993
FXUS62 KMLB 100942
AFDMLB

Area Forecast Discussion
National Weather Service Melbourne FL
542 AM EDT Mon Jun 10 2024

...New DISCUSSION, MARINE, FIRE WEATHER, CLIMATE...

.DISCUSSION...
Issued at 536 AM EDT Mon Jun 10 2024

Today-Tonight...One last day of abnormally hot weather, then the
streak finally comes to an end as the mid-upper level ridge
responsible is shunted to the southeast by broad troughing over
the CONUS digging down to the Atlantic seaboard. An attendant
surface front associated with the trough stalls near or just north
of North Florida, while the Atlantic high retreats south and
seaward a bit, backing low-level flow southwesterly, and lifting
copious (and much needed) tropical moisture to Florida. Increasing
cloud cover brings temperatures down a notch from previous days,
but still well above normal in the M-U90s inland and L-M90s along
the coastal corridor. A couple high temperature records could be
broken again today, with Leesburg and Vero Beach the most likely
candidates. Heat index values also come down a notch, but remain
just below Heat Advisory criteria at 100-107, highest from Osceola
and southern Brevard south. Winds WSW-SW 5-10 mph pick up to
10-15 mph and a bit gusty in the afternoon , especially along the
coast.

As for rain chances, we`ll start the day with a fairly sharp PWAT
gradient across ECFL from around 1.8-1.9" in Martin County to
1.2-1.3" in northern Lake and Volusia counties, which are forecast
to increase to 1.7"-2.1" (between the climatological 75th
percentile and daily maximum) by the evening. This will support
increasing rain chances through the day, starting at 20 pct across
the southern counties by late morning, 30-50 pct across most of
ECFL by the afternoon, and topping out at 60-70 pct from Orlando
to Titusville south. CAMs have a bit of variation in timing, for
example the HRRR getting things going mainly in the afternoon, but
overall coverage is in pretty good agreement. While 500mb
temperatures are a somewhat unimpressive at -6C to -4C, the
additional instability provided by the increasing moisture looks
to push MUCAPE values over 2,500 J/kg in the afternoon, and those
hot conditions will cause low-level lapse rates to exceed 7-8
C/km, resulting in a favorable environment for clusters of pulse
thunderstorms after 2 PM. Dry mid-levels could enhance downdrafts,
and indeed soundings show DCAPE values 900-1,000 J/kg, leading to
gusty thunderstorm winds to 50 mph, and a locally severe/damaging
gust to 60 mph can`t be ruled out. Other storm hazards will be
occasional to frequent lightning, and torrential downpours.
Adequate low-mid level flow should keep storms on the move, but
repeated rounds could result in locally high rainfall amounts of
2-3", with a upper limit of 4" not out of the question.

Additional rounds of showers and storms are expected through the
night, and while they won`t pack the same punch as those this
afternoon as we lose instability from daytime heating, we`ll
continue to see those rainfall totals increase.

Tuesday-Friday...Fairly straight forward forecast at this point.
Southwesterly flow around the Atlantic high transports juicy
tropical moisture across Florida, which combined with a broadening
shortwave trough becoming quasi-stationary over the GOMEX and
Florida, will result in high rain chances and an increasing
potential for localized flooding through the week. To paraphrase
WFO MLB wisdom, weather in Florida is often the mean of two
extremes, and as we look at the potential of going from drought to
flooding, this certainly holds true. We`ll see multiple rounds of
showers and lightning storms through the period with daily rain
chances 80-90 pct. The big question will be where we see those
repeated rounds of heavy showers and storms, and how much rainfall
accumulates. A fairly common theme across the various guidance is
24-hour rainfall amounts of 1-3 inches, with locally higher
amounts up to 4" possible, and a total QPF through Friday night of
5-8" down south and 2-4" to the north. Based on these numbers and
the cumulative effect over several days, the Weather Prediction
Center has issued a Marginal Risk for excessive rainfall across
all of ECFL through the period, and a Slight Risk starting across
the south Tuesday that shifts further north each day, reaching
Orlando to Titusville by Friday.

