Alert archive / North Carolina / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 101, NWS Greenville-Spartanburg, SC

May 31, 2017Union County, North Carolina

NWS Greenville-Spartanburg, SC issued this severe thunderstorm warning at May 31, 2017, 5:42 PM EDT for Union County, North Carolina. It was in force for 51 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
May 31, 2017, 5:42 PM EDT (21:42 UTC)
Expired
May 31, 2017, 6:33 PM EDT
In force
51 min
Issued by
NWS Greenville-Spartanburg, SC
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

County Union County, NC

The radar

The Columbia radar (KCAE), 143 km from the middle of the area, began a volume at 21:43 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
May 31, 5:58 PM EDTTSTM WND GST 593 Se Mint Hill, NCTRAINED SPOTTER MEASURED WINDS GUSTING TO 59 MPH AT STEVENS MILL ROAD AND LAWYERS ROAD.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched one storm report to this severe thunderstorm warning; the first came 16 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 9.7 hours before the alert went out and 118 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Greensboro/Hi Pt, NC at 12:00Z on 2017-05-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 222 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Greensboro/Hi Pt, NC at 12:00Z on 2017-05-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 11 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
222 J/kg
Mixed-layer CIN
-89 J/kg
Mixed-layer LCL
1216 m above ground
0-6 km bulk shear
50 kt
0-1 km storm-relative helicity
11 m²/s²
0-3 km storm-relative helicity
78 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

446 
WUUS52 KGSP 312142
SVRGSP
NCC179-312245-
/O.NEW.KGSP.SV.W.0101.170531T2142Z-170531T2245Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Greenville-Spartanburg SC
542 PM EDT WED MAY 31 2017

The National Weather Service in Greenville-Spartanburg has issued a

* Severe Thunderstorm Warning for...
  Union County in the Piedmont of North Carolina...

* Until 645 PM EDT

* At 542 PM EDT, severe thunderstorms were located along a line
  extending from 11 miles south of Downtown Concord to 8 miles
  southeast of Uptown Charlotte, moving southeast at 15 mph.

  HAZARD...60 mph wind gusts. 

  SOURCE...Radar indicated. 

  IMPACT...Expect damage to trees and power lines. 

* Locations impacted include...
  Monroe, Indian Trail, Weddington, Stallings, Unionville, Wesley
  Chapel, Wingate, Marshville, Lake Park and Hemby Bridge.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Scattered trees and power lines will be blown down in the warned
area. Seek shelter inside an interior room.

These storms are also producing extremely heavy rainfall. Flooding of
drainage ditches and low lying areas may occur. Small streams will
rise rapidly. Do not drive through areas where water is flowing over
the road.

Please report damaging winds, hail, or flooding to the National
Weather Service Greenville-Spartanburg by calling toll free, 1, 800,
2 6 7, 8 1 0 1, or by posting on our Facebook page, or Tweet it using
hashtag nwsgsp. Your message should describe the event and the
specific location where it occurred.

&&

LAT...LON 3481 8032 3481 8036 3504 8076 3521 8055
      3518 8049 3518 8048 3517 8047 3516 8044
      3517 8042 3516 8041 3518 8037 3517 8036
      3518 8031 3519 8030 3519 8028
TIME...MOT...LOC 2142Z 300DEG 15KT 3524 8057 3513 8075 

HAIL...<.75IN
WIND...60MPH
 
$$

TDP
1 follow-up statement
656 
WWUS52 KGSP 312233
SVSGSP

Severe Weather Statement
National Weather Service Greenville-Spartanburg SC
633 PM EDT WED MAY 31 2017

NCC179-312243-
/O.CAN.KGSP.SV.W.0101.000000T0000Z-170531T2245Z/
Union NC-
633 PM EDT WED MAY 31 2017

...THE SEVERE THUNDERSTORM WARNING FOR UNION COUNTY IS CANCELLED...
            
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore the warning has been cancelled.

