359
FXUS62 KMLB 130840
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
440 AM EDT Mon May 13 2024

...New DISCUSSION, AVIATION, MARINE, FIRE WEATHER...

.DISCUSSION...
Issued at 440 AM EDT Mon May 13 2024

Key Messages:

-Marginal Risk for a few strong to severe storms this afternoon and
 evening.

-Potential for strong to isolated severe storms will continue
 through mid-week.

-Unseasonably hot conditions Tuesday into late week, with highs in
 the 90s most days and peak heat index values rising to 100-105.

Today & Tonight...

Synoptic Overview:

A fairly amplified weather regime continues to affect the eastern
half of the U.S. A weak shortwave ridge axis is approaching Florida
this morning, out ahead of a stout subtropical jet segment along the
Northern Gulf Coast. To the west, an upper trough is slowly moving
across the High Plains. At the surface, high pressure is now moving
into the W Atlantic. As the high moves seaward, moisture will
continue to increase today as boundary layer flow veers toward the
SE. The ridge axis will essentially reside overhead this afternoon
and tonight, but the mid-level zonal flow will continue to increase
as the subtropical jet encroaches, exceeding the 90th percentile of
climatology at H5. Additionally, a weak perturbation is evident on
some guidance this afternoon, perhaps convectively enhanced from a
complex of storms off to our northwest. A robust sea breeze
circulation is forecast by hi-res guidance, with a collision
favoring the center of the peninsula.

Sensible Weather & Impacts:

Today...

We begin the week with an opportunity for some needed rain, but that
will come with a risk of storms. Despite relatively poor mid-level
lapse rates beneath the ridge, HREF members indicate sufficient
moisture (PW > 1.5") and instability (MLCAPE 750-1250 J/kg) for
convection to develop on the sea breeze collision this afternoon and
early evening. Combine the potential weak impulse aloft riding
through here at peak heating, and we have come up with increased
rain/storm chances, now at 40-60%. 0-6km shear increases to 40+KT,
and 0-3km helicity will approach 200 m^2/s^2. Thus, a few storms
could become strong to severe. There is at least a 5% risk of gusty
winds and large hail, with the SPC highlighting a Marginal (level 1
of 5) risk today. A tornado or two cannot be ruled out: much of the
helicity resides in the 0-3km layer, but boundary collisions could
introduce localized pockets of higher 0-1km helicity and surface
vorticity. Storms are forecast to develop after 2 PM over the
interior, with the mean flow aloft favoring storm motions back
toward the East Coast in the early evening. Frequent lightning is
expected, and anvils propagating toward the coast may cause strikes
well away from the storm cores.

It will be breezy this afternoon, especially on the coast with SE
gusts of 15-25 MPH. This will hold temperatures in check along the I-
95 corridor for one more day, with mid 80s at the coast warming to
the low 90s over the interior. Heat indices may approach 100F along
the Kissimmee Basin to Okeechobee.

Tonight...

Will hang onto a few showers and storms along the coast in the early-
mid evening hours before most areas dry out for the overnight
period. Fresh SE flow will begin to veer more SSE overnight, keeping
low temperatures above normal with low 70s over the interior and
mid/upper 70s on the barrier islands. Another ripple of energy in
the subtropical jet will fire off rounds of storms to our northwest
late tonight. A minority of CAMs suggest this activity could
approach Lake/Volusia counties overnight. Will handle this with a
20% storm chance after 5 AM in those areas.

Tuesday-Wednesday...Warm front will have lifted north of the area by
Tuesday morning, with another cold front moving into the southeast
U.S. into Tuesday/Tuesday night. This will lead to unseasonably hot
conditions with highs into the low to mid 90s over much of the area,
and peak heat index values up to 100-105. Breezy S/SW flow will
develop into Tuesday afternoon, and should the east coast sea breeze
be able to develop, it will likely remain stalled near the coast
with the slight offshore component in the low level winds. A moist
airmass will remain in place across the area, with PW values around
1.7 to 1.9 inches. This should be sufficient for at least scattered
showers and storms to develop, especially into the afternoon, with
PoPs around 40-50 percent for much of the area.

However, some of the CAM guidance also showing a band of showers and
storms from MCS pushing through north FL into northern portions of
east central FL. The HRRR is currently an outlier showing a much
faster arrival of this system into early Tuesday morning. Therefore,
there remains some uncertainty with overall evolution of convection
into Tuesday. Strong to isolated severe storms will be possible
regardless, especially near to north of Orlando where 850-700mb W/SW
flow will be a little stronger up to 30-40 knots. However, late day
interactions with the east coast sea breeze may enhance convection
along the coast before it shifts offshore. SPC for now has extended
the Marginal Risk for severe weather southward into Lake, Volusia
and Seminole counties for Tuesday.

