Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 181719
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
119 PM EDT Mon Mar 18 2024

.SYNOPSIS...
Drier and cooler conditions into Tuesday as Canadian high pressure
moves over the Southeast.  Warmer temperatures return by mid-week
with continued dry weather.  A low pressure system will bring cooler
temperatures and rain chances back on Friday, with rain chances
potentially lingering into early Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Noon Update...The fcst remains in good shape this afternoon. Fire
danger remains a concern this afternoon/evening as a good overlap of
low RH and gusty winds will occur across the NC mtns and fthills. A
Fire Danger Statement remains in effect until 800 PM.

Previous Forecast...The main concern over the next 24 hours
will be the cool and dry continental air mass moving in behind the
front today and tonight. A strong short wave diving down across the
central Plains will help to carve out a deeper mid/upper trof over
the East through tonight, with the trof axis swinging through the
region this evening. In general, the short wave will bring only weak
forcing and should also be moisture-starved, thus a dim view is
taken of the GFS depiction of precip across the Charlotte metro area
late in the day. The CAMs might have the right idea in that a few
showers could develop as the wave passes, but they would be more
isolated and not likely to produce measurable rainfall. The fcst
will keep less than 15% precip chances there. Mid/high clouds ahead
of the wave will help to keep high temps on the order of five
degrees below normal. The dewpoint fcst is tricky because of the
cloud cover, but indications are that we should be able to mix
fairly deeply this afternoon. Have leaned toward the drier guidance
for the RH, which means we continue to have the afternoon RH
bottoming out in the 20-25 percent range east of the mtns and down
to 25-30 pct in the mtn valleys. Fortunately, wind gusts will not
pick up until this evening. See the Fire Weather section.

As for tonight...the moisture looks relatively meager along the TN
border behind the wave as well. If a few upslope showers manage to
develop, then the type would be snow owing to the cold air mass,
as thickness really tumbles behind a secondary boundary that
crosses with the short wave, but for now the chance is too small
to mention. High pressure will build into the region overnight
with enough of a pressure gradient to keep a NW breeze, but the
air mass is cold enough to bring low temps down below freezing
across almost all of the fcst area outside of some of the larger
lakes and urban heat islands. The guidance lends enough confidence
to convert the Freeze Watch to a Freeze Warning for tonight.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 230 AM EDT Monday: With temps remaining below freezing across
the forecast area early Tuesday morning, and with breezy NW winds in
place (especially across the mountains), it will be a brisk start to
the day. Wind chills in the teens are expected across the mountains,
with wind chills in the low to mid 20s east of the mountains. The
higher elevations in the NC mountains may see wind chills ranging
from a few degrees below zero to the single digits. The Freeze
Warning will remain in effect through mid-morning across the SC
Upstate, portions of northeast GA, and the southern NC Foothills and
Piedmont as the growing season has started in these areas. Temps in
these zones should rise above freezing around 10 AM. Temps likely
won`t rise above freezing across the NC mountains until the late
morning to early afternoon hours. Winds will gradually turn W`ly
across the mountains and SW`ly east of the mountains by the early
afternoon hours on Tuesday. Breezy winds and the dry airmass will
allow RH values to dip into the upper teens to mid 20s across most
of the forecast area Tuesday afternoon leading to another round of
fire wx concerns. Low-end wind gusts will continue through late
Tuesday night across most of the forecast area. Despite plentiful
sunshine on Tuesday, highs will remain 4 to 9 degrees below climo.
Lows Tuesday night should remain above freezing east of the
mountains and near or just below freezing across the mountains.
Thus, no additional freeze products should be needed as the growing
season has not yet started in areas where freezing temps are
expected.

