Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 151059
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
659 AM EDT Fri Mar 15 2024

.SYNOPSIS...
Rain showers are expected today ahead of a cold front, with
the potential for embedded thunderstorms. Rain chances will taper
off by Saturday morning, but may return Sunday. Daytime temperatures
will be warm and spring-like through the weekend. Below normal
temperatures return early next week before above normal temperatures
return mid-week. Drier conditions are expected much of next week
thanks to high pressure.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 645 AM EDT Friday: The main concern continues to be the
severe thunderstorm possibilities today. The first batch of deeper
convection has weakened and moved into northeast TN and the adjacent
areas of the NC mtns, while scattered showers and storms have
developed along an outflow down into northeast GA. Meanwhile,
the main band of thunderstorms continues to march to the east
across southeast TN and northern AL, with several warnings in
effect along the line. The stronger storms were developing into
the sfc-based CAPE plume nosing up across MS/AL, while the nrn
extent of the line weakens as it moves off the plume and into the
more stable air mass over the Great Valley. The bouyancy has not
been able to develop any farther east.

The band of convection is expected to move east across the srn
Appalachians this morning and then east of the mtns thru early
afternoon, driven east by vorticity and upper divergence associated
with the right entrance region of the upper jet...all well out ahead
of the sfc front. The CAMS have come into more of a consensus with
timing and with how this activity may present itself as it crosses
the mtns and pushes east, with most members of the HREF depicting
a linear feature worthy of some attention given deep layer shear
around 35 kt. At the same time, the guidance comes up short with
the available buoyancy, generally 500 J/kg or less at best but
more likely only a few hundred J/kg. The SPC has backed off with
the northern extent of the Day 1 Marginal Risk, and that seems
reasonable. I would not rule out some wind damage potential as the
main band comes east across northeast GA and Upstate SC. The bulk
of the convection will move east by early/mid afternoon, leaving
behind a rain-cooled air mass that will attempt to recover, but
most likely not. High temps have been lowered a few degrees based
on the guidance blend. For tonight, the sfc front drops in from the
NW and brings an increased chance of upslope enhanced precip along
the TN border, while most of the area east of the mountains has a
lowering precip prob. The wildcard will be how far south the daytime
convection moves before a wave develops on the outflow and possibly
brings more storms east across the srn edge of the fcst area thru
the evening hours. For now, we hold onto a relatively high precip
prob to the south to account for this. Temps will remain mild again.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 230 AM EDT Friday: What`s left of the NW flow rain showers
will taper off early Saturday morning. The cold front (from the near
term) will slowly push southward across the southern half of the
forecast area throughout the day Saturday, allowing cloud cover to
gradually decrease in coverage, becoming mostly sunny to partly
cloudy. Drier conditions are expected Saturday into Saturday night
but a few guidance sources (00Z ECMWF and Canadian) show rain
chances lingering. With both the 00Z HRRR and NAMNest showing dry
conditions during this timeframe, went with a dry forecast for now.
Despite the cold front, highs should end up around 9-12 degrees
above climo Saturday afternoon, with lows ending up around 8-10
degrees above climo (thanks a slight increase in cloud cover).

