Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
867
FXUS62 KGSP 280747
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
347 AM EDT SUN AUG 28 2016

.SYNOPSIS...
Surface high pressure will remain over the region early this 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.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 325 AM: IR satellite images indicated that a large area of mid
to high clouds will push SW across the region early this morning. MOS and
latest near term guidance indicates fog and low clouds will develop
across the region over the next several hours. However, it appears
that the mid and high clouds will linger over the region longer than
guidance indicates. I will limit mention of restrictive fog and
ceilings to dawn. Drier air under a deep H5 ridge should build SW
across the western Carolinas, as a ridge of sfc high pressure slowly
increases from the mid-Atlantic states. Based on the position and
timing of the drier air, the potential for deep convection across
the foothills and Piedmont appears very low. Lingering moisture
across the mtns and extreme NE GA may support iso to sct
thunderstorms late this afternoon into the early evening. Winds
through today and tonight should remain light from the ENE. Using a
blend of MOS, I will forecast mid 80s within the mtn valleys to low
90s across the Piedmont.

Tonight, the low located between the Carolina coast and Bermuda will
track slow west overnight. GFS and ECMWF indicate that dry air
should remain over the middle of the forecast area. However,
moisture associated with the low should begin to build west across
the eastern Carolinas. I will forecast cloud cover to increase from
the west after midnight. The combination of the dry environment and
little to no forcing should favor dry conditions tonight. Low
temperatures are forecast to range from the mid 60s across the mtns
to low 70s across the Piedmont.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 315 AM Sunday, The subtropical ridge will continue to dominate
much of the southern 2/3 of the Conus through the short term. Weak
surface ridging is expected to maintain low level NE flow and a
relatively low theta-E air mass across the forecast area through the
period. Therefore, the diurnal convective cycle looks to be a bit
less active than typical of late summer. The best chances will exist
over the mtns, and across the southeast/southern areas, as moisture
and showers circulating around a weak tropical wave stalled near the
NC coast may make a run for our Piedmont zones, especially late
Monday into Tue. However, chances even in those areas will not be
high, 20-30 percent at best through the period. Temps will generally
be near climo.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 320 AM Sunday, the tropics remain quite the challenge for
human and computer forecasters during the medium range. The headline
du jour is that the 00Z ECMWF now carries the disturbance currently
centered north of Cuba into the warm waters of the Gulf by Tue,
where it promptly develops it into a major tropical cyclone just off
the west coast of Florida by the end of the week. Interestingly
enough, the latest GFS is similar to the ECMWF in terms of the track
and timing of this feature. In fact, between about 18Z Thu and 18Z
Friday, both models are virtually identical with surface low
placement. It`s just that the ECMWF is 15-20 mb stronger. Meanwhile,
the Canadian model remains the most consistent model in landfalling
a major cyclone along the Gulf Coast later this week, although the
timing of this has been erratic and the 12Z/27th run appeared to
back away from this scenario.

However, as all this is occurring, heights are falling along the
eastern seaboard, allowing a somewhat modest frontal boundary to
drop toward the Southeast coast by the end of the week. The effect
of this should be to keep any impacts associated with the tropical
cyclone along the coast (the Canadian solution notwithstanding). In
fact, a perfect prog of the ECMWF (ha!), which depicts a hurricane
moving northeast just off the Carolina coast next weekend would
likely result in a subsidence-induced pleasant/breezy late week
across our forecast area. Nevertheless, with such rampant
uncertainty, we opted to make minimal changes to that part of the
forecast attm, allowing the chance pops for convection associated
with the frontal zone to stand. Temps will begin the period a bit
above climo, falling back to near or even below climo in the
vicinity of the frontal zone by the end of the week.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: As of 2 am, a thunderstorm with frequent
lightning was tracking across KCLT early this morning. Based off the latest
TCLT trends, this thunderstorm should move east of the terminal by
230 am. IR satellite images indicated that a large area of mid to
high clouds will push SW across the region. MOS and latest near term
guidance indicates fog and low clouds develop across the region over
the next several hours. However, it appears that the mid and high
clouds will linger over the region longer than guidance indicates. I
will limit mention of restrictive fog and ceilings to dawn,
highlighted with a TEMPO. KHKY should see the greatest chc for MVFR
ceilings, I will highlight with a FM group between 13z to 15z. Drier
air under a deep H5 ridge should build SW across the western
Carolinas, as a ridge of high pressure slowly increases from the
mid-Atlantic. Based on the position and timing of the drier air, the
potential for deep convection across the foothills and Piedmont
appears very low. Lingering moisture across the mtns and extreme NE
GA may support iso to sct late afternoon to early evening showers
and thunderstorms. Winds through today and tonight should remain
light from the ENE.

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...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       Med   67%     Med   77%     High 100%     High 100%
KGSP       Med   76%     Med   70%     High  91%     High 100%
KAVL       Med   78%     High  80%     High 100%     High 100%
KHKY       Med   79%     High  82%     High 100%     High 100%
KGMU       High  99%     High  80%     High  83%     High 100%
KAND       High  93%     High  86%     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...LEV
NEAR TERM...NED
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...NED



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.