Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston SC
357 am EDT Wed Oct 26 2016
high pressure will prevail through Thursday. A weakening cold
front should approach Friday followed by more high pressure for
the weekend and early next week.
Near term /through tonight/...
today: the upper air pattern will consist of a long wave trough
axis situated off the East Coast. Weak ridging will build over
the region in the afternoon. At the surface, a broad area of high
pressure will be east of the Appalachians. This pattern will
favor a dry forecast. Models hint at some light showers forming
around the Gulf Stream in the afternoon, then trying to approach
the Georgia coast. Kept the pops along the Georgia coast capped at roughly
10% because fairly dry air in place over the region should
prevent any showers from making it inland. Expect NE winds
to shift to the east in the afternoon as the high starts shifting
offshore. Despite this wind direction, temperatures will be above
normal for this time of year due to mostly sunny skies and good
thickness values. Temperatures should peak in the mid to upper 70s
across most of the area and near 80 degrees near the Altamaha.
Tonight: weak ridging over the region in the evening will
shift offshore as a shortwave/trough approaches from the west,
stretching from the Great Lakes into the Tennessee Valley. Meanwhile,
the broad surface high pressure will gradually shift offshore as
a system impacts the northeastern states late. A weakening cold
front should approach the Tennessee Valley late. High clouds in advance
of the cold front will overspread the area as the night
progresses, helping to keep temperatures warmer than the past few
nights. Expect lows in the mid 50s far inland, the upper 50s
closer to the coast, and the lower to mid 60s at the immediate
Short term /Thursday through Saturday/...
thursday: at the start of the day, there is a break in mid level
subtropical ridging across the lower Gulf Coast region. An
approaching vort lobe embedded in this weakness is forecast to
dampen out as a stronger upper wave across the Great Lakes and
northeast states leave it to stagnate well to our west. A lack of
moisture advection and isentropic ascent should ensure dry weather
will persist but an isolated sprinkle with a decaying coastal trough
cannot be totally be ruled out during the morning. Areas of layered
clouds in the morning should give way to more late day sunshine and
warm temps in the upper 70s to lower 80s.
Friday: a weakening cold front will brush the Carolinas but the
story will be building upper heights and expanding high pressure
across the forecast area. A bit of downslope flow in the boundary
layer will make for another warm day with highs in the lower to
mid 80s after some morning clouds scatter out by afternoon.
Saturday: deep layered ridging on tap with dry weather continuing
along with very warm temps touching the mid 80s across much of the
inland forecast area as sunshine and light winds prevail.
Low temps each morning will be fairly similar with readings in the
mid to upper 50s inland to the lower 60s adjacent to the beaches and
Long term /Saturday night through Tuesday/...
expansive deep layered ridging looks to persist through the period
with both the GFS and European model (ecmwf) indicating the center of the mid level
high will settle over the region during the first half of the
upcoming week. A backdoor dry cold front on Monday should turn the
low level flow more onshore, but this will do little to impact temps
which should continue to run well above climo. Many areas are likely
to see highs in the lower 80s with overnight lows in the mid 50s to
near 60 coast.
Aviation /08z Wednesday through Sunday/...
VFR at kchs and ksav through 06z Thursday.
Extended aviation outlook: VFR conditions expected to prevail
through this weekend with low probabilities for late night or
early morning restrictions in patchy fog prior to the weekend.
today and tonight: broad high pressure east of the Appalachians
will create a weak pressure gradient across the waters. NE winds
this afternoon will shift to the east tonight as the high starts to
shift offshore. Expect winds to be no more than 15 kt with 2-3 ft
seas within 20 nm and 3-4 ft across the outer Georgia waters.
The surface ridge axis will extend into the waters Thursday and
Friday resulting in mainly light winds. Directions will turn
southeast and eventually variable South Carolina waters and onshore
Georgia waters Thursday, perhaps more variable on Friday. Seas will
average 2 to 3 ft with 3 to 5 ft waves closer to Gulf Stream well
off the Georgia coast.
This weekend: high pres will prevail with light and often variable
winds and seas 2 to 3 ft on average.