The weakening front will eventually settle and stall across northern
portions of east central FL into Wednesday/Wednesday night.
Additional showers and storms may develop ahead of this front
later into Tuesday night/early Wednesday, especially near to north
of Orlando. Then expecting increasing coverage of convection
through the day. Highest rain chances, around 60 percent will
reside across Osceola/Brevard counties northward, closer to the
front and where greatest moisture will reside, and 50 percent to
the south. Strong to isolated severe storms will again be possible
as elevated westerly flow (around 30- 40 knots from 925-700mb)
and cooler temps aloft (-10 to -11C at 500mb) will produce a
threat of strong to locally damaging winds and coin-sized hail
with any storms that form. SPC has a Marginal Risk for severe
weather across much of central FL. Greater cloud cover and
potential earlier start to showers and storms across north central
FL will keep highs limited to the upper 80s/low 90s, but hot and
muggy conditions expected to continue for Okeechobee County and
the Treasure Coast where max temps are forecast to reach the mid
90s with peak heat index values closer to 104-108 (nearing Heat
Advisory thresholds).

Thursday-Sunday...Greatest moisture begins to focus across southern
portions of east central FL south of stalled front across the region
into Thursday. Scattered showers and storms will still be possible,
especially into the afternoon near to south of Orlando where PoPs
will range from 30-50 percent. Then as front and deeper moisture
lift back north into late week, potential for scattered afternoon
showers and storms return area-wide, with chance PoPs (30-50
percent) across all of east central Florida Friday and into the
weekend. Hot conditions continue through the period, with highs into
the 90s and humid conditions producing peak heat index values around
100-105 each afternoon.

&&

.AVIATION...
(06Z TAFs)
Issued at 440 AM EDT Mon May 13 2024

Quiet weather is forecast through 18Z, with SE winds increasing to
10-15 KT this morning. For the coastal terminals, gusts to 18-24 KT
are expected after 14Z. Scattered storms are then expected to
develop, with 40-60% coverage around Greater Orlando from 13/20Z-
14/00Z. This activity will tend to propagate toward the East Coast
terminals after 21Z through around 14/02Z. Attempted to capture this
timing in the TAFs. One or two storms could be strong to severe in
the late afternoon/early evening.

&&

.MARINE...
Issued at 440 AM EDT Mon May 13 2024

Today-Tonight...High pressure pushes offshore today as a weather
disturbance moves into the Red River Valley. In response,
southeast winds freshen over the marine area to 15-20 KT this
afternoon and tonight. Small craft will need to exercise caution
this afternoon across much of the local Atlantic; a Small Craft
Advisory will go into effect for winds around 20 KT beyond 20 NM
after 8 PM. Seas build to 3-4 FT this afternoon and tonight, with
short periods contributing an enhanced chop. Scattered storms over
the mainland will attempt to push toward the coast this evening.
In so doing, offshore-moving storms with erratic/gusty winds and
lightning could affect the coastal waters from 5 PM to 10 PM this
evening. The highest chance of this activity is north of Sebastian
Inlet. Otherwise, Intracoastal and inshore waters will be choppy
at times through the next 24 HR.

Tuesday-Friday...Poor to hazardous boating conditions will persist
across the waters into Tuesday/Tuesday night as S/SE flow of 15-25
knots veers to the S/SW into the evening. Seas will be choppy with a
dominant period of 5-6 seconds and wave heights up to 4 to 6 feet
offshore. A Small Craft Advisory will continue for the offshore
waters through late Tuesday night, and may have to consider
expanding to at least the nearshore waters of the Treasure Coast for
Tuesday afternoon into Tuesday night.

Poor boating conditions look to persist offshore for much of
Wednesday into Wednesday night as offshore flow remains up to 15-20
knots. However, more favorable boating conditions expected into late
week as winds diminish into Thursday morning before becoming onshore
late in the day and veering to the S/SE into Friday, with speeds
around 5-10 knots. Seas 3-5 feet on Wednesday fall to 2-4 feet
Thursday and 1-2 feet on Friday.

Scattered offshore moving storms will be possible each day,
especially during the afternoon and evening hours, with some strong
to isolated severe storms possible on Tuesday and Wednesday.

&&

.FIRE WEATHER...
Issued at 440 AM EDT Mon May 13 2024

Today-Tonight...SE winds increase to 10-15 MPH, with gusts to 25
MPH along the coast. This will feed more moisture into the area,
with afternoon RH readings only falling to 45-50% along the
Kissimmee Basin (higher elsewhere). Scattered storms are forecast
to develop in the afternoon and evening hours. Frequent lightning
strikes are possible with this activity with erratic/gusty winds
beneath them. Some areas will get needed wetting rains today, with
rain coverage at 40-60%.

Tuesday-Friday...Increasing moisture will keep Min RH values above
critical values through the work week, but unseasonably hot
conditions with highs in the 90s will at times lead to RH values as
low as the low to mid 40s over the interior during the afternoon
hours. Isolated to scattered showers and storms will continue each
day, with some strong to isolated severe storms possible on Tuesday
and Wednesday. Winds will be breezy out of the S/SW on Tuesday and
out of the W/SW on Wednesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  85  72  92  74 /  50  50  60  40
MCO  89  73  94  75 /  60  40  50  30
MLB  85  75  91  74 /  50  40  50  20
VRB  87  74  93  73 /  40  40  40  20
LEE  90  74  92  76 /  60  30  50  40
SFB  89  73  94  75 /  50  50  50  30
ORL  90  73  95  76 /  60  40  50  30
FPR  87  74  94  72 /  40  40  40  20

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory from 8 PM this evening to 4 AM EDT
     Wednesday for AMZ570-572-575.

&&

$$

SHORT TERM...Heil
LONG TERM...Weitlich
AVIATION...Heil