Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 230746
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
346 AM EDT Sat Sep 23 2017

.SYNOPSIS...
Drier and stronger high pressure will continue to build through the
weekend and persist through at least the middle of next week. In the
meantime, Tropical Cyclones Jose and Maria will remain off the east
coast.

&&

.NEAR TERM /THROUGH TONIGHT/...
A rather straightforward fcst is in store over the next 24-36 hrs.
Good confidence continues with a persistent synoptic scale pattern.
The main synop difference outside of a persistence type fcst for
today will be the nrn movement of Hurricane Maria, which is progged
to well northeast of the Bahamas by the end of the near term. The
nw/rn influence zone of Maria may enhance the already strong subs
over the area however. Meanwhile...continued dry BL air will adv in
from the NE due to an interaction of a 590 dm high and the remnants
of Jose. Thus...will expect a lower chance of convec today than
yesterday with the best chances, although low-end, confined to the
far sw/rn NC mtns and up and mtn spine within weak e/ly mech lift.
Limited sbCAPE will preclude much of a stg/svr threat and will
anticipate only a few general pulse tstms outside of isol/sct -shra.

Max temps shud have no problem reaching a cat or so abv normal while
mins also continue a few degrees above normal over the srn zones.
Drier llvl air working in from the NE will allow for better rad
cooling overnight...but the morning fg threat will be lower as tdd/s
remain a little too high outside the mtn valleys.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 325 AM Saturday: Stagnant dry/unseasonably warm weather will
persist through the short term and into the medium range, as a
highly amplified upper ridge tightens its grip on the eastern Conus.
The air mass is expected to become drier and more stable early in
the week, as surface ridge strengthens with the upper anticyclone
gradually spilling east of the northern/central Appalachians, and the
surface gradient tightens in response to Tropical Cyclone Maria
moving north from the Bahamas. Thus, even the isolated diurnal
convection that is expected over portions of the high terrain today
is expected to be a thing of the past by early next week. Temps will
remain above climo, but moderated slightly from recent days by
northeast low level flow.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 330 AM Saturday: Upper ridging will persist along the East
Coast into the medium range, although model run-to-run consistency
is resulting in increasing confidence that a pattern change is on
the horizon, as a series of potent short wave troughs are depicted
breaking down the ridge late in the week. In the interim, the
seasonably dry and not-so-seasonably warm weather will persist into
at least mid-week, as large scale subsidence persists within the
axis of the upper ridge, but also on the west side of T.C. Maria.

A cold front associated with the introduction of large scale height
falls into the eastern Conus will likely impact the area within the
late Thursday through early Friday time frame. However, it`s looking
increasingly likely that this will be largely a dry front for the
forecast area, as the circulation around Maria maintains a dry NE
low level flow. Slight chance pops will be maintained for mainly the
far western mountains during the aforementioned time frame, although
even that may be on the generous side. By the end of the week, temps
should be much closer to normal, if not a bit cooler than climo, as
continental high pressure builds into the Southeast.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and Elsewhere: High pressure centered north continues to
dominate the pattern making for generally weak ne/ly to e/ly winds
thru the BL during the TAF period all sites. Tdd/s are running a
little low this morning so will expect patchy ground FG outside the
mtns in calm winds. The mtn sites are a little problematic with the
continued stcu...but still shud see very low cigs/vsby arnd daybreak
as breaks in llvl clouds increase. Not much moisture to work with
this afternoon...so expect VFR Cu with little or no good chance of
-shra or tstms outside of the far wrn NC mtns and NE GA.

Outlook: Precip chances will wane through the weekend and early next
week. With clear skies and calm conditions, fog and/or low stratus
are likely to return in the mtn valleys each of the next few
mornings.

Confidence Table...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       High  96%     High  96%     High 100%     High 100%
KGSP       High  83%     High  96%     High 100%     High 100%
KAVL       Med   65%     High  96%     High 100%     High 100%
KHKY       High  86%     High  96%     High 100%     High 100%
KGMU       High  86%     High  96%     High 100%     High 100%
KAND       High  90%     High  96%     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...JPT
NEAR TERM...SBK
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...SBK



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