Scattered to numerous thunderstorms developed in advance of a cold front across western North Carolina during the afternoon. Multiple severe storms produced isolated tornadoes, with a couple of strong tornadoes impacting the northwest Piedmont.
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 to numerous thunderstorms developed in advance of a cold front across western North Carolina during the afternoon. Multiple severe storms produced isolated tornadoes, with a couple of strong tornadoes impacting the northwest Piedmont. Sporadic wind damage occurred across the remainder of the area.
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 24, 9:11 AM EST, 1 hour 4 minutes earlier.
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1011 AM EDT Wed May 24 2017
.SYNOPSIS...
An area of low pressure to our west will pull a warm front northward
through the area today. Unstable conditions south of the front
will lead to showers and thunderstorms producing heavy rain. A few
more showers may occur Thursday before drier and warmer conditions
return to end the work week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM EDT Wednesday: Was just in the middle of the morning
update and was going to make the case for why we would probably need
a Watch by this afternoon, when SPC came out with the coordination
for the new Tornado Watch. So, this is timely. Convection upstream
continues to grow and evolve, with more storms acquiring supercell
characteristics over NW Georgia on a trajectory to reach the NC mtns
in the next hour or two. The morning raob from FFC shows a fcst CAPE
around 1500 J/kg and effective shear of 50kt. The mesoscale model
output looks compelling, with supercellular echoes tracking along
the I-85 corridor through late afternoon/early evening as suggested
by maxima of updraft helicity. So often these environments fail to
produce much in the way of severe weather, but this one looks
different as we are unwedged and have enough thin spots in the
overcast to allow for some destabilization. It also helps that we
can see the supercells developing upstream as of 14Z. The entire
fcst area will be in the threat area for severe storms and
tornadoes. The CLT metro area will be last to see the threat, but
the decision was made to put the whole area in the Watch now, rather
than have to do it when the storms were bearing down later this
afternoon.
Otherwise, the rainfall roller coaster continues through the
near-term, but in this case we are looking at a slightly more
clear-cut situation due to the large-scale ascent/synoptic forcing
ahead of the digging upper low over the Mid-Mississippi Valley.
Strong SW flow aloft ahead of this system with really lovely upper
diffluence will allow the surface low to lift from the Tennessee
Valley northeast up the western side of the Appalachians today, with
strong cold front stretching down the mountains into the Southeast.
All near-term guidance is also inducing mesolow formation along the
lee of the Appalachians across western NC, which will serve to help
back the surface flow today (more on that later). 120-130kt upper
jet and strong DPVA will push across the area today, so in addition
to the upper diffluence, jet-level divergence will also be a factor,
as well as southerly 850mb LLJ (40kt). And of course plenty of
moisture to work with as well.
So what does this mean for convective trends today? Well, after this
morning's lull, low-level isentropic upglide as well as frontal
forcing will begin to increase convection across especially the
southwest mountains. Despite temperatures a good 5-10 degrees below
seasonal normals, should still be enough surface moisture and
heating to result in sbCAPE increasing today to between 1000-
1500J/kg especially across the Piedmont. Add to this the deep-layer
bulk shear of 50-60kt (70 if you believe the NAM) and low-level
helicity >100m2/s2 and you have an interesting setup. Because of the
depth of the trough aloft, we see some veering with height to about
500mb, but then backing again slightly up toward jet-level. Low-
level hodographs are impressively curved, but then straighten out
aloft. STP values on both the NAM and GFS are over 3 (NAM is over
5). So confidence is increasing in severe convection today. Hail
will be a threat today, but locally think that strong winds are the
primary threat, but with the increasing concern for tornadoes.
Heavy rain threat today will be limited to convective elements.
Given that the past two Flash Flood Watches are now 0-for-2, opted
to not extend/expand/reissue for today. While soils remain primed
from recent rain, Flash Flood Guidance remains generally >3" in 6hr,
and 1-2" for 1hr. Again, isolated locations could certainly see this
and expect that small stream/rivers will respond much more rapidly
today with more runoff, but even the Day1 Excessive Rainfall Outlook
just has Marginal across our area, so just do not think it worthy of
another watch at this time. Will leave the option open for the day
shift to issue one, however, if convective trends end up adjusting
more toward widespread heavy rain vs. severe.
If it wasn't for the thunderstorms, today would be an incredibly
pleasant day with temperatures in the lower 70s (5-10 degrees below
seasonal normals) across the Piedmont and 60s in the mountains. More
of a cool-down expected tonight behind the front, with lows dropping
below seasonal normals with loss of deep layer moisture, as we'll be
in the dry slot between the front and the approaching upper low
(which we'll have to deal with for the short term).
