Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 161101

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
701 AM EDT Sat Sep 16 2017

Weak high pressure will persist across the region into early next
week, keeping rain chances low. Hurricane Jose is forecast to remain
over the Atlantic and appears unlikely to impact the Carolinas or
Georgia.  A more summer like pattern will highlight the weather next
week with diurnal rain chances and above normal temperatures


As of 650 AM EDT: IR satellite imagery and surface observations
around daybreak continue to indicate a mid deck of clouds across
mainly the NC piedmont under a mid-level inversion at 8 to 10 kft.
Foggy conditions have developed in the mountain river valleys and an
SPS has been issued to address visibilities locally less than one
quarter mile in fog.

Otherwise, 1022 mb surface high pressure centered over the central
Appalachians this morning will continue to nose southward across our
region today through tonight, as Hurricane Jose remains well east of
the GA coastline. Other than the aforementioned shallow moist layer
beneath the mid-level inversion, profiles will remain relatively
dry, with light northerly flow around the high pressure to the
north. The models do continue to produce light QPF along the eastern
slopes of the mountain in weak convergence this afternoon, but
shower coverage should be quite limited given the persistent
mid-level inversion. Will confine any afternoon PoPs to slight
chance along the eastern slopes. Max temps will be about a category
above climo this afternoon, with mins one to two categories above
climo tonight. Another round of mountain river valley fog is likely
late tonight.


As of 200 AM EDT Saturday:  Little change in the short term period
of the fcst as broad deep layer ridging continues to dominate the
synoptic pattern on Sunday morning, while TC Jose remains a few
hundred miles off the Carolina coastline.  Jose looks to continue
tracking northward leading to virtually no impact for northeast GA
and the Carolinas, other than reinforcement of the drier nely flow
thanks to the northeast surface high.  Otherwise, a cold front
associated with an Upper Midwest shortwave will extend southward
through the Plains states.  Pattern evolution on Sunday and Monday
is rather uneventful as the only thing to note is the persistence of
the deep ridge, and further northward advancement of Jose, possibly
posing some threat to the New England shores.  As for the fcst
closer to home, token below climo pops over the high terrain, dry
elsewhere with temperatures returning to near or slightly above
normal levels amongst abundant sunshine.


As of 215 AM EDT Saturday:  The medium range fcst period kicks off
on Tuesday morning as upper ridging flattens slightly over the
eastern CONUS, while a weak shortwave moves into the OH Valley
region as it`s associated cold front stalls to the west.  At the
surface, high pressure centered over the northeast will be weakening
as well thanks to falling heights from the aforementioned upper
shortwave, as well as gradient impacts from TC Jose which looks to
be moving up the east coast a few hundred miles offshore.  That
said, this weak upper shortwave doesn`t look to completely erode the
surface ridge as it re-strengthens on Wednesday while the H5 ridge
axis amplifies further.  By late week, confluent flow around the
amplified ridge across the eastern CONUS is expected to strengthen
the surface anticyclone even more with a nearly 1030mb high centered
over Nova Scotia by Friday evening, with nely/ely dammed flow
extending southward in lee of the central/southern Appalachians.
All in all across northeast GA and the western Carolinas, pops will
gradually increase each day through the period to account for
diurnally favored mtn convection, however still remaining at or
below climo levels.  At this point, pops outside the mtns are held
low given the expected subsidence from deep ridging, thus no
mentionable pops east of the high terrain through Thursday with only
slight/chance levels working in by Friday.  As for temperatures,
expecting a gradual warming trend leading to highs each day a few
degrees above normal regionwide.


At KCLT and Elsewhere: A mid-level cloud deck at 8 to 10 kft
persists around KCLT, but some clearing of the mid clouds has
permitted lower stratus to form at KHKY around daybreak. This should
dissipate through 14Z. Mountain river valley locations will see LIFR
to VLIFR restrictions in low clouds and fog through at least 14Z
before scattering. Expect light northerly flow throughout the region
today with high pressure centered to the north of the area. A
VFR-level FEW to SCT cumulus field will develop with heating today,
and any ridgetop showers will likely stay away from the TAF sites.
Expect another round of low clouds/fog at KAVL again late tonight.

Outlook: Isolated, mainly high terrain diurnal showers will continue
through the late weekend into early next week. Morning mountain
valley fog/stratus are also expected each day.

Confidence Table...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       Med   62%     High 100%     High 100%     High 100%
KHKY       Low   56%     High 100%     High 100%     High 100%
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:




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