What forecasters said that day
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Greenville-Spartanburg, SC wrote its last area forecast discussion before the first event at Aug 21, 5:31 AM EST, 4 hours 9 minutes earlier.
Area forecast discussion, Aug 21, 5:31 AM EST, 4 hours 9 minutes before
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
631 AM EDT Fri Aug 21 2020
.SYNOPSIS...
An upper level trough will persist across the Lower Mississippi River
through Saturday. This will result in high temperatures a little
below normal with elevated rain and thunderstorm chances across the
region. The upper trough will weaken over the weekend, allowing
temperatures and precipitation chances to return to normal as we head
into next week. Attention will turn to the tropics next week as a
potential hurricane is expected to pass Florida on Tuesday.
&&
.NEAR TERM /THROUGH TONIGHT/...
600 AM Update...Ongoing precip and few embedded tstms are remaining
confined to the wrn zones this morning. Expect continued coverage
and some expansion east over the next few hrs as highly moist sw/ly
flow interacts with a sfc wedge. Rainfall amts will be generally
under an inch over all locales thru the next update with perhaps
some minor hydro issues over ern Spartanburg and wrn Union SC
counties.
An area of widespread rain with embedded thunder continues to affect
the wrn zones. Precip rates have fallen and lightning has become
less prevalent while updrafts weaken as is evident in warming cloud
tops. Not anticipating a sigfnt hydro threat, but a few poor
drainage areas and low-lying locales could see moderate ponding
across the srn/cent NC mtns.
The atmos will be quite moist today as PWATs remain elevated abv
normal arnd 1.8 inches. This is due to very good moist flux off the
GOM while a l/w h5 trof axis with a closed upper low remains across
the Deep South. The alignment of the upper trof will also provide
good general lift as difl flow persists and periods of vort energy
traverse the flow. Meanwhile...a sfc wedge will remain in place and
trap llvl moisture this morning and hold in widespread clouds and
rain until noon or so. With the aforementioned lift and h85 flow
bringing Atl moisture, expect isol/sct tstms will efficiently
generate by the early afternoon.
Some of these cells will be good rainmakers and any training or
anchoring could create flooding issues. In fact, with the high
antecedent conds and expected coverage of of deep convec over the
wrn zones...will issue a Flash Flood Watch for parts of NE GA, the
higher elevations of the Upstate and the NC mtns effective from 6am
this morning until 6am Sat morning.
Soundings show skinny sbCAPE, yet areas of differential heating will
allow some storms to become severe as an active TMB looks to develop
while the wedge begins to break down late in the afternoon. This
bndry will likely set up across the I-85 corridor and provide a
focusing zone for deep stg/svr convection as it slowly progresses
north into the evening hrs. Overnight...the pattern still looks
highly moist and active with the better coverage of storms and heavy
precip occurring across the wrn zones closer to the upper and mech
lift/forcing. Max temps will be held abt 10 degrees below normal
with a small diurnal drop off to the mid/upper 60s overnight.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 100 AM Fri: The Bermuda High will deepen and retrograde
slightly from Saturday through Monday morning. A light but moist
southerly to southwesterly flow should persist thru the period. The
well defined shortwave over the lower OH and TN valleys at the
start of the period will fill and basically be absorbed into
a shortwave passing across the northern Great Lakes. A lobe of
vorticity associated with the wave looks to swing across our CWA
Saturday afternoon and evening, which in light of the seasonable
CAPE progs and southerly flow, would suggest at least climatological
scattered to numerous PoPs; model QPF is uncharacteristically
muted on the NAM and Canadian during the diurnal max Saturday,
perhaps reflecting the subsidence associated with the ridge. The NAM
and Canadian are a little slower to lift the shortwave out of the
region, which may explain their uptick in QPF Saturday night. Lapse
rates and buoyancy appear to be no better Sunday, and perhaps even
a bit worse due to the continued building of the ridge. PWATs will
rebound, though, and the additional moisture may make up for that,
so PoPs are only about 10 percent lower. Max temps will be near
climo, with mins a bit above climo. Storm motion should be fairly
slow owing to weak flow within the column, and locally heavy rain
(particularly Sunday) could maintain wet antecedent conditions
heading into what could be an active medium range.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 245 AM Fri: The available deterministic models are fairly
close to the hurricane models in taking TD 14 into the far eastern
Gulf of Mexico early in the medium range. For what it's worth,
they similarly agree on TD 13 heading northward toward the Texas
coast. The systems will approach the CONUS within the relative
weakness between a deep anticyclone centered over the Rockies
and that associated with the Bermuda High. If nothing else
their arrival should bring abundant moisture to a broad swath
of the Southern states, but it is not yet clear how that will be
distributed and therefore how pronounced an impact that moisture
will have in our CWA. Monday and Tuesday afternoons could end up
with initiation/coverage suppressed by either poor lapse rates
associated with the deep ridge or by subsidence around the eastern
Gulf storm. PoPs below climo look warranted those days, at any
rate. Temps should rise back a little above climo, especially if
we manage to stay at least partly sunny.