A secondary cold front will track across the forecast area on Sunday
while a southern stream disturbance lifts northeast out of the Gulf
Coast. How far north this system will track remains the main
question. The 00Z GFS and Canadian keep the disturbance far enough
south for dry conditions to persist over the western Carolinas.
However, the 00Z ECMWF and NAM show the disturbance tracking far
enough north that  rain chances would reach the portions of the
forecast area. Thus, went with chance PoPs nearly everywhere, with
the exception of the far northern tier of the forecast area. Have
the highest PoPs confined to the far southern tier of the SC Upstate
and northeast GA. This system will at the very least increase cloud
cover through Sunday evening. With increased cloud cover and the
potential for rain, highs will end up a few degrees lower compared
to Saturday, but still 5-9 degrees above climo. Cloud cover will
gradually decrease from west to east behind the departing front,
allowing lows across the mountains Sunday night to drop near climo.
Lows elsewhere will still end up 3-5 degrees above climo as cloud
cover east of the mountains will linger longer. Low-end wind gusts
should develop across portions of the NC mountains Sunday night.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 300 AM EDT Friday: Below climo temps finally return early next
week as dry Canadian high pressure sinks southward from the Great
Plains to the Gulf Coast. Highs on Monday should fall into the upper
50s to lower 60s east of the mountains, with the mid 40s to lower
50s across the mountain valleys. Higher elevations in the NC
mountains should only see highs reach into the mid 30s and 40s on
Monday! With breezy NW winds expected to develop on Monday, it will
be a brisk day, especially across the higher elevations of the NC
mountains. Wind gusts look to remain well below advisory criteria at
this time. With clear skies in place Monday night, lows should drop
below freezing across most of the forecast area. Since the growing
season will have started for the SC Upstate (with the exception of
the SC mountains), portions of northeast Georgia (Rabun and
Habersham being the exceptions), the southern NC Foothills and the
southern NC Piedmont, Freeze products will likely be needed. Winds
will gradually decrease Monday night, but will remain elevated
across the NC mountains. High temps on Tuesday should be a few
degrees warmer across the mountains, and a few degrees cooler east
of the mountains (compared to Monday). Breezy winds look to linger
across the mountains Tuesday, with gusts returning east of the
mountains Tuesday afternoon. Lows Tuesday night should be several
degrees warmer compared to Monday night, with only the NC mountains
seeing temps near or below freezing. Once again, wind gusts will
taper off east of the mountains Tuesday night, but will linger
across the NC mountains. Low RH values are possible each afternoon
on both Monday and Tuesday. This combined with breezy winds may lead
to increased fire danger.

Above climo temps return middle of the week, but dry high pressure
will linger over the region. Highs will rebound into the upper 60s
to lower 70s on both Wednesday and Thursday east of the mountains.
Highs across the mountain valleys should climb into the mid to upper
60s, with highs across the higher elevations climbing into the upper
40s and 50s. Breezy winds look to linger across the mountains once
again on Wednesday, with gusts returning east of the mountains
Wednesday afternoon. Low RH values combined with breezy winds, may
lead to increased fire danger again on Wednesday. Wind gusts finally
look to taper off Wednesday night across the forecast area. Lows
Wednesday night should be near or at freezing across the NC
mountains, with temps elsewhere above freezing. Lows Thursday night
should be above freezing across the entire forecast area thanks to
increasing cloud cover ahead of the next approaching system. This
system may increase rain chances as early as Thursday night, so have
chance PoPs in place starting around 00Z Friday. However, the bulk
of the rain looks to push into the region after Day 7.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: VFR thru mid-morning, with a light SW wind. A
line of convection with trailing stratiform rain is expected to
move eastward across the fcst area from mid-morning to early
afternoon. Instability is expected to be minimal and elevated
east of the mtns, so the thunderstorm chances remain difficult
to quantify, but the trend in the guidance supports keeping the
thunder in the fcst. Will employ a TEMPO to handle the TSRA,
centered on the most likely time period shown by the consensus of
several HRRR runs. The convection will bring the ceiling down to
MVFR at least temporarily, along with gusty SW winds. After a 3-4
hr period, the precip should move east and break up, so ceiling
should improve to VFR in the late afternoon or early evening. Wind
direction will not change much from SW. Low ceiling may persist
over the mtns thru the overnight.

Outlook: Low clouds could linger into Sunday morning. Another
front will cross the area on Sunday but the front will have less
moisture to work with for precip or restrictions. A couple of upper
disturbances could bring precipitation and restrictions Monday
and Tuesday. Gusty winds are more likely than precip each day.

&&

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

&&

$$

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


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