881 
FXUS62 KMLB 270927
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
525 AM EDT Tue Aug 27 2019

.DISCUSSION...

...Tropical Storm Dorian Moving West-Northwest Toward the Northeast 
Caribbean Sea...

Today-tonight...Mesomodel guidance indicated light WNW surface and 
steering level winds today with sufficient moisture to produce 
scattered to locally numerous showers/storms along local sea/lake 
breeze boundaries. H85-H50 mean winds indicate steering flow of 
around 10MPH out of WNW-NW today. Main concerns will be heavy 
rainfall along with locally gusty winds and frequent CG lightning
strikes. Kept the inherited POPs of 40 north/50 central/ 60 south.
Highs around 90 along the immediate coast, L90s elsewhere. Mins
generally in the M70s.

Wednesday-Friday...Weak gradient between sfc ridge over the central 
GOMEX and exiting tropical system up the Mid Atlantic states will 
lead to light northwest to westerly flow on Wednesday, with slight 
variability in the afternoon with the east coast sea breeze 
development. Wedge of dry air along the western FL coast hinted at 
in previous model runs has been overrun completely by PW values over 
2.00" across the peninsula. This will in turn maintain 40-50% PoPs 
Wednesday with diurnally driven convection forming along sea breeze 
and boundary collisions. 

By late Wednesday/early Thursday, another cold front drives across 
the Deep South, stalling out across the FL/GA border. Models 
continue to favor a sfc low developing along this front off the SC 
coast, veering winds south/southeast by late Thursday. Deep moisture 
pulls in from the southeast, assisting in higher rainfall coverage 
Thu/Fri, with 50-60% PoPs forecast areawide. Latest package expands 
likely PoPs both days, covering a bit more land area and a portion 
of the Atlantic waters. 

Seasonal temps persist, with highs in the low 90s and lows in the 
mid 70s.

Labor Day Weekend...The main focus of the weekend forecast continues 
to be the fate of Tropical Storm Dorian.

The bottom line is that much uncertainty still exists at this point, 
with multiple factors determining its track and especially its 
strength as it approaches the FL peninsula. Consequently it remains 
much too early to speculate on specific impacts to Florida, and will 
remain that way until the system (or possibly what's left of it) 
emerges north of the Greater Antilles on Thursday. The two variables 
over the next 48 hours are (1) The extent to which it is impacted by 
a TUTT trough low to its north, and (2) Whether the storm interacts 
significantly with the island of Hispaniola, or remains just to the 
east, slipping across the Mona Passage or western PR. This will 
determine how much the storm will have weakened and once it emerges 
over the Bahamas.

Regardless of these factors, tropical moisture will saturate the 
region Saturday through Monday, leading to rain chances of 60-70%.

Residents and visitors to Florida should continue to monitor the 
latest forecast from NHC and your local NWS office. Review your 
hurricane preparedness plan and make sure necessary supplies are 
fully stocked.

&&

.AVIATION...VFR through around 16-17Z, followed by isolated SHRA/TS
development, increasing in coverage through the afternoon. 03Z-06Z 
mesomodel guidance now supports TEMPO groups for the interior but are 
a little less certain for the coastal aerodromes. Current 06Z TAF 
set has VCTS for all sites, but am leaning toward adding a 2 hour 
TEMPO TS for the inland sites somewhere in the 20Z-23Z time frame, 
and possibly the MLB-SUA corridor 22-24Z as well.

&&

.MARINE...Today-tonight...Buoy and wave model guidance indicates 
that the swell period as lengthened out to around 9s with seas 
averaging about half a foot higher than h24 ago. Current forecast 
follows this by having a small area of 3-4ft season today north of
Sebastian inlet, subsiding a bit back to 2-3ft tonight. There is
the potential for some strong offshore moving thunderstorms late
this afternoon into early this evening, mainly south of the Cape.

Wednesday-Friday...Weak gradient between a sfc high over the GOMEX 
and exiting TD 6 will lead to light westerly flow across the 
Atlantic waters Wednesday, with brief shifts to onshore with the 
afternoon sea breeze development. A low pressure system will develop 
along off the SC coast along an approaching cold front, which will 
veer westerly winds to the southeast late Thursday. Winds 5-10 kts 
Wed increasing to 10-15 kt on Thu, with seas steady at 3 ft. 
Scattered to numerous showers and thunderstorms over the waters each 
day.

Weekend...Hazardous boating conditions potentially developing this 
weekend as Tropical Storm Dorian reaches the Bahamas, with impacts 
to the local Atlantic waters beginning late Friday night. All marine 
interests should closely monitor the National Hurricane Center and 
local NWS forecasts regarding Tropical Storm Dorian.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  90  76  91  76 /  30  30  40  30 
MCO  93  76  93  76 /  50  20  50  20 
MLB  90  77  90  77 /  50  30  50  40 
VRB  90  75  90  76 /  50  30  50  40 
LEE  93  77  92  77 /  40  20  50  20 
SFB  93  76  94  77 /  50  20  50  30 
ORL  93  76  93  77 /  50  20  50  20 
FPR  92  76  91  75 /  50  30  50  40 

&&

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

$$

SHORT TERM/AVIATION...Cristaldi
LONG TERM/IMPACT WX...Smith