Scattered thunderstorms developed across western portions of the Upstate during the afternoon in the vicinity of a stationary front. One storm produced brief severe weather in Oconee County.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS GSP wrote it up.
Scattered thunderstorms developed across western portions of the Upstate during the afternoon in the vicinity of a stationary front. One storm produced brief severe weather in Oconee County.
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 May 22, 1:11 PM EST, 29 minutes earlier.
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
211 PM EDT Mon May 22 2017
.SYNOPSIS...
Low pressure will form today along a stalled front over the northern
Gulf coast and track northeast across our region tonight. A deep
upper trough forms over the Mississippi Valley Tuesday night and
Wednesday with the axis crossing the southern Appalachians early
Thursday. This results in cooler than normal temperatures until an
upper ridge builds over our area for the weekend bringing a return
to Spring temperatures.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 2 pm: Little has changed from earlier thinking. However, with
convection developing into the Upstate, northeast GA, and the
southern mtns, and the potential for cells to train in locations
characterized by poor antecedent hydro conditions, wanted to go
ahead and get a Flash Flood Watch out for these areas. More watches
may be added shortly.
Otherwise, weak cold front is analyzed extending roughly from the ATL
metro area northeast through the GA/SC/NC Blue Ridge. This boundary
along with terrain influences/differential heating is resulting in
development of scattered deep convection across our western areas,
with much better coverage just west and south of the area. Coverage
should gradually expand from the west through the afternoon, and
likely pops are featured across much of the southern half of the
area through early evening. A handful of severe storms (with
damaging winds the main, and perhaps the only threat) cannot be
ruled out, but the larger concern will be with localized flash
flooding, especially in locations with wet antecedent conditions
(the foothills and northern Piedmont of SC and our GA zones, as well
as the southern mtns of NC).
Bigger heavy rain concern is with the slug of moisture that lifts
out of the Gulf overnight. All models have some depiction of this,
though the GFS is by far the strongest with this feature, though it
seems to be suffering from some convective feedback issues that can
really be seen in the vorticity fields. Development of 850mb jet
late in the period collocated with the higher PW values also
contributes to concern, but model differences result in slightly
lower confidence. GFS has 50+kt 850mb jet just southeast of the
mountains (surface low progged to track close to the escarpment)
that would add a hefty amount of orographic lift, but NAM and ECMWF
are farther east with this feature. So, confidence in overall QPF is
moderate, but location is low. With this uncertainty, will hold off
on issuing any Flash Flood Watches for now to let the day shift
reevaluate antecedent rainfall, today's convective trends, and to
see if there is better model consensus in the track of the low
overnight tonight.
Temperatures today will be pretty close to seasonal normals, though
of course that will be dependent on if/when/where convection
develops. Not much change to overnight lows with plentiful low-level
moisture remaining in place.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 200 AM Mon: Consensus of the American models is for the
stalled frontal boundary to be on our southeastern fringe Tuesday
morning, extending back southwest toward the central Gulf Coast. The
surface wave of low pressure should exit to the east by midday,
and in its wake some drier air may wrap in from the north. NAM
does show a secondary frontal wave moving thru the I-20 corridor
of AL/GA later in the day; this is not shown on the GFS as it has
the front further south by that time. Hence the latter shows a
more distinct lull in precip activity. The 21/12z EC and 22/00z
CMC wave tracks are similar to the GFS, but slower, suggesting
essentially no lull until Tuesday night.
Wherever the frontal wave sets up Tuesday, the enhanced midlevel
flow preceding it will produce appreciable shear/helicity. On
the warm (southeast) side of the low this is expected to
overlap with sufficient instability to pose a small severe wind
threat. Subsidence and downsloping in the immediate wake of the low
will stabilize the eastern CWFA for the aftn, but meanwhile heights
begin to fall from the west as the upper low cuts off and moves
south into the mid Mississippi Valley. This leads to better lapse
rates and some destabilization at least over the mtns if not the
foothills plus GA and the western Upstate. Though low to midlevel
winds will be weak by the time this occurs, enough shear remains
that a few robust updrafts are possible within multicell clusters.
