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656
FXUS62 KGSP 200737
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
337 AM EDT Fri Sep 20 2024

.SYNOPSIS...
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High pressure will begin to build into the region from the north
today although we could see a few scattered showers and storms
this afternoon and evening. High pressure will linger over the
area into early next week with temperatures warming above normal
over the weekend.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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As of 305 am: Patchy dense fog continues across the mountain valleys
this morning, and has also expanded to include some of the major
river drainages outside the mountains. Still do not anticipate the
fog becoming widespread enough to warrant an Advisory, but a Special
Weather Statement appears in order for the morning commute.
Otherwise, heights will gradually rise through the period, as a
trough drifts way from the East Coast, and a ridge extending from an
upper anticyclone over Texas nudges into the region. This will allow
the warming trend to continue, with max temps expected to be at
least 1-2 degrees above Thursday`s reading, which will place them 3
or 4 degrees above normal. Conditions should be slightly less
favorable for deep convection today, but we still expect some spotty
showers and a couple of storms to develop, especially across western
NC. However, PoPs are limited to 20% or less across the entire
forecast area. Any convection should be gone by late evening, giving
way to another warm and relatively muggy night, with min temps
expected to be at least a category above normal. Fog/low stratus
will redevelop by daybreak Saturday, but a slightly drier boundary
layer suggests this may be a touch less widespread than this
morning.
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&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
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As of 2:55 AM EDT Friday: The short-term fcst picks up at 12z on
Saturday with broad upper ridging centered over Texas and spread
across the central and  SE CONUS. The ridge will remain over our
area thru the period, though it does get suppressed towards the
end of the period by an embedded upper trof that rides up and over
the ridge from the SW. At the sfc, elongated high pressure will
settle over our area from the north by the start of the period
early Saturday. A weak upper shortwave is progged to move thru
our area from the north Saturday afternoon/evening, even as the
broader high pressure remains in place. Towards the end of the
period late Sunday and into Monday, a more substantial low will
move a broad area of deeper moisture across the Ohio River Valley,
down the spine of the Appalachians, and into our CWA. The period
should be mostly dry except for some slight chance PoPs over our
NC zones associated with the above-mentioned upper shortwave.
The bigger story will likely be the warming temperatures over
the weekend. Highs on Sunday will approach and/or exceed 90 deg
across most of our Upstate zones, and will reach the mid to upper
80s over our NC Piedmont zones.
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&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
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As of 3:05 AM EDT Friday: The extended fcst picks up at 12z on
Monday with upper ridging getting suppressed over the central
CONUS by an embedded upper trof. Broad upper trofing will con-
tinue to linger off the Atlantic Coast early in the period, but
will eventually move well offshore by the middle of next week.
As this happens, another broad upper trof will dive southward
from central Canada and over the Great Lakes. Most of the latest
long-range guidance has the trof axis passing just to our north
towards the end of the period next Thursday. At the sfc, what`s
left of broad high pressure will be lingering to our south as
the period begins early Monday. At the same time, weak low pre-
ssure to our north will move a weak front thru our area with
the front east of our CWA by late Monday. The broader area of
deeper moisture associated with this low will likely linger just
to our north thru the first half of next week, with another,
more robust cold front expected to move thru our area by mid-
week. More specific timing of this stronger front remains un-
certain, but PoPs do increase across our area for Tues and
Wed. Daytime temperatures will moderate with the increasing
cloud cover early next week, however these clouds will help
keep overnight lows above normal thru at least Wed.
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&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Fog and/or low stratus is already becoming
widespread in the mountain valleys early this morning, and LIFR is
expected to continue until after sunrise at KAVL, with brief periods
of VLIFR also possible. Periodic IFR, w/ possible LIFR/brief VLIFR
is also expected to continue at KHKY until 13Z or so. Tempo IFR cigs
are forecast at KCLT toward sunrise, but only brief periods of MVFR
are expected at the other sites. All restrictions will lift by 15Z.
Winds will be very light through the period...possibly favoring a NE
direction later this morning, then E/SE during the afternoon. A few
showers, possibly a TSRA or two are expected to develop again this
afternoon/evening, but chances for a direct hit at any TAF sites is
at most 20%, so no mention is warranted at this time.

Outlook: No appreciable return of moisture or precip chances
expected until early to middle of next week. Daybreak restrictions
could recur each morning especially in mountain valleys.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$

SYNOPSIS...JPT
NEAR TERM...JDL
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...JDL