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 245 AM Wed: The upper low will wobble northeastward into the
Mid-Atlantic states on Thursday. Lapse rates will remain strong
over our area as a result, and a lobe of vorticity will also spin
through. Thus scattered showers and potentially some thunderstorms
will occur over mainly western NC, with chances limited further
south by warmer midlevel temps. Instability is greatest in the
late morning to midday and that is when peak thunder chances will
be advertised; convection should wane in the aftn with rising
heights aloft. With broken cloud cover over much of the area, and
breezy winds, max temps will be similar to today's, 7 to 10 degrees
below climo. With deep mixing, a few brisk gusts could occur simply
within the gradient, if not due to outflow from the showers/storms.
Heights continue to rise Thu night into Friday. Subsidence will
inhibit convection and skies should remain mostly clear. Temps are
expected to bounce back to near normal. A warm front will develop
over the mid-Mississippi Valley as the next low gets cranking in
the Plains. Guidance generally indicates clouds will begin to return
by early Saturday, with a small chance of showers developing along
the TN-NC border, as a result of a weak wave moving into the Tenn
Valley at that time.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 315 AM Wed: The Bermuda high will remain somewhat suppressed
over the South Atlantic region this weekend, with another broad upper
trough moving east out of the northern Plains. In response the
developing Plains low will activate a baroclinic zone over the
mid-Mississippi Valley on Saturday. The cold front associated with
the trough most likely will approach the area late Sunday or Monday.
Some differences in timing and speed of this fropa do exist between
the 00z GFS and EC. They do generally agree that the front will hang
up over the Coastal Plain Tuesday, so a small PoP is retained then
for the possibility it is slower to do so, or a wave develops along
it in our vicinity. Max temps thru the period will hover near normal,
with mins initially held warmer by clouds/precip, but those return to
near normal by Tuesday night.
Impact-wise, some diurnal thunderstorms are possible each day until
the front passes. Deep shear parameters are on the high side given
the gradient around the trough, but a capping inversion is progged by
the GFS over much of the Piedmont until the front arrives. Thus the
large CAPE values it is generating may not be realized.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: IFR to occasionally LIFR cigs continue at TAF
time. Expect slow but steady improvement through the morning hours
to MVFR. VFR late this afternoon into the evening, and with
lingering low-level moisture, should see MVFR again toward the end
of the period for NC TAF sites. Convection will initiate across the
area early this afternoon, spreading east through the aftn/evening
hours. Have carried VCTS at most TAFs for a period of time,
narrowing the greatest threat down in TEMPOs from 17-21z for western
TAFs and 19-23z for KCLT/KHKY, but that could easily change. Winds
will generally range from SSE to SW and will pick up to between 5-
10kt this afternoon, but will likely see some gusty winds (possibly
severe gusts) in TSRA.
Outlook: Scattered showers and thunderstorms will continue on
Thursday as the upper trough passes. Drying is expected to finally
occur Thursday night through Saturday.
Confidence Table...
14-20Z 20-02Z 02-08Z 08-12Z
KCLT High 90% Med 70% High 87% High 85%
KGSP High 84% High 93% High 97% High 98%
KAVL High 82% High 91% High 98% High 88%
KHKY High 90% High 86% Med 68% Med 67%
KGMU High 89% High 95% High 100% High 100%
KAND High 88% High 97% High 100% High 100%
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 until 10 PM EDT this evening for GAZ010-017-
018-026-028-029.
NC...Flash Flood Watch until 10 PM EDT this evening for NCZ033-
035>037-048>053-056>059-062>065-068>072-082-501>510.
SC...Flash Flood Watch until 10 PM EDT this evening for SCZ001>014-
019.
&&
SYNOPSIS...Wimberley
NEAR TERM...PM/TDP
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...TDPHazardous Weather Outlook National Weather Service Greenville-Spartanburg SC 1047 AM EDT Wed May 24 2017 GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065- 068>072-082-501>510-SCZ001>014-019-251500- 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- 1047 AM EDT Wed May 24 2017 ...FLASH FLOOD WATCH IN EFFECT UNTIL 10 PM EDT THIS EVENING... ...TORNADO WATCH 262 IN EFFECT UNTIL 6 PM EDT THIS EVENING... This Hazardous Weather Outlook is for northeast Georgia, piedmont North Carolina, 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. Tornado Watch. Flash Flood Watch. Numerous thunderstorms are expected to develop today. Conditions are favorable for some of these storms to produce severe weather, in the form of damaging winds, large hail, frequent lightning, and very heavy rain. A few of the severe storms will be organized enough to produce a tornado. The most likely time for any severe weather will be through mid afternoon over the mountains, during the early to mid afternoon over northeast Georgia, the western upstate of south carolina, and the foothills of North Carolina, and then the mid to late afternoon over the western Piedmont of North Carolina and the Charlotte metro area. The threat for severe weather will end from the west in the late afternoon and early evening. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. ..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. ..Monday...No hazardous weather is expected at this time. ..Tuesday...No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Skywarn spotters are requested to forward any reports of large hail, damaging winds, tornadoes, or flash flooding to our office. PM
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1104 AM EDT WED MAY 24 2017
NCZ051-058-241615-
Graham NC-Swain NC-
1104 AM EDT WED MAY 24 2017
...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN SWAIN AND GRAHAM
COUNTIES UNTIL 1215 PM EDT...