Tuesday night, another shortwave moves into the ArkLaMiss region,
reactivating the front and deepening low pressure over the lower
Ohio Valley on Wed. Isentropic upglide will strengthen over our CWFA
allowing PoPs to ramp back up by morning. The warm sector envelops
the area and some degree of buoyancy will develop, though there is
disagreement among guidance how far north this occurs. Wind profiles
will be rather impressive owing to the proximity of the low, posing
a risk of organized severe storms where buoyancy is sufficient
enough. SPC has included a Marginal Risk for the Southeast states
on the new Day 3 outlook, though it includes only a sliver of our
southernmost zones; this certainly could be extended northward if
there were more confidence in the instability progs.
The heavy rain focus will mainly be over the Piedmont Tuesday, near
the front. With that shifting northward, the threat may increase
a bit near the Blue Ridge Wednesday. Most likely the hydrologic
concerns will remain localized to areas hit by multiple rounds of
t-storms thru the early week. For now we will going to advertise
a flood threat in the HWO, with the threat appearing localized
enough to preclude a watch.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 145 AM Monday: The axis of the deep upper trough will pass
over the western Carolinas either Thursday morning or around mid day
Thursday as it moves northeast. Although the ECMWF very little
instability at 18Z Thursday, the GFS has a core of CAPE over I-77
just north of CLT. The 18Z run of the GFS had around 600 CAPE and
the newest run now has around 1000 CAPE from north of CLT to near
the VA border. With the lower freezing level under the upper trough,
this core of higher CAPE may help generate some convection which
would result in hail producers. This higher CAPE will shift to the
RDU and north by 00Z Friday with heights building in from the west
as the upper trough leaves our region.
Weak high pressure dominates our weather from Thursday night through
Saturday night. The shallow upper ridge that forms in the wake of
the departure of the upper trough deamplifies late Saturday and
flattens out for zonal west to east flow on Sunday. A series of
shortwaves pass through west to east next week with the first
bringing convection to the mountains by late Sunday and over all
areas Sunday night. Instability will be increasing from the west
little by little but will moisture arrive in time to result in
storms late Sunday. At this time we are going with slight to low
chance of that happening.
Temperatures start out almost 10 degrees below normal Thursday
rising to above normal over the weekend.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Convection continues to blossom across the
area this afternoon, and should continue to fill in through late
afternoon. All terminals receive a tempo for TSRA at some point over
the next 6 hours, along with gusty/vrbl winds. A bit of a lull is
expected in the convection this evening. However, conditions will
eventually go downhill again, as the first in a series of waves of
low pressure developing along a stalled frontal boundary is expected
to bring a round of widespread showers and embedded thunderstorms to
the area after midnight. Cigs should also deteriorate to IFR or lower
tonight around the time that the showers move in. There may be
another lull in the precip after sunrise Tue, only to likely be
followed by another round at some point later on Tue.
Outlook: Periods of showers and thunderstorms with associated
restrictions will continue off and on through Thursday. Drying is
expected to finally occur through the end of the week.
Confidence Table...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT High 82% High 94% High 81% High 86%
KGSP High 81% High 93% Med 68% High 85%
KAVL High 86% High 92% Med 74% High 93%
KHKY High 100% High 92% Med 73% Med 78%
KGMU High 81% High 93% Med 71% High 82%
KAND Med 77% Med 75% High 88% High 89%
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...Flash Flood Watch through late Wednesday night for GAZ018-026-
028-029.
NC...Flash Flood Watch through late Wednesday night for NCZ064-065-
509-510.
SC...Flash Flood Watch through late Wednesday night for SCZ001>014-
019.
&&
SYNOPSIS...DEO
NEAR TERM...JDL/TDP
SHORT TERM...Wimberley
LONG TERM...DEO
AVIATION...JDLHazardous Weather Outlook National Weather Service Greenville-Spartanburg SC 535 AM EDT Mon May 22 2017 GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065- 068>072-082-501>510-SCZ001>014-019-230945- 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- 535 AM EDT Mon May 22 2017 This Hazardous Weather Outlook is for northeast Georgia, piedmont North Carolina, western North Carolina and upstate South Carolina. .DAY ONE...Today and Tonight. A cold front will push through the region today, encountering abundant moisture and instability. Scattered thunderstorms are expected to develop as a result. The primary threats will be cloud- to-ground lightning, gusty winds, and locally heavy rain. Though the likelihood of thunderstorms will decrease tonight, rain will increase in coverage as the front stalls and low pressure moves along the front and into the area. Isolated flooding could develop in poorly drained areas, or areas where soils remain saturated after heavy rain Sunday. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. ..Tuesday...Heavy rain with flooding possible. Heavy rainfall may continue until the stalled front moves out of the area, to the south and east. ..Wednesday...Heavy rain with flooding possible. Another round of rainfall will occur as a warm front moves into the area from the south. Rainfall totals will likely reach 2 to 4 inches in many places. Some creeks and streams may rise out of their banks. In addition, embedded thunderstorms may produce localized flash flooding. ..Thursday...No hazardous weather is expected at this time. ..Friday...No hazardous weather is expected at this time. ..Saturday...No hazardous weather is expected at this time. ..Sunday...No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Storm spotters are asked to forward any reports of flooding or fallen trees to our office. Wimberley
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1249 PM EDT MON MAY 22 2017
NCZ033-050-503-505-221715-
McDowell Mountains NC-Burke Mountains NC-Avery NC-Mitchell NC-
1249 PM EDT MON MAY 22 2017
...THUNDERSTORMS WITH TORRENTIAL RAINFALL WILL IMPACT NORTHEASTERN
MCDOWELL...SOUTHEASTERN MITCHELL...SOUTHERN AVERY AND NORTHWESTERN
BURKE COUNTIES UNTIL 115 PM EDT...
At 1248 PM EDT, Doppler radar was tracking thunderstorms with
torrential rainfall 5 miles south of Spruce Pine, moving northeast at
15 mph.
Locations to be impacted include...
Spruce Pine, Crossnore, Linville Falls, B.R. Parkway-Linville Falls
To Grandfather, B.R. Parkway-Little Switzerland To Linville, Ingalls,
Altamont, Pineola, Ashford and Woodlawn.
Wind gusts up to 40 mph, pea size hail and heavy rainfall rates up
to 2 inches per hour will be possible in these areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
The combination of gusty winds and saturated soil conditions may
cause scattered trees and power lines to fall. Seek shelter inside
an interior room.
&&
LAT...LON 3599 8179 3596 8181 3595 8180 3595 8178
3577 8194 3574 8197 3581 8214 3582 8213
3584 8215 3586 8214 3590 8215 3610 8205
TIME...MOT...LOC 1648Z 209DEG 13KT 3584 8204
JPTPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
109 PM EDT MON MAY 22 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0101 PM HAIL 4 SW ASHFORD 35.83N 81.99W
05/22/2017 E0.25 INCH MCDOWELL NC BROADCAST MEDIA
&&
JPTSpecial Weather Statement
National Weather Service Greenville-Spartanburg SC
223 PM EDT MON MAY 22 2017
SCZ001-002-004-221900-
Pickens Mountains SC-Greater Oconee SC-Oconee Mountains SC-
223 PM EDT MON MAY 22 2017
...A STRONG THUNDERSTORM WILL IMPACT WEST CENTRAL PICKENS AND
NORTHEASTERN OCONEE COUNTIES UNTIL 300 PM EDT...
At 223 PM EDT, Doppler radar was tracking a strong thunderstorm 4
miles north of Walhalla, or near Oconee State Park, moving southeast
at 10 mph.
Locations to be impacted include...
Seneca, Walhalla, Salem, Lake Keowee and Oconee State Park.
Wind gusts up to 40 mph, pea size hail and 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. Do not drive across
flooded roads.
Lake Keowee is in the path of this storm. Cloud to ground lightning
and gusty winds will create dangerous boating conditions.
Move to shore immediately.
&&
LAT...LON 3479 8318 3495 8308 3489 8281 3483 8284
3481 8289 3478 8288 3476 8289 3475 8289
3474 8290 3464 8295
TIME...MOT...LOC 1823Z 296DEG 7KT 3484 8305
ARKThe Greer radar (KGSP), 77 km away, was scanning. The volume nearest the first event began at 18:38 UTC.
1 thunderstorm wind. Local standard time, as filed.
FD reported a few trees and powerlines blown down off Highway 183 near Walhalla.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Carolina in 2017Every state in 2017This day in weather historyWarnings in South Carolina, May 2017
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 702619.