National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 260754
AFDGSP

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

.SYNOPSIS...
-- Changed Discussion --
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.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Cloud cover will increase this morning as the FA remains in a sw/ly
channeled flow aloft while sfc hipres ridges in from the NE. Expect
precip to begin across the NC mtns and NE GA arnd daybreak and
become more widespread across the rest of the FA throughout the day
as pockets of ulvl vort energy traverse the region.

The increasing dyno 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 u30s to l40s 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/...
-- Changed Discussion --
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.
-- End Changed Discussion --

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
-- Changed Discussion --
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.
-- End Changed Discussion --

&&

.AVIATION /08Z 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...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       High  91%     Med   77%     High  89%     High  97%
KGSP       High  90%     Med   73%     High  83%     High  91%
KAVL       High  80%     Med   69%     High  94%     High  85%
KHKY       High  90%     Med   72%     Med   79%     High  93%
KGMU       High  90%     Med   72%     High  83%     High  91%
KAND       High  90%     Med   67%     Med   78%     High  83%

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 from 7 AM this morning to 10 PM EST
     this evening for NCZ033.
SC...None.

&&

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