Area Forecast Discussion
Issued by NWS Melbourne, FL
FXUS62 KMLB 250827
Area Forecast Discussion...Corrected
National Weather Service Melbourne FL
405 AM EDT THU AUG 25 2016
...Closely watching Invest 99L, currently north of Hispaniola...
Today and Tonight...Full extent of sfc ridge nosing swd from the US
eastern seaboard will manifest locally with deep NE flow, breezy at
times from mid morning and into the afternoon. Presence of this
ridge closer to the region wl bring some drying of the airmass,
especially across Northern sections where PoP coverage will be less
than other areas. Isold/scattered showers and a few storms will be
possible, spreading from the coast and inland during the day.
Measurable rain amounts in affected areas will average a tenth of an
inch or less. For tonight shower chances will taper during the
evening with further drying expected across more of the area from N-
S. Best rain chcs will be south of Sebastian Inlet this evening in
*CAVEAT* The discussion that follows is based on current model data
and trends. There is an inherently large uncertainty that comes with
forecasting tropical weather systems. This is especially true with
99L, given the system isn`t even a tropical cyclone yet, and the
heretofore model continuity/consensus issues, which are just now
starting to iron themselves out. We strongly advise everyone to pay
close attention to this system and monitor the latest forecasts and
outlooks from the National Hurricane Center, Storm Prediction Center
and the National Weather Service.
Friday-Sunday...While the global model solutions continue to show
some track and intensity differences with respect to Atlantic Invest
99L, as is usually the case they are narrowing their continuity and
consensus issues to some degree as the event draws nearer. A general
WNW track of the system (in whatever form it may take) is indicated
from the Turks/Caicos Across the SE/central Bahamas through Saturday
night, with continued onshore ENE-NE flow across ECFL and adjacent
Atlantic waters. Some tightening of the local pressure gradient is
shown beginning Saturday afternoon, especially across the southern
half CWA with an attendant increase in moisture. This portends an
increase in both daytime and nocturnal showers.
By Sunday, timing, intensity, and track differences begin to become
more noticeable, and thus favoring one deterministic model run over
another would be an effort in futility. Consensus/ensemble approach
shows a slightly more NW-ward bend, to the south of the MLB CWA,
possibly between south FL and Lake Okeechobee.
Of course, the extent of increase in moisture/windflow for our CWA,
particularly the southern counties, will be highly dependent upon
the strength of the system, and given its current disheveled state,
it is simply too early to get specific or quantitative about wind
speeds and rainfall. Higher rain chances and a further increase in
coverage and intensity of rainfall squalls seems likely, however,
especially south. Although coverage of thunderstorms will be low
given the strengthening gradient flow, some of the fast moving
intense showers will be accompanied by gusty squalls, especially
along the coast.
Current forecast continues the trend of increasing clouds and rain
chances, with occasionally breezy conditions near the SE coast.
Temps near climo should trend slightly below for maxes, given the
above mentioned factors.
Monday-Wednesday...The overall model trend for early next week has
been to show a faster erosion of the eastern CONUS/western Atlantic
ridge. This would result in 99L (again in whatever form it may take
by that time) making a sharper northward bend through the eastern
GOMEX Monday-Tuesday, much closer to the Florida west coast, and
eventually toward the Florida big bend sometime on Tuesday. If this
scenario were to come to fruition, it would extend the time frame of
impacts through Tuesday, especially in the form of heavy rain and
Of course, a more gradual westward turn, which is entirely possible
and may be indicated by subsequent model runs (given the continuity
issues we`ve already seen) would mitigate these threats to some
degree. In any event, the forecast shows winds veering more to the
south, with very deep moisture and high cloud cover/rain chances.
Above average rain chances are also indicated for Wednesday with
the flow forecast to veer more southwesterly.
Max temps are shaded slightly below normal for early week, trending
a little closer to climo toward mid week.
.AVIATION...Primarily VFR conds at forecast sites with brief to
occasional interruptions of light to moderate showers/ and isold TS.
Any CIG/VSBY restrictions during brief shower periods to MVFR conds.
SFC WND G nr 20 kts in showers will be possible mainly along the
coast as well.
.MARINE...Today and Tonight...NE gradient winds near 12 to 16 kts
through tonight will bring seas of 3 to 5 ft over most of the
waters. The Fort Pierce 6 mile buoy was reporting 5 ft seas early
this morning and Gulf stream conditions of around 4-6 ft are
expected, however the open waters should remain just below caution
Friday-Monday...a steady moderate to fresh ENE-NE wind will continue
through Saturday, between a fairly stout late summer high pressure
ridge to the north of Florida and the disturbance to the south.
Later period wind/wave forecasts remain tied to the eventual track
and intensity of Invest 99L, and its resultant increase of local
pressure gradient. Based on the current forecast, it appears that we
could see enough increase in winds/seas to warrant off SCA to lower
end SCA conditions from Saturday night through Sunday. Also, the
increasing coverage and intensity of gusty showers/squalls appears
likely to pose a significant hazard to boaters. Increasing choppy
surf and rip currents will pose hazards for beach interests.
Again the magnitude of these impacts remains uncertain, and tied to
the current forecast, which is based on a consensus of an ever-
changing model suite. Marine interests are urged to closely monitor
Invest 99L, as well as the latest forecasts/outlooks for the system.
.PRELIMINARY POINT TEMPS/POPS...
DAB 88 77 89 77 / 30 20 30 20
MCO 90 75 90 77 / 40 20 30 10
MLB 88 79 90 78 / 50 40 50 30
VRB 88 76 90 77 / 60 40 50 40
LEE 92 74 91 76 / 30 20 30 10
SFB 90 75 91 77 / 30 20 30 10
ORL 90 76 90 77 / 30 20 30 10
FPR 88 77 90 77 / 60 40 50 40
LONG TERM/IMPACT WX....Cristaldi