915
FXUS62 KMLB 132035
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
435 PM EDT Fri Sep 13 2024

...New DISCUSSION, MARINE, HYDROLOGY...

.DISCUSSION...
Issued at 434 PM EDT Fri Sep 13 2024

- High coverage of showers and storms capable of heavy rainfall,
  occasional to frequent lightning, and gusty winds through
  Saturday

- Remaining very warm and humid this weekend with heat index
  values up to 102-107+

- Saint Johns River at Astor forecast to remain in Moderate Flood
  through early next week

Currently-Tonight... Local radar imagery shows numerous showers
and scattered lighting storms over west Florida moving east-
northeast. Isolated showers and lightning storms are also developing
over Brevard to Martin counties along the east coast sea breeze
as it moves inland. Analysis charts show a surface trough to the
northeast of the Florida coast with a stationary boundary over
north-central Florida. Additionally, a weak upper level
shortwave is located over the northeast Gulf of Mexico and
northern Florida where there are widespread showers and scattered
lightning storms moving east-northeast. Temperatures are
generally in the mid 80s to mid 90s across east central Florida
(except cooler where it has recently rained) with heat index
values up to 102-108 (mainly across south central Florida). A Heat
Advisory is in effect until 6 PM for Okeechobee, St. Lucie, and
Martin counties. This level of heat can affect anyone without
adequate precautions. It is recommended to take frequent breaks
from the heat and stay hydrated, especially if spending extended
periods of time outdoors this afternoon.

Scattered to numerous showers (PoPs ~ 50-60%) and scattered
lightning storms are forecast to develop into this evening as
interactions occur between the sea breezes and outflow from
previous storms. Rain and storm chances gradually diminish after
sunset (PoPs ~ 20-40%) before ending over land around midnight. The
main hazards will be heavy rainfall, occasional to frequent
lightning, and wind gusts up to 30-45mph. Rainfall amounts of 1-3"
(locally up to 4-5") will have the potential to produce minor
flooding of urban, low-lying, and poor drainage areas due to
already saturated soils. Low temperatures in the low to upper
70s with partly to mostly cloudy skies are forecast overnight.

Saturday- Scattered to numerous showers (PoPs ~ 60-70%) and
scattered lightning storms are forecast to develop into the
afternoon and evening as interactions occur between sea breezes
and outflow from previous storms. Coverage of showers and storms
are expected to increase as the west coast sea breeze pushes
inland and west- northwest winds veer onshore along the east
central Florida coast with the east coast sea breeze Saturday
afternoon into the evening. Rain and lightning storms chances
decrease Sunday with drier air expected over east central Florida
as the aforementioned trough moves northeast away from the north .
The main hazards will be heavy rainfall, occasional to frequent
lightning, and wind gusts up to 30-40mph. Rainfall amounts of 1-3"
(locally up to 4") will have the potential to produce minor
flooding of urban, low- lying, and poor drainage areas due to
already saturated soils. Afternoon highs in the upper 80s to low
90s are forecast with heat index values generally up to 100-107,
as well as a Moderate HeatRisk. This level of heat affects most
individuals who are sensitive to heat.

Sunday-Thursday (modified previous discussion)... Drier air is
expected to slowly filter over east central Florida as the
aforementioned surface trough strengthens and moves northeast
away from the northeast Florida coast into early next week. The
low is forecast to gradually push northward into the Carolinas and
mid Atlc States Monday into Tuesday. Drier air over the GoMex
early in the period will gradually build into the FL peninsula
slowly promoting lower values of PWAT. Storm steering flow should
remain WRLY for much of the period. Aloft, an unsettled pattern
develops with troughiness across the Deep South and southeast U.S.
with this messy pattern pushing into the FL peninsula Sun
overnight- Tue, then much of this activity lifts north along the
Atlc Seaboard. Have opted for 40-50pct PoPs thru the extended.
With any luck, there will be a lower coverage each day, thus
allowing already saturated basins to slowly recover from all of
the recent heavy rainfall. Afternoon highs in the U80s to around
90F each day, with overnight mins in the L-M70s, except U70s along
the immediate Space/Treasure coasts.

&&

.MARINE...
Issued at 434 PM EDT Fri Sep 13 2024

Currently-Tonight...  Scattered generally offshore moving showers
and lightning storms are forecast this evening with a surface
trough to the east-northeast of the local waters. The main
hazards will be occasional to frequent lightning, wind gusts up
to 30-45mph, and heavy rainfall. West-northwest winds at 6-12kts
with seas up to 2-3ft nearshore and up to 4ft over the Gulf Stream
are forecast.

Saturday-Tuesday (modified previous discussion)... A weak surface
boundary lingers across the region for a couple more days with
deep moisture in place and elevated shower and lightning storm
chances, before some drier air moves into the area Sunday into next
week with lower coverage of showers and storms expected. Offshore
moving showers/storms across the local waters are forecast each
day. There should be ECSB formation today thru the weekend as
light NNE/NE winds develop in the afternoon. Winds speeds AOB 15
kts (outside of convection) thru this weekend and into next week.
Seas 3-4 ft nearshore and 4-5 ft offshore to begin the day, with
wave heights subsiding to AOB 3 ft later tonight thru early Sunday
morning. Due to increasing swells seas are forecast to build,
once again, Sun thru early next week, reaching 6 ft offshore Sun
aftn - possibly 6-7 ft thru Mon before subsiding, again, Mon
night-Tue. Seas during this time may build 4-6 ft near shore (late
Sun into Mon).

&&

.HYDROLOGY...
Issued at 434 PM EDT Fri Sep 13 2024

The Saint Johns River near Astor is forecast to remain in Moderate
Flood (around 3.1-3.3 ft) through early next week. The potential
exists for small additional rises if locally heavy rainfall
develops over the river basin.

Additional rises are forecast for points farther south along the
Saint Johns River, such as Deland, Sanford, and Geneva (Above Lake
Harney) where Action Stage is forecast this weekend.

&&

.AVIATION...
(18Z TAFs)
Issued at 120 PM EDT Fri Sep 13 2024

Showers starting to pop up across east central Florida this
afternoon, with VCTS forecast to begin after 19Z at the
terminals. TEMPOs for VIS and CIG reductions due to TSRA generally
between 19-23Z at all terminals except for DAB. Confidence in
these TEMPOs has decreased a bit, as guidance is not overly
aggressive on coverage through the remainder of the afternoon and
we have started to become clouded over across portions of east
central Florida, which would potentially help limit convection.
However, decided to keep them in for now and will amend as needed.
Activity is expected to diminish into the overnight hours beyond
00Z, with winds becoming light and variable. Some guidance is
hinting at potential VIS reductions overnight at LEE, but
confidence in this was not high enough to include it with this
package. Will reassess with future TAF packages. Northwest flow
will pick up after 15Z across the interior terminals, with some
indication of VCSH across the interior around this time. Winds out
of the Northeast along the coast after 16Z as the east coast sea
breeze begins to develop tomorrow. Main convection will occur
after 18Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  76  89  75  88 /  30  70  30  50
MCO  76  91  75  90 /  30  70  20  50
MLB  76  91  75  89 /  30  60  30  50
VRB  76  91  74  89 /  30  60  30  50
LEE  76  89  75  89 /  30  70  20  50
SFB  76  90  74  89 /  20  70  20  50
ORL  77  90  76  90 /  30  70  20  50
FPR  76  91  74  89 /  30  60  30  60

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...Heat Advisory until 6 PM EDT this evening for FLZ058-159-164-259-
     264.

AM...None.
&&

$$

DISCUSSION...Fehling
AVIATION...Tollefsen