Area Forecast Discussion
Issued by NWS Melbourne, FL
FXUS62 KMLB 272020
Area Forecast Discussion
National Weather Service Melbourne FL
420 AM EDT SAT AUG 27 2016
Deep easterly flow will continue as the peninsula is sandwiched btwn
a strong over the ern CONUS and a weak t-wave (INVEST 99L) over
central Cuba and Andros Island. Tight moisture gradient remains
draped over the I-4 Corridor with H100-H70 mean RH btwn 70-85pct
acrs Polk/Osceola Co, decreasing blo 60pct over Volusia/N Lake Co.
Aftn shra/tsra activity reflecting this with almost all activity
occurring south of I-4.
The lcl airmass remains rather lethargic with minimal H85-H30
vorticity/H30-H20 divergence upstream. No sig changes in mid lvl
temps with H70 readings btwn 10C-11C and H50 btwn -5C/-6C...
resulting in lapse rates arnd 6.0C/KM thru the lyr. With diurnal
heating as the primary driving factor for precip and easterly flow
pushing it steadily into the west peninsula, anticipate any deep
convection will dissipate or will be well west of the CWA by sunset.
Will keep a small chance for coastal showers overnight...a few of
which may push into the interior counties given the depth/strength
of the easterly flow. Strong maritime influence will keep min temps
well abv avg...M/U70s with L80s along the immediate coast.
SUN-TUE...(modified prev disc)
Deep lyr ridge centered over the Mid Atlc states with axis trailing
SW into the ArkLaTex will steer the t-wave into the ern GOMex
through daybreak Mon. At the same time, the ridge itself will
retrograde into the Great Lake region and erode as it interacts with
a short wave trof over the upr Midwest riding over its nrn flank,
and a weak easterly wave SW of Bermuda pushing toward the Carolina
coast. Meanwhile the Bermuda Ridge Axis...which has been absent from
the lcl WX pattern of late...will rebuild over the W Atlc as
hurricane Gaston recurves into the N Atlc.
This will allow the low level flow to gradually veer to southeast
and southerly through the first part of the upcoming week. The
easterly wave (INVEST 99L) approaching the Florida straits now seems
increasingly unlikely to attain any significant development.
However, it`s axis will pass from SE to NW across the peninsula
brining a period of unsettled weather in its wake.
Forecast will hinge on the development and track of INVEST 99L as it
pushes into the ern GOMex. Latest GFS model guidance shows the wave
pulling acrs the FL peninsula and merging with the Bermuda t-wave
approaching the Carolinas, pulling very high PWAT air into the state
that will promote numerous diurnal showers and storms with activity
lingering well past sunset. The 27/12Z solution is about 24hrs
slower with this evolution, however, due to the creeping nature of
the t-wave. This results in 30/40pct coverage on Sun (down from
50/60pct)...and 50-60pct on Mon (down from 70Pct). Pops for Tue
remain unchanged (70 pct areawide), though even these numbers may
wind up being too low as the event draws closer.
Clouds/precip should hold max temps a couple degrees below normal,
possibly ending the streak of consecutive days AOA 90 degrees at
both Melbourne and Daytona Beach.
Some fairly significant disparity shows up in the extended range.
The ECM model shows upstream ridge building into Florida through
late week with a trough downstream over the western Atlantic. The
GFS, on the other hand, has more short wave energy coming down into
the SE States by next Friday. The current forecast favors more
ridging, which would be accompanied by gradual drying and lowering
of rain chances from mid to late week. Temps will rise back to near
or slightly above normal.
Sfc Winds: Thru 28/00Z...E/NE 8-13KTS with ocnl sfc G20KTS. Btwn
28/00Z-28/03Z...bcmg E/NE 3-6KTS. Btwn 28/12Z-28/15Z...bcmg E 8-
Vsbys/WX/Cigs: Thru 28/00Z...N of KISM-KEVB sct MVFR shras/isold IFR
tsras...N of KISM-KEVB isold MVFR shras. Btwn 28/00Z-28/15Z...
coastal sites sct MVFR shras/isold IFR tsras...interior sites isold
MVFR shras. Aft 28/15Z...sct MVFR shras/isold IFR tsras all sites.
Tonight-Sunday...Weak t-wave over Cuba/Andros Island will push thru
the FL Straits/Keys and into the SE GOMex...generating a gentle to
moderate easterly breeze as it interacts with a hi pres ridge over
the eastern CONUS. Seas 3-4ft nearshore and 4-5ft offshore. Sct
shras/isold tsras. Wave models picking up on a long pd swell
generated by distant hurricane Gaston impacting from distant the
east FL coast aft sunset Sunday...dominant pds incrsg to 14-15sec.
Mon-Mon Night...Winds bcmg a gentle to moderate E/SE breeze by mid
aftn...then a gentle S/SE breeze overnight as the t-wave rounds the
wrn flank of the hi pres ridge and drifts northward, paralleling the
west FL coast. Seas 3-5ft nearshore and 4-6ft offshore. Sct-nmrs
Tue-Tue Night...Gentle to moderate S/SE breeze thru the day...bcmg
light to gentle SW overnight as the center of the t-wave recurves
back to the NE and into the FL Big Bend region. Seas 3-4ft nearshore
and 5-6ft offshore. Nmrs shras/sct tsras. Mariners should note that
this fcst is subject to significant change should the t-wave track
further west before recuvature occurs.
Wed-Thu...T-wave fcst to pull into the W Atlc with a trof axis
trailing back acrs the FL peninsula through midweek. Light to gentle
W/SW breeze will prevail. Seas subsiding with the diminishing wind
field...from 3-4ft nearshore and 4-6ft offshore arnd daybreak
Wed...to AOB 2ft nearshore and 2-3ft offshore aft sunset Thu.
.PRELIMINARY POINT TEMPS/POPS...
DAB 78 89 77 88 / 30 50 40 70
MCO 76 91 76 89 / 20 50 30 70
MLB 80 90 78 88 / 30 60 40 70
VRB 78 89 77 87 / 30 60 50 70
LEE 75 92 76 90 / 20 50 20 70
SFB 76 92 76 89 / 20 50 30 70
ORL 76 92 76 89 / 20 50 30 70
FPR 78 89 76 87 / 30 60 50 70