Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
255 PM EDT Sat Jul 10 2021

.SYNOPSIS...
A Bermuda high will maintain seasonably hot and humid conditions
with above normal coverage of afternoon and evening showers and
thunderstorms through at least the middle part of next week.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 225 PM EDT Saturday: Convective coverage has been slow to
move eastward over the past few hours and at present we're only
seeing activity over our far western zones. With the weak front
still hung up across the middle of the fcst area, the latest
guidance remains unclear whether or not the front will actually
make any more progress before it washes out.

Otherwise, the rest of this aftn/evening should be less active
compared to yesterday, largely due to a lack of mid/upper-lvl
support. However, if the front does not make it far enough south
of the fcst area, the slight increase in low-lvl forcing might
be enough to offset the lack of mid/upper-lvl support, at least
over the higher terrain. Overall, the last few runs of the CAMs
have trended slower moving convection eastward and most suggest
that little activity will make it to the I-77 corridor. As for
the severe potential, it's looking less likely that any cells
will produce larger hail and/or strong downbursts, but I wouldn't
completely nix the possibility. The higher terrain still remains
under a Marginal Risk for Excessive Rainfall today/tonight. After
the activity winds down later this evening, the overnight hours
should be quiet, with another round of patchy fog likely over the
mtn valleys and possibly the Upstate and Piedmont, depending on
where the precipitation falls. Another round of diurnally-driven
convection is likely for Sunday aftn/evening with better coverage
expected across the CWA. The severe potential still appears muted
overall, however it does look better just to our west over TN.
Temps will remain a degree or 2 above climatology.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 200 pm Saturday: A blocking pattern will predominate over much
of the Conus through the short term, with anticyclones centered off
the NC coast and the Desert Southwest, and a trough along the
Mississippi Valley. Resultant deep southerly flow over our forecast
area will result in seasonably warm/muggy conditions and robust
instability Monday and Tuesday afternoons. As such, solid coverage
(i.e., above-climo levels) of diurnal convection is anticipated both
days, with PoPs generally favoring likely across the mountains and
foothills and solid chance across the Piedmont. Mid/upper
tropospheric flow between the trough and anticyclone will be a
little stronger than usual for the time of year, so chances for
storm clustering along with the magnitude of coverage that is
anticipated may yield a severe storm risk that's a bit higher than
usual for early/mid summer. Localized excessive rainfall will also
be possible with training cells and/or backbuilding multicells.
Temps will be right around normal.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 215 pm Saturday: Blocking pattern is forecast to steadily
relent during the middle-to-latter part of the week, as a series of
short wave troughs passing through the northeast quadrant of the
country are expected to weaken the anticyclone just off the NC
coast. As a result, deep layer flow will weaken and moisture not
quite as deep/abundant. Diurnal convective coverage is expected to
become a little more typical for the time of year, with usual
threats of a pulse severe storm or two and locally excessive
rainfall from slow-moving cells. By next weekend, there's enough of
a signal in global model guidance to increase PoPs above climo again
as a frontal boundary could begin sagging toward the region. Temps
are forecast to remain very close to normal.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
At KCLT and elsewhere: In spite of a weak boundary drifting south
and washing out across the area today, winds should mainly be light
and SLY to SWLY. The only exception will be KAVL, where winds will
favor a NWLY direction. The coverage of convective storms remains
questionable for the remainder of today, but should be less than
yesterday. Nonetheless, I kept TEMPOs for TSRA from roughly 20 to
24z for all taf sites based on the most recent CAM guidance. Overall,
confidence remains somewhat lower that convection will reach KCLT,
but opted to keep a TEMPO going for them per the CWSU. Convective
debris this evening will gradually dissipate and winds will go light
and vrb again overnight. Patchy fog will likely develop again during
the pre-dawn hours on Sunday and linger into mid to late morning.
Another round of diurnally-driven convection is expected for Sunday
aftn/evening with better coverage expected across the fcst area.

Outlook: An unsettled pattern, with diurnal convection and morning
stratus/fog restrictions, is expected to persist thru the weekend and
into early next week.

Confidence Table...

            19-01Z        01-07Z        07-13Z        13-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High  95%     Med   76%     High  96%
KHKY       High 100%     High 100%     High 100%     High  96%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     High 100%     High  98%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

SYNOPSIS...JDL
NEAR TERM...JPT
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...JPT

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
704 AM EDT Sat Jul 10 2021

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-111115-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Avery-Alexander-
Iredell-Davie-Madison-Yancey-Mitchell-Swain-Haywood-Buncombe-Catawba-
Rowan-Graham-Northern Jackson-Macon-Southern Jackson-Transylvania-
Henderson-Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-Union NC-
Caldwell Mountains-Greater Caldwell-Burke Mountains-Greater Burke-
McDowell Mountains-Eastern McDowell-Rutherford Mountains-
Greater Rutherford-Polk Mountains-Eastern Polk-Oconee Mountains-
Pickens Mountains-Greenville Mountains-Greater Oconee-
Greater Pickens-Greater Greenville-Spartanburg-Cherokee-York-
Anderson-Abbeville-Laurens-Union SC-Chester-Greenwood-
704 AM EDT Sat Jul 10 2021

This Hazardous Weather Outlook is for northeast Georgia, western
North Carolina and upstate South Carolina.

.DAY ONE...Today and tonight.

Thunderstorms are expected to develop across the region this
afternoon. One or two of the thunderstorms will be strong to severe
with damaging wind gusts and large hail possible. Frequent lightning
and heavy downpours will also accompany any storms.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

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