309
FXUS62 KMLB 270958
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
558 AM EDT Fri Sep 27 2024

.DISCUSSION...
Issued at 550 AM EDT Fri Sep 27 2024

Key Message:

- Hot and humid today into the weekend behind Helene due to
  offshore flow and plume of deep moisture returns. Locally heavy
  rain is possible over the weekend.

Today...T.S. Helene continues to rapidly pull away from the area
with local winds veering SW around its south side. The tight
pressure gradient will continue to loosen but gusty winds will
continue esp this morning. So have raised a Wind Advisory for this
morning all counties for 20-25 mph winds still gusting near 35
mph. These winds will gradually subside this afternoon but still
remain gusty. Some drier air will settle across northern sections
during the day but until then, bands of fast moving showers will
move thru this morning producing brief downpours. Higher moisture
plume will remain across our southern FA. So rain chances will
decrease 20-30 percent north, but remain 50-60 percent south. Due
to the offshore (SW) flow, max temps will be hot reaching the
lower 90s even at the coast with near record highs at Melbourne
and Vero Beach. Combined with high dewpoints, peak heat indices
will reach near 108 across southern and eastern portions of the FA
so have raised a Heat Advisory along the Space and Treasure
coasts incl Okeechobee.

Sat-Sun... Helene will merge with a cut-off low over the
Tennessee Valley and this upper level low will slowly weaken over
the weekend as a high pressure ridge over the western Atlantic
builds westward over the Florida peninsula and the Deep South.
Locally, winds will remain southwesterly through the weekend,
decreasing to around 10 mph on Saturday, and 5-10 mph on Sunday.
Deep tropical moisture from the Caribbean will remain over the
local area through the weekend, with the moisture band returning
across central Florida on Saturday and Sunday. Beneath it,
scattered- numerous (50-70%) shower and storm coverage is forecast
particularly in the afternoon/evening hours. Additional rounds of
heavy rainfall can not be ruled out, thus increasing concerns of
flooding over locations that have already seen a lot of rainfall
this month.

With deep moisture in place, high humidity will persist over the
area, with dew points in the mid to upper 70s. Combined with the
offshore flow, afternoon highs will be in the low 90s. These
temperatures combined with humidity will produce near heat advisory
criteria with heat indices ranging from 102-107F each afternoon.
Overnight lows will be in the low to mid 70s each night.

Monday-Wednesday...The upper level ridge will begin to retreat
into the Atlantic through mid week. As the upper ridge sits
nearby, the deep tropical moisture overhead will trend closer to
normal. Some members show bouts of even drier air infiltrating the
area from time to time, but confidence lessens overall. This
yields continued 30-50% shower/storm coverage each day with highs
in the upper 80s to lower 90s. Heat indices will subtly "dip"
closer to 98-103F as surface moisture trends toward normal values.
Overnight lows will remain in the low to mid 70s.

&&

.MARINE...
Issued at 550 AM EDT Fri Sep 27 2024

Tropical Storm warnings have transitioned to Small Craft
Advisories across all the Atlc waters this morning with
occasional gusts to Gale force early. Seas will quickly subside
nearshore due to the offshore (SW) flow so will likely transition
to a Caution headline by late morning nearshore. Winds SW 8-15 KT
this weekend. Scattered- numerous showers and storms with
offshore-moving activity expected.

&&

.AVIATION...
(06Z TAFs)
Issued at 143 AM EDT Fri Sep 27 2024

Hurricane Helene made landfall in the late evening as a major
category 4 hurricane in the Florida Big Bend, just east of the
mouth of the Aucilla River. It continues to shift quickly
northward into southern Georgia. The large wind field with this
system will continue to produce tropical storm force wind gusts
35-40 knots through 9Z, with winds steadily decreasing through
early morning as Helene continues to shift northward. Kept mention
of LLWS for northern TAF sites for 55-60 knots at 2kft through
9Z. Winds will still be breezy into today, with SW winds 13-15
knots and gusts up to around 25 knots, decreasing to 5 knots out
of the S/SW into tonight.

MVFR cigs at times will persist through tonight into early Friday
morning, but should largely become VFR into the afternoon and
evening. Some passing outer rain bands will produce tempo IFR/MVFR
visibilities through the rest of the night and into early
morning. The greatest potential for additional scattered showers
and isolated storms will then continue across areas south of
Orlando into this afternoon. Have kept VCSH mentioned from KMLB to
KSUA as not quite as confident in TSRA coverage, but may need a
period of VCTS for these sites during the afternoon hours.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  93  75  90  75 /  20  10  60  20
MCO  92  77  90  76 /  30  20  60  20
MLB  93  77  90  76 /  40  30  60  40
VRB  93  77  91  75 /  60  40  60  30
LEE  89  75  89  76 /  20  10  50  20
SFB  91  76  90  76 /  20  10  60  20
ORL  92  77  90  77 /  20  10  60  20
FPR  92  77  91  75 /  60  40  60  30

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...Wind Advisory for FLZ041-044>046-053-058-141-144-154-
     159-164-247-254-259-264-347-447-547-647-747.

     Heat Advisory from 11 AM this morning to 6 PM EDT this evening
     for FLZ058-154-159-164-247-254-259-264-347-447-547-647-747.

     High Surf Advisory until 11 AM EDT this morning for FLZ141-154-
     159-164-347-447-647-747.

AM...Small Craft Advisory AMZ550-552-555-570-572-575.

&&

$$

DISCUSSION...Kelly
AVIATION...Weitlich