321
FXUS62 KGSP 061840
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
240 PM EDT Thu Jun 6 2024

.SYNOPSIS...
Scattered showers and thunderstorms will continue through this
evening. Canadian high pressure will build into the area Friday and
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 FRIDAY/...
As of 205 PM Thursday: Convection ongoing across the area at this
time, ahead of a short wave and cold front. Latest CAM guidance
agrees on a better chance of convection across NC than NE GA or the
Upstate. There`s a little of a split decision on chances across NE
GA and the Upstate. Given the current and forecast coverage, have
higher chance PoP across NC with lower chance values for the Upstate
and NE GA. Meso analysis shows instability and low level shear are
similar to what was forecast, but DCAPE values have been slower to
increase. An isolated severe storm or two is still possible,
especially if DCAPE does increase, with damaging straight line winds
the main threat. Gusty winds will continue through the afternoon
even outside of thunderstorms.

Convection should taper off this evening with loss of heating.
However, lingering moisture and developing NW flow behind the
departing cold front could lead to isolated showers along the TN
border into the early overnight hours. Otherwise, clearing skies and
diminishing winds expected overnight. Lows will range from near to 5
degrees above normal.

A somewhat tight pressure gradient will remain across the area
Friday 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 /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 200 PM EDT Thursday...

Key Messages:

1) Dry conditions linger through Saturday night

2) Shower and thunderstorm chances return Sunday

The short term starts off dry thanks to a sfc high building into the
Southeast from the west. A shortwave will track overhead Saturday
afternoon and evening, mainly increasing cloud cover slightly. A
cold front will approach out of the west Saturday night into Sunday
morning before tracking across the western Carolinas Sunday into
Sunday night. This front will allow shower and thunderstorm chances
to return starting late Sunday morning, with activity lingering
through Sunday night. Have the highest PoPs contained to the
mountain zones (40%-54%) with lower PoPs elsewhere (15%-40%). Latest
global model guidance generally agrees that there should be ~35-45
kts of deep shear on Sunday. However, guidance diverge regarding the
amount of SBCAPE during peak heating on Sunday. The NAM is the most
bullish showing 1,500+ J/kg of SBCAPE mainly east of the NC
mountains while the GFS/Canadian/ECMWF generally show 1,000 J/kg or
less of SBCAPE. So, isolated strong to severe storms are possible on
Sunday but confidence on the severe potential will be lower than
usual thanks to model disagreement. Highs will be near climo to a
few degrees above climo on Saturday, becoming 3-5 degrees above
climo on Sunday. Lows Saturday morning will start out a few degrees
below climo, becoming a few degrees above climo Sunday morning and
Sunday night thanks to cloud cover.

&&

.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 /19Z THURSDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Convection beginning to develop across the
area ahead of a cold front. CAM guidance shows better chance over
the NC sites than the SC sites. Have kept a TEMPO in all areas given
the radar presentation but toned down some of the impacts except for
KCLT where CAMs show the highest chance. Gusty SW to WSW winds
continue ahead of the front with a wind shift to NW but diminishing
wind behind the front. Drier air moves in behind the front as well
limiting the chance of restrictions overnight. Dry conditions with
NW wind continues Friday. KAVL will see NNW wind overnight with
gusts redeveloping on Friday.

Outlook: High pressure will linger through Saturday before another
frontal system moves in on Sunday bringing a chance of precipitation
and associated restrictions. These may linger into Tuesday should
the front stall near our area.

&&

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

&&

$$

SYNOPSIS...AR
NEAR TERM...RWH
SHORT TERM...AR
LONG TERM...AR
AVIATION...RWH