Funnel Cloud in Florida, September 17, 2023

Area Forecast Discussion
National Weather Service Melbourne FL
239 PM EDT Sun Sep 17 2023

...New MARINE, AVIATION...

.DISCUSSION...

Key Messages:
- HIGH Risk of Life-Threatening Rip Currents Continues
- Incoming Swells Leading to Poor Boating Conditions Near Inlets
- Very Warm and Humid with Peak Heat Indices up to 105F this
  Afternoon

Current-Tonight...Temperatures in the L90s this afternoon and
combined with higher humidity will allow for peak heat indices to
approach 105F in many locations. Surface winds have veered toward
SW/W today, except SE near the coast where the ECSB has formed.
The WCSB will be most dominant tracking across the peninsula for
an eventual collision with its east coast counterpart late in the
day over the eastern peninsula. Shower and lightning storm
coverage will continue to increase into late afternoon/early
evening, eventually moving off of the coast. Storm steering flow
will be out of the WSW at 10-15 mph. Models continue to suggest
areas near Orlando southward and toward the east coast as the
highest threat locations for afternoon-evening convection.
Primary storm threats remain heavy downpours (minor flooding
possible), gusty winds to around 40-45 mph locally, and occasional
to frequent lightning strikes.

Moderate, long period NE swells continue to impact the surf
zone/beaches resulting in a HIGH risk of life-threatening rip
currents at all central FL Atlantic beaches. Swimmers are strongly
advised to stay out of the ocean.

Storms will push offshore around or shortly after sunset leading to
a quiet overnight as winds become light westerly and min temps
forecast in the M70s. Clouds will also thin through the night.
Ahead of sunrise Mon morning, light surface winds will veer more
NW/N due to another weak boundary sliding southward down the
peninsula (mainly near I-4 northward).

Previous Extended Forecast Discussion...

Monday-Tuesday...A mid-level trough will sweep northeastward across
the eastern US Monday into early Tuesday, with some continued weak,
localized troughing persisting through Tuesday. The associated
surface low will move northeastward toward the Mid-Atlantic on
Monday, with its attendant cold front sagging southward across the
Florida peninsula. The front will weaken into Tuesday, becoming
nearly stationary across central Florida. As a result of this setup,
scattered to numerous showers and storms will be possible both
Monday and Tuesday. Current guidance depicts some drying behind the
front, so some areas (mainly north of the I-4 corridor as of now)
could potentially see less coverage of showers and storms depending
on how far south the boundary sags on Tuesday. In general though,
plenty of moisture will be present for the development of showers
and storms out ahead of the boundary, with heavy rainfall continuing
to be the primary threat. Quick rainfall accumulations up to 3
inches will continue to be possible both Monday and Tuesday, which
could lead to localized flooding in areas that see slow storm
motions, multiple rounds of showers and storms, and in urban and low-
lying areas with poor drainage. Additionally, gusty winds and
lightning strikes will also be possible with storms. In a similar
fashion to previous days, activity is forecast to decrease across
the peninsula during the overnight hours, with some continued
development across the local Atlantic waters possible. Favorable
wind regimes could assist some showers and storms moving onshore
during the overnight hours. Afternoon highs will remain in the upper
80s to low 90s Monday and Tuesday, with overnight lows in the upper
60s to low 70s.

Wednesday-Saturday...Weak troughing aloft near the Ark-La-Tex region
on Wednesday will strengthen through late week as it shifts further
east, eventually becoming a cut-off low on Friday. This mid-level
low will then become almost stationary and strengthen, situated
across the Florida-Georgia region into the weekend. At the surface,
the aforementioned weak stationary boundary draped across the
peninsula will begin to move northward on Wednesday in response to
the mid-level troughing, leading to increasing moisture through the
end of the week. For now, the models are struggling to depict the
formation of a low until Friday. The Euro and GFS both are currently
indicating the development of a surface low off of the immediate
eastern Florida coast late Friday into Saturday, with the GFS being
the stronger solution of the two. While it is still far too early to
make any conclusions about the exact strength of this low, it will
result in higher moisture across the Florida peninsula along with
the potential for strong onshore winds, high surf and beach erosion.

