Area Forecast Discussion
Issued by NWS Melbourne, FL
FXUS62 KMLB 262001
Area Forecast Discussion
National Weather Service Melbourne FL
300 PM EST Sun Feb 26 2017
Tonight-Monday...The large eastern CONUS surface high will slide
east and into the western Atlantic over the next 24 hours. Northeast
surface winds will veer to east overnight and southeast on Monday,
while remaining at moderate strength. This results in the remnant
frontal boundary extending NE from Grand Bahama Island to begin to
pivot back to the NW overnight and eventually northward tomorrow.
As residual frontal moisture starts to spread back toward the SE
coast, clouds along with a few low topped sprinkles or light rain
showers should begin to develop near the northern Bahamas and push
toward the coast and possibly onshore. As such, kept the low POP
for Martin/Saint Lucie Counties tonight, but held off on potential
for activity to move onshore until after midnight. Min temps will be
milder, but show a large spread from the far NW CWA (near 55F) to SE
Surface winds becoming SE will continue to advect shallow moisture
back N across the CWA, resulting in increasing clouds SE to NW along
with and a small diurnal shower chance for much of the area. Temps
will warm to the U70s to near 80F for the coastal areas, and L80s
Tuesday night...H100-H70 anticyclone off the Carolina Coast will
trail a ridge axis back acrs the central/northern FL peninsula.
Aloft, an H85-H50 anticyclone will build over the GOMex region,
reinforcing the H100-H70 ridge. A deep and steady S/SE flow will
result that will tap a modest amount of low lvl moisture...H100-H85
mean RH values btwn 70-80pct and PWat values btwn 1.00"-1.25" will
require small PoPs in the fcst. However, the S/SE H100-H70 flow
suggests any precip will be confined to the coastal region.
The ridge axis will maintain a weak subsidence inversion in the H85-
H70 lyr while blocking out any meaningful mid lvl short wave energy.
Aloft, a zonal H30-H20 jet streak over the Deep South will be too
far to the north to provide any significant upr lvl divergence. Any
precip will be in the form of low-topped shras with QPF AOB 0.10".
Warm air advection generated by the SE flow will keep temps well abv
avg...aftn maxes in the L/M80s...mrng mins in the M/U60.
Wednesday...The ridge will retreat into south FL as a storm system
over the Great Lakes lifts into ern Canada and pulls a cold front
into the Deep South. Sfc/low lvl flow will veer to the S by early
aftn, then to the SW by sunset. Low lvl moisture advection will push
PWat values to arnd 1.25" by aftn...and to 1.25"-1.50" by sunset.
Lingering suppression or at the very least weak mid lvl dynamic
support as the proximity of the ridge axis continues to block out
mid lvl short wave energy. Meanwhile, the core of the jet stream is
progged to pass too far to the north to provide any meaningful upr
lvl support. However, the warm srly flow will drive temps into the
L/M80s...which according to model soundings will be AOA the
convective triggers. Will keep slgt chc of precip in the fcst to
account for this, but overall instability parameters and a very dry
mid lyr (dewpoint depression btwn 20-25C thru H85-H50) do not
support deep convection.
Extended forecast (previous)...
Thursday...weak southern portion of mid level trough axis crosses
FL, allowing a weak/shallow frontal boundary to cross central
Florida Thursday or Thursday night. Weak moisture convergence and
isentropic lift will bring a low chance for showers and perhaps a
few embedded lightning storms during the day, with showers lingering
across southern areas into the overnight period. Some cooling should
reaching northernmost CWA with max temps close to 80 (unless frontal
timing slows), with mid 80s central/south.
Friday-Sunday...Zonal flow redevelops aloft. Surface frontal
boundary slows/stalls over the Bahamas Friday which may allows small
shower chance to linger further into the day over southern areas.
High pressure then builds from the Midwest to the Mid Atlantic
region bringing a period of cooler/drier wx to east central Florida.
Max temps in the 70s CWA-wide and mins in the 50s north/interior
portion of CWA and low/mid 60s south/coastal areas.
.AVIATION...VFR overnight save for a few ISOLD MVFR SHRA possible
INVOF SUA-FPR, mainly after 08Z. VFR CIGs near BKN035-040 spreading
NW late tonight into Monday with brief ISOLD SHRA possible at most
of the aerodromes, although Probs/coverage too low to merit VCSH
away from the coast.
Tonight-Monday...12Z model guidance shows progged winds/seas have
dropped by about 2-4KT. Consequently wave models now show lower peak
seas (6-7FT) over a smaller area, which makes pulling the nearshore
SCA south of SIPF1 look like the right call. SCA conditions beyond
20NM should end from north to south from early evening onward, but
will still have to keep Cautionary Statement in place near shore and
north for winds 15-20KT and seas up to 6FT.
Tuesday...Ridge axis extending from off the Carolina Coast thru the
GOMex will maintain a gentle to moderate S/SE breeze acrs the lcl
Atlc. Seas diminishing from 4-5FT nearshore and 5-6FT offshore at
daybreak Mon to 3-4FT nearshore and 4-5FT offshore.
Wednesday...Ridge axis will erode and drift into the south peninsula
ahead of a new cold front that will push into the Deep South thru
the day, then into the FL Panhandle overnight. Gentle to moderate
S/SE breeze thru the day, bcmg a gentle to moderate S/SW overnight.
Seas 3-4FT nearshore and 4-5FT offshore.
Thursday...The approaching cold front will push thru central FL,
reaching the Treasure Coast/Lake-O region by sunset, then into
south FL overnight. Sfc/bndry lyr winds will veer from a gentle to
moderate W/SW breeze at daybreak to a light to gentle W/NW breeze
with the fropa. Post frontal winds will surge out of the north
overnight, bcmg a moderate to fresh breeze as a strong ridge builds
over the Deep South. Seas 2-3FT nearshore and 3-4FT offshore thru
the day, building to 4-5FT north of Sebastian Inlet. Slgt chc tsras
ahead of and with the frontal passage.
Friday...Post frontal wind surge will continue as high pressure
builds toward the Mid Atlc Coast. Moderate to fresh north breeze
slowly veering to NE. Seas building to 5-7FT north of Sebastian
Inlet and 4-6FT south of the Inlet thru the day, then 6-8FT areawide
.PRELIMINARY POINT TEMPS/POPS...
DAB 58 78 66 80 / 0 20 20 20
MCO 58 83 65 85 / 0 20 10 10
MLB 65 80 68 82 / 10 20 20 20
VRB 66 80 68 81 / 10 20 20 20
LEE 55 83 64 85 / 0 20 10 10
SFB 57 82 65 84 / 0 20 10 10
ORL 58 83 65 85 / 0 20 10 10
FPR 66 80 69 82 / 20 20 20 20
AM...Small Craft Advisory until 4 AM EST Monday for Sebastian Inlet
to Jupiter Inlet 20-60 nm.
Small Craft Advisory until 10 PM EST this evening for Volusia-
Brevard County Line to Sebastian Inlet 20-60 nm.