-- Discussion containing changed information from previous version are highlighted. --
520
FXUS62 KGSP 071326
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
926 AM EDT Fri Jun 7 2024

.SYNOPSIS...
High pressure will slowly filter in across the area today, following
the departing cold front, leading to drier conditions through
Saturday. Shower and thunderstorm chances return on Sunday as
another cold front tracks across the Carolinas. Forecast confidence
lowers starting next week as the overall pattern is uncertain by the
end of the seven day period.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 925 AM EDT Friday: Increased cloud cover for areas near/along
I-77 the next few hours per the latest visible satellite loops.
Otherwise, the forecast remains on track.

The axis of an upper trough will gradually develop east of the
forecast area today, with lower theta-E filtering into the CWA in
the wake of a departed frontal boundary. Surface dewpoints are
expected to dip into the 50s...if not the 40s this afternoon,
resulting in anomalously low RH, mostly sunny skies, and virtually
no instability. Chances for diurnal convection are therefore
essentially 0. Max temps are expected to be slightly above climo.
The relatively dry air will result in rather large diurnal temp
ranges, with min temps tonight expected to be around 5 degrees below
normal under continued mostly clear conditions.
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&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 200 AM EDT Friday: Dry conditions will linger through Saturday
as weak high pressure sets up shop over the southeastern CONUS. The
flow aloft remains out of the west-northwest as an upper-level
low centered over eastern Canada and New England will send a
trailing cold front across the Midwest and gradually encroach
the CFWA through the forecast period. Embedded vort energy will
present within the west-northwest flow aloft, while the area
of high pressure slowly slips offshore during the daytime period
Saturday. As a result, a return flow in the low-levels will increase
dewpoints with lee troughing developing east of the mountains. Some
of the global models suggest the potential for an MCS to form within
the mean flow and send it towards the region late Saturday into
early Sunday, ahead of the main frontal boundary, but uncertainty
in run to run trends lower confidence, especially considering the
airmass will remain rather stable and dry. In this case, have a
hard time seeing any type MCS reaching this far east, but could
disrupt the overall temperature forecast due to the potential
cloud debris that may reach the area as heating begins on Sunday.

Otherwise, the front will continue to inch closer to the CFWA by
Sunday. PWAT values rise back above 1.50" as the front enters the
area and the global models suggest that up to 1500 J/kg of sbCAPE
could be available ahead of the front, with the exception of the
Canadian. Not much in the way of forcing as the better dynamics
remain well to the north and only very subtle height falls suggest
that the trailing front will have a hard time initiating much in
coverage, especially east of the mountains. However, this is the
Summertime and a front will be present with high PWATS, so still
going to stick with mentionable PoPs for Sunday afternoon/evening
as the front pushes into the CFWA from the northwest, but coverage
is in question at this point until we get a better read from the
CAMs. The overall consensus is for the front to make a complete
fropa, but some of the 00Z guidance actually stalls the boundary
just south of the CFWA and sets up a potential unsettled pattern
for Monday. Temperatures are expected to run near-normal Saturday,
while rising as high as ~5 degrees above-normal Sunday as the area
settles under the warm sector of the encroaching frontal boundary
during peak heating.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 300 AM EDT Friday: Overall synoptic pattern starts to differ
amongst model guidance by the start of the extended forecast
period. The GFS stalls the aforementioned frontal boundary and cuts
off a closed low that drifts from the Northern Great Plains into
the OH Valley, while the stalled boundary activates and a stout low
pressure system develops over the southeastern CONUS. This would
provide multiple days of heavy rainfall and could lead to a hydro
threat, if this scenario played out. However, the ECMWF stalls
the frontal boundary as far south as the Gulf Coast and allows
for a continental surface high to filter in from the northwest
and low-amplitude upper ridging slowly building across the Eastern
Seaboard by the middle part of the week, with the Canadian favoring
the ECMWF. In this case, the sensible weather would remain dry
and rather pleasant for June, but forecast confidence remains
low as global models diverge significantly through D7. The GFS
brings in drier air behind the low pressure system as it pushes
northeast and dry high pressure filters in behind by D6/D7. The
ECMWF shifts the continental high offshore and brings in a return
flow, which will lead to diurnal showers and thunderstorms during
the same time frame. The Canadian continues to follow suit with
the ECMWF through much of the medium range. Decided to run with
the NBM mostly, but did adjust PoPs down slightly due to the
uncertainties. Temperatures are forecasted to run at or slightly
above normal through the upcoming workweek.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
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At KCLT and elsewhere: Drier air will continue filtering into the
area from the west through the period, resulting in very little in
the way of instability this afternoon, so convective chances are
basically non-existent. Generally light/vrbl and/or light W/SW winds
will become W/NW at 5-10 kts by late morning...continuing through
the afternoon. At KAVL, the NW winds will be more like 10-15 kts,
with some low end gusts possible. Winds will become light northerly
tonight.

Outlook: High pressure lingers through Saturday. Another system
moves in Sunday with a chance of precipitation and associated
restrictions. These may linger into Tuesday should the front stall
near the area.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...CAC
NEAR TERM...AR/JDL
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...JDL