164
FXUS62 KMLB 181443
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
1043 AM EDT Wed Sep 18 2024

...New UPDATE...

.UPDATE...
Issued at 1040 AM EDT Wed Sep 18 2024

We are off to a quiet start this morning with temperatures
climbing into the mid 80s under mostly clear conditions. Not a
whole lot has changed in this update from the early morning
forecast. A slightly more dominant west coast sea breeze today
will help fuel shower and lightning storm development this
afternoon. Storm motions will be generally from west to east as a
result. By the time some of this activity reaches the coast early
in the evening, a collision with the east coast sea breeze will
provide another focus for lightning storms through midnight. The
strongest activity will be capable of gusty winds around 50 mph,
frequent lightning strikes, and locally heavy rainfall. Hi-res
guidance today compared to yesterday indicates lower bulk shear
values, though storm-scale boundary collisions along a locally
backed coastal breeze this afternoon/evening could allow a couple
of storms to weakly rotate.

Outside of the storm potential later on, temperatures are still
forecast to push into the low 90s for most, pushing heat indices
into the 100-105 degree range. Also, a high risk for life-
threatening rip currents remains at area beaches.

&&

.PREVIOUS DISCUSSION...
Issued at 422 AM EDT Wed Sep 18 2024

Key Messages:

- Scattered showers and storms increase in coverage along the coast
late this afternoon and into the evening.

- A high risk of rip currents continues at all area beaches.

- High astronomical tides promote elevated water levels this week,
a Coastal Flood Advisory continues.

Current-Tonight... Quiet and calm early this morning under mostly
clear skies. Clear skies are expected to continue into late morning,
initiating early surface heating. GOES-16 precipitable water
analysis indicates a modest moisture column (~ 1.6-1.8") while
surface dew points are observed in the mid 70s. Scattered showers
and storms are forecast across much of the area into the afternoon
as the east coast sea breeze develops and mesoscale boundary
collisions occur. CAMs key in on the greatest coverage (~60%)
occurring in vicinity of the I-95 corridor late in the afternoon and
into the evening as storms push back towards the coast. Coverage
then dissipates or moves offshore into the late evening. Model
soundings indicate drier air above 700mb, and DCAPE values of
1,000-1,200 J/Kg suggest the potential for localized wind gusts
of 40-50 mph where an updraft can sustain itself and dry air
mixing can occur. Otherwise, storm hazards include occasional to
frequent lightning strikes and locally heavy rainfall. High
temperatures are forecast to range the low 90s with peak heat
index values between 100-105.

A high risk of life threatening rip currents continues at area
beaches today. This evening`s high tide cycle is forecast near
minor flood stage and the Coastal Flood Advisory continues.

Thursday-Friday... Mid level troughing and associated vorticity
pulses slide southeastward across the state. A weak surface boundary
settles near the Florida Straits on Friday. Diurnal showers and
storms are forecast, and a gradient of dry air will keep the highest
coverage across the south each day (~60%). Continued dry air
advection will cut down PoPs along and north of the I-4 corridor
on Friday (~20-30%). Westerly steering flow continues on Thursday,
becoming light and variable into late week. Primary storm hazards
include occasional to frequent lightning strikes, wind gusts of
40-50 mph, and locally heavy rainfall. High temperatures range
the upper 80s to lower 90s each afternoon. Minor coastal flooding
concerns are expected to continue, focused around each high tide
cycle.

Saturday-Tuesday... Ridging across the central U.S. flattens as a
500mb cutoff low progresses eastward. Troughing along the eastern
U.S. coast is nudged further seaward. High pressure builds at the
surface and northeast flow develops locally. A moisture boundary
remains in place across the Florida Straits with dry air
situated to its north. Onshore flow should provide enough low
level moisture to support isolated to scattered showers each
afternoon. High temperatures are forecast to range the upper 80s.

&&

.MARINE...
Issued at 422 AM EDT Wed Sep 18 2024

Today-Tonight...Favorable boating conditions return as seas
subside to 3-4 ft. Light and variable winds become onshore near
the coast as the east coast seabreeze develops. Coverage of
offshore moving lightning storms increases late this afternoon and
into the evening (40-60%).

Thursday-Sunday...Seas of 3-4 ft continue. A weak pressure
gradient will continue to promote light and variable winds on
Thursday. Winds become northeast Friday and into the weekend as a
surface boundary moves south of the local waters. Showers and
storms decrease in coverage by the weekend.

&&

.AVIATION...
(12Z TAFs)
Issued at 725 AM EDT Wed Sep 18 2024

VFR conditions prevailing outside of convection. Westerly winds
this morning will veer onshore with the development of the east
coast sea breeze around 16-18Z. The sea breeze will then push
inland this afternoon, reaching MCO/ISM by late afternoon. The sea
breeze is not currently forecast to make it to LEE. Scattered to
numerous showers and storms are expected today, mainly after 20Z.
TEMPOs have been included for all sites except LEE, with storms
forecast to linger along the coast through around 01Z. Lightning
strikes, gusty winds to around 45 kts, and locally heavy rainfall
will be possible. Convection will diminish after sunset, as will
winds. Light and variable flow overnight.

&&

.HYDROLOGY...
Issued at 422 AM EDT Wed Sep 18 2024

The Saint Johns River at Astor is forecast to remain in Moderate
Flood stage through the weekend and into early next week. The
potential exists for small additional rises if locally heavy
rainfall develops over the river basin. Farther upstream, a slow
and steady rise of the Saint Johns at Deland, Sanford, and Geneva
is expected to continue, so interests along the river should
monitor for future forecast updates.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  91  73  90  73 /  60  50  40  10
MCO  92  74  91  73 /  40  30  50  20
MLB  90  73  89  74 /  50  60  50  50
VRB  91  73  90  72 /  50  60  60  50
LEE  91  74  90  73 /  30  20  40  10
SFB  91  73  91  73 /  50  30  50  10
ORL  92  75  92  75 /  40  30  50  20
FPR  91  73  90  72 /  50  50  60  50

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Advisory until 2 PM EDT Friday for FLZ141-154-159-
     164-347-447-647-747.

AM...None.
&&

$$

UPDATE...Schaper
AVIATION...Leahy