Scientific Forecaster Discussion
fxus62 kgsp 201046
Area forecast discussion
National Weather Service Greenville-Spartanburg SC
646 am EDT Fri Sep 20 2019
dry high pressure will persist over the region today through the
weekend, with temperatures gradually warming. A cold front will
cross the region from the northwest early next week, but with
limited moisture. Dry and warm high pressure will return for the
rest of next of next week.
Near term /through tonight/...
as of 645 am friday: made some tweaks to the weather grids to
reflect latest fog development in the mountain valleys and the
northern Catawba lakes. The fog should burn off quickly after
sunrise. Otherwise, forecast is on track.
Another quiet day on tap, as the center of sfc high pressure remains
anchored across the mid-Atlantic. A mid-lvl subsidence inversion
thanks to a building 592 Dam Ridge will keep skies mostly clear and
the atmosphere capped. The exception will be the smokies, where
guidance shows just enough moisture to support some shallow shower
chances around peak heating this aftn. A stratocu deck that has been
trapped under the inversion should mix out a little better today, as
dry air filters in around the mid-lvl high. So temps will be a
little warmer than yesterday, topping out in the 70s to lower 80s.
Tonight, with center of high pressure near by, light winds and
mostly clear skies should allow temps to drop in the 50s (a category
or two below normal). Patchy fog will likely develop in the mountain
Short term /Saturday through Sunday night/...
as of 200 am EDT friday: a 592 dm 500 mb ridge will dominate the
southeast over the weekend, with surface high pressure over the
eastern Seaboard centered near the NC Outer Banks. Very dry profiles
will continue over the region, with temperatures steadily rebounding
to 5 to 8 degrees above climatology by Sunday afternoon.
Long term /Monday through Thursday/...
as of 200 am EDT friday: the Southeast Ridge will flatten on Monday
as a closed low pressure system deepens over the Great Lakes. An
associated cold front will move from the Ohio Valley to the
Appalachians, but with gradually diminishing moisture along the
boundary Monday into Monday night. Will limit pops along the
southern Appalachians to slight chance with the fropa.
The Great Lakes system will sweep quickly eastward across New
England on Tuesday, with dry northwest flow resulting across the
southern Appalachians and surrounding areas. A zonal flow pattern
will then set up by midweek before heights rebuild over the south on
Thursday downstream from a plains system. The returning heat and
modest instability could yield isolated Ridgetop convection on
Wednesday and Thursday afternoons. Temperatures will remain well
above climatology through the week.
Aviation /12z Friday through Tuesday/...
at kclt and elsewhere: some fog has developed across the lakes of
the NC northern foothills and in the some of the mountain valleys
that have cleared out from the stratocu. The rest of the area is
currently sky clear. Once the fog Burns off by around 13z, it should VFR
at all sites, as dry high pressure remains dominant over the region. A
few cu possible in the Piedmont, while the mountains will have
sct-bkn thru the aftn. Skies should clear out for the most part this
evening, allowing for more widespread Mountain Valley fog and likely
around some of the lakes again tonight. Winds will be light and
rather variable thru the period, favoring a north/NE direction this
morning, then S/southeast this aftn.
Outlook: patchy Mountain Valley fog will possible each morning.
Otherwise expect VFR.
10-16z 16-22z 22-04z 04-06z
kclt high 100% high 100% high 100% high 100%
kgsp high 100% high 100% high 100% high 100%
kavl low 55% high 100% high 100% high 100%
khky low 30% high 100% high 100% high 100%
kgmu high 100% high 100% high 100% high 100%
kand high 100% high 100% high 100% high 100%
The percentage reflects the number of guidance members agreeing
with the scheduled taf issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link: