be S/SE and rather weak as the pressure gradient weakens in
relation to the ridge position nearby. By Thu, medium range models
show a weak low pressure developing over the southern Gulf and near
the Yucatan Peninsula.

Coastal convergence across ECFL likely weaker as a result with
potential for lower precip coverage than realized the past few
mornings. However, fairly deep moisture remains over the area with
PWAT values hovering between 1.75-2.00 inches. Deepest convection
likely over the interior in the afternoon on Wed with daytime
heating and highest chances (50pct) likely across Osceola and
Okeechobee counties. PoPs 30-40pct elsewhere on this day. Will bump
PoPs up just a little bit higher on Thu areawide from Wed`s
forecast. Highs each day in the L-M80s near the coast and M-U80s
interior. Lows mild and in the U60s to L70s.

Fri-Mon...(modified previous) Memorial Holiday Weekend...Aloft, an
unsettled pattern develops with troughing over the GOMEX and Deep
South. This will send occasional vorticity impulses over the
forecast area thru this time. Deeper moisture with PWAT values in
excess of 2 inches forecast during this period. Surface high
pressure becomes reinforced initially northward over the southeast
U.S. and mid Atlc states. Much uncertainty exists between medium
range models in placement/track/strength of aforementioned weak
surface low over the Gulf. This will all play a role in
precipitation chances over the period. For now it appears the weak
low will track northward toward the north central Gulf coast and
further north/inland into early next week. This will all provide for
a potentially very wet Holiday Weekend. As such, and given recent
rainfall amounts piling up across ECFL, a Flood Watch may become
necessary during this period for much if not all of the coverage
warning area. Further model consistency and forecaster confidence
will be key in determining this. At the very least, heavy rainfall
and localized flooding seem probable across already saturated
ground. It will remain humid with max temps in the L-M80s with min
temps continuing in the U60s to L70s.

&&

.AVIATION...Low level moist southeast winds are gradually
weakening while a weak impulse aloft will lift northeast away from
the Space/Treasure Coast this evening. The models are trending
drier, so we are not anticipating widespread coastal showers
developing late tonight and lifting northward across the area
like the last few days. Guidance is showing mainly VFR, though
local MVFR is possible especially close to isolated showers.

After isolated morning showers near the coast on Wed, more daytime
heating should allow convection to propagate inland with generally
scattered coverage anticipated.

&&

.MARINE...
Tonight...Southeast winds to up to 15 knots are expected with seas 3-
4 ft near shore and 4-5 ft offshore. Scattered showers are expected
and a few lightning storms will be possible.

Wed-Thu...The Atlantic ridge remains forecast to sink southward
towards the northern local waters while weakening. Winds appear to
vary between the S and SE with a slight gradual decrease in speeds
as a weaker pgrad will be in place. Expect speeds mainly AOB 15 kts
areawide. Seas mainly 2-3 ft very near shore and offshore south of
Ft. Pierce and generally 3-4 ft elsewhere. Moisture will remain high
enough for at least scattered showers and isolated storms.

Fri-Sun...The Atlantic ridge appears to become re-established but to
the north of the area. A very unsettled pattern develops in the Gulf
for the Holiday Weekend. Low pressure near the Yucatan Peninsula or
southern Gulf will move northward toward the Louisiana coast into
the weekend and gradually points further inland across the Deep
South. Exact track, position, and strength on this feature will play
a role in both wind speed/direction. At present directional
component appears SE to S with some occasional wavering toward the
SSW. Wind speeds could approach 15-20 kts at times (potentially
stronger) over the open Atlc. Building seas will also result with
poor to hazardous small craft boating conditions. Potentially high
rainfall probabilities across the local waters with isolated
lightning storms and gusty winds from heavier showers/storms can be
expected.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  69  84  71  85 /  20  20  10  30
MCO  69  88  72  88 /  20  40  20  50
MLB  72  84  73  85 /  20  30  20  40
VRB  70  84  71  85 /  20  40  30  40
LEE  70  89  73  88 /  20  30  20  50
SFB  69  88  72  88 /  10  30  20  40
ORL  69  87  73  88 /  20  40  20  50
FPR  70  84  71  85 /  20  40  30  50

&&

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

$$



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