A shortwave will dig into eastern Canada by the middle of next week,
carrying a cold front into the Northeast or maybe even Mid-Atlantic
(GFS is most bullish in that sense). If that front were to reach
our area in conjunction with the remnant of one of these TCs, the
latter half of next week could be especially wet. Model consensus
is good enough on the tropical moisture and QPF to at least trend
higher on PoPs from the early week, and lower on temps by Thursday.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
At KCLT and Elsewhere: An active and changing wx pattern will
persist across all TAF sites thru the period. Ongoing convection
will linger this morning across the wrn zones and bring periodic low
CIGs and VSBY into the MVFR/IFR range at KAVL and KHKY over the next
couple hrs. A ridge of hipres will keep CIGS low, likely in the IFR
range, thru noon with some lifting and scattering possible by the
afternoon. The ridge axis begins to break down in the later
afternoon and this will bring a bndry north along the I-85 corridor
where stg/svr tstms will be possible while the whole line pushes
northeast into the evening affecting all TAF sites with either TS,
VCTS, or PROB30 TSRA with flight restrictions thru the period. Winds
will remain aligned ne/ly outside the mtn valleys, with a shift to
se/ly at KCLT aft 02z. Winds at KAVL will remain upvalley generally
nw/ly to nne/ly.
Outlook: Coverage should then steadily decline for each
afternoon/evening from Sat into early next week. Fog and low
stratus restrictions will be possible each morning, especially over
the usual mountain valleys.
Confidence Table...
10-16Z 16-22Z 22-04Z 04-06Z
KCLT High 80% High 90% High 100% Med 72%
KGSP Med 70% High 80% Med 75% Med 72%
KAVL Med 70% Med 77% High 80% Low 47%
KHKY Low 42% High 87% High 82% Low 41%
KGMU High 82% Med 77% High 80% Med 68%
KAND Med 67% Med 72% High 82% Med 72%
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...Flash Flood Watch through late tonight for GAZ010.
NC...Flash Flood Watch through late tonight for NCZ033-048>053-058-
059-062>065-501>507-509.
SC...Flash Flood Watch through late tonight for SCZ001>003.
&&
SYNOPSIS...SBK
NEAR TERM...SBK
SHORT TERM...08
LONG TERM...08
AVIATION...SBKHazardous weather outlook, Aug 21, 3:58 AM EST, 5 hours 42 minutes before
Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
458 AM EDT Fri Aug 21 2020
GAZ017-018-026-028-029-NCZ035>037-056-057-068>072-508-510-SCZ004>008-
010-011-220900-
Habersham-Stephens-Franklin-Hart-Elbert-Alexander-Iredell-Davie-
Catawba-Rowan-Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-
Greater Rutherford-Eastern Polk-Greater Oconee-Greater Pickens-
Greater Greenville-Spartanburg-Cherokee-Anderson-Abbeville-
458 AM EDT Fri Aug 21 2020
This Hazardous Weather Outlook is for northeast Georgia, piedmont
North Carolina, western North Carolina and upstate South Carolina.
.DAY ONE...Today and tonight.
Numerous showers and thunderstorms are expected today. Any of the
thunderstorms will be capable of dangerous cloud-to-ground lightning
and torrential rainfall. Isolated flooding is possible, especially in
poorly drained areas such as urban centers, and in locations where
heavy rain fell late Thursday night or early this morning. Showers
and storms will become less common tonight, though a few torrential
downpours will remain possible.
.DAYS TWO THROUGH SEVEN...Saturday through Thursday.
No hazardous weather is expected at this time.
.SPOTTER INFORMATION STATEMENT...
None.
GAZ010-NCZ033-048>053-058-059-062>065-501>507-509-SCZ001>003-220900-
Rabun-Avery-Madison-Yancey-Mitchell-Swain-Haywood-Buncombe-Graham-
Northern Jackson-Macon-Southern Jackson-Transylvania-Henderson-
Caldwell Mountains-Greater Caldwell-Burke Mountains-Greater Burke-
McDowell Mountains-Eastern McDowell-Rutherford Mountains-
Polk Mountains-Oconee Mountains-Pickens Mountains-
Greenville Mountains-
458 AM EDT Fri Aug 21 2020
...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT...