Warmer temps return on Wednesday despite a dry cold front tracking
across the CWA. Sunny skies and SW`ly winds ahead of the front will
allow high temps to climb back into the upper 60s to lower 70s east
of the mountains, which is around 4-8 degrees above climo. The front
will keep breezy winds in place across the mountains on Wednesday,
with wind gusts returning east of the mountains by late Wednesday
morning. Warmer temps and breezy winds will allow RH values to drop
into the mid 20s and 30s across much of the forecast area Wednesday
afternoon. Although RH values will have recovered a bit compared to
Tuesday, fire wx concerns will return once again. Lows Wednesday
night will be a few degrees warmer compared to Tuesday night`s lows,
and near climo to a few degrees below climo. Cloud cover will
increase slightly Wednesday night as the next system approaches out
of the west.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 300 AM EDT Monday: Temps will be slight cooler, mainly east of
the mountains, on Thursday behind the aforementioned dry cold front.
Winds will be lighter on Thursday, but RH values may still fall into
the mid 20s and 30s across much of the forecast area. If this trend
holds, we may have yet another day of fire wx concerns. Highs on
Thursday should end up around climo to a few degrees above climo.
Clouds will continue to gradually increase Thursday into Thursday
night, becoming mostly cloudy by daybreak Friday. This will lead to
lows around 3 to 6 degrees above climo Thursday night. A sfc high
centered over eastern Canada will extend down into the Carolinas
thursday night into Friday, allowing cold air damming to develop
ahead of an approaching low pressure system. The 00Z ECMWF is once
again trending towards a wetter solution, better lining up with the
00Z GFS and Canadian. Have PoPs ramping up late Thursday night into
Friday afternoon and lingering through Friday night, but capped PoPs
to chance for now. All models continue to agree that instability
will be lacking, especially with CAD in place, so will maintain the
no thunder mention this update. With widespread rain and CAD
limiting daytime heating, blended in some of the NBM 10th percentile
for high temps Friday afternoon. This led to temps around 10 to 13
degrees below climo on Friday. Temps may need to be lowered further
on Friday, but we will have to see how models trend in the coming
days. With widespread cloud cover and rain lingering through Friday
night, lows should end up a few to several degrees above climo.

The low pressure system will gradually lift northeast away from the
western Carolinas Saturday, allowing any lingering rain chances to
taper off throughout the day. Thus, capped PoPs to slight chance for
now as some timing differences remain between the 00Z model
guidance. Warmer temperatures can be expected on Saturday thanks to
gradually decreasing cloud cover and diminishing rain chances. Dry
sfc high will gradually build in from the north on Sunday leading to
drier conditions and lingering warm temperatures.

&&

.AVIATION /17Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: VFR conds will continue across all sites thru
the period. Strong high pressure will maintain moderate nw/ly winds
with gusts developing this afternoon into the later evening hours.
Clouds remain high-based with clearing conds after midnight
associated with a passing upper s/w trof. More westerly winds weaken
on Tue with occasional low-end gusts probable by the late period.

Outlook: VFR conditions are expected thru the middle part of the
week. An active frontal system arrives Thursday night into Friday,
with rainfall and associated restrictions possible.

&&

.FIRE WEATHER...
A dry and cooler air mass will filter into the area today as a cool
Canadian high pressure builds in from the north. Afternoon mixing
heights will be slower to rise, however, expect dry air within this
layer to mix to down to the sfc today leading to RH values dropping
into the low to mid 20s mainly east of the mountains. However, the
mountain valleys will see RH values fall into the upper 20s and
lower 30s this afternoon. A tight pressure gradient will lead to
breezy NW winds today, with gusts ranging from 20 to 30 mph. In
coordination with local land managers yesterday evening, an SPS for
Increased Fire Danger was issued for the NC zones along the northern
NC mountains, Blue Ridge Escarpment, and foothills. Elsewhere, no
products have been coordinated as fuel moisture was deemed too high.
Wind gusts will diminish east of the mountains late this evening,
but wind gusts will linger across the North Carolina mountains. Wind
gusts look to increase tonight across the mountains, ranging from 25
to 40 mph, before decreasing slightly overnight into daybreak
Tuesday.

Fire weather concerns may return on Tuesday with RH values falling
into the upper teens to mid 20s across the western Carolinas and
northeast Georgia. Winds will start out NW Tuesday morning before
gradually turning to the SW (east of the mountains) and W/WNW
(across the mountains) Tuesday afternoon. Breezy winds are expected
again on Tuesday, but they will not be as strong as today`s winds,
ranging from 15 to 25 mph.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Freeze Warning from midnight tonight to 10 AM EDT Tuesday for
     GAZ018-026-028-029.
NC...Freeze Warning from midnight tonight to 10 AM EDT Tuesday for
     NCZ068>072-082-508-510.
     Increased Fire Danger until 8 PM EDT this evening for NCZ033-
     035-048>050-053-064-065-068-501>510.
SC...Freeze Warning from midnight tonight to 10 AM EDT Tuesday for
     SCZ008>014-019-104>109.

&&

$$

SYNOPSIS...AR
NEAR TERM...PM/SBK
SHORT TERM...AR
LONG TERM...AR
AVIATION...SBK
FIRE WEATHER...


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