586
FXUS62 KMLB 111454
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
1054 AM EDT Tue Jun 11 2024

...New UPDATE, MARINE...

.UPDATE...
Issued at 1054 AM EDT Tue Jun 11 2024

A moist airmass already in place across central Florida this
morning, with morning soundings at XMR/TBW showing PW values
around 2.1-2.2". PW values will continue to increase through the
day, as S/SW flow continues to transport deep tropical moisture
northeastward across the region. Convective coverage is isolated
to scattered this morning, but some breaks in the cloud cover
should ramp up shower and storm coverage through the remainder of
the day, with high rain chances in place (PoPs 80-90%).

Forecast rainfall totals for today into tonight range from 1-2"
to the north to 2-3" to the south, with locally higher amounts of
4" or higher possible, especially in any repeated rounds of
showers and storms through this afternoon and evening. This could
produce minor flooding in low-lying, poor drainage, and urban
areas. Additional storm threats will include lightning strikes
and gusty winds up to 40 to 45 mph as low level southerly winds
increase through this afternoon. This may also lead to breezy
conditions along the coast from the Cape southward, with sustained
speeds to 15 to 20 mph and gusts up to 25 to 30 mph possible this
afternoon.

Cloud cover and increasing rainfall coverage should hold max temps
in the mid to upper 80s over much of the area, which are values
that are near to below normal for this time of year. Still, it
will be warm and muggy as dewpoints remain in the mid to upper
70s.

&&

.MARINE...
Issued at 1054 AM EDT Tue Jun 11 2024

Increased wind speeds, especially for the nearshore waters, as
low level southerly flow will be on the rise through this
afternoon, and should lead to sustained winds of 15-20 knots over
much of the waters. Small craft exercise caution headlines are
now in place for this afternoon across all waters, except
nearshore Volusia. These southerly winds will remain elevated into
tonight, and will have to monitor for any potential short fused
upgrades to a Small Craft Advisory should winds come in a little
stronger than forecast. Seas will build from 2-3 feet this morning
to 3-5 feet tonight.

&&

.PREVIOUS DISCUSSION...
Issued at 525 AM EDT Tue Jun 11 2024

Today-Tonight...Atlantic ridge axis remains suppressed well to
the south across the Caribbean, while to the north the stationary
front meanders north and south a bit over North Florida. A weak
surface disturbance forming along the boundary over or just
offshore of Northeast Florida will tighten the pressure gradient
across the area, building SW-S winds a bit to 10-15 mph with some
gusts to 20 mph this afternoon. All the rain and cloud cover will
prevent any meaningful development of the sea breeze, and keep
temperatures at or below normal, generally in the M-U80s. While
less hot, the very high humidity keep heat indices in the 90s.

No significant change in rain chances and amounts since the
afternoon forecast. PoPs 40-60 pct this morning increase to 70-90
pct this afternoon, then back off to 30-50 pct tonight, with the
higher chances to the south. This results in a NW-SE oriented QPF
gradient across the area ranging from 1-2" to the north to 2-3" to
the south, with locally higher amounts of 4" or more possible
where repeated rounds of heavy showers and storms setup. Long and
skinny thermodynamic profiles characteristic of these high
rainfall events show enough CAPE for occasional cloud to ground
lightning, and 850mb winds 30-40 kts could lead to surface gusts
up to 40 mph in heavier precipitation, but the primary storm
hazard will be heavy rain. Any heavy showers or storms that become
slow/stationary, like the one yesterday that produced 2-3" of
rainfall in the eastern Orlando/Sanford metro and over 5" in the
rural areas to the east, could produce minor flooding in low-
lying, poor drainage, and urban areas. The antecedent dry
conditions mean the ground will be able to handle this kind of
rainfall for a time, especially if given a quiet period to soak
in, but repeated rounds will eventually lead to more impactful and
persistent flooding.

Wednesday-Friday...The surface disturbance/low near Northeast
Florida is forecast to continue developing as is pushes
northeastward into the western Atlantic. The ECM is the faster
solution, developing a closed low by Wednesday morning, while the
GFS lags behind by about 24 hours. The ECM then gives up on the
low, absorbing it into another weak frontal boundary approaching
the eastern seaboard, while the GFS further deepens the low as it
tracks northeast. The ECM solution would result in a further
lowering of rain chances and QPF across the north half of ECFL
than currently advertised as early as Wednesday, while the tighter
pressure gradient across Florida between the low and the Atlantic
high advertised by the GFS would continue to transport the deep
tropical moisture across Florida and continue high rain chances,
especially to the south. Thus far the GFS has been performing
better, so going to keep the forecast leaned towards that solution
for now, calling for high rain chances with continued rounds of
showers and lightning storms, including during the overnight
hours. Daily rainfall amounts of 1-3" with locally higher amounts
of 4" remain possible, with event totals reaching 2-3" up north
and 3-4" down south by Saturday morning. Occasional cloud to
ground lightning and gusty winds will also remain possible with
storms. Afternoon highs remain at or below normal but muggy in the
M-U80s.

