Area Forecast Discussion
Issued by NWS Melbourne, FL
FXUS62 KMLB 020856
Area Forecast Discussion
National Weather Service Melbourne FL
456 AM EDT SAT JUL 2 2016
Little overall change in the lcl WX pattern as an expansive frontal
trof over the ern CONUS will keep the axis of the Bermuda ridge
suppressed over the south half of the FL peninsula. Deep lyr S/SW
flow will prevail acrs central FL that will delay the formation of
the east coast sea breeze until early aftn while steering diurnal
convection toward the east FL coast.
Deep lyr moisture remains abundant acrs the region, though RAP40
analysis shows a pocket of lower moisture working its way into the
SW peninsula early this mrng. RAP40 and evng RAOBs measured PWat
values btwn 2.00"-2.25" over east FL, and btwn 1.75"-2.00" over west
FL. Mid lvl temps somewhat rather warm side with H70 readings btwn 8-
9C and H50 readings btwn -5C/-6C. Even so, soundings do not reveal a
sig mid lvl cap that would impede vertical motion. Mid lvls will
unstable as an H85-H30 short wave has worked into the FL Bid Bend
and extends nwd to the Carolina Coast. Indeed, bands of enhanced mid
lvl vorticity over N FL and the ern GOMex associated with the short
wave will enhance the lcl storm environment especially north of the
GFS MOS continues to under appreciate the supply of moisture and
instability plus S/SW H85-H50 steering flow that will focus diurnal
convection over the CWA. Storm overage should be higher than the
02/00Z guidance indicates. Sct/nmrs coverage, higher over the nrn
counties given the closer proximity to the vort supply and lower
moisture values upstream over the SW peninsula. Isold strong storms
psbl but the warm mid lvl temps will keep the svr wx threat muted.
The lack of any thermal capping should allow convection to dvlp
shortly aft convective triggers are reached, U80s as suggested by
model soundings. Convection should initialize by midday, a
relatively early start that will allow storms to burn up most of the
convective energy by early evng. Will keep slgt chc of storms in
through late evng to account for residual boundary interaction, but
lcl WRF models suggests convection will be done by sunset or shortly
thereafter. S/SW flow will keep temps at or slightly abv avg for mid
summer...L/M90s for aftn maxes and L/M70s for mrng mins.
Sun-Mon...The Atlantic high pressure ridge will oscillate across
central and south FL which will maintain a deep lyr S/SW flow across
central FL. Moisture will remain present and sufficient to produce
scattered aftn/eve storms both days but building ridge aloft will
nose in from the east and increase suppression/drying in the mid
levels. As a result, precip water values are forecast to drop
below 2 inches but not by much. While there do not appear to be
any significant impulses aloft, sufficient moisture and sfc
heating will combine with sea/lake breeze boundaries to generate
scattered lightning storms both aftns. Have drawn 50 PoPs on
Sunday and 40/50 PoPs Monday.
Mid level temps near -7C are not especially cold/unstable but
drier air aloft will be sufficient for isold strong storms with
gusty winds. The primary threat from storms will continue to be
cloud to ground lightning this holiday weekend. Max temps will
remain above normal in the Low to Mid 90s but probably below any
Tue-Fri...Both 00Z GFS and ECMWF build the upper ridge over FL
mid week (595 dm at 500 mb) which will increase the subsidence
and drying and result in lower storm coverage. Rain chances are
forecast to decrease near 30 percent this period which is below
normal for early July. Temperatures will be hot with highs in the
mid 90s over the interior (with a few upper 90s possible) and
lower 90s coast and peak heat indices around 105. This is not too
unusual for July in FL but there will be less opportunity for
relief from cooling rains. The GFS shows some weak troughing aloft
developing over the southern appalachians/piedmont by Fri which
weakens the ridge aloft over FL but the ECMWF maintains the ridge
over FL and will continue to lean towards that model solution.
.AVIATION...Thru 03/06Z Sfc Winds:
Thru 02/12Z...S/SW 3-6KTS. Btwn 02/12Z-02/17Z...W/SW 6-10KTS.
Btwn 02/17Z-02/20Z...coastal sites bcmg E/SE 8-12KTS. Btwn
02/22Z-02/24Z...interior sites bcmg SE 5-9KTS.
Vsby/WX/Cigs: Thru 02/16Z...VFR all sites. Btwn 02/16Z-02/24Z...N of
KVRB-KGIF nmrs MVFR shras/IFR tsras...S of KVRB-KGIF sct MVFR
shras/IFR tsras. Btwn 03/00Z-03/03Z...slgt chc MVFR shras all sites.
Today-Tonight...Frontal trof extending from the Lwr MS Valley to the
Mid Atlc will keep the Bermuda ridge axis suppressed over the south
FL Peninsula. Gentle to moderate srly breeze will result...S/SW thru
late mrng...shifting to S/SE by early aftn with the formation of
the east coast sea breeze. Seas 2-3ft...up to 4ft in the Gulf
Stream. Afternoon/early evening storms moving offshore will be
capable of generating sfc G34KTS.
Sun-Wed...The Atlantic high pressure ridge will meander over the
central and southern FL peninsula...resulting in little overall
change to the current southerly flow pattern. Winds will shift
southeast assocd with the sea breeze circulation each afternoon.
Seas near 2FT nearshore and 2-3FT offshore. Scattered aftn/eve
lightning storms moving offshore Sunday and Monday, then coverage
will decrease mid week as upper ridging builds over the area.
.PRELIMINARY POINT TEMPS/POPS...
DAB 93 74 92 76 / 60 20 50 20
MCO 93 74 94 75 / 60 20 50 20
MLB 93 75 92 77 / 60 20 40 30
VRB 92 75 92 76 / 60 20 40 30
LEE 91 75 94 78 / 60 20 50 20
SFB 92 74 94 77 / 60 20 50 20
ORL 93 75 94 76 / 60 20 50 20
FPR 92 74 92 76 / 50 20 40 30