Altamonte Springs, Florida Weather Forecast Discussion

828
FXUS62 KMLB 210612
AFDMLB
Area Forecast Discussion
National Weather Service Melbourne FL
212 AM EDT Sun Sep 21 2025
...New KEY MESSAGES, DISCUSSION, MARINE...
.KEY MESSAGES...
Issued at 210 AM EDT Sun Sep 21 2025
- Increasing risk of life-threatening rip currents today into
  the upcoming week
- Below-normal rain and storm chances today, followed by
  increased chances (40-65%) Monday and Tuesday as moisture
  increases
- Near normal temperatures through Tuesday, climbing slightly
  above normal mid to late week with peak heat indices ranging
  from 98 to 103 degrees
&&
.DISCUSSION...
Issued at 210 AM EDT Sun Sep 21 2025
Today-Tonight...Lingering dry air is keeping most of the area rain-
free this morning, with only a sporadic, onshore-moving shower
occurring. Weak high pressure remains overhead and the northeast
breeze has weakened for now. Similar conditions to what we
experienced yesterday are forecast today with little change in
temperatures (upper 80s-low 90s). It will be breezy with occasional
gusts around 20 mph, especially on the Volusia Coast. PW 1.5" or
less look to meander across the northern half of the area (north of
Melbourne), which should limit isolated shower development there.
Farther south, a bit more SFC-850mb moisture could result in a few
more onshore-moving showers and an isolated storm. All in all, the
highest rain chances are forecast across the southern reaches of the
Treasure Coast (20-30%), and measurable rains will be isolated at
best. Temps into early Monday settle in the low to mid 70s.
Also today, a high risk of dangerous rip currents exits for most
east central Florida Atlantic beaches (moderate risk for Saint Lucie
and Martin County beaches). Entering the water is discouraged!
Monday-Tuesday...A very weak surface boundary is expected to stall
over the area early in the week, while mid level shortwave energy
moves overhead, embedded in SW 500mb flow. With a surge of
moisture arriving Monday from south to north, we re-enter a more
favorable pattern for scattered showers and storms. The highest
rain chances (up to 60%) are focused around Lake Okeechobee
Monday, spreading as far north as the Greater Orlando area
Tuesday. Forecast soundings indicate generally less than 2000 J/kg
0-6km MLCAPE across the area Monday with slightly higher values
on Tuesday. Lapse rates appear marginal at best, even 0-3km
values, and mid level temps look to hover around -7C. With these
environmental parameters, it would appear that brief heavy
rainfall and occasional/frequent lightning strikes will be the
main concern from early week storms. Rain amounts between the two
days range from a few hundredths (north) to 0.50-1.00" (south),
though locally heavier downpours could produce a quick 1-2" of
rain. As CAMs come into range, we should gain more insight into
convective evolution.
The pattern of onshore flow continues through Tuesday, although
wind speeds do come down overall (8-12 mph). The diurnal
temperature trend remains similar to this weekend with highs
ranging from the upper 80s to low 90s, which is near to slightly
above normal for this time of year. Heat index values could
eclipse the 100-degree mark, especially by Tuesday.
Worth noting, a long period swell arrives at area beaches on Monday
and continues through Tuesday. A high risk of life-threatening rip
currents is likely to affect all area beaches. Take this into
account if heading to the coast early this week, as entering the
water will be highly discouraged!
Wednesday-Saturday...High pressure and weak 500mb ridging builds
over the FL Peninsula Wednesday and persists through at least the
first half of Thursday, before height falls begin Thursday night
into Friday. Our focus will be on a developing 500mb cutoff low
over the Midwest, which is progged to dig southeastward late week
into next weekend. There is some disagreement as to exactly what
happens with this low from Sunday onward, but it effectively
stalls over the TN/OH Valley through Saturday. In association, a
semi-stacked surface low and cold front gradually push
southeastward toward FL Friday into Saturday.
Starting Wednesday, the previously stalled front over the area is
forecast to dissipate with high pressure becoming established.
Onshore flow remains but is relatively light and weak forcing
translates to lower-than-climo rain chances through Thursday.
Light southwest flow returns on Friday ahead of the approaching
front, turning onshore in the afternoon along the coast. There is
some uncertainty regarding a ribbon of drier air moving over the
peninsula prior to Saturday, and if that does occur, rain chances
may be reduced Friday as well. However, this forecast stays near
or slightly under climo/consensus (~40%) for now. By Saturday, a
band of higher moisture (PW > 2") pools along and ahead of the
approaching cold front. The timing of this front remains unclear.
Furthermore, its behavior as it reaches Florida is more uncertain,
but models do indicate the potential of it stalling over north-
central Florida through the remainder of the weekend. Thus, rain
chances generally increase areawide on Saturday (maybe Sunday,
too). With increased upper level support, we`ll have to keep an
eye on the potential for a couple stronger storms as well.
A warming trend is anticipated mid to late week, as more sun and
lesser overall cloud cover supports afternoon temperatures in the
low to mid 90s. Peak heat indices Wednesday-Friday will reach 98-103
degrees, so it is something to keep in mind for any outdoor work or
activities.
&&
.MARINE...
Issued at 210 AM EDT Sun Sep 21 2025
Northeast winds today 10-15 kt will gust 15-20 kt across the waters
(around 20 kt along the Volusia coast). Seas generally 3-4 ft, but
cannot rule out 5 ft waves across the Volusia waters due to a wind
chop. Isolated showers are possible, though drier air will likely
keep activity to a minimum.
Early this week, a front stalls near or just north of the waters. We
maintain onshore flow, albeit lighter each day (8-14 kt) and more
east-northeasterly. Longer period swells increase to 3-5 ft Monday
and Tuesday, gradually decreasing to 2-4 ft by mid to late week.
Increasing moisture overhead Monday and Tuesday will promote
scattered rain and lightning storms over the waters. Lower rain
coverage is forecast Wednesday and Thursday.
&&
.AVIATION...
(06Z TAFs)
Issued at 112 AM EDT Sun Sep 21 2025
Generally VFR conds prevail, though could see some OCNL MVFR
along the coast. Light winds become NE/ENE 10-15 kts on Sun with
some higher gusts. Below normal (20-30%) diurnal convective
chances, highest south of KMCO where moisture is deepest.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB  87  74  87  73 /  20  20  30  20
MCO  90  74  91  74 /  20  10  40  20
MLB  87  76  87  75 /  20  30  40  30
VRB  88  75  88  74 /  20  30  50  30
LEE  90  73  90  73 /  10  10  30  10
SFB  89  73  90  74 /  20  10  40  20
ORL  90  74  90  74 /  20  10  40  20
FPR  88  75  88  74 /  20  30  50  30
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
DISCUSSION...Schaper
AVIATION...Sedlock

NWS MLB Office Area Forecast Discussion