930
FXUS62 KGSP 070609
AFDGSP

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

.SYNOPSIS...
Canadian high pressure will build into the area through Saturday
leading to drier conditions. Shower and thunderstorm chances return
on Sunday as a cold front tracks across the Carolinas. Dry high
pressure returns early next week.

&&

.NEAR TERM /THROUGH TODAY/...
As of 150 am Friday: A few upslope/NW flow showers are weakening
across the French Broad Valley early this morning, while additional
showers over the Piedmont continue to push east of the CWA. The most
likely area for additional development will be in aforementioned
upslope locations, but with the flow being so weak, and gradually
depleting moisture anticipated, chances for additional development

Otherwise, clearing skies and diminishing winds expected this
morning. Lows will range from near to 5 degrees above normal. A
somewhat tight pressure gradient will remain across the area later
today between the departing cold front and approaching high
pressure. Gusty winds are likely to redevelop across the mountains
with low end gusts possible elsewhere. Skies should become mostly
sunny with dry conditions. Highs will be slightly below normal
across the mountains and slightly above normal elsewhere.

&&

.SHORT TERM /TONIGHT 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 230 PM EDT Thursday...

Key Messages:

1) Shower and thunderstorm chances may linger on Monday

2) There is low confidence regarding the sensible weather rest of
the long term period due to model disagreement

Shower and thunderstorm chances may linger through Monday so have
chance PoPs (25%-30%) across the mountains with slight chance PoPs
(22%-24%) elsewhere. Models diverge regarding both the upper-level
and lower-level patterns Tuesday through Thursday as the latest GFS
shows a trough tracking across the Southeast while the latest ECMWF
and Canadian show upper-level ridging over the region. The GFS
solution would result in shower and thunderstorm chances returning
Tuesday and lingering through Thursday, while the Canadian and ECMWF
solutions would result in dry weather Tuesday into Wednesday night
thanks to sfc high pressure building into the region. The Canadian
and ECMWF then show a southern stream system bringing shower and
thunderstorm chances back to the region by late Thursday. Thus,
confidence remains low regarding the majority of the long term forecast
period. Capped PoPs to slight chance (15%-24%) area-wide
Tuesday through Wednesday night. Went with chance PoPs (25%-30%)
across the mountains on Thursday, with slight chances PoPs
(20%-24%) elsewhere. Highs should be a few degrees below climo
on Tuesday, becoming a few degrees above climo the rest of the
long term forecast period. Lows will be near climo to a few
degrees below climo on both Tuesday morning and Wednesday
morning. Lows should trend a few degrees above climo Thursday
morning

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Drier air will gradually filter into the area
from the west through the morning. Areas of VFR stratocu will
otherwise waft over the area, while light winds are also expected in
most areas. Although low level moisture remains plentiful across the
area early this morning, the above factors are expected to preclude
development of widespread fog across the Terminal Forecast Area this
morning. Having said that, some BR has already been observed in the
mtn valleys since last evening, and a tempo for 4SM is carried at
KAVL toward daybreak. Otherwise, VFR is forecast through the period.
The drier air will result 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.

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.

&&

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

&&

$$

SYNOPSIS...AR
NEAR TERM...CP/JDL/RWH
SHORT TERM...AR
LONG TERM...AR
AVIATION...JDL