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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 261443
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
943 AM EST Fri Feb 26 2021

.SYNOPSIS...
A cold front will remain stalled south of the region today as high
pressure builds over to the north. Gulf moisture will return over
the front today through tonight. The boundary will retreat northward
as a warm front through the weekend, with warmer temperatures
gradually returning. Another cold front will cross the area from the
northwest Sunday night through Monday with abundant moisture. Brief
drying is expected Monday night before unsettled weather likely
returns to the region through the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 935 AM Friday...sct to numerous light showers have spread
over roughly the western third of our CWFA over the past few hours
with the heavier showers still to our west. Still expecting the
sfc ridge to build in as the day progresses and keep temps from
warming little from what they currently are.

Otherwise, the increasing dynamical lift will combine with mech
lift over the srn NC mtns and produce decent rainfall rates with
rainfall amts adding up to arnd 2.0 inches in localized areas by
late this evening...and this could create some minor hydro issues
in this area. The WPC still has the area in a marginal risk for
excessive rainfall, which seems okay at least for the srn NC mtns
and srn BR. Elsewhere, rainfall amts will generally remain under
an inch thru tonight, with the srn most zones likely only receiving
a half inch or less of rainfall. Temps will fall during the day as a
cold cP airmass works in from the NE and high temps will be reached
arnd daybreak, then drop into the upper 30s to lower 40s by the
afternoon. The latest NAM is still more certain of an ice event
across the far nrn NC mtns, mainly Avery county this afternoon, as
noted by it/s quite cold partial thicknesses. The GFS on the other
hand has a cold partial thickness trof in the same area as well, yet
sigfnt/ly warmer. Thus, have blended the thermal profiles of these
two models and ran a top down approach for wintry precip. This gave
a couple tenths of ice accum across the higher elevs of Avery arnd
Beech Mtn, which makes sense given the amt of precip expected in
that area between 18z-00z. So, the winter weather advisory will be
continued for more of a -fzra concern with this package. Temps
tonight will also be non/diurnal as the wedge breaks down and a
strong warm nose aloft lowers to the sfc. Temps shud start rising
after midnight, but only a couple degrees leading to readings arnd
40 F most areas by daybreak Sat.
-- End Changed Discussion --

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 230 am EST Friday: Deep-layer southwesterly flow will set up
over the region by Saturday between a trough digging through the
Rockies to the west and a shallow ridge axis over the Atlantic to
the east. The lingering surface wedge boundary should retreat
northward through the day on Saturday, with modest rain shower
chances the best over the NC mountains and north of I-40. The
southwesterly upper flow will persist through weekend, and the
deeper moisture and forcing will continue to wrap mainly west and
north of the forecast area through much of the weekend ahead of an
approaching cold front. Lingering low-level moisture and occasional
upglide will likely lead to more cloudiness than not through the
weekend, but with thicknesses steadily climbing and maxes reaching
the upper 60s in the mountain valleys to lower or even middle 70s
east of the mountains Sunday afternoon.

Much deeper moisture along the frontal boundary sagging southeast
will arrive on Sunday night. Heavy rainfall could occur at times,
especially in the southern NC mountains, where a few nighttime
rumbles of thunder will be possible as well.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 230 am EST Friday: Progressive northern tier energy will brush
the region Monday through Monday night, while a closed southern
stream system remains much slower to move east from the Four Corners
region to north Texas. Ahead of the northern stream forcing, a cold
front and associated moisture will cross the region early Monday and
settle southeast of the area Monday night. Mainly morning PoPs will
pare away from the northwest by late Monday, but with uncertain
clearing of the southern tier Monday night depending on the
boundary`s progress. 1030+ mb surface high pressure will then build
from the Midwest to the mid-Atlantic coast Monday night through
Tuesday, spilling chilly thicknesses down across the region and
producing temperatures a couple of categories below climo in most
areas by Tuesday afternoon.

The southern stream system should open up and then reach the
southern Appalachians by Tuesday night, with a return of briefly
deeper moisture. The main question centers around how quickly
upglide moisture returns ahead of this wave, with PoPs increasing
through Tuesday, but with maximum PoP values more likely Tuesday
night. Brief ptype issues will be possible in the NC mountains
depending on the precipitation timing.

Model solutions then become out of phase Wednesday through Thursday,
with the ECMWF featuring a central CONUS trough while the GFS
indicates a shallow ridge axis moving east. However, sensible
weather differences are actually not that stark despite these
differences given a westerly component to the low-level flow and
somewhat limited moisture. So, will feature mainly low end chance
PoPs for now on Wednesday and Thursday with temperatures rebounding
to near, or slightly above, climatology.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
At KCLT and elsewhere: VFR flight conds currently will begin to
deteriorate aft sunrise across most TAF sites as hipres ridging in
from the NE will interact with a moist frontal boundary thru the
period. Expect MVFR conds to persist at KCLT a little longer than the
other TAF sites, but then drop into IFR/LIFR late evening and persist
thru the period. Across the other terminals, IFR conds will likely
develop arnd the earlier afternoon and be maintained thru the
evening. Periods of heavier rain and lower VSBY associated with
passing upper energy will cross the FA from the west and have
short-lived TEMPO groups to account for this possibility generally
beginning and ending arnd mid to late morning. Winds outside the mtn
valleys will become defined more ne/ly with low-end gusts today as
the sfc high builds in.

Outlook: Widespread precip and associated flight restrictions
developing today are expected to persist into the weekend and possibly
extending into early next week.

Confidence Table...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       High  80%     High  91%     High  95%     High  93%
KGSP       Med   73%     High  84%     High  83%     High  91%
KAVL       Med   67%     High  95%     High  84%     Med   78%
KHKY       High  80%     High  80%     High  97%     High 100%
KGMU       Med   70%     High  84%     High  82%     High  90%
KAND       Med   63%     High  82%     Med   79%     High  86%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:

www.weather.gov/gsp/aviation
-- End Changed Discussion --

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Winter Weather Advisory until 10 PM EST this evening for
     NCZ033.
SC...None.

&&

$$
SYNOPSIS...HG
NEAR TERM...JPT/SBK
SHORT TERM...HG
LONG TERM...HG
AVIATION...JPT/SBK