100
FXUS62 KMLB 121925
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
325 PM EDT Sat Jul 12 2025

...New KEY MESSAGES, DISCUSSION, MARINE...

.KEY MESSAGES...
Issued at 314 PM EDT Sat Jul 12 2025

- A disturbance and associated deep moisture moves over central
  Florida Sunday into next week. Regardless of development, above-
  normal lightning storm chances and heavy rainfall with be the
  primary impacts.

- High daily rain chance up to around 80% expected through the
  rest of the weekend and into much of the coming week.

- Hot and humid conditions with peak heat index values 101 to 107
  degrees continue into early next week; residents and visitors
  are encouraged to stay cool and well-hydrated to avoid heat-
  related illness

&&

.DISCUSSION...
Issued at 314 PM EDT Sat Jul 12 2025

Currently...Showers and storms that developed very early on the
west coast sea breeze are pushing into East Central Florida. The
east coast sea breeze north of the Cape formed early this
afternoon, while to the south was pinned to the coast for a while,
but is now moving inland. A couple brief sprinkles have popped
up on our sea breeze, but the main show has been the west coast
breeze.

Rest of Today-Tonight...GOES satellite imagery shows a fairly
supportive environment for convection across much of the East
Central Florida, with a healthy cumulus field, including some
towering-cu, and PWATs between 1.9-2.0", confirmed by the 1715Z
MCO ACARS sounding. While model soundings place a considerable dry
layer between 850-500mb, the ACARS sounding shows it a little
higher between 700-500mb, which would explain why convection has
been over performing the CAMs. Expect the ongoing activity to
continue pushing eastward, eventually colliding with the east
coast sea breeze on the eastern side of the peninsula in the late
evening. A few showers and storms could develop on the east coast
sea breeze, but the highest coverage and main event will be the
collision. Sounding profiles continue to show very steep low level
lapse rates around 8 C/km and decent mid- level lapse rates
around 6 C/km, and copious instability of +2,000 J/kg MUCAPE
(latest RAP analysis goes to nearly 5,000 J/kg), despite some
modest warming in the mid-levels as T500 ring in around -7 C in
the XMR 15Z sounding. This will support very quick updraft
development, but with little to no shear, will also support quick
downdraft development. As a result individual cells have been
short-lived, with activity propagating along and with boundaries.
All in all, the environment remains supporting of stronger storms
capable gust gusty winds to 55 mph, frequent cloud to ground
lightning, and torrential downpours. There is potential for
excessive cloud to ground lightning, small hail, and one or two
storm capable of severe wind gusts to 60 mph, especially along
the sea breeze collision. So far storms and heavy showers have
been marching steadily inland, but those that form on multiple
boundary collisions and the sea breeze collision could have
slow/erratic motion, delivering locally high rainfall amounts that
could lead to ponding of water on roads and minor flooding of
low-lying and poor drainage areas. High temperatures in the low-
mid 90s combined with high moisture will result in peak afternoon
heat indices 101-107.

Sunday-Monday...(Modified Previous Discussion) The eastern side
of a H5 pressure ridge begins to erode on Sunday with the northern
jet stream situated well north of Florida. A weak mainly mid-
level disturbance rotates around the high and across the central
Florida Atlantic coast Sunday afternoon. Despite slightly warmer
H5 temps, the disturbance may provide additional upper level
support to convection. PW getting close to daily maximums in some
spots (2.1+") means the "skinny CAPE" look to sounding profiles
returns. This indicates a moisture-laden environment capable of
producing greater shower and lightning storm coverage.
Additionally, the threat of localized flooding will increase,
especially on Monday, as a developing broad area of low pressure
shifts from near the Carolina coast across Florida. The National
Hurricane Center is monitoring this disturbance, and has given it
a low (20%) chance of gradual tropical development over the next
7-days, but heavy rainfall will be the primary impact regardless
of develop. Total QPF from various ensemble output remain not
overly impressive as of the 06Z and 12z runs, but several members
in each of the EC-AIFS, EC, GEFS, and CMC suites do point to
locally heavier amounts (2-3"+) across the southern half of the
area by Tuesday morning. Once CAM guidance is within range, we
could have a better look at what locally higher totals may be
tomorrow and Monday. A few strong storms with gusty winds and
frequent lightning also cannot be ruled out, as waterlogged
downdrafts collapse and occasionally produce 40-50 mph gusts.

