Area Forecast Discussion
Issued by NWS Melbourne, FL
FXUS62 KMLB 172021
Area Forecast Discussion
National Weather Service Melbourne FL
321 PM EST Tue Jan 17 2017
...Above normal temperatures through this weekend...
...Rain chances expected to return this weekend...
Tonight...Diurnal CU field will dissipate post-sunset, leaving
mostly clear skies with thin broken cirrus streaming overhead.
Mins in the U50s to around 60F for much of the area again. Mins
could be a little tricky for the Treasure Coast, as this morning
saw U60s there. Anticipate BLYR flow won`t be strong enough to
keep winds up, and therefore mins will be a few degrees closer to
those across the rest of the CWA.
W/R/T fog potential for tonight, we`ve had several nights already
this winter where followed the lead of MAV/LAV MOS aggressively
advertising fog in a SE BLYR flow, and subsequently busted. Often
times, a tip-off that MOS might be overdoing dense fog is when it
shows low VSBYs but nil CIGs, as is the case again tonight. So for
better or worse, plan to pare back mention of fog to "patchy" for
all but the immediate Space/Treasure coast areas. Mins in the U50s
to around 60F again for much of the area, but similar to this
morning they could be a little tricky for the Space/Treasure Coasts
Wednesday...Low level winds veer to SW, which delay ECSB onset,
but not completely hold it off, as gradient flow is too weak. Max
temps will reach 80F near the coast and L80s inland, with coastal
readings falling behind the sea breeze.
Thursday-Tuesday...Ridging aloft will slowly migrate east of the
Florida peninsula by late Thu. The W/SW flow aloft will allow for
periodic shortwave impulses to traverse the deep south and brush
central Florida through Sat. A strengthening wave will then move
out of the Desert Southwest Sat night and dig into the Gulf of
Mexico on Sunday. While the upper low associated with this
deepening upper trough will lie well to the north over the
Tennessee Valley early Mon morning, expect the trough itself to
move across the FL peninsula on Mon then become negatively tilted
as it moves east away from the area Mon night and Tue.
At the surface, an area of low pressure over the ArkLaTex region
with associated upper energy will lift northeastward into the Ohio
Valley Thu night while weakening, which will keep the Deep South in
the warm/moist sector through the weekend. If fact, any frontal
activity over the Deep South will not be able to dive southward
toward ECFL until very late Sun overnight and Mon morning. The
pressure gradient will remain relatively weak thru Sat night with
generally light southerly winds. The flow will pick up on Sun out of
the south ahead of an approaching strong cold front. This
southerly flow will only slowly increase deep layer moisture
though, until late Sun as the cold front nears. Precipitable
water values should surge up to 1.8 to 1.9 inches just ahead of
the front Sun night.
For PoPs, Thu still looks dry. The GFS and ECMWF have trended
drier for Fri, so have removed small POPs in the north. On Sat,
enough moisture and heating, combined with some weak energy aloft
may allow for isolated-scattered convection north of Melbourne to
Lake Kissimmee, mainly in the afternoon and early evening. Have
retained a slight chance of thunder north of an Orlando to
Titusville line for Sat aftn/evening, even though the GFS and
ECMWF have trended farther north with precip and higher moisture.
Pre-frontal convection on Sun afternoon looks showery in nature
except for a slight of chance thunder along/west of I-4.
Precipitation chances go up considerably Sun night areawide as a
potentially organized squall line moves onshore WCFL, then across
ECFL overnight into early Mon morning. Have a 60 percent chance for
this period over most of the area, and strong storms are possible
into early Mon morning. It remains too early to pin down exact
storm threats/timing. The best guess is for the squall line to
push into the west coast Sun evening and exit the Treasure Coast
Mon morning. Decreasing precipitation chances will follow from
north to south through the morning/early afternoon as a westerly
flow brings drying.
Little change in temperatures is indicated through the period,
meaning they will remain well above normal thru Sun night. Highs
look close to 80 degrees each day with overnight lows around 60 to
the mid 60s. Temps should drop back closer to normal from Mon
afternoon thru Tue.
.AVIATION...As mentioned above, the current forecast reasoning is
that the fog will not be as dense/widespread as MAV MOS suggests.
Therefore, have confined VSBYs for most aerodromes to no worse
than 2-3SM in MIFG/BR during the 08Z-13Z time frame. Have also
kept any mention of fog out of the VRB-FPR-SUA TAFs for the time
Tonight/Wednesday...Synoptic surface winds will veer from a moderate
SE breeze to light southerly tonight and southwest Wednesday. This
will keep seas in the 2-3Ft range.
Thursday-Sunday...Weak surface high pressure over the area early
Thu will slide slowly southeast into the weekend. The pressure
gradient will be weak Thu and winds will be variable less than 10
knots. A south/southwest flow will ensue Thu night and speeds look
to be 10-15 knots Fri-Sat. South winds will pick up to around 20
knots on Sunday as a strong cold front approaches from the Gulf of
Mexico. Seas will be 2-3 feet except up to 4 feet well offshore
through Sat, then build to 3-5 feet nearshore and 5 to 6 feet
.PRELIMINARY POINT TEMPS/POPS...
DAB 58 79 60 77 / 0 0 0 0
MCO 59 82 61 81 / 0 0 0 0
MLB 60 80 60 79 / 0 0 0 0
VRB 61 80 59 80 / 0 0 0 0
LEE 58 81 60 81 / 0 0 0 0
SFB 58 82 61 80 / 0 0 0 0
ORL 60 82 62 80 / 0 0 0 0
FPR 58 80 58 79 / 0 0 0 0
LONG TERM/IMPACT WX...Lascody