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Area forecast discussion 
National Weather Service Greenville-Spartanburg SC
234 PM EDT Sat Oct 10 2015

high pressure will move into our area from the west and north
tonight and Sunday. A dry cold front will cross our region early
Tuesday with cooler air settling in for the second half of the week.


Near term /through Sunday/...
as of 230 PM...nearly cutoff upper low is embedded in shortwave now
centered over the southern tail of the Appalachians. The deformation zone
associated with this feature will progress across the County warning forecast area this afternoon and
early evening...and as the low level reflection moves across SC weak
warm upglide will continue over our NC and northern SC zones. The broad
area of stratiform rain is expected to remain somewhat stationary
on account of these features...gradually diminishing from the west
late in the afternoon in the wake of the low. Meanwhile...surface front is
stalled across SC as well. While weak elevated instability is present
over the cool air north of that boundary...trends this morning have
suggested any convection will remain near the front. This is most
likely to affect our srnmost zones. Latest weather grids mention only
small thunder chances and mostly south of the NC border.

The upper low will slowly move east of the area tonight...while
front remains stalled. Middle to upper level forcing diminishes
accordingly. Low level wind fields feature slight backing by
morning as dry high pressure over the Mississippi Valley begins to
build south and east...but the winds do not back enough to expect
a great deal of low level drying. Forecast profiles do dry out quickly
in the upper levels which should aid cloud top cooling
abundant low clouds should remain. More significant backing and low
level downsloping/drying occurs during the day Sunday. Subsidence
aloft will suppress any convection so forecast will be dry.

Mins tonight will be around or slightly below normal. Maximum temperatures
Sunday will be about a category below normal with the presence of
a cool airmass offset by sunshine.


Short term /Sunday night through Tuesday/...
as of 215 PM EDT Saturday...the next forecast concern will be the
passage of a cold front Monday night or early Tuesday. Prior to the
frontal passage...the weather still looks benign...owing to weak
high pressure supported by a deamplifying upper ridge pinched
between the old upper low opening off the Carolina coast Sunday
night and the next upper trough digging down over the northern
plains/Midwest on Monday. Will keep the forecast dry through sunset it does not appear that any pre-frontal precipitation will make
it to the mountains by then. Which brings US to the main event...such as
it is. The models differ quite a bit in terms of timing and
response. In particular...the GFS is most unimpressed with precipitation
potential...and that seems the system should remain
cut off from Gulf/Atlantic moisture. The short wave should move into
the region Monday night and across the forecast area early Tuesday with
some fairly decent middle/upper forcing. The front itself should push
eastward steadily...also with some decent forcing. Thus...have split
the difference between the wetter NAM/European model (ecmwf) and the dry GFS...but
still limited the chance pop to the NC part of the forecast area. We
should be able to dry out quickly Tuesday afternoon with strong
downslope developing behind the front...and not much residual
moisture upstream. Temperatures will still be around normal.


Long term /Tuesday night through Saturday/...
as of 230 PM EDT Sat...finally it looks like we will have a stretch
of dry and fair weather typical of October in this part of the
country. The operational models are in good agreement with the
overall upper pattern...featuring a long wave trough over eastern
North America and ridge out west...that changes very little through the
medium range. This pattern will support high pressure at the
surface...building in from the west through middle week...with temperatures
near normal. The dry air mass should be reinforced late in the week
after a clipper-like short wave drops down across the Great Lakes/northern
middle Atlantic Thu/Fri. At this appears as though that
system will pass too far to the north to affect the western Carolinas/NE the entire period should be dry. If this happens as
planned...the main effect will be to drop temperatures down a category or
two for Friday night/Saturday. Min temperatures might get cold enough to
worry about frost across the NC mountains early Saturday morning...but
that is still a long way out.


Aviation /19z Saturday through Thursday/...
at kclt...relatively steady rain should continue through the afternoon
beneath upper deformation zone and low level warm upglide just
north of stalled cold front. As upper low progresses eastward into
the evening these features will lose influence and the rain band
should dissipate. Occasional IFR visibility/ceiling likely until rain ends. High
pressure will slowly build in from the north tonight...but low levels
remain moist and MVFR stratus are expected to linger until after
daybreak. More appreciable drying and backing of low level winds will
occur Sunday bringing clearing skies. With cold advection occurring
at the surface overnight winds should remain breezy from the NE with
a few gusts.

Elsewhere...deformation zone -ra will continue over all sites except
kand through late afternoon. Kand however is likely to see -shra develop and
move through until the upper low moves sufficiently east. A rumble of
thunder at the S.C. Sites would be no surprise given weak elevated
buoyancy...but a ts is much too unlikely to mention. Some occasional
IFR is expected around the region due to rain...and is included
mostly based on trends seen with precipitation during the midday. As at
kclt restrictions are expected to remain through tonight...and though
Mountain Valley and otherwise patchy fog could occur cold advection
into the area should hold up enough to preclude IFR visibility. Clearing
after daybreak with winds weakening but generally remaining north to NE.

Outlook...dry weather is expected Sunday afternoon through Monday...with
another weak front arriving from the west on Tuesday...and more
drying on Wednesday.

Confidence table...

18-24z 00-06z 06-12z 12-18z
kclt high 92% high 84% high 96% high 90%
kgsp high 93% high 93% high 84% high 80%
kavl high 97% medium 72% high 84% high 83%
khky high 84% high 83% medium 72% high 97%
kgmu high 91% high 84% medium 71% high 80%
kand high 92% medium 76% high 92% medium 73%

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: (must be lower case)



Gsp watches/warnings/advisories...


near term...Wimberley
short term...PM
long term...PM

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