Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 181946

Area Forecast Discussion
National Weather Service Melbourne FL
345 PM EDT Fri May 18 2018


Diurnal convection off to a relatively slow start compared to recent
days given the drier and less unstable airmass overhead. Convection
firing along both seabreeze by mid aftn but interior precip largely
confined to the I-4 Corridor and points northward. Lcl wind
profilers show weak H100-H70 flow arnd 5KTS over central FL, SW at
KTBW, S/SW at KMLB, and E/SE and KAMX. Precip will continue to
increase in coverage thru sunset, peaking arnd 00Z west of the FL
Turnpike where seabreeze merger is anticipated. Flow is too weak to
generate any blow back to the east coast this evng, bulk of any
lingering precip should remain confined to points west of the FL

The "rex" blocking pattern that has persisted over the nation`s
midsection for the past few days will break down tonight as an H85-
H50 anticyclone over the Great Lakes drifts east into New England
and the Canadian Maritimes, allowing the accompanying mid lvl trof
over the Mid MS Valley to drift north into the Midwest. In its wake,
the Bermuda ridge axis over the FL Straits will drift north into
central FL. H100-H70 mean flow will gradually back from S/SW to
S/SE. While this will begin to nudge a band of deep moisture (PWat
aoa 2.00") currently over the Bahamas back toward the FL Peninsula,
the wind shift will be too slow/subtle to push the moisture much
further west than the Gulf Stream. Will cover coastal zones with chc
PoPs aft midnight, but the bulk of any precip assocd with this
feature will most likely occur aft daybreak.

Light srly flow and sfc dewpoints generally in the U60s/L70s will
keep min temps on the same order, a few degs abv avg.

Deep lyr trof centered over the mid south will lift north into the
Great Lakes region where it will be absorbed by the nrn stream. This
will allow the Bermuda Ridge over the FL Straits to build north in
its wake, eventually anchoring itself over the Deep South/Carolinas
by daybreak Sun. Low/mid lvl flow will shift to the S/SE, bcmg brisk
on Sun as an inverted trof dvlps over the ern GOMex and tightens the
lcl pgrad. These winds will push a band of deep moisture extending
from the Carolinas into the wrn Carib back into the FL peninsula
that will keep high precip chances in the fcst.

The dvlpg S/SE flow regime will allow the east coast sea breeze to
become dominant, though with the H85-H50 flow becoming roughly
parallel to the spine of the FL Peninsula, inland propagation will
be slow. With fcst PWat values arnd 2.00" and H100-H70 mean RH
values btwn 80-90pct, will not try to get too fancy with overall
coverage...painting the area with 70pct both days, decreasing to
30/40pct for the overnight pds. Will focus instead on precip timing,
focusing highest daytime coverage along the coast btwn 12Z-20Z,
shifting inland btwn 16Z-24Z to coincide with the progression of the
sea breeze. Nocturnal coverage will favor the interior btwn 00Z-04Z
to cover dissipating diurnal convection, shifting to the coast btwn
08Z-12Z to account for deep onshore flow.

Bkn-ovc skies and rain cooled air will keep max temps near or
slightly blo avg (L/M80s), onshore flow and high sfc dewpoints will
keep min temps abv avg (U60s/L70s).

Mon-Thu...(prev disc)
The low level Atlantic ridge axis will move northward into mid week
with a period of low level southeast flow around the ridge expected.
Moisture levels will continue to support mainly diurnal showers and
storms along the inland moving east coast sea breeze with rain
chances 50 to 60 percent each day. Should see some morning sun into
next week before afternoon cloudiness increases with daily
convection. Max temps mainly in the mid 80s and min temps upper
60s/lower 70s.


Shower and thunderstorm activity is not as widespread as originally
anticipated, but storms are beginning to develop along the east
coast sea breeze from Volusia County south through eastern Orange
County and northern Brevard County. I have included TEMPO groups at
all terminals through at least 18/22Z for the interior terminals and
KDAB, and through 18/20Z from KTIX-KSUA. High resolution models are
indicating showers and storms developing around Lake County & west
of the Orlando Metro area from 18/22Z through 19/02Z. Some
amendments may be needed if widespread development does occur.
Models are also indicating showers and possibly some thunderstorms
developing along the Treasure Coast around 19/06Z, then moving
northward towards the Brevard Coast. Have included VCSH from KTIX-
KSUA to account for the possibility of showers. Confidence is not
high enough to include a TEMPO group or VCTS, but this will be
revisited for the 00Z TAF issuance. Otherwise, expecting VFR
conditions to prevail after sunset at all terminals.


Tonight...Troffing over the ern GOMex will lift into the TN/OH River
Valleys, allowing the Bermuda Ridge axis over the FL Straits/Nrn
Bahamas drift north acrs the FL peninsula. Sfc/bndry lyr winds will
respond by backing to the S/SE in a gentle to moderate breeze. Seas
2-3FT nearshore and 3-4FT offshore...up to 5FT in the Gulf Stream
north of Sebastian Inlet. Choppy seas over the Treasure coast waters
with dominant wave pds AOB 5sec due to the Bahama shadow. Nmrs
shras/sct tsras expected, mainly over the Gulf Stream and nearshore
Treasure Coast waters.

Sat-Wed...Little change in the dvlpg WX pattern as the Bermuda
anchors itself over the Deep South/Carolina Coast and becomes the
dominant WX feature. Gentle to moderate SErly breeze will prevail...
moderate to fresh on Sun as an inverted trof dvlps over the ern
GOMEX and tightens the lcl pgrad. Little change in the overall sea
state...2-4FT nearshore and 3-5FT offshore...up to 6FT in the Gulf
Stream as the persistent SE flow pushes ocnl swell trains into the
lcl Atlc. Slightly drier air will work its way into the lcl Atlc on
Sun that should lead to a reduction in shra/tsra coverage.


DAB  71  83  70  82 /  40  70  40  50
MCO  71  85  72  84 /  40  70  40  60
MLB  72  84  72  84 /  40  70  40  50
VRB  72  83  72  84 /  50  70  40  50
LEE  71  86  71  83 /  50  70  40  60
SFB  71  85  70  83 /  40  70  40  60
ORL  71  85  70  84 /  40  70  40  60
FPR  72  83  72  84 /  50  70  40  50





Short/Mid Term....Bragaw
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