Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 251356
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
955 AM EDT SUN SEP 25 2016

.UPDATE...

...Lingering swells will keep the Rip Current risk high at area
beaches today...

Current...Local pressure pattern remains amorphous with a dearth of
surface/low level flow this morning. The large mid to upper level
low has become a little better defined, with its circulation center
now over the western panhandle. The area of convection that formed
overnight along/just offshore from southern Brevard County southward
has become more expansive as it pushes farther away from central/SE
FL coast. Upper divergence along the SE periphery of the ULL is
helping to maintain this activity. Other than some thin CI/CS debris
along the Volusia/northern Brevard coasts, skies are sunny.

Morning RAOBs continue to show healthy north-south disparity in mean
moisture across the peninsula, with PWATs ranging from 1.55"/1.65" at
JAX/TBW to ~1.9" at XMR and ~2.0" at MFL. Mean layer flow is a bit
lighter than Saturday, generally AOB 10Kt from just off the deck up
through H30, with most levels reporting and only about 4-8KT. H50
temps are a tad cooler, between -7C and -8C.

Remainder of today...The stagnant pattern continues ad nauseam.
Looking at yet another day of little wind outside of the wind flow
generated by sea/lake breezes and convective outflows. Scattered
slow-moving afternoon showers/storms a safe bet, once again highest
coverage around the Lake Okeechobee/Treasure Coast regions. Heavy
rain and frequent lightning remain primary storms threats, however
we could see a few stronger storms pulse up, given that mid level
temperatures are a little on the cool side. Lack of steering winds
will inhibit persistent updrafts and thus individual storms will
quickly become downdraft dominant today.

The current suite of products has situation well-handled. No changes.

&&

.AVIATION...VFR/SKC to SCT250, with late morning diurnal CU field
producing some MVFR CIGS BKN025-030 after 15Z. IMC in scattered
SHRA/TS starting 17Z-18Z INVOF SUA-FPR-VRB, spreading north up thru
at MLB-TIX through 19Z-20Z, and then inland toward the interior
aerodromes, with a little higher chance toward ISM-MCO 21Z-01Z.

&&

MARINE...After peaking at around 4FT earlier this morning, seas at
buoy 41009 have settled back to around 3.5FT, which indicates that
the highest seas had probably decreased to 4FT by ~12Z. Current
grids indicate this taking place between 12Z-15Z, but seem to have
larger area of 4FT seas creeping into the 0-20NM legs than what is
actually the case. For the late morning update, will trim this area
back outside 20NM such that nearshore seas this afternoon will drop
back to 2-3FT, and 3-4Ft for the 20-60NM legs.

&&

FORECAST UPDATE...Cristaldi
AVIATION/RADAR/IMPACT WX...Glitto

&&

.PREV DISCUSSION... /issued 330 AM EDT Sun Sep 25 2016/

Monday...East central FL will be between two mid level shortwave
troughs...one over the FL panhandle and the second weaker wave which
is currently kicking off convection over the Atlantic east of the
Treasure coast will move father offshore into the afternoon on
Monday. Low level winds will become light onshore allowing the east
coast sea breeze to move slowly inland in the afternoon. PWATs are
forecast around 1.6 inches across the north and 1.8 around Lake
Okeechobee. Rain chances will range from 40 percent for nrn areas
and the coast and 50 percent for the srn interior. Highs will be in
the upper 80s to lower 90s over the nrn interior.

Tuesday...Panhandle mid level wave will elongate across the ern Gulf
as deep mid-upper closed low heads toward the Great Lakes. Mid level
winds increase from the WSW to around 10 knots with light low level
S-SW flow. GFS has substantially drier air across far nrn areas with
deeper moisture lingering across the south. This should again favor
the srn forecast area for slightly higher coverage of afternoon
showers and storms. POPs 30-40 pct far nrn areas to around 50
percent for Okeechobee county and the Treasure coast.

Wed-Sun...Mid-upper trough will move from the Great Lake toward the
mid Atlantic into late Thu and bring a front into north Florida by
Wed evening and toward central Fl on Thu. 00Z ECM continues to be
deeper and stronger with the mid/upper level closed low and drops it
farther south before meandering northward toward the lower Great
Lakes toward the weekend. The GFS continues more progressive with
the trough allowing it to move offshore along the NE seaboard over
the weekend. The differing model solutions have similar wind
moisture profiles Wed/Thu with some drier air making it in across
the nrn peninsula by Thu afternoon. For now will continue to lean
toward the GFS which will bring a prolonged period of stronger
onshore flow late Friday through the weekend. GFS has trended
slightly south with the highest moisture convergence from Brevard
county south to the Treasure coast and have trended highest POPs in
these areas Fri-Sun with onshore moving showers and isolated storms
expected front the Atlantic. If GFS solution verifies this would set
up the potential for a coastal heavy rain event toward next weekend.
With model discrepancies at the longer ranges will cap highest POPs
around 50 percent with further refinement as we draw closer.

&&

.AVIATION...Another late evening/night for nocturnal convection from
KMLB thru KSUA. Will probably see this happen again late tonight due
to the proximity of the upper low across north FL. Continue VFR
conds outside of convection over the next 24 hrs. After sunrise,
mainly afternoon/evening shra/tsra ISOLD-WDLY SCT across the I-4
corridor with SCT coverage south of here. Tempo MVFR vsbys/cigs in
convection. Fairly light/variable morning winds becoming light ENE/E
again this afternoon as the ECSB develops and pushes slowly inland.
L/V winds again this evening/overnight.

&&

.MARINE...Today-Tonight...The general light pressure pattern
will continue with winds mainly 10 kts or less over the next 24
hours. Winds will become onshore near the east coast by late
morning/early afternoon with sea breeze formation and march inland.
A light offshore flow will develop again later this evening and
overnight.

TC Karl will be responsible for the lingering easterly long period
swell (11 seconds). Seas generally building to 3-4FT near shore and
4FT offshore.

Showers and storm coverage will be isolated to scattered thru the
period with highest chances south of the Cape. The persistent
weather pattern dictates another late evening/night for nocturnal
convection along the Space/Treasure coasts. Torrential downpours,
gusty winds, and cloud to water lightning remain the threats.

Mon-Tue...light onshore wind will veer to the southerly on Tuesday
with a continued higher swell to 3-4 ft well offshore and 2-3 ft
near the coast. Scattered showers and storms are expected to be
higher in coverage south of Sebastian Inlet early this week.

Wed-Thu...Offshore winds are forecast Wed with a frontal boundary
moving into the waters on Thu. Seas 2-4 ft Wed will decrease some
Thu to 2-3 ft. Stronger onshore winds are expected to build seas by
Friday into the weekend as the pressure gradient tightens with high
pressure well north of the area.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  88  73  87  71 /  30  20  40  40
MCO  90  73  91  72 /  40  20  40  30
MLB  89  74  89  73 /  40  30  40  40
VRB  88  73  87  71 /  50  40  40  40
LEE  92  74  90  73 /  40  20  40  30
SFB  91  74  91  72 /  30  20  40  30
ORL  91  75  90  74 /  40  20  40  30
FPR  87  72  88  71 /  50  40  40  40

&&

.MLB Watches/Warnings/Advisories...
FL...None.
AM...None.

$$



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