Model soundings show mostly that long-skinny profile associated
with high rainfall events, but CAPE values still manage to reach
1,000-1,500 J/kg in the afternoons, so storms capable of gusty
winds and at least occasional cloud to ground lightning will be
possible.

Almost as good news as the rain will be temperatures, which are
forecast to barely make it to 90 in northern Lake and Volusia
counties Tuesday and Wednesday, but otherwise and elsewhere only
make it to the M-U80s thanks to the cloud cover and rain. While
not a cold snap by any means, they will be at or below normal,
which is at least something.

Saturday-Sunday...Guidance has further diverged and further
decreased forecast confidence going into the weekend. GFS develops
a surface cyclone in the Gulf of Mexico, while the ECM develops
little more than a wave. This results in a much drier solution
from the GFS while the ECM keeps some moisture across the area and
continues rain chances. Official forecast reflects a compromise
blend between the two, keeping relatively high rain chances and
near to below normal temperatures through the weekend, but changes
are likely as we drawn nearer.

&&

.MARINE...
Issued at 536 AM EDT Mon Jun 10 2024

Today-Tonight...The Atlantic high retreats southeastward as a
frontal boundary stalls near or north of North Florida. Flow
starts to become more SW-SSW later in the day as a result, but the
sea breeze circulation remains the primary driver of winds,
backing them to the S-SE at 10-15 kts in the afternoon, then
returning to SW-WSW overnight. Another nocturnal offshore surge
to 15-20 kts is expected, but limited to well offshore of the
Volusia waters tonight. Increasing moisture from the SWrly flow
will result in SCT-NUM offshore moving showers and lightning
storms, some of which could become strong, capable of winds over
35 kts and locally higher seas. Outside of storms, seas 1-3.

Tuesday-Friday...Pattern remains fairly static through Friday.
SWrly winds Tuesday shift to Srly Wednesday and Thursday, then
start to shift to the SE Friday as high pressure over the Atlantic
builds back. High rain chances through the period with rounds of
SCT-NUM showers and lightning storms. High cloud cover will
prevent meaningful development of the sea breeze. Seas generally
1-3 ft outside of storms, maybe creeping up to 4 ft in the Gulf
Stream Tuesday night.

&&

.FIRE WEATHER...
Issued at 536 AM EDT Mon Jun 10 2024

Sensitive fire weather conditions due to near record heat and
drought conditions continue today, then a gradual improvement is
expected through the request of the week as moisture and
subsequent rain chances increase. Min RHs 50 pct or higher except
north of I-4 at 35-40 pct today. SCT- NUM showers and lightning
storms expected this afternoon.

&&

.CLIMATE...
Issued at 536 AM EDT Mon Jun 10 2024

Record high temperatures (including last year set) for Monday,
June 10th:

Daytona Beach  100 1981
Leesburg        96 2007
Sanford         99 1985
Orlando         99 1907
Melbourne       96 1981
Vero Beach      95 2007
Fort Pierce     97 1948

&&

.AVIATION...
(06Z TAFs)
Issued at 200 AM EDT Mon Jun 10 2024

VFR continue outside of convection this TAF period. FEW to SKC
will persist thru 16z-17z, before SCT low-mid level cu develop in
the presence of some high level clouds. VCTS beginning at most
sites 19z-20z with TEMPOs from MCO/SFB east to TIX/MLB for TSRA
and reduced VIS. Further CIG/VIS reductions to IFR and brief wind
gusts are likely. Outside of storms, WSW winds remain 10 kt or
less but back along the coast after 17z due to the ECSB. TSRA will
gradually decrease after 02z with VCSH still possible from MLB
south.

&&

.PRELIMINARY POINT TEMPS/POPS...
DAB  96  73  89  73 /  30  60  80  50
MCO  95  76  87  75 /  60  60  80  50
MLB  93  74  87  74 /  70  70  90  70
VRB  93  75  87  73 /  60  70  90  70
LEE  95  76  90  76 /  30  60  80  40
SFB  96  76  89  75 /  50  60  80  50
ORL  96  76  89  75 /  60  60  80  50
FPR  93  74  87  73 /  60  70  80  70

&&

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

$$

DISCUSSION...Haley
AVIATION...Schaper