676
FXUS62 KMLB 171804
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
204 PM EDT Tue Sep 17 2024

...New AVIATION, PREVIOUS DISCUSSION...

.AVIATION...
(18Z TAFs)
Issued at 204 PM EDT Tue Sep 17 2024

VFR conditions are forecast outside of showers/storms. Scattered showers
and lightning storms are forecast into the PM. VCTS begins between
19-20Z with TEMPO TSRA groups between 20-24Z (except for KLEE/KDAB/KTIX).
Isolated generally ENE moving storms over ECFL will be capable of
wind gusts up to 50-60mph. Light and variable winds are forecast
to become ESE into the afternoons/evenings at 5-10kts.

&&

.UPDATE...
Issued at 1040 AM EDT Tue Sep 17 2024

Temperatures are quickly warming this morning into the 80s, on the
way to the 90 degree mark this afternoon. Mid level clouds remain
over the area, predominantly across the Treasure Coast. An
increase in low/mid level cumulus is expected over the next
several hours, spreading from south to north. Residual MLCIN over
the north-central portion of the area, as outlined by RAP
analysis and near-term modeling, suggests that the area to first
see convective initiation will be from Titusville southward this
afternoon. 13z HRRR guidance shows this fairly well, with
convection spreading from south to north into the early evening
hours.

Steep low level lapse rates, DCAPE around 1000 J/kg, and
20-25 kt of sfc-6km shear will support a few strong storms,
capable of producing strong to damaging wind gusts. 500mb temps
are expected to stay around -6C to -7C, as already evidenced by
the 10z XMR sounding. While the threat is very low, some small
hail with the most intense updrafts cannot be completely ruled
out. As the east coast sea breeze tries to push inland, especially
farther south where it may struggle a bit more, local backing of
winds in the lowest 0.5km could support weakly rotating storms.
While the threat for a tornado is very low, storm and outflow
boundary collisions (especially along a lingering surface front
from the Treasure Coast to the Orlando metro) may briefly enhance
low-level shear.

Rain chances will be highest for locations south of I-4 through
most of the afternoon (coverage scattered at most), though a few
storms could develop by early evening as far north as Lake and
Volusia counties due to outflow and sea breeze collisions. Most
activity will be on a downward trend after dark, eventually
shifting toward the Atlantic waters.

&&

.PREVIOUS DISCUSSION...
Issued at 451 AM EDT Tue Sep 17 2024

Key Messages:

- A marginal risk for isolated severe storms exists across all of
east central Florida today.

- Poor to hazardous boating and surf conditions continue today.

- High astronomical tides will promote elevated water levels this
week, and a Coastal Flood Advisory continues through at least
tonight.

Current-Tonight... High cloud cover is in place across much of east
central Florida this morning while observing stations indicate
localized areas of lower stratus. Patchy fog remains forecast across
the interior, hinting at visibility reductions where clouds lower. A
few showers continue in vicinity of Lake Okeechobee while lightning
has remained over the local Atlantic waters.

A weak surface boundary across the southern half of the peninsula
gradually lifts northward late today into tonight. Aloft, a mid
level shortwave swings across the area. Scattered diurnal showers
and storms are forecast as surface heating and boundary interactions
occur. Model soundings suggest steep low level lapse rates this
afternoon which will be supportive of quick strengthening storm
updrafts. An isolated marginal threat exists where updrafts can
interact with dry air and shortwave energy aloft. However, it is
worth noting some uncertainty in the forecast. Continued broken
cloud cover and occasional light showers are forecast to continue
across the south where the greatest moisture exists. This could
delay or limit surface heating where CAMs generally suggest the
greatest convective coverage should occur. An isolated severe storm
which can develop will be capable of localized damaging wind gusts
up to 60 mph, frequent lightning strikes, and torrential downpours.
Westerly steering flow will push convective coverage back towards
the coast late this afternoon and into the evening.

Hazardous beach and coastal conditions continue today. Long period
swells around 9-10 seconds will promote a a high risk of life
threatening rip currents at all area beaches. Additionally,
astronomical high tides will continue a minor coastal flood threat
through at least this evening`s high tide cycle.

High temperatures remain near seasonal in the upper 80s to low 90s.
Peak heat index values are forecast between 98-105.

Wednesday-Thursday... Mid level low pressure across the southeast
U.S. becomes an open trough into Thursday. A surface boundary
continues to lift northward Wednesday, shifting back southward
across the area on Thursday. Local boundary interactions and pulses
of shortwave energy aloft should support scattered afternoon and
evening convection (40-50%) across much of east central Florida each
day. Slightly higher coverage of showers and storms (~60%) is
forecast across Okeechobee and the Treasure Coast in vicinity of
higher moisture. Westward steering flow should allow inland
convection to push back toward the coast each evening. Dry air aloft
could promote isolated wind gusts up to 50 mph where stronger
convective mixing can occur. Otherwise, hazards associated with
isolated stronger storms include occasional to frequent lightning
strikes and locally heavy downpours. Temperatures mostly in the low
90s Wednesday fall a few degrees cooler on Thursday, ranging the
upper 80s to near 90. Peak heat index values are forecast between
98-103 degrees.

Friday-Monday...A 500mb vorticity boundary slides southeastward
across the state late week as mid level troughing moves offshore the
eastern seaboard. A surface boundary settles across south Florida as
high pressure builds across the southeast U.S. The greatest moisture
remains southward late week into early next week. However, scattered
PoPs remain in the forecast each day as sustained onshore flow
develops. Seasonal temperatures are forecast each afternoon ranging
the upper 80s to near 90.

&&

.MARINE...
Issued at 451 AM EDT Tue Sep 17 2024

Today-Tonight...Hazardous seas up to 7 ft offshore gradually subside
through late morning, and a Small Craft Advisory remains in effect
through 11 AM. Otherwise, small craft should exercise caution this
morning for seas up to 6 ft across nearshore Brevard and the nearshore
Treasure Coast. Seas become widely 4-5 ft late tonight. Winds
remain light and variable, developing an onshore component near
the coast as the sea breeze develops. Scattered offshore moving
showers and storms are forecast into the afternoon and evening. An
isolated severe storm will be possible, producing wind gusts up
to 34 kts.

Wednesday-Saturday...Seas continue to subside Wednesday becoming 3-4
ft. Winds remain light and variable before becoming onshore into
late week. Scattered to numerous showers and scattered lightning
storms are forecast through the period.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  73  91  73  89 /  10  40  30  30
MCO  75  92  74  91 /  20  50  20  50
MLB  75  90  75  89 /  30  50  50  50
VRB  73  91  74  90 /  30  50  40  60
LEE  74  91  74  90 /  10  40  10  40
SFB  73  91  73  90 /  20  50  20  50
ORL  75  92  75  91 /  20  50  20  50
FPR  73  91  74  90 /  30  50  40  60

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Advisory until midnight EDT tonight for FLZ141-154-
     159-164-347-447-647-747.

AM...None.
&&

$$

UPDATE...Schaper
AVIATION...Fehling