If you observed large hail or wind damage, please report it to the
National Weather Service Greenville-Spartanburg by calling toll free,
1, 800, 2 6 7, 8 1 0 1, or by posting on our Facebook page, or Tweet
it using hashtag nwsgsp. Your message should describe the event and
the specific location where it occurred.

LAT...LON 3481 8032 3481 8036 3504 8076 3521 8055
      3518 8049 3518 8048 3517 8047 3516 8044
      3517 8042 3516 8041 3518 8037 3517 8036
      3518 8031 3519 8030 3519 8028
TIME...MOT...LOC 2230Z 300DEG 15KT 3514 8036 3503 8054 

$$

TDP

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, 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 this severe thunderstorm warning went out at May 31, 4:50 PM EDT, 52 minutes earlier.

Area forecast discussion, May 31, 4:50 PM EDT, 52 minutes before
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
450 PM EDT Wed May 31 2017

.SYNOPSIS...
A weak cold front slowly moves through the area early Thursday.
Dry high pressure will follow the front for late Thursday and
Friday, but as high pressure slides offshore, moist southerly flow
returns and shower and thunderstorm chances increase heading into
the weekend. Temperatures will remain near normal until another
cold front moves through the region early next week with drier
and cooler conditions to follow.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 440 PM EDT Wednesday:  A broken line of convection continues
to dominate the weather across the region this afternoon thanks to
abundant buoyancy and a zone of sfc convergence.  Said convergence
axis lines up fairly well with the current radar depiction of tsra,
which is generally moving into the I85 corridor.  Modest dcape
also presents a nonzero threat for microbursts in addition to
hail, therefore a few svr warned storms are possible over the
next few hours.  Tweaked pops/t/td through the remainder of the
afternoon and left the rest of the fcst unchanged.

As of 235 PM EDT: a few widely sct cells have begun to develop
across the CWFA over the past hour or so with one cell producing
a few cloud to ground lightning strikes. The latest CAM guidance
has not changed much since earlier today with additional convection
expected to fire off the escarpment and higher terrain over the next
few hours and drift eastward. Coverage still looks hit or miss for
most locations, but the region along the escarpment will likely have
the best coverage overall.  Convection should die down after 00z or
so, with instability waning.  Otherwise, the axis of the broad upper
trough will continue to shift east across the Ohio Valley, as steep
upper ridging persists over the Rockies. The deeper moisture will
shift SE later this evening as broad sfc high pressure begins to
spread over the fcst area. This trend will continue thru tomorrow
with winds becoming NWLY by late morning and remaining WLY TO NWLY
thru the evening. Convection potential looks lower tomorrow than
the past couple of days with minimal instability across the CWFA,
but some isolated to sct coverage is possible. The severe threat
looks very low. Overnight low temps should be near normal with
some patchy fog likely to develop. High temps tomorrow will be
similar to today, if not a degree or 2 higher.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 240 PM Wednesday: The end of the week looks fairly uneventful
as we remain in an overall W/NW flow aloft with a lack of mid/upper
forcing and a relatively dry air mass, which should be generally
unfavorable to diurnal convection. The trend in the new guidance
is for less in the way of convection each day and the new forecast
follows that trend. The model guidance is especially uninterested
in convective development on Friday, so we have cut back to only a
slight chance over the higher terrain of the central and southern
mountains of NC that ends around sunset. Saturday afternoon holds
a better opportunity for convection, but nothing more than climo
at best if the model trend is correct, so we have cut back to a
chance over the higher terrain and a slight chance outside the
mtns. Some of the convection could linger into the evening east of
the Blue Ridge, but should end by midnight. Little indication of
any MCS activity, so the fcst will be dry for the pre-dawn hours
on Sunday. Temps will be seasonally warm with a warming trend from
Friday into Saturday.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
A shortwave moves across the Great Lakes Sunday afternoon with
an attendant weak trough axis moving across the region that may
help to increase shower and thunderstorm coverage given moist
southerly low-level flow on the back side of a subtropical ridge.
However, instability parameters are rather anemic, with weak
deep-layer shear, a deep boundary layer, and moist mid-levels
(poor lapse-rates) leading to unimpressive CAPE.  This appears
to be a change from previous guidance which had more robust
shear parameters.  Given previous guidance and potential modest
shortwave forcing in a moist environment, we will have to continue
to monitor the potential for storms but scattered coverage of
showers is still expected at this time.

