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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 171056
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
656 AM EDT Tue Sep 17 2019

.SYNOPSIS...
A cold front will drop southward through the area today and tonight,
with cool, surface high pressure building in behind this feature,
and remaining in place through the end of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 655 AM EDT Tuesday: Main update for the 12Z TAF issuance
along with minor adjustments made to temperatures to coincide
with latest trends, as the rest of the forecast remains well on
track. Aside from patchy mountain valley fog, expect conditions
to remain dry and quiet across the area this morning, with
temperatures in the low to upper 60s.

As Hurricane Humberto continues to churn well off (and slowly away
from) the Carolina coast this morning, a weak backdoor cold front
just to the north will drop down through the area today, as upper
ridging continues to shift eastward overhead. As a result, expect
increasing clouds today, with the potential for isolated showers and
thunderstorms. Into tonight behind the front, as showers/tstorms
gradually taper off, cool sfc high pressure will begin to build in
from the NE - the beginning stages of the wedge scenario on tap for
rest of the week. Temperatures today will be above normal once
again, but the warmest day of the rest of the work week.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 300 AM EDT Tuesday: The short term begins Wednesday morning
with upper ridging stretching from the TX Gulf Coast to the Great
Lakes, Humberto off the East Coast moving toward Bermuda and slowly
phasing with a deep trough off eastern Canada, and another trough
pushing into the Pacific Northwest. Surface high pressure in place
over eastern Canada under the confluent flow aloft will dam down the
eastern slopes of the Appalachians, with a marked change in
temperatures in store...10 to in some areas almost 15 degrees cooler
for highs on Wednesday than what we`ll see today. Orographic lift
combined with a little wave moving down the northerly flow aloft
will lead to some precip chances especially across the mountains,
though certainly not a wash-out. Much cooler temperatures for
Wednesday night as well.

The upper ridge will elongate to the northeast as we move into
Thursday, but the damming will remain even as the parent high slides
south toward Long Island. Another really beautiful day in store for
Thursday with skies clearing and highs again 3-5 degrees below
seasonal normals.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 310 AM EDT Tuesday: Damming high will be in place as we move
into the extended, but with the upper ridge continuing to shift
east, the high will slide toward the Carolinas and continue to
moderate as it does so. Northeasterly winds will shift around to
southeasterly as the high works toward the region. As we move into
the weekend, the western trough will push east along the northern
tier, forcing the upper ridge to stretch E-W across the South and
Gulf Coast, and the surface high will push just offshore. Expect a
slow warming trend through the period, such that by early next week
we`ll be back 5-7 degrees above normal. At the end of the period, a
weakening cold front will be approaching the area and may bring some
showers to the mountains, but otherwise no rain expected through the
period.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Aside from patchy mountain valley fog this
morning, expect VFR to prevail at all TAF sites through the morning
hours. This afternoon, expect increasing coverage of VFR cloud cover
with isolated to scattered showers and thunderstorms as a weak back
door cold front drops southward through the area. SHRA/TSRA activity
could linger into the overnight hours, but given lower confidence,
have not highlighted this in going fcst. Cigs will gradually lower
per latest guidance, to MVFR late overnight into, with patchy areas
of fog possible. Winds overall will NE AOB 5 kts, increasing to AOB
10 kts tonight.

Outlook: Anticipate the return of VFR by Wednesday afternoon. Dry
high pressure builds in for the end of the week, with just some
mountain valley fog each morning for restrictions.

Confidence Table...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       High 100%     High 100%     High 100%     High  80%
KGSP       High 100%     High 100%     High 100%     High  90%
KAVL       High 100%     High 100%     High 100%     Low   58%
KHKY       High 100%     High 100%     High 100%     High  95%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     High 100%     High 100%

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...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...SGL
NEAR TERM...SGL
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...SGL