The wet pattern across east central Florida will continue through
the end of this week, with PoPs generally 60 to 80 percent each
afternoon. Storm development will be possible, and the strongest
storms will likely be capable of producing heavy rainfall, gusty
winds, and lightning strikes. Activity will continue to follow a
similar pattern, with conditions generally improving during the
overnight hours across the peninsula. Isolated to scattered shower
activity will likely continue across the local Atlantic waters
overnight, possibly moving onshore in favorable wind regimes.
Afternoon temperatures will be close to climatological norms for
this time of year, generally in the 80s. Overnight lows in the upper
60s to low 70s.

&&

.MARINE...
Issued at 239 PM EDT Sun Sep 17 2023

Afternoon-Tonight...The weak frontal boundary formerly across
central FL has lifted north today veering winds to SSW/SW, though
the ECSB has backed winds S/SE along the coast where it has
formed. The pgrad remains fairly light with winds 7-12 kts and
perhaps a little stronger at times over the Gulf Stream. Late
day/evening showers and lightning storms will push off of the
coast with winds returning to SW/W tonight. Storm threats include
torrential downpours, gusty winds in excess of 35 kts, and cloud-
to-water lightning strikes.

The primary contribution to wave height remains a long period swell
of 5-7 ft at 12-13 sec. There is only a small wind wave component
associated. While the Small Craft Advisory expired at 14Z/10AM,
in favor of Cautionary Statements (SCEC) for the slowly subsiding
seas, buoy 41009 has continued to show some 6-7.5 ft seas. Will
continue the SCEC offshore as winds remain under 10 kts. Boaters
will still need to Exercise Caution near shore, as well,
especially for poor conditions at inlets during the outgoing tide
due to the incoming long period swell. Tonight, seas are forecast
to continue to subside to 3-5 ft near shore and 4-6 ft offshore,
but this remains a slow process.

Previous Extended Marine Forecast Discussion...

Monday-Thursday...Seas will remain 2 to 4 feet Monday through
Wednesday, with northwesterly winds around 10 knots on Monday
gradually veering to out of the northeast around 10 knots on Tuesday
and Wednesday. Thursday, easterly winds between 10 to 15 knots will
help seas build to 4 to 6 feet. A wet pattern will continue through
the period as a moist airmass remains in place across the local
Atlantic waters. Scattered to numerous showers and storms will be
possible through the period, with gusty winds, lightning strikes,
and locally higher seas being the main threats associated with the
strongest storms.

&&

.AVIATION...
(18Z TAFS)
Issued at 239 PM EDT Sun Sep 17 2023

VCTS at all terminals at the top of the 18Z package. W flow around 6-
8kt has delayed the development of the east coast seabreeze and will
keep it close to the coast as it attempts to slowly progress
westward this afternoon. Winds will back E at coastal terminals
behind the sea breeze. A sea breeze collision is expected across the
eastern peninsula this afternoon, and MVFR VIS/CIG tempos are
included at all coastal terminals around 20/21Z. Most convection
will diminish around sunset with VCSH lingering into the evening
along the Treasure Coast. Light winds will gradually veer overnight
becoming N after sunrise.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  90  73  86  74 /  60  50  20  10
MCO  92  76  90  73 /  70  20  50  20
MLB  91  75  89  76 /  70  50  60  30
VRB  92  74  89  75 /  70  40  70  40
LEE  91  74  90  71 /  60  20  20  10
SFB  91  75  89  72 /  60  30  30  10
ORL  92  76  90  74 /  70  30  40  20
FPR  92  74  90  75 /  70  50  70  40

&&

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

ALL FORECAST GRIDS...Sedlock
RADAR/IMPACT WEATHER....Leahy
AVIATION...Law

Hazardous Weather Outlook...Updated
National Weather Service Melbourne FL
1005 AM EDT Sun Sep 17 2023