At 1104 AM EDT, Doppler radar was tracking a strong thunderstorm 13
miles northwest of Murphy, moving northeast at 40 mph.
Locations to be impacted include...
Robbinsville, Town Of Santeetlah, Smoky Mountains-Fontana Area, Lake
Santeetlah, Fontana Lake, Fontana Village, Smoky Mountains-Twentymile
Creek, Stecoah, Cheoah and Deals Gap.
Wind gusts up to 50 mph and pea size hail will be possible in these
areas.
A tornado watch remains in effect until 600 PM EDT for western North
Carolina.
LAT...LON 3537 8401 3541 8402 3546 8396 3547 8392
3552 8388 3553 8382 3556 8377 3557 8365
3537 8350 3525 8381 3525 8385 3522 8396
3523 8400 3527 8401 3529 8403 3531 8402
3531 8404 3535 8404
TIME...MOT...LOC 1504Z 230DEG 31KT 3524 8418
CDGThe Knoxville radar (KMRX), 102 km away, was scanning. The volume nearest the first event began at 15:13 UTC.
5 thunderstorm wind, 4 tornado, 2 flash flood. Local standard time, as filed.
County comms reported mutliple trees blown down across the county.
EM reported trees blown down on Old Glenwood Rd in the Glenwood community.
EM reported trees blown down at Montford Cove Rd and Hensley Rd.
EM reported multiple trees and power lines blown down at Ostwalt Amity Rd and Triplett Rd.
NWS storm survey found the path of a weak tornado that began near the intersection of Aileen Ln. and Hillndale Ln. The tornado traveled northeast for about a mile before lifting near Musket Ln. Minor structural damage was reported to several homes and a storage building while multiple trees were uprooted.
NWS storm survey found the path of a second, more significant tornado in Iredell County. This one touched near the intersection of New Salem Rd and Highway 64. The tornado moved northeast, crossing Highway 64 between Crooked Ln and Hunters Ridge Ln. The most significant damage occurred in this location, as a brick home had its roof completely removed and interior walls collapsed. Material from this home along with tree debris acted as projectiles, causing damage to the exterior of adjacent homes. About a dozen homes were damaged in this fashion. The tornado apparently weakened as it continued northeast, but uprooted or snapped dozens of trees before lifting in the vicinity of 5th Creek Rd. This was only the strongest tornado to impact Iredell County since 2005, and was only the second official significant tornado (E/F2 or greater) in the county's history.
County comms reported multiple trees blown down across the south and southeast side of Charlotte.
NWS storm survey found the path of a strong tornado that touched down just south of the intersection of highways 601 and 801. Damage was initially limited to downed trees. However, the tornado intensified as it moved north/northeast, especially from Four Corners Rd to the Yadkin County line. A mobile home was flipped and completely destroyed in this area. An occupant was thrown approximately 30 feet, but survived. Another home had much of its roof blown off and a storage building also destroyed in this area. Numerous trees were also blown down. The tornado crossed into Yadkin County near Chinquapin Creek. The tornado was the strongest in Davie County since 2008, and was only the second official significant tornado (E/F2 or stronger) in the county's history.
NWS storm survey found a weak tornado tracked northeast from Lancaster County, SC into Union County in a rural area west of South Rocky River Rd. Two walls and much of the roof was blown off a barn off in this area, which was the most significant damage associated with the tornado. Otherwise, damage was primarily confined to numerous downed trees, damage or destruction to multiple outbuildings, and minor structural damage to multiple homes as the tornado tracked northeast, lifting near Joe Collins Rd.
FD reported flash flooding developed along Muddy Creek after 2 to 3 inches of rain fell in just a couple of hours. Gilbert Byrd Rd was closed for a while due to flood water from the creek.
Public reported the Yadkin River overflowed its banks near Patterson after 2 to 3 inches of rain fell in the headwaters in just a couple of hours. Yadkin River Rd was closed briefly.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in North Carolina in 2017Every state in 2017This day in weather historyThe tornado archive for North Carolina, 2017Warnings in North 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: 702783, 702785, 702786, 702792, 703176, 703177, 702791, 703192, 702815, 703419, 704506.