Temperatures will remain quite warm on Sunday (90s) with heat
index values ranging from 101 to 106. However, increasing coverage
of storms and cloud cover will provide relief by mid to late
afternoon. On Monday, forecast highs drop another degree or two,
reaching the upper 80s (coast) to low 90s (inland). High rain
chances will put a cap on any higher temps to start the week.

Tuesday-Friday...(Modified Previous Discussion) The broad area of
low pressure shifts in the Gulf Tuesday morning, as a couple of
mid level energy impulses move over north and south Florida. High
rain and storm coverage is anticipated to continue Tuesday as the
low continues to pull moisture over Florida, with the highest
chances (80%) focused west of I-95. Model discrepancies are
introduced as early as Wednesday, when questions arise pertaining
to 500mb steering flow and the development of a mid level high
over the western Atlantic. Still, high PW will remain over the
peninsula, supporting 60%+ rain and storm chances through
Thursday. Daytime temperatures slide closer to normal for mid
July, only peaking in the upper 80s to around 90 degrees. Low
pressure retrogrades westward, then northwestward across the Gulf
mid to late week. With it goes the better support for widespread
rain chances, so this forecast keeps rain chances in the 50-60%
range from Friday onward. Rain chances will not go away, but
moreso resemble the typical sea breeze convective pattern by next
weekend.

&&

.MARINE...
Issued at 314 PM EDT Sat Jul 12 2025

Favorable boating conditions persist in the absence of heavy rain
and lightning storms. Weak high pressure will linger over Florida
and the adjacent Atlantic waters through a portion of Sunday
before a broad area of low pressure begins to develop later Sunday
into early next week. The National Hurricane Center is monitoring
this disturbance, and has given it a 20% chance of gradual
tropical development over the next 7-days. Higher than normal
chances for lightning storms will be the primary impact through
the first half of the week, with lingering high moisture
continuing those high chances into the second half of the week.
Prevailing winds become more westerly through Sunday as the low
develops and approaches, shifting through the day Monday as the
low passes, and return to southerly Tuesday as the low moves into
the Gulf and the Atlantic high builds back towards Florida.
Outside of storms, winds 5-15 kts and seas 1-3 ft.

&&

.AVIATION...
(18Z TAFs)
Issued at 131 PM EDT Sat Jul 12 2025

A line of storms on the west coast of Florida is steadily moving
eastward this afternoon. Have moved up the time for VCTS for LEE
to start at 18Z, and ISM to start at 19Z to account for these
storms moving in from the west. May need to move up the VCTS
timing for MCO, but there remains some uncertainty due to model
guidance indicating convection will die as it reaches ECFL. So
will monitor and amend as necessary. Have maintained the TEMPOs
for MCO/ISM, but confidence is not high this will materialize.
VCTS for the rest of the terminals this afternoon, starting from
18-22Z. Convection will diminish around sunset (23-01Z), with
winds becoming light and variable overnight. W/WNW winds will
increase to 5-8KT by mid- morning on Sunday before backing
onshore along the coast in the afternoon with the sea breeze.
Scattered showers and storms are once again forecast for Sunday
afternoon, with VCTS starting at MCO around 20Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  76  92  75  91 /  30  70  30  60
MCO  76  94  75  93 /  20  70  40  80
MLB  75  91  74  88 /  20  70  40  70
VRB  73  91  72  89 /  20  70  50  70
LEE  77  93  76  92 /  20  70  40  80
SFB  77  94  76  93 /  20  70  40  70
ORL  77  94  76  92 /  20  70  40  80
FPR  74  91  72  88 /  30  70  50  70

&&

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

$$

DISCUSSION...Haley
AVIATION...Watson