Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 100753
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
253 AM EST Sun Dec 10 2017

.SYNOPSIS...
Below normal temperatures and dry conditions will persist through
the balance of the weekend and early next week. Very cold air and
mountain snow chances will return Wednesday as another system moves
through the area before another drying trend commences.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 230 AM EST Sunday: A downward trend was seen on satellite
imagery in the past hour or two as cloud top temps are warming
in the NW Flow Snow region, but still well down in the dendritic
growth zone, so no doubt we are still seeing snow flurries in spite
of the weak appearance in the radar imagery. The moisture is still
expected to pull out around daybreak, which should bring a quick
end to snow production. Some flurries may linger into mid morning,
but no additional accumulation should be expected after sunrise.

The next 24 hours should be relatively tranquil compared to what
we have been dealing with the past few days. The deep upper trof
over the east will gradually fill and lose amplitude. Another
short wave diving down into the trof will move past well to the
north late tonight. At the surface, high pressure over the deep
south will ridge in from the southwest. Sky should remain mostly
clear except for some passing mid/high cloudiness this evening
ahead of the previously mentioned upper wave. Temps will remain
well below normal.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
As of 230 AM Sunday: We should see a decent rebound in temps on
Monday, as a shortwave ridge briefly flattens the upper flow atop
the region. This will be short-lived, as another potent shortwave
trough will dive southeast across the Midwest and help dig another
deep longwave trough across the eastern CONUS Tuesday. A strong vort
lobe associated with this wave will cross the southern Appalachians
during the day on Tuesday, bringing a brief shot of moisture to the
TN border. Models continue to trend a little drier and faster with
this feature, resulting in what will likely be a sub-advisory level
NW flow snow event. CHC PoPs will be carried along the TN line, with
light snow accums. The rest of the CWFA will dry and mostly clear,
except perhaps Tuesday as the upper vort passes by and allows clouds
to break containment. Strong NWLY low-level CAA will bring temps
back down about 10-15 degrees below normal for Tuesday night and
Wednesday. The combination of cold temps and windy conditions may
result in sub-zero wind chills (advisory level) in elevations above
3500 ft. Wind gusts may also reach wind advisory criteria in spots.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
As of 230 AM EST Sunday: The medium range begins 00Z Thursday with
broad upper troughing over the eastern CONUS. Numerous embedded
shortwaves will round the trough Thursday...though with no impact on
sensible weather due to the lack of moisture. A clipper system will
swing through the Appalachians as the upper trough sharpens on
Friday, bringing a period of northwest flow snow to the NC/GA
mountains during the day on Friday.

By Saturday, the southeast will come under the influence of a
surface high, with drier air able to briefly work into the area and
remain in place through much of the weekend. The medium range
concludes just before another possible system arrives in our area,
though model agreement is quite poor on the timing and location of
the surface low, so pops were only slightly increased early Sunday.
Strong upper troughing will briefly flatten over the weekend,
moderating temperatures back to near/just below average through next
weekend.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
At KCLT: VFR through the period. Wind will stay NW thru daybreak
with an occasional few high based stratocu floating by. Wind comes
around to a more westerly direction after daybreak and have opted
for 250 deg thinking that weak lee troffing will bring the wind
around to S of W. Wind should stay WSW thru the end of the period.

Elsewhere: Similar to KCLT. The exception will be KAVL where low
clouds continue to blow up the Fr. Broad Valley, but cloud base
remains VFR. Will not rule out another snow shower moving in from
the TN border in the pre-dawn hours, thus the TEMPO through 10Z
to account for a possible brief MVFR visibility with a light snow
shower. Wind will be NW with occasional gusts.

Outlook: Dry conditions expected at all sites into early next
week. Another NW flow snow event could take place Tuesday and
Tuesday night, with some brief restrictions possible at KAVL.

Confidence Table...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       High  81%     High  82%     Med   68%     Low   56%
KGSP       Med   70%     Med   75%     High  83%     Med   64%
KAVL       High  94%     High  85%     Med   70%     High  87%
KHKY       High 100%     High  83%     Med   66%     High 100%
KGMU       Med   76%     High  86%     High  85%     Med   63%
KAND       Med   76%     Med   65%     High  90%     Med   61%

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

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Winter Weather Advisory until 10 AM EST this morning for
     GAZ010-017.
NC...Winter Weather Advisory until 10 AM EST this morning for
     NCZ033-035>037-048>053-056>059-062>065-068-069-501>510.
SC...Winter Weather Advisory until 10 AM EST this morning for
     SCZ001>003.

&&

$$
SYNOPSIS...Carroll
NEAR TERM...PM
SHORT TERM...ARK
LONG TERM...Carroll
AVIATION...PM



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