993
FXUS62 KMLB 121809
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
209 PM EDT Wed Jun 12 2024

...New AVIATION...

.AVIATION...
(18Z TAFs)
Issued at 207 PM EDT Wed Jun 12 2024

-RA continues at the Treasure Coast terminals with coverage
expanding northward into the afternoon. MVFR CIGs are forecast to
develop and generally prevail. TEMPOs for lowering VIS and CIGs in
thunderstorms which develop today. Overall coverage of showers and
storms diminish from north to south after 0Z. Lingering VCSH
included from SFB southward overnight. Winds generally out of the
south to southwest through the period. However, winds often variable
across the north this afternoon as low pressure tracks across the I-
4 corridor. Winds also variable in vicinity in thunderstorms.

&&

.PREVIOUS DISCUSSION...
Issued at 502 AM EDT Wed Jun 12 2024

- Repeated rounds of heavy rainfall are forecast to continue
  across Florida, regardless of development of Invest 90.
- There is a risk for parts of east central Florida to receive
  substantial rainfall this afternoon, potentially over 7", which
  could lead to minor to moderate flooding.

Today-Tonight...NHC continues to monitor Invest 90L, which has
moved onshore over Tampa Bay early this morning and is forecast to
track slowly northeastward through the day, emerging into the
Atlantic waters between the Cape and Jacksonville tonight into
early Thursday morning. There is only a 10 pct chance of tropical
development over the next 48-hours. Regardless of development of
this feature, heavy rainfall will continue to be the primary
hazard. Deep tropical moisture with PWATs over 2" continues to
stream across the peninsula between the stationary front to the
north and the Atlantic high suppressed well to the south. We`ll
continue to see rounds of scattered to numerous showers and
scattered lightning storms through the day and night, with the
highest coverage around peak daytime heating in the afternoon and
evening. Heavier showers and storms will be capable of delivering
a quick 1-2" of rainfall in an hour, leading to widespread
rainfall amounts of 1-3" and locally higher amounts over 4". CAMS,
especially the HRRR, have been indicating potential for banding
of heavy showers along the southern to southeast periphery of
Invest 90L with rainfall amounts in excess of 7", which could lead
to minor to moderate flooding of low- lying, poor drainage, and
urban areas. Location, timing, and intensity of these bands has
been inconsistent between models and runs, and thus there`s
currently low confidence where or if it will materialize. General
model consensus puts the highest potential across the Okeechobee
and the Treasure Coast counties (and to the south). Development of
the east coast sea breeze, which will be dependent on breaks in
the clouds and showers in the afternoon, would greatly increase
the risk of these higher rainfall amounts along the Treasure
Coast.

As for the rest of the forecast, storms remain capable of
occasional cloud to ground lightning and gusty winds in addition
to the locally heavy rainfall. Afternoon highs mostly at or below
normal, albeit muggy, and the M-U80s. A few spots well to the
north could touch 90.

Thursday-Saturday...Finally seeing some better model agreement
late week into the beginning of the weekend. Invest 90L, in
whatever form it ends up at this point, should be well northeast
of east central Florida and continuing to pull away. In it`s wake,
the stationary front drops south across central Florida, keeping
the deep tropical moisture in place across much of the peninsula
and providing a focus for continued high rain chances. Daily PoPs
remain 70-90 pct area wide through at least Friday. Currently have
50-80 pct PoPs Saturday, pulled down by uncertainty as the ECM
and the GFS begin to diverge again. Global deterministic and
ensemble model guidance keeps widespread rainfall amounts through
Sunday morning similar to previous forecasts at 5-7" to the south
and 2-4" to the north. Going to stick with these values for now
given the low confidence of those higher rainfall amount from
Invest 90L.

Other storm threats continue to be occasional cloud to ground
lightning and gusty winds. Afternoon highs remain mostly at at or
below normal in the M-U80s, but will likely see a few more
northern spots hitting 90.

Sunday-Tuesday...Should finally start to see a change in the
pattern, but there continues to be uncertainty in timing. High
pressure over the CONUS building into the western Atlantic and
over Florida should eventually push the front to our south, and
the higher moisture to the south and east. The ECM is faster and a
little more aggressive, lowering rain chances as early as Sunday,
while the GFS is slower and a little more conservative, keeping
higher rain chances in the forecast until Tuesday. Either way,
there appears to be enough moisture in moderate onshore flow to
continue near normal rain chances into mid next week.
Temperatures start to creep back up but still around normal in the
U80s-L90s.

&&

.MARINE...
Issued at 502 AM EDT Wed Jun 12 2024

Today-Tonight...A stationary front remains draped across North
Florida, just north of the local Atlantic waters, with the ridge
of the Atlantic high suppressed well to the south. A weak low
pressure system (Invest 90L) will track slowly northeastward from
the Tampa Bay area across the peninsula, emerging off the east
coast between the Cape and Jacksonville late tonight to early
Thursday morning. Somewhat low confidence in the wind forecast as
weakening of the invest would reduce winds while development would
result in an increase. Assuming weakening, which is the most
likely scenario, S-SSW 15-20 kts south of the Cape should retreat
to the offshore waters this morning, where small craft should
continue to exercise caution, with winds generally at or becoming
10-15 kts across the rest of the waters. Winds could become light
and shift across the Volusia waters late tonight. Rounds of SCT-
NUM showers and SCT lightning storms continue, which could develop
bands across the local Atlantic waters, especially the Treasure
Coast waters. Seas 2-4 ft.

Thursday-Sunday...Invest 90L in some form departs to the
northeast, dropping the stationary front south across the waters
in its wake. Winds generally S-SW 5-10 kts become variable at
times through Saturday, then high pressure building off the Mid-
Atlantic seaboard pushes the front south and shifts winds back to
easterly. Seas 1-3 ft. High moisture and the frontal boundary will
continue high rain and storm chances.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  73  90  73  89 /  60  80  60  80
MCO  75  88  74  88 /  70  80  60  90
MLB  73  89  73  88 /  70  80  80  90
VRB  73  89  72  88 /  70  80  80  90
LEE  75  90  75  92 /  60  80  50  80
SFB  75  90  74  91 /  70  80  60  80
ORL  75  90  75  90 /  70  80  60  80
FPR  72  89  72  87 /  70  80  80  90

&&

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

$$

DISCUSSION...Law
AVIATION...Haley