• Currently

    Reported at Hilton Head Automatic Weather Observing / Reporting System, SC
    9:35 PM EST WED MAY 24 2017
  • 72°F22°C
  • Clear
    Clear
  • Feels Like:72°F22°CDew Point:66°F19°CHumidity:83% Winds:SW 9 mph 14 kph
    Pressure:29.59 in1002 hPaVisibility:10.00 miles16090.00 meters
  • Area Forecast Discussion

947 PM EDT Wed May 24 2017

.SYNOPSIS...
A cold front will push over the Atlantic by early Thursday
morning. Large high pressure will build over the region through
Thursday and will linger through this weekend. A weak cold front
is expected to slow slide over the region on Tuesday.

&&

.NEAR TERM /THROUGH THURSDAY/...
On the evening update, we adjusted POPs in many areas to reflect
ongoing radar trends with minor adjustments to winds and sky
cover.

The cold front has recently moved through Macon GA and was
approaching east central GA. Ahead of the front, clusters of
convective rains remained low-topped and have tended to diminish
as they approach the coast where the air mass was more stable.
The final batch of showers and tstms right along the front has
had a bit of a flare-up recently as it moves into a region of
increased MUCAPES, however latest HRRR and RAP13 high resolution
progs show this instability will wane before moving into our
inland zones prior to midnight. Isolated to scattered showers
and a few tstms will persist for the next few hours, ending
from west to east overnight as the cold front moves through.
Since the deep layered environment still has 40-50 KT of bulk
shear, the risk of severe weather is non-zero, but extremely
low given the lack of significant instability. Skies will also
clear from west to east later tonight and with the passage of
the front, slightly cooler temps and drier air will be moving
in.

Thursday, high pressure is forecast to become centered near FL
and will ridge north across the CWA. WSW winds will see gusts
gradually strengthen shortly after sunrise. Conditions will
feature mostly sunny conditions with near zero PoPs. High temps
should range in the upper 70s. Breezy to windy conditions are
likely by afternoon with the passage of a strong mid level
vort and deeper mixing. We may need a Lake Wind Advisory if
model trends continue to show higher surface wind gusts.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
Thursday: The upper level trough axis will cross the forecast
area mid-day as stacked low pressure continues its trek
northeast into the mid-Atlantic region. Surface high pressure
will begin to spill back in from the south and Gulf of Mexico
behind the cold front as weak upper-level ridging slides slowly
east. This should result in primarily dry conditions Thursday,
but a shower or thunderstorm cannot be entirely ruled out. A
tight pressure gradient will exist across the region, leading to
elevated and gusty surface wind speeds. Temperatures look to be
slightly below normal, with highs just under 80 degrees most
locales and low temperatures averaging around 60 inland and
around 65 at the coast.

Friday: Surface high pressure will overspread the region under
weak ridging aloft, continuing a period of calm weather with
almost zero probability for precipitation and mostly sunny skies
anticipated. Near-normal temperatures are anticipated with
highs reaching the lower to mid-80s before cooling into the mid
to upper 60s overnight away from the coast.

Saturday: Strengthening trough aloft to the west will induce an
area of low pressure at the surface over the central US. The
associated cold front will begin a slow trek southeast towards
the forecast area. High pressure at the surface will persist
locally under a ridge aloft, and another dry day looks highly
probable under this scenario. Temperatures climb back above
normal, aided by subsidence and some compression in advance of
the front. Expect high temperatures to reach the lower 90s away
from the coast and upper 80s at the beaches, with low
temperatures only dropping to around 70.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A ridge over the East Coast combined with surface high pressure
will result in mostly dry weather through the remainder of the
weekend. The surface cold front will approach the area through
the first half of the week as the trough aloft slides east,
bringing the potential for another period of unsettled weather
Monday through Wednesday.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Occasional MVFR cigs and showers are expected at both terminals
through the evening ahead of a surface cold front. There are
small chances for brief IFR cigs and vsbys below 3 NM in heavier
showers. Risk for thunder is generally low. Marginal low level
wind shear is possible overnight but most of shear will be speed
shear off the surface inversion. Skies will clear for Thursday
but it will become breezy to windy with west winds in the 20 to
30 mph range at time, especially at KCHS.

Extended Aviation Outlook: Expect VFR conditions to prevail
into the weekend.

&&

.MARINE...
Tonight: A cold front is expected to sweep across eastern GA/SC
late, pushing over the marine zones early Thursday morning.
Gusty SW winds will continue across the marine zones. Gusts
could reach near gale levels across portions of AMZ374 and 350
late this evening. Wave heights will continue to build through
this evening, reaching 5-9 feet within 20 nm and possibly
reaching near 10 feet beyond 50 nm. Small Craft Advisories will
remain in place all waters.

Thursday through Sunday: Tight pressure gradient behind the
surface cold front will lead to elevated and gusty SW to WSW
winds and increasing seas. A Small Craft Advisory has been
hoisted for all zones Thursday, with conditions gradually
improving Friday into Saturday under high pressure.

&&

.TIDES/COASTAL FLOODING...
Evening high tide levels will trend higher each day as we
approach the new moon and perigee this Friday, though we expect
tides to remain just below Coastal Flood Advisory stage. The
current tide is close to 7 FT MLLW at high tide this evening.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until midnight EDT tonight for AMZ330.
     Small Craft Advisory until 8 PM EDT Thursday for AMZ352-354.
     Small Craft Advisory until midnight EDT Thursday night for
     AMZ350-374.

&&

$$
NEAR TERM...
SHORT TERM...JMC
LONG TERM...JMC
AVIATION...
MARINE...
TIDES/COASTAL FLOODING...