AMZ550-552-555-570-572-575-FLZ041-044>046-053-058-141-144-154-159-
164-247-254-259-264-347-447-547-647-747-180000-
Flagler Beach to Volusia-Brevard County Line 0-20 nm-Volusia-
Brevard County Line to Sebastian Inlet 0-20 nm-
Sebastian Inlet to Jupiter Inlet 0-20 nm-Flagler Beach to Volusia-
Brevard County Line 20-60 nm-Volusia-
Brevard County Line to Sebastian Inlet 20-60 nm-
Sebastian Inlet to Jupiter Inlet 20-60 nm-Inland Volusia-
Northern Lake-Orange-Seminole-Osceola-Okeechobee-Coastal Volusia-
Southern Lake-Coastal Indian River-Coastal Saint Lucie-
Coastal Martin-Inland Northern Brevard-Inland Indian River-
Inland Saint Lucie-Inland Martin-Mainland Northern Brevard-
Northern Brevard Barrier Islands-Inland Southern Brevard-
Mainland Southern Brevard-Southern Brevard Barrier Islands-
1005 AM EDT Sun Sep 17 2023

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL FLORIDA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

.THUNDERSTORM IMPACT...
Deep moisture and a late day sea breeze collision over east
central Florida will produce a high coverage of showers and
lightning storms focused on the coastal counties mainly between
4pm and 8pm but could develop a little earlier along the Martin
coast. Stronger storms will be capable of producing wind gusts up
to 45 mph, frequent lightning strikes, and torrential downpours.
Move indoors to safety at the first sign of threatening skies, or
if you hear thunder.

.FLOOD IMPACT...
Storms will be capable of very heavy rain, accumulating up to 3
inches in an hour or two in localized areas. Rapid ponding of
water and temporary flooding of some roads and poor drainage areas
will be possible.

.EXCESSIVE HEAT IMPACT...
Afternoon peak heat index readings will reach 102 to 105. If engaged
in any outdoor activity, stay well hydrated and take indoor rest
breaks as needed, preferably in an air conditioned location. Protect
yourself from the sun by wearing sunscreen and a hat, especially
during the hottest part of the day.

.RIP CURRENT IMPACT...
A High Risk of numerous life-threatening rip currents continues at
all central Florida Atlantic beaches. Entering the ocean remains
strongly discouraged! Heed all warnings from the beach patrol.

.MARINE THUNDERSTORM GUST IMPACT...
Scattered lightning storms will move toward the east to northeast
at 10 to 15 knots and collide late in the day with the east coast
sea breeze just inland from the coast. Frequent lightning strikes
and wind gusts up to 40 knots may affect portions of the
intracoastal and nearshore Atlantic waters.

.WATERSPOUT IMPACT...
A brief waterspout or two will be possible over the Atlantic and
intracoastal waters.

.WIND AND SEA IMPACT...
Swells will produce seas 4 to 5 feet near the coast and up to 6 feet
offshore. Conditions will be poor near inlets, especially during the
outgoing tide. Small craft should continue Exercise Caution.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.
A Moderate to High risk of strong rip currents is forecast.

Above normal coverage of lightning storms is forecast. Heavy
rainfall, gusty winds and cloud to ground lightning strikes will
be the main storm threats.

Low pressure may form just east of Florida late this week which
could bring strong and gusty onshore winds, bands of heavy rain,
high surf and beach erosion to portions of east central Florida.

.SPOTTER INFORMATION STATEMENT...
Spotter activation will not be needed this afternoon and tonight.

Sedlock/Kelly

Preliminary Local Storm Report
National Weather Service Melbourne FL
656 PM EDT Sun Sep 17 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0641 PM     Tstm Wnd Gst     6 SSE Playalinda Beach  28.58N  80.58W
09/17/2023  M52 mph          Brevard            FL   Other Federal

            USSF tower 41 measured a thunderstorm wind gust of
            45kts/52mph.

&&

Event Number MLB2300623

ZTL