Area Forecast Discussion Issued by NWS Greer, SC
000
FXUS62 KGSP 160736
AFDGSP
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
336 AM EDT Sat Mar 16 2024
.SYNOPSIS...
Northwest flow rain showers along the Tennessee border will
taper off through daybreak. Drier conditions are expected today, but
rain chances will return on Sunday. Daytime temperatures will remain
warm and spring-like through the weekend. Drier and cooler
conditions will return early next week as Canadian high pressure
builds into the Carolinas.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 235 AM Saturday...The KMRX radar continues to pick up
scattered upslopw showers aided by convergence along a weak
quasi-stationary front draped over the west slope of the mtns
at this early hour. The few showers east of the mtns have
dissipated. The precip probs over the Smokies look really good
still, with a slow decay through sunrise. Extensive high level
cloudiness will keep temps mild, so lows will remain about 10 to 15
degrees above normal. At this late hour, its still difficult to say
what the extent of fog will be through daybreak given conflicting
evidence, but a few spots will become locally dense. Expect Vis
to be highly variable, thus an Advisory appears unlikely.
The weak boundary should drop down across the fcst area early
in the day with relatively little notice. Instead, our weather
looks like it will be relatively benign today as we are caught
under a confluent, nearly-zonal flow aloft. Most of the mid/high
clouds will be pushed off to the east this morning as the upper
jet shifts eastward. A few of the CAMs show an isolated shower
or two east of the mtns this afternoon associated with weak
convergence around a weak low pressure center on the boundary,
but the chances look too remote to include in the forecast at this
point. Temps should rebound this afternoon with more sun, climbing
up to about ten degrees above normal across the region. Not much
change for tonight either, as the boundary sags southward out of
the fcst area. The next rain chances will probably not reach the
area from the west before sunrise on Sunday. Low temps will stay
5-10 degrees above normal.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 230 AM EDT Saturday: Upper vort lobes will track over the
Carolinas the first half of the short term. The first lobe looks to
track directly overhead the western Carolinas Sunday morning and
afternoon, while the second lobe looks to track just south and east
of the forecast area (lifting across the eastern Carolinas).
Meanwhile at the sfc, a cold front will push across the western
Carolinas throughout the day Sunday, before pushing east Sunday
evening. This will allow cloud cover to increase, becoming broken to
overcast, as well as bring rain chances back through Sunday evening.
PoPs went up slightly, mainly across the southern half of the
forecast area, but went ahead and capped them to chance per model
disagreement. 00Z guidance generally agrees that light rain will
only skirt the southern zones, while the bulk of the precip remains
to our south and east. The exception is the 00Z ECMWF, which shows
rain pushing into most of the forecast area Sunday into Sunday
night. The 00Z HRRR and NAMNest both show light rain pushing across
the forecast area as well on Sunday, but the NAMNest is wetter with
higher coverage while the HRRR is drier with lower coverage. All
this to say, confidence on PoPs the first half of the short term is
low. Breezy NW winds can be expected across the mountains Sunday
into Sunday night along and behind the front. Highs on Sunday will
end up several degrees cooler than Saturday`s highs but remain warm
(especially east of the mountains) and still around 5-8 degrees
above climo. Lows Sunday night will be around 10-15 degrees cooler
than Saturday`s lows thanks to cloud cover decreasing from west to
east.
Dry Canadian sfc high pressure will build into the central and
southern US Monday into Monday night bringing a cooler and much
drier airmass to start the workweek. This will allow below normal
temps to finally return to the western Carolinas. Highs across
mountain valleys will range from the mid to upper 40s, with the
higher elevations only climbing into the mid 30s and lower 40s.
Highs east of the mountains will be slightly warming, ranging from
the mid 50s to lower 60s. With a tight pressure gradient developing
on Monday, breezy NW winds will develop across the forecast area
throughout the day, lingering through the evening hours. This will
lead to a brisk day, especially across the mountains where the
higher wind gusts are expected. The dry airmass and gusty winds will
also lead to fire wx concerns Monday afternoon, as forecast RH
values should drop into the 20s east of the mountains. Gusts still
look to remain well below Wind Advisory criteria at this time. It is
still looking like most of the forecast area will see freezing temps
Monday night. Freeze products will likely be needed across Northeast
Georgia (outside of Rabun and Habersham Counties), the SC Upstate
(outside of the SC mountains), the southern NC Foothills, and the
southern NC Piedmont Monday night as freezing temps still look like
a good bet (and since the growing season will have started in these
areas). Wind gusts will taper off east of the mountains Monday
night, but will remain elevated across the NC mountains.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 300 AM EDT Saturday: Dry conditions will linger through late
Thursday per the 00Z global model guidance, and thanks to sfc high
pressure being the main mesoscale feature. Below climo temps stick
around on Tuesday before above climo temps return Wednesday into
Thursday. A dry cold front may track across the forecast area on
Wednesday, but this will mainly lead to high temps on Thursday being
a few degrees cooler compared to Wednesday`s highs. Winds will
remain elevated, especially across the northern mountains, through
Wednesday morning before gradually tapering off Wednesday afternoon.
Low-end gusts will be possible east of the mountains on Tuesday
afternoon and again Wednesday morning into Wednesday afternoon, but
they should generally be lower compared to Monday`s gusts. Fire wx
concerns return again Tuesday afternoon with RH values dropping into
the 20s across most of the forecast area. RH values will recover
somewhat on Wednesday, but may still drop into the mid to upper 20s
east of the mountains. An upper low will track out of the Southern
Plains and into the Tennessee Valley Thursday into Friday. During
this timeframe, a sfc low pressure system will develop and lift
northeast out of the western Gulf Coast. Cold air damming looks to
develop across the western Carolinas ahead of the system Thursday
night into Friday thanks to a sfc high to the north. The CAD
combined with increasing rain chances throughout Friday should allow
below climo temps to return once again. Have Pops increasing from
chance on Thursday night to likely on Friday. Maintained likely PoPs
through late Friday night as most of the model guidance agrees that
widespread rain will stick around. Instability looks to be lacking
at this time, so do not have any thunder mentioned with this system.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Expect plenty of mid/high level cloudiness
overnight, which really adds a lot of uncertainty to the visibility
forecast. Low level moisture remains plentiful and favorable
for fog, but weak downslope flow as a boundary passes will be
working to dry us out. The Charlotte metro area might be the most
susceptible to fog formation through daybreak. Even if it does
form, the vis will likely be variable. Have included a TEMPO
for an MVFR restriction at KCLT for the hours before daybreak,
more or less as a placeholder. Once the inversion breaks, most
places will have scattered stratocu through the day with wind
coming around from N early to SW in the afternoon. Wind will go
light SW Saturday evening.
Outlook: Another front will cross the area on Sunday but with
less moisture to work with for precip or restrictions. Dry high
pressure builds with gusty winds, especially on Monday.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...AR
NEAR TERM...PM
SHORT TERM...AR
LONG TERM...AR
AVIATION...PM