Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 280249

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1049 PM EDT SAT AUG 27 2016

Surface high pressure will build over the region through the
weekend, keeping temperatures above average through next week. A
frontal boundary will push through by the end of the next work week,
though a lack of moisture will keep rain chances near or below
normal for most of the week. The tropics remain active as we near
the peak of the season...though no systems appear to be a threat to
our area at the current time.


As of 1045 PM EDT Saturday:  Convective coverage continues to
decrease with loss of heating this evening.  Thus, tweaked pops in
the immediate near term to account for recent radar trends and
current analysis.  Also adjusted t/td and sky through the overnight
by way of consshort which still favors increasing low stratus by
daybreak.  Otherwise, removed all hazard wording from the HWO with
the exception of extreme portions of northeast GA, the western
Upstate, and the southwest NC mtns where current weakening tsra is

At 200 PM Saturday: An upper ridge will drift northeast from VA to
the NJ coast by Sunday, while a weak upper low drifts from the Gulf
Stream toward the SC coast. Modest upper level divergence west of
the upper low is expected to move inland toward the southern Blue
Ridge on Sunday

At the surface, a band of low level moisture is expected to drift
west from the Piedmont to the Blue Ridge this afternoon and evening.
Instability will be sufficient for convection, with enough downdraft
cape present for a few damaging wind gusts. Convection may be slow
to taper off this evening as instability lingers. Another round of
convection is expected again on Sunday, perhaps supplemented by the
modest aforementioned upper divergence. This activity could end as
early as late afternoon however if a dry slot moves inland to the
east of a band of coastal moisture. Temperatures will generally
run slightly above normal.


As of 140 PM Saturday: A weak offshore Atlantic circulation may
migrate west toward the SC/GA coast on Monday as a weakness develops
in the mid level ridge and the nose of surface high pressure draped
across the region. Low and mid level drying will continue to work
into the area from the NE and this will translate into very limited
surface based instability and below climo PoPs - shunted mainly
toward far southern/southwestern parts of the CWA during the
diurnally favored period. Monday morning mins will continue well
above climo, with maxes at or just above climo in the NE flow.

Most of the vorticity and upper divergence with the approaching
offshore system will likely stall along the coast through Tuesday.
Generally easterly to northeasterly flow is expected to continue,
but without much of a corresponding increase in Atlantic moisture.
Expect scattered ridgetop convection to redevelop Tuesday afternoon
in weak mountain wind convergence. Temps may rise a notch over
Monday values.


As of 200 PM EDT Saturday...the medium range picks up on 00Z
Wednesday with the area under the influence of general height falls.
An open wave that is currently being monitored by the National
Hurricane Center for tropical development (Invest 91L) will begin to
near the coastal Carolinas Wednesday morning, though recent model
runs suggest that only a modest increase in moisture could occur in
our area before a frontal boundary associated with an upper trough
sweeps the weak system out into the northern Atlantic. As far as
Invest 99L is concerned, the majority of global models do not
develop it to any noticeable extent, and keep it on a track that
would have almost no influence over our area. Both systems will
continue to be watched, but the likelihood of tropical impacts
through the extended period still looks quite low at the current

As far as sensible weather is concerned, northeasterly flow at the
surface will keep the CWA relatively warm and dry Wednesday through
Friday. Guidance now disagrees on the timing of a frontal boundary
that approaches the area on Friday, though the front is generally
weak in most models. Without much moisture to work with, it does not
generate much QPF response, so pops were kept just below climo
through the end of next work week. Heights rise on Friday briefly
before a couple of shortwaves cross over the southern Appalachians
next weekend, and with the surface flow taking on a more
southeasterly component, the upper support coupled with better
moisture suggests that pops should be raised to near climo by the
end of the period. Max temps are above average for most of the
medium range, though modest height falls and an increase in sky
cover/pops led to max temps being decreased to normal levels by next


At KCLT and elsewhere: VFR/MVFR and possibly IFR at all sites this
evening associated with a plume of moisture advection from the e/ne
which will favor the development of low stratus.  Initialized tafs
with vcts/vcsh or tsra tempos to account for scattered convection
spread about the region early this evening.  Winds are a bit vrb as
outflow boundaries race across the fcst area from various
directions.  That said, the prevailing wind should remain out of the
ese before backing ne through the evening/overnight.  Low stratus is
progged to develop at all sites by mid morning with cigs falling to
mvfr/ifr.  Not all that confident in fog this evening as nocturnal
cooling will be stunted a bit due to the a fore mentioned stratus.
Winds will increase out of the ne by daybreak with low end gusts
possible into the afternoon at the piedmont sites.  Skies will sct
by mid morning leading into mid/high clouds at KHKY/KCLT where drier
air will reside, however a few low cu and perhaps shra/tsra will be
possible over the mtns as well as at KAND.

Outlook: Deep ridging will persist across the region through the
start of the new work week. Diurnal convection will be favored each
day with the best chances residing over the mtns/fthills.  Patchy
fog will be possible any morning following a late afternoon to early
evening shower or thunderstorm.

Confidence Table...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       High 100%     Low   29%     High  84%     High 100%
KGSP       High 100%     Low   51%     High  81%     High 100%
KAVL       High 100%     Low   30%     Med   76%     High 100%
KHKY       High  95%     Low   24%     High  86%     High 100%
KGMU       High 100%     Med   63%     High  80%     High 100%
KAND       High 100%     Low   57%     High  83%     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:




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