This Hazardous Weather Outlook is for northeast Georgia, western
North Carolina and upstate South Carolina.
.DAY ONE...Today and tonight.
Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.
Flash Flood Watch.
.DAYS TWO THROUGH SEVEN...Saturday through Thursday.
No hazardous weather is expected at this time.
.SPOTTER INFORMATION STATEMENT...
Spotter activation may be needed. Please relay any information about
observed severe weather to the NWS while following all local, state,
and CDC guidelines.
NCZ082-SCZ009-012>014-019-220900-
Union NC-York-Laurens-Union SC-Chester-Greenwood-
458 AM EDT Fri Aug 21 2020
This Hazardous Weather Outlook is for piedmont North Carolina and
upstate South Carolina.
.DAY ONE...Today and tonight.
Numerous showers and thunderstorms are expected today. Any of the
thunderstorms will be capable of dangerous cloud-to-ground lightning
and torrential rainfall. A few of the storms may also pose a risk of
brief damaging wind gusts. Isolated flooding is possible, especially
in poorly drained areas such as urban centers, and in locations
where heavy rain fell late Thursday night or early this morning.
Showers and storms will become less common tonight, though a few
torrential downpours will remain possible.
.DAYS TWO THROUGH SEVEN...Saturday through Thursday.
No hazardous weather is expected at this time.
.SPOTTER INFORMATION STATEMENT...
None.
8
In the hours before
Local storm report, Aug 21, 8:44 AM EST, 56 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
944 AM EDT FRI AUG 21 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0920 AM FLOOD 4 SE GAFFNEY 35.03N 81.60W
08/21/2020 CHEROKEE SC EMERGENCY MNGR
EMERGENCY MANAGER REPORTED WATER BEGINNING TO RISE OVER
THE BRIDGE ON PEELER CREEK ROAD.
&&
TPALMERSpecial weather statement, Aug 21, 9:00 AM EST, 40 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1000 AM EDT Fri Aug 21 2020
SCZ009-014-211445-
York SC-Chester SC-
1000 AM EDT Fri Aug 21 2020
...AN AREA OF HEAVY RAIN WILL IMPACT CHESTER AND YORK COUNTIES UNTIL
1045 AM EDT...
At 959 AM EDT, Doppler radar indicated the leading edge of an area of
heavy rain along a line extending from 8 miles west of York to 5
miles northwest of Chester, and moving northeast at 15 mph.
Locations to be impacted include...
York, Chester, Rock Hill, Clover, Newport, Sharon, Hickory Grove,
Mcconnells, Lowrys and Smyrna.
Very heavy rainfall rates up to 2 inches per hour will be possible in
these areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.
&&
LAT...LON 3459 8142 3464 8142 3468 8145 3472 8145
3473 8148 3475 8148 3476 8145 3478 8145
3482 8148 3485 8145 3490 8148 3503 8149
3505 8147 3505 8141 3514 8140 3517 8137
3515 8106 3455 8101
TIME...MOT...LOC 1359Z 212DEG 14KT 3497 8138 3476 8128
TDPSpecial weather statement, Aug 21, 9:02 AM EST, 38 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1002 AM EDT Fri Aug 21 2020
NCZ035-036-056-069-211445-
Iredell NC-Lincoln NC-Alexander NC-Catawba NC-
1002 AM EDT Fri Aug 21 2020
...AN AREA OF HEAVY RAIN WILL IMPACT CATAWBA...ALEXANDER...
NORTHWESTERN IREDELL AND LINCOLN COUNTIES UNTIL 1045 AM EDT...
At 1001 AM EDT, Doppler radar indicated the leading edge of an area
of heavy rain along a line extending from 5 miles south of Boomer to
5 miles southeast of Lincolnton, and moving north at 25 mph.
Locations to be impacted include...
Hickory, Newton, Lincolnton, Taylorsville, Statesville, St. Stephens,
Conover, Longview, Bethlehem and Maiden.
Very heavy rainfall rates up to 2 inches per hour will be possible in
these areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.
&&
LAT...LON 3604 8083 3540 8106 3543 8144 3574 8139
3580 8133 3592 8134 3599 8133 3603 8123
TIME...MOT...LOC 1401Z 187DEG 20KT 3599 8127 3541 8120
TDPLocal storm report, Aug 21, 9:26 AM EST, 14 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1026 AM EDT FRI AUG 21 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1025 AM FLOOD GROVER 35.17N 81.45W
08/21/2020 CLEVELAND NC EMERGENCY MNGR
A COUPLE OF ROADS FLOODED, AND WASTEWATER TREATMENT PLANT
BEGINNING TO HAVE FLOODING ISSUES.
&&
TPALMER