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 20, 9:00 PM EST, 1 hour 45 minutes earlier.
Area forecast discussion, Aug 20, 9:00 PM EST, 1 hour 45 minutes before
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1000 PM EDT Mon Aug 20 2018
.SYNOPSIS...
A warm and humid air mass will remain in place across the region
tonight as a cold front approaches from the west. The cold front is
forecast to move across the region on Tuesday afternoon and evening
with scattered to numerous thunderstorms expected. In the front's
wake, drier high pressure will spread over the area for the latter
half of the week.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 9:30pm EDT Monday: Showers and thunderstorms have become more
isolated this evening with some activity in the mountains likely to
continue for another hour or two. Over night, some widely scattered
light showers will be possible, mostly over the higher terrain.
Tuesday morning will be very similar to Monday morning, with a
continuation of high levels of humidity, and generally light
southwesterly winds. Some patches of fog are also possible Tuesday
morning, especially in mountain valleys and any area seeing
appreciable rainfall on Monday.
The weather will be begin to change on Tuesday as a major
frontal/upper storm system approaches from the west. Upper low
currently over the central CONUS reaches the Appalachians Tuesday
evening, with a northeast-to-southwest surface cold front reaching
the foothills by 00Z. Ahead of the front there is ample moisture
with precipitable water amounts just over 2 inches. Front will be
accompanied by upper support, and widespread showers and
thunderstorms seem likely Tuesday afternoon through the evening,
with activity progressing from the mountains to the southeast. Wind
profiles strengthen on Tuesday due to influence of storm system,
with bulk shear rising a notch to 25 or 30 knots Tuesday afternoon.
This will give some increase in the chances for severe weather,
primarily severe wind gusts in storm outflows, and is covered by the
SPC Marginal Risk for the area. Instability levels will be similar
to recent history, with lapse rates and surface moisture similar to
Monday. More rapid storm motion than we have seen in recent days
will help limit excessive rain potential, though some potential
exists should any areas be subject to training or repeated rounds of
rain.
Rain and clouds associated with approach of front will limit highs
on Tuesday to the low to mid 80s. Winds will be more persistently
southwesterly ahead of the front, with some increase and some
gustiness late on Tuesday as the front approaches.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 205 PM EDT Monday: A sharp upper trough axis moves east of the
area to be replaced by a more broad and weaker trough for Wednesday
and Thursday. At the surface, a cold front moves east of the area
Wednesday, but a weak lee trough remains over the area. Low level
flow turns northwesterly behind the departing front with deep
moisture moving east as well. There will be some lingering low level
moisture, so scattered diurnal convection may develop across the
mountains, with isolated convection possible near the lee trough.
High pressure builds in from the northwest for Thursday. This turns
the low level flow more northerly or northeasterly. The atmosphere
looks to be too stable for any diurnal convection to develop. Highs
will be near normal Wednesday then fall to nearly 5 degrees below
normal on Thursday as the cooler air mass associated with the
building high pressure moves in. Lows follow a similar pattern.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 200 PM EDT Monday: Surface high pressure will build down into
the forecast area on Friday leading to a cooler than normal day.
Dewpoints are expected in the 50s to lower 60s which will feel very
comfortable for this time of year. The high will slowly move off the
coast over the weekend with a gradual modification to more normal
conditions. Mid level ridging is expected to develop for the early
part of next week with hot and muggy conditions returning. Some
scattered storms are expected early next week primarily in the
mountains.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Showers and some thunder will linger for a couple more hours this
evening, primarily over the mountains, with very sparse activity
after 02Z. Areas which saw significant rainfall today will be the
ones most like to see restrictions due to fog Tuesday morning,
particular the KAVL, KGSP, and KGMU aerodromes.
On Tuesday, a major front will approach the region from the
northwest, with the frontal position reaching KAVL by 0Z Tuesday
evening. Winds will remain southwesterly ahead of the front at 5 to
15 kts, and will veer more northerly after 00Z when the front
passes. Front will help to focus showers and thunderstorms on
Tuesday, with significant activity expected along and ahead of the
front. Timing in TAFs for VCTS and PROB30 TS reflect expected
progress of the front, with storms once again beginning over the
mountains and spreading southeastward.
Outlook: Expect good coverage of diurnal showers and thunderstorms
thru early Wednesday. After which, drier high pressure is expected
to build in behind a passing cold front. Until then, restrictions
are likely mainly during the morning as low clouds form, and then
under any afternoon and evening showers and thunderstorms.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 100% Med 75% High 85% High 100%
KGSP High 97% Low 55% Med 72% High 100%
KAVL Low 55% Low 29% High 81% High 100%
KHKY Med 60% Low 44% Med 79% High 100%
KGMU High 91% Low 58% Med 72% High 90%
KAND High 100% Low 55% High 83% Med 63%
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...SW
NEAR TERM...WJM
SHORT TERM...RWH
LONG TERM...SW
AVIATION...WJMHazardous weather outlook, Aug 20, 3:08 PM EST, 7 hours 37 minutes before
Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
408 PM EDT Mon Aug 20 2018
GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-212015-
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-
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-Chester-Greenwood-
408 PM EDT Mon Aug 20 2018
This Hazardous Weather Outlook is for northeast Georgia, piedmont
North Carolina, western North Carolina and upstate South Carolina.
