Area Forecast Discussion
Issued by NWS Melbourne, FL
FXUS62 KMLB 230812
Area Forecast Discussion
National Weather Service Melbourne FL
412 AM EDT SAT JUL 23 2016
Today-tonight...as ridge drops southward to northern CWA, light
onshore gradient will continue with drier air advecting toward
Volusia coast, but still residual moderate precipitable water
inland and south for scattered afternoon convection...driven by
diurnal boundary interactions. Lowest rain chances along
Volusia/Brevard coast with highest coverage over Treasure coast
toward Lake Okeechobee. Slight cooling aloft with presence of mid
level dry air suggests some strong downbursts with deep convection
today. Slow storm motion will also result in some locally heavy
rain...especially southern CWA. Isolated to low end scattered
activity may linger into early evening inland and south. Max temps
near to slightly above climo, with mins 3-5 degree above normal.
Sun-Sun Night...Unusually dry mid summer WX pattern to continue for
east central FL. An amplifying short wave trof over the Mid Atlc/New
England states will pull into the N Atlc, allowing a broad
anticyclone over the Deep South to lift into the Mid Atlc and merge
with the Bermuda Ridge. This merger will push a weak H100-H70 cut-
off low from the Carolina Coast to the S/SW into the nrn Bahamas/FL
Straits, effectively placing much of the central/north peninsula on
its descending left flank.
As the low drops into the region, it will drag a slug of rather low
RH air into the central/nrn peninsula. RAP40 analysis already
measuring H100-H70 RH values blo 60pct impinging on the I-4 corridor
with values as low as 50pct extending up the coast all the way to
the NC Outer Banks. Avg lyr dewpoint depressions are quite high with
H100-H70 values arnd 10C...H85-H50 values btwn 20-25C. GFS MOS
guidance continues to advertise 20-30 PoPs along the Treasure
Coast/Lake-O region...single digit PoPs along the I-4 corridor as
well as the Space Coast.
Can see no compelling reason to deviate very far from this solution
given the amount of dry air advection that is anticipated,
especially as winds thru the H100-H70 back to the E/NE, a direction
that climatologically is unfavorable for diurnal convection for east
central FL. GFS model soundings indicate PWat values in the 1.00"-
1.25" range over the central/nrn counties, increasing to arnd 1.75"
around Lake-O. Near full sun thru the peak heating hrs will couple
with the dry air advection to generate warm aftn temps over the
interior with maxes in the L/M90s, while the onshore component keeps
coastal temps in the U80s/L90s. Min temps near avg in the L/M70s.
Mon-Mon Night...Once the anticyclone over the Deep South merges with
the Bermuda Ridge, the cut-off low will steadily weaken into an open
inverted trof over south FL by daybreak. H100-H70 mean flow will
return to a S/SE direction that will pull a ribbon of moisture up
from the central Bahamas as the FL peninsula gains the ascending
flank of the trof. Sct PoPs areawide...30pct acrs Volusia/Nrn
Lake...increasing to 50pct Treasure Coast/Lake-O region. Maxes
U80s/L90s...a few M90s over the interior. Mins L/M70s.
Tue-Fri...Trof should dampen out completely by daybreak Tue as the
newly formed ridge shunts it into the GOMex. This will leave the
Bermuda Ridge as the dominant WX feature thru the remainder of the
week. Position of the ridge axis will meander acrs the FL peninsula,
as it is want to do this time of year. 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 the presence of
a large Saharan dust plume. Srly wind component will keep aftn maxes
in the U80s/L90s along the coast...L/M90s interior. Mrng mins in the
.AVIATION...included VCSH after sunrise KMLB southward with TS
chance mainly inland from TAF sites 17-21Z and omitted TS
KTIX/KDAB. Highest TSRA prospect for interior TAF sites 18-20Z.
Today-tonight...lax pressure pattern will keep winds generally
onshore and very light...enhanced by sea breeze circulation
nearshore late morning through late afternoon. Minimal seas...2 ft
or less and up to 3 ft offshore.
Sun-Wed...Overall, favorable boating conds through the first half of
the upcoming week. Light to gentle Erly breeze on Sun will back to
the SE Sun Night as a weak inverted trof pushes acrs the FL
peninsula. Winds bcmg a gentle S/SE breeze on Mon as the trof
dampens out and the Bermuda Ridge rebuilds overhead. The ridge will
then meander acrs the FL Peninsula thru midweek...maintaining the a
to gentle SErly breeze. Seas 2-3FT. Sct shras/tsras Sun and Mon...
bcmg isold Tue and Wed.
.PRELIMINARY POINT TEMPS/POPS...
DAB 92 75 88 74 / 10 10 10 10
MCO 93 74 93 75 / 30 20 20 10
MLB 91 76 88 74 / 20 20 20 10
VRB 91 74 88 74 / 20 30 30 20
LEE 93 75 94 75 / 30 30 20 10
SFB 93 74 94 75 / 30 20 20 10
ORL 93 75 93 75 / 30 20 20 10
FPR 90 73 88 74 / 30 30 30 20