On Monday, the guidance is in better agreement about a positively
tilted closed upper-level low dropping south over the Great Lakes
while we remain in a moist, southwesterly flow.  The presence of
this deeper trough in advance of an attendant cold front to our
west should increase shear and lower our LCLs, thereby increasing
CAPE across the area and increasing the potential for some stronger
storms.  Nevertheless, heading into Tuesday, while guidance is in
disagreement regarding the progressiveness of the upper-level low,
precip chances wane as the cold front moves through.

It appears the operational guidance (GFS/Canadian/ECMWF) has slowed
the frontal passage from the evening runs.  There is plenty of time
to nail down the details, but the current forecast is essentially
a blend of the guidance and is closest to the 12 UTC GFS with a
Tuesday afternoon passage.

In advance of the front, high temperatures will remain near-normal
with low-temperatures up to 5 degrees above normal with high
humidity and cloud cover. Below-normal high and low temperatures
are in store by Tuesday as the front moves through the region and
the dry continental airmass brings an unusual reprieve from what
should be early summer heat and humidity.  High temperatures may be
hard-pressed to reach 80 in the Piedmont under mostly sunny skies
next Wednesday, with dewpoints in the mid 50s.  If this comes to
pass, this childhood Yankee will be the first to celebrate.

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
At KCLT and elsewhere: expect VFR conditions thru TAF period with
a TEMPO from 20 to 23z for reduced visby and gusty winds from TSRA
at KCLT. Confidence is not very high that convection will affect the
site, but it is high enough to include the TEMPO. Otherwise, sct mid
and high clouds will continue to stream over roughly the southeastern
half of the CWFA area thru the afternoon with isolated to scattered
SHRA and TSRA likely to develop across the Blue Ridge and drift east
into the Piedmont. Conditions should clear out later this evening,
with patchy fog possible where precip occurs. Drier conditions are
expected tomorrow under broad high pressure, and winds should veer
around to NWLY by the late morning.

Outlook: we get back into a warm-season pattern on Friday that will
allow a return of afternoon SHRA/TSRA through the weekend.

Confidence Table...

            21-03z        03-09Z        09-15Z        15-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     High 100%
KHKY       High 100%     High 100%     High 100%     High 100%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     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...None.
NC...None.
SC...None.

&&

SYNOPSIS...JMP
NEAR TERM...CDG/JPT
SHORT TERM...PM
LONG TERM...JMP
AVIATION...JPT
Hazardous weather outlook, May 31, 4:10 AM EDT, 13 hours 32 minutes before
Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
410 AM EDT Wed May 31 2017

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-010815-
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-
410 AM EDT Wed May 31 2017

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

.DAY ONE...Today and Tonight.

Scattered showers and thunderstorms will continue into the evening.
Strong gusty winds, brief heavy rainfall, and frequent cloud to
ground lightning could occur with any of the storms.

.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...

None.

In the hours before

Special weather statement, May 31, 4:18 PM EDT, 1 hour 24 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
418 PM EDT WED MAY 31 2017

SCZ003-005>007-312100-
Greater Pickens SC-Greenville Mountains SC-Spartanburg SC-
Greater Greenville SC-
418 PM EDT WED MAY 31 2017

...STRONG THUNDERSTORMS WILL IMPACT NORTHEASTERN GREENVILLE...
NORTHERN SPARTANBURG AND EAST CENTRAL PICKENS COUNTIES UNTIL