.DAY ONE...Tonight.
Scattered to numerous thunderstorms will continue into the evening
across the western Carolinas and northeast Georgia. The greatest
threat will be frequent cloud to ground lightning. The storms may
produce high rainfall rates that could lead to isolated urban, low
lying, and small stream flooding. The flooding threat will be highest
over the foothills and Piedmont of North Carolina. Additionally, a
few storms could become severe and produce large hail and damaging
wind gusts.
.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.
On Tuesday, a robust cold front will approach the forecast area from
the west and help to generate numerous thunderstorms. Some of these
storms could become severe and produce large hail and damaging wind
gusts. Isolated urban and small stream flooding is also a threat
with these storms. The flooding threat will be greatest over the
higher terrain.
.SPOTTER INFORMATION STATEMENT...
None.
In the hours before
Special weather statement, Aug 20, 5:36 PM EST, 5 hours 9 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
636 PM EDT MON AUG 20 2018
NCZ501-502-202300-
Caldwell Mountains NC-Greater Caldwell NC-
636 PM EDT MON AUG 20 2018
...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN CALDWELL COUNTY
UNTIL 700 PM EDT...
At 635 PM EDT, Doppler radar was tracking a strong thunderstorm 10
miles west of Boomer, or near Elkville, moving northeast at 15 mph.
Locations to be impacted include...
Kings Creek.
Wind gusts up to 50 mph and pea size hail will be possible in these
areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Gusty winds can blow down trees that are dead, or that have weakened
root systems. Outdoor furniture and similar items can be tossed
around if not anchored. Seek shelter indoors.
&&
LAT...LON 3609 8147 3609 8145 3607 8144 3607 8141
3605 8139 3604 8139 3604 8137 3600 8133
3598 8133 3594 8142 3603 8156 3610 8151
3610 8150
TIME...MOT...LOC 2235Z 223DEG 12KT 3603 8142
LANESpecial weather statement, Aug 20, 5:37 PM EST, 5 hours 8 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
637 PM EDT MON AUG 20 2018
NCZ053-202300-
Buncombe NC-
637 PM EDT MON AUG 20 2018
...A STRONG THUNDERSTORM WILL IMPACT SOUTH CENTRAL BUNCOMBE COUNTY
UNTIL 700 PM EDT...
At 637 PM EDT, Doppler radar was tracking a strong thunderstorm 9
miles north of Hendersonville, or near Arden, moving northeast at 20
mph.
Locations to be impacted include...
Fairview In Buncombe County, Arden and B.R. Parkway-Nc Arboretum To
East Asheville.
Wind gusts up to 50 mph and pea size hail will be possible in these
areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Gusty winds can blow down trees that are dead, or that have weakened
root systems. Outdoor furniture and similar items can be tossed
around if not anchored. Seek shelter indoors.
&&
LAT...LON 3551 8235 3547 8240 3547 8242 3546 8243
3545 8247 3545 8252 3557 8249
TIME...MOT...LOC 2237Z 212DEG 16KT 3546 8248
LANESpecial weather statement, Aug 20, 6:48 PM EST, 3 hours 57 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
748 PM EDT MON AUG 20 2018
NCZ035-210030-
Alexander NC-
748 PM EDT MON AUG 20 2018
...A THUNDERSTORM WITH TORRENTIAL RAINFALL WILL IMPACT NORTHEASTERN
ALEXANDER COUNTY UNTIL 830 PM EDT...
At 747 PM EDT, Doppler radar was tracking a thunderstorm with
torrential rainfall 7 miles northeast of Taylorsville, or 6 miles
west of Love Valley, moving northeast at 5 mph.
Locations to be impacted include...
Vashti.
Torrential rainfall rates up to 3 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 3596 8107 3600 8116 3603 8115 3604 8113
3604 8111 3603 8110 3603 8107 3604 8105
3604 8103
TIME...MOT...LOC 2347Z 231DEG 6KT 3601 8110
LANESpecial weather statement, Aug 20, 7:26 PM EST, 3 hours 19 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
826 PM EDT MON AUG 20 2018
NCZ037-210100-
Davie NC-
826 PM EDT MON AUG 20 2018
...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN DAVIE COUNTY UNTIL
900 PM EDT...
At 826 PM EDT, Doppler radar was tracking a strong thunderstorm 5
miles northeast of Mocksville, or 4 miles southwest of Bermuda Run,
moving northeast at 15 mph.
Locations to be impacted include...
Mocksville, Bermuda Run, Fork Church, Advance and Farmington.
Wind gusts up to 45 mph and pea size hail will be possible in these
areas.
LAT...LON 3590 8037 3586 8052 3593 8060 3605 8051
3604 8049 3606 8047 3606 8046 3603 8044
3600 8041 3599 8042 3596 8038 3593 8037
TIME...MOT...LOC 0026Z 236DEG 13KT 3595 8048
LANE