Saturday-Monday...Model agreement might be a little better early
this morning than previous days, but there`s still enough
variation between models and runs to keep forecast confidence low.
GFS continues to be much more aggressive with development of the
low pressure system ejecting northeast off the Mid-Atlantic
seaboard at this point, and a wave/disturbance/low forming in the
Gulf of Mexico over the weekend (the organization and location of
this feature changes from run-to-run). On the other hand, the ECM
kills the low in the western Atlantic, and barely develops a wave
in the Gulf. As a result, the GFS now continues rain chances for
Florida while the ECM becomes drier, a flip-flop form this time
yesterday. Given the low confidence, went with a blend that
continues to favor the GFS given its aforementioned performance,
keeping relatively high rain chances and near to below normal
temperatures through the weekend and into next week, until a
clearer picture comes into view.

&&

.AVIATION...
(12Z TAFs)
Issued at 733 AM EDT Tue Jun 11 2024

VFR conditions become MVFR generally after 15z with increasing
SHRA/TSRA at the sites thru 21z. Hi-res guidance suggests rain
chances decreasing north to south 00z and beyond with VCSH left
behind. IFR CIG/VIS are possible among heavier SHRA/TSRA. Winds
10-12 kt may gust up to 20 kt outside of convection, gradually
veering S after 21z. Continued lower confidence in SHRA after 03z,
though the highest chances remain MLB south.

&&

.MARINE...
Issued at 525 AM EDT Tue Jun 11 2024

Today-Tonight...Winds and seas generally favorable for boating
close to shore, but SCT-NUM offshore moving showers and SCT
lightning storms are expected through the period. Small craft
should exercise caution offshore later this afternoon and
overnight as conditions become poor due to increasing winds and
building seas. Ridge axis of the Atlantic high remains suppressed
well to the south across the Caribbean, with a stationary front
draped across north Florida and into the adjacent Atlantic waters,
producing SW-SSW winds 10-15 kts through the early afternoon. A
surface disturbance slowly forming near/offshore Jacksonville will
tighten the pressure gradient, shifting winds to the SSW-S and
increasing to 15-20 kts across the offshore waters from the late
afternoon and through the overnight. Seas 1-3 ft this morning
increase to 3-5 ft, occasionally up to 6 ft in the Gulf Stream.

Wednesday-Saturday...Subtle shifts in the position of the Atlantic
ridge axis and a bit of uncertainty in the development of the
disturbance/low pressure system off the southeastern seaboard
decrease confidence in the surface wind forecast. Winds should
generally remain Srly at 5-15 kts after they settle Wednesday
afternoon, but how far SWrly or SErly winds become, and further
increases to 15-20 kts, will depend on evolution of the
aforementioned features. Better confidence the period will remain
wet with SCT-NUM showers and SCT lightning storms moving offshore,
and that while conditions could become poor, the should remain
below advisory levels. Seas 2-4 ft Wednesday-Thursday settle to
1-3 ft Friday-Saturday.

&&

.FIRE WEATHER...
Issued at 525 AM EDT Tue Jun 11 2024

Increased moisture and shower and storm chances, as well as
greater cloud cover will lead to near to below normal highs in the
mid to upper 80s through the remainder of the week. This will keep
Min RH values well above critical levels. Improvement of drought
conditions will also occur across areas that receive heavier
rainfall. Main concern from storms will be lightning strikes that
may be able to start new fires, and gusty winds that could lead to
control issues from any existing brush fires.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  87  73  87  73 /  80  60  80  60
MCO  84  74  86  74 /  90  70  90  70
MLB  85  74  85  74 /  90  80  90  70
VRB  85  73  86  73 /  90  80  90  80
LEE  87  76  89  75 /  80  60  80  60
SFB  86  74  88  74 /  80  60  80  60
ORL  84  75  87  75 /  90  60  90  60
FPR  84  73  86  73 /  90  80  90  80

&&

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

$$

UPDATE...Weitlich
AVIATION...Schaper