Area Forecast Discussion
Issued by NWS Melbourne, FL
FXUS62 KMLB 191429
Area Forecast Discussion
National Weather Service Melbourne FL
929 AM EST Thu Jan 19 2017
...Increasing threat for severe storms Sunday afternoon/evening...
Today-Tonight...A backdoor front was dropping south over the
Atlantic waters while a weak high pressure ridge oriented
north/south was situated over the local area. A large area of
stratus/fog over the northern peninsula was just grazing northern
sections of Volusia county. We will have to watch out for some sea
fog working down the Volusia coastal waters and possibly pushing
ashore late in the day. The HRRR model has been showing this and
will follow the latest trends to see if clouds/temperatures will
need adjustment, or if fog will need to be mentioned towards
evening/overnight for coastal Volusia.
Otherwise, good weather today with no changes to previous forecast.
Friday-Wednesday...Shortwave impulses moving across the deep south
will break down the upper ridge over FL through late week.
Then a strengthening trough will move out of the desert Southwest
Sat night with a deepening closed upper low moving east into the
lower MS valley Sunday. This will cause the upper ridge axis over
FL to shift east this weekend. While the upper low will remain to
the north, expect the deep trough to move across the FL peninsula
on Mon then develop a negative tilt as it moves east away from the
area Mon night and Tue.
East Central FL will remain in the warm sector through the weekend
with deepest moisture staying just north and west through
Saturday. So Fri still looks dry with a slight chance for diurnal
showers on Saturday afternoon mainly north of Orlando.
Then a strong mid level jet of 100 knots is forecast to move east
across the Gulf of Mexico atop strong moisture advection. This
should induce a squall line over the eastern Gulf which should
translate east across the FL peninsula Sunday aftn/Sunday night.
Rain chances around 70 percent with the front as precipitable
water values surge to 1.80". While rains will be beneficial with
widespread 0.50"-1.0" accumulations with locally higher amounts,
strong wind fields in the low levels (50 knots at 925 mb) will
pose an increasing threat for severe storms. Very strong vertical
shear will combine with moderate buoyancy (CAPE values over
1000J/kg) to produce a damaging wind/large hail and tornado
threat. Helicity values (0-1km) are forecast to peak at 200-300
m2/s2 late Sunday/Sunday evening across much of EC FL.
The 00Z GFS and ECMWF have come into better agreement with timing
and intensity which is increasing our confidence of an organized
squall line punching across central FL, focused on Sunday
afternoon/evening, and pushing offshore the Treasure coast by
Drying is expected to be slow until the upper trough axis passes
to our east later Monday so we`ll hold onto a chance/slight chance
for showers most of the day.
Temperatures will remain well above normal thru Sun night with
highs around 80/low 80s each day with overnight lows around 60
to the mid 60s. A few mid 80s will be possible given enough
surface heating and these may approach record highs. Temps should
drop back closer to normal from Mon afternoon thru Tue, returning
a little above normal Wed.
VFR except at KDAB where a patch of stratus had broke off from large
area to the north. The latest HRRR model shows stratus and low
visibility lingering just offshore this afternoon, then pushing back
into the coast before sunset. The GFS/MOS guidance did not pick up
on this, so will have to watch the I-4 corridor TAFs and KLEE late
tonight for fog potential too.
Today-Tonight...Favorable small craft boating conditions continue
with winds 10 knots or less and seas 1-2 feet nearshore and up to 3
feet well offshore. Will have to watch the Volusia coastal waters
for sea fog especially from this evening through the overnight.