Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 240237
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1037 PM EDT Fri Jun 23 2017

.SYNOPSIS...
Shower and thunderstorm coverage will increase from the west into
early Saturday morning. Light showers will linger Saturday morning
as the front slowly crosses the area, and thunderstorms may
redevelop just ahead of the cold front over the piedmont.
Unseasonably cool and dry conditions will spread over the forecast
area in the wake of the front and persist through the middle of next
week.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
As of 10:30pm EDT Friday:  Storms so far this evening have
demonstrated brief heavy rain rates and some strong wind gusts.
CAPE will continue to decline diurnally, and deep layer shear will
also decline as tropical wave moves by.

Tropical wave now embedded in upper synoptic flow which represents
the remnants of Cindy is moving along a frontal boundary and passing
through Kentucky and will continue eastward, exiting the CONUS by
Saturday morning as the front moves southeastward across the
Appalachians and into the piedmont.  Combination of tropical wave and
front will bring showers to the area tonight and Saturday.  There is
some moisture reduction behind the front, but dewpoints do not
really begin to decline until Saturday evening. Sufficient moisture
will remain such that with diurnal warming Saturday afternoon, MLCAPE
values will still reach over 1000 j/kg.  Moisture declines
significantly Saturday evening as northwesterly surface flow over
the mountains develops and showers will be ending from northwest to
southeast Saturday evening.

Strong 850mb flow around Cindy remnant of around 30kts gradually
weakens overnight as the wave moves through with gusty surface winds
continuing until early Saturday morning, especially at higher
elevations.

Latest high-res guidance brings an area of stronger storms through
the area from now through 8z with a period of relatively light and
widely scattered showers Saturday morning, followed by the next
round of showers and storms Saturday afternoon.  Severity of any
storms on Saturday will be mitigated by much weaker wind shear, but
showers will be prodigious rain producers as PWAT values remain over
2 inches.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
As of 215 PM EDT Friday: Will plan on basing the Saturday evening
pop timing by extrapolating the NAMNest sfc refl which is progging
scattered deep convection translating acrs the piedmont 21-02z. Sfc
front should then translate to the coastal plain before sunrise
Sunday.  Broad upper troughing builds into the eastern conus
starting on Sunday with an influx of drier continental airmass
expected atop the cwfa. Sunday afternoon sfc dwpts should be around
10 deg F lower than Saturday`s values.  Upper trough continues to
build toward the eastern seaboard on Monday while a persistent llvl
northerly flow allows for further drying.  Sfc dwpts should fall
into the 50s, impressive values for late June.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 145 PM EDT Friday: Not much change from the previous fcst. The op
guidance remains in general good agreement with the synoptic pattern
which features a strong upstream ridge enforcing good subsidence
across the FA. There is a strong h5 s/w depicted to cross the area
on Tue...but with nil moisture to work with...will anticipate only
mid/high level clouds with this feature. The atmos remains rather
stable thru most of the period as a Canadian high slowly crosses
overhead. There could be some limited mtn-top convg shra/tstms
developing late Thu however confidence is too low attm to include in
the fcst grids. The best chance for precip will be Fri thru the
period when a cold front approaches from the west and by that time
the Bermuda high will be back in it/s normal config allowing sw/ly
moist adv and seasonal sfc heating. Shower and tstm activity will be
limited mainly to the higher terrain aided by mech lift. Max/min
temps will begin the period a couple cats below normal with a
gradual increase to near normal levels by the weekend.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: A round of showers and thunderstorms related
to the remnants of Cindy is expected overnight with timing of most
intense period from around 3z to 8z as system moves across the area
from west to east. SW winds will continue and remain gusty until the
upper wave/Cindy remnants pass early Saturday, with a weakening
gradient as the frontal boundary settles into the region from the
northwest on Saturday. Low ceilings down to 800 ft AGL or less are
possible early Saturday due to a very moist boundary layer.
Following a general reduction in showers Saturday morning,
additional showers and thunderstorms are expected Saturday afternoon

Outlook: A passing cold front will move southeast of the area
through the late weekend, with drier weather developing through most
of next week.

Confidence Table...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       High 100%     Med   62%     High  91%     High 100%
KGSP       High 100%     Med   60%     Med   73%     Med   78%
KAVL       High  90%     Med   67%     High  91%     High 100%
KHKY       High 100%     Med   71%     High  98%     High 100%
KGMU       High  90%     Med   61%     High  88%     Med   70%
KAND       High  90%     Low   55%     High  81%     Med   69%

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...SBK
NEAR TERM...WJM
SHORT TERM...CSH
LONG TERM...SBK
AVIATION...HG/WJM


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