Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Melbourne Florida
246 PM EDT sun Jul 24 2016
..a few locally strong storms possible this afternoon and early
evening, mainly south of Orlando...
Current-tonight...the 15z kxmr sounding continues very dry with some
cooler air aloft. The precipitable water is only 1.09 inches thanks to an upper
low moving westward across the south/south-Central Peninsula this
afternoon. Water vapor imagery highlights this drier air north of
Lake Okeechobee. 700/500mb temps respectively at +8.2c/-8.7c. Cape
wind profilers show very light easterly flow up through around
4.5kft and light/variable above this level. Nexrad 88d shows
isolated cells struggling to develop across the I-4 corridor with
scattered activity developing south of here.
The moisture gradient remains quite impressive with nearly 2 inches
for pwats near Lake Okeechobee and southward. Threats from
afternoon/early evening storms continue to be frequent cloud to
ground lightning in a few storms, locally heavy downpours with
possible nuisance flooding of low-lying areas, gusty outflow
winds...especially with the cooler/drier air above the surface, and
perhaps some small hail. Storm motion generally slow toward the west
or northwest, but occasionally erratic. Few lingering storms
possible into early evening, mainly Lake County and near the
Overnight lows remain very warm and generally in the l-m70s
areawide. Cloud debris from earlier storms will thin through the
night. Deep layer moisture will begin to return areawide later
tonight as the upper low continues its westward track away from the
..previous extended forecast discussion...
Mon-Mon night...disorganized area of low pressure embedded within
the wrn extension of the Bermuda ridge will merge with a weak h100-
h70 trof over the NE Gomex by daybreak. As the Florida Peninsula gains
the ascending flank of the consolidated trof, the Bermuda ridge will
reorganize and merge with a weak anticyclone over the deep south/mid
Atlc. This in turn will allow the mean h100-h70 flow to shift to the
S/southeast and tap a relatively moist airmass just east of the Bahama bank
and pull it into the Florida Peninsula.
Shra/tsras chances looking pretty decent compared to recent days.
Model soundings indicate precipitable water values increasing to arnd 2.00"
areawide by 18z as a respectable knuckle of 850 mb-h50 vorticity works
its way acrs the peninsula in the wake of the trof. The 24/00z GFS
MOS pops came in btwn 50-60pct, as high as they have been in over a
week. However, am hesitant to bite off completely as the moisture
distribution thru the column, as indicated by the model soundings,
is not concentrated in the low/mid lvls. Instead, it is more
uniformly distributed thru the column...particularly abv h50.
Indeed, rap40 analysis indicates dew point depressions acrs the
Bahamas are largely at or above 5c thru both the h100-h70 and 850 mb-h50 lyrs.
The dvlpg S/southeast h100-h70 flow will favor the interior counties for
diurnal convection. However...given the issues with the deep lyr
moisture...will opt to keep pops in the sct category. Highest
chances (50pct) over the interior from Osceola nwd...40pct
elsewhere. Onshore flow will keep Max temps in the u80s/l90s...a few
m90s over the interior. Mins l/m70s.
Tue-Sat...the inverted trof will dampen out by daybreak Tue...
leaving the Bermuda ridge as the dominant weather feature for central Florida
thru the remainder of the week. Upstream analysis of the upr lvl
winds show an 80kt lifting jet over the nrn plains, an 80kt zonal
jet over BC, and an 80-100kt zonal jet over the Aleutians. None of
these will be in position or will have the energy necessary to
induce the type of hi amp short wave trof capable of dislodging the
Bermuda ridge. Furthermore, tropical Atlc analysis shows the closest
T-wave btwn 40-45w, too far away to impact the ridge until the tail
end of the fcst at earliest.
Position of the axis will meander acrs the Florida Peninsula, as it is
wont to do this time of year. Light but steady S/serly flow will
prevail thru the h100-h70 lyr, a direction that favors the interior
counties for highest pops. Even so...will keep precip chances aob
40pct as analysis of the tropical/subtropical Atlc shows a
surprising amount of dry air east of the Windward Passage assocd
with a large Saharan dust plume. No change in airmass...little
change in temps. Aftn maxes in the u80s/l90s along the coast...
l/m90s interior. Mrng mins in the l/m70s.
Aviation...continued VFR outside of isolated-scattered aftn/early evening
convection. Higher coverage of showers/storms today south of Orlando
where deeper moisture exists. However, cooler and drier air aloft
may allow for gusty downburst winds from any shower/storm. Light
east-southeast/southeast winds will become light/variable to calm again this
evening/overnight. Deeper moisture pools over all of ecfl on Mon
with higher shra/tsra chances areawide. East-southeast/southeast winds again for Mon.
Marine...current-tonight...E/se winds will again become
light/variable at times later this evening/overnight, perhaps light
offshore near the coast. Generally favorable small craft boating
conditions with minimal seas...1-2 ft near shore and up to 3 ft
across offshore waters. Dominant wave periods around 8-9 seconds.
Isolated/widely scattered showers/storms...mainly south of Sebastian
Inlet where deepest moisture resides.
..previous extended marine forecast discussion...
Mon-Thu...favorable boating conds for most of the upcoming week as
the Bermuda ridge settles over the central North Florida peninsula. Light
to gentle S/southeast breeze will prevail from Cape Canaveral southward...
S/SW to the north, bcmg east/southeast near the coast each aftn with the
formation of the East Coast sea breeze. Seas 2-3ft. Sct shras/tsras
Preliminary point temps/pops...
dab 74 89 75 91 / 10 40 20 30
mco 74 92 75 93 / 20 50 20 40
mlb 76 90 76 91 / 20 40 20 20
vrb 72 89 74 91 / 20 40 20 20
Lee 75 91 77 93 / 20 50 20 40
sfb 74 92 75 93 / 10 50 20 40
orl 75 91 76 93 / 20 50 20 40
fpr 73 90 75 91 / 20 40 20 20