406
FXUS62 KMLB 151955
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
355 PM EDT Sun Sep 15 2024

...New DISCUSSION, MARINE...

.DISCUSSION...
Issued at 355 PM EDT Sun Sep 15 2024

Key Messages...

- Drier air will continue to limit shower/storm development the
  remainder of this afternoon and evening

- Poor to hazardous boating and surf conditions will continue into
  early this week

- Saint Johns River at Astor forecast to remain in Moderate Flood
  through midweek

Currently-Tonight...Significantly drier air in the mid levels will
continue lower rain chances across the area through the late
afternoon. However, isolated shower/storm development (PoPs 20-30%)
will still be possible as the east coast sea breeze moves inland.
Any convection lingering after sunset should quickly diminish, with
dry conditions expected overnight. HREF guidance showing some
support for patchy fog development late tonight across the
southern half of east central FL, near to south of a line from
Lake Kissimmee to Melbourne, so have added some patchy fog
mention to the forecast over this region. However, confidence in
fog development is rather low. Not as muggy into tonight, with
lows in the low to mid 70s.

Monday-Wednesday...Low pressure offshore South Carolina continues
to have a 50 percent chance of subtropical/tropical development
as it is forecast to move north-northwest and onshore along the
Carolina coastline into early this week. This system will keep a
weak frontal boundary across the Florida peninsula. Some moisture
recovery will occur across the area, with PW values gradually
increasing to around 1.7-2.0 inches. This combined with passing
mid level disturbances and cooler temps aloft should help aid in
destabilization for at least scattered shower/storm development
each afternoon and evening along the inland moving east coast sea
breeze. PoPs will range from 30-50 percent Monday, to 40-50
percent on Tue-Wed. Isolated stronger storms will be possible,
with the main threats being strong wind gusts to 40-45 mph,
frequent lightning and locally heavy rainfall. Highs will continue
to be closer to normal, but still very warm, in the upper 80s/low
90s Monday and low 90s most locations on Tuesday and Wednesday.
Peak heat index values will reach around 100-105F. Overnight lows
will range from the low to mid 70s.

Higher astronomical tides will continue through this week and lead
to above normal water levels. However, levels at this time look to
remain just below Coastal Flood Advisory thresholds for the east
central Florida coast. Will be keeping a close eye on observed and
forecast levels, however, in case these levels end up a little
higher than currently anticipated.

Thursday-Saturday...Closed low aloft over the Ohio Valley/Mid
Atlantic region will eventually evolve into an open trough across
the eastern seaboard into late week. This trough will shift the weak
front south of central FL with a light N/NW flow across the area. PW
values drop just a tad to around 1.6-1.8" across the area, but
scattered shower/storm development will still be possible each
afternoon and evening, with PoPs 30-50 percent. Highs drop to the
upper 80s to around 90 degrees on Thursday and then mostly in the
upper 80s Friday and Saturday, with lows in the low to mid 70s.


&&

.MARINE...
Issued at 355 PM EDT Sun Sep 15 2024

Tonight...Swell from low pressure off the South Carolina coast
will produce poor to hazardous boating conditions across the
coastal waters with sea building up to 6-8 feet. Small craft
should exercise caution for seas up to 6 feet nearshore, while a
Small Craft Advisory will expand to include the entire offshore
waters into tonight for seas up to 7-8 feet. Winds will be light
out the W/NW north of the Cape and W/SW to the south.

Monday-Thursday...(Modified Previous Discussion) Scattered
showers and lightning storms will remain in the forecast. Mariners
are still reminded to keep an eye to the sky westward as the
storm steering flow will continue to be WRLY, which will bring
offshore moving showers and storms across the local waters. There
should be ECSB formation each day as light onshore winds develop
each afternoon.

Winds speeds AOB 15 kts (outside of convection) through this
week. Wave heights will remain elevated up to 5-6 feet nearshore
and up to 6-8 feet offshore into Monday, with Small Craft Advisory
continuing offshore Monday and Monday evening. Seas will
gradually subside into Monday overnight with values falling to 4-6
feet Tuesday and then to 3-4 feet into midweek.

&&

.HYDROLOGY...
Issued at 355 PM EDT Sun Sep 15 2024

The Saint Johns River near Astor is forecast to remain in Moderate
Flood stage (around 3.2-3.3 ft) through midweek. The potential
exists for small additional rises if locally heavy rainfall
develops over the river basin.

Southward, additional heavy rainfall across the Saint Johns River
basin has caused a steady rise in river levels with the forecast
point at Deland now in Action Stage and the point at Sanford
forecast to reach Action Stage tonight. Geneva Above Lake Harney
is now forecast to to remain just below Action Stage into early
this week, with a brief rise to Action Stage possible toward
midweek. Additional heavy rain could cause further rises, so
interests along the river should monitor for forecast updates.

&&

.AVIATION...
(18Z TAFs)
Issued at 120 PM EDT Sun Sep 15 2024

Drier air moving across the peninsula will limit rain and storm
chances this afternoon. Have kept VCSH at DAB and the Treasure
Coast terminals and VCTS elsewhere. Confidence in development this
afternoon does remain low. Lower CIGs remain in place across some
terminals, with the forecast calling for these ceilings to lift
to VFR over the next couple of hours. If any activity does get
going across the peninsula this afternoon, it will likely
diminish around 00Z, with winds becoming light and variable
overnight. Cannot rule out CIG reductions overnight, and there is
some guidance hinting at VIS reductions across the Treasure Coast
terminals due to fog. However, confidence in this does remain low
at this time, so have kept it out of the TAFs for now. Will
continue to reevaluate with future packages and amend as needed.
Winds pick back up tomorrow around 15Z out of the NW to NE, with
wind speeds generally between 5 to 10 knots. Potential for showers
and storms tomorrow afternoon beyond 18Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  74  87  73  90 /  20  50  20  40
MCO  75  91  75  91 /  20  50  20  50
MLB  76  90  75  90 /  10  30  20  40
VRB  74  91  75  90 /  10  30  30  50
LEE  74  89  74  90 /  20  50  20  40
SFB  74  89  74  90 /  20  50  20  50
ORL  76  91  75  91 /  20  50  20  50
FPR  74  91  75  90 /  20  30  30  50

&&

.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory until 10 PM EDT Monday for AMZ570-572.

     Small Craft Advisory from 8 PM this evening to 10 PM EDT Monday
     for AMZ575.

&&

$$

DISCUSSION...Weitlich
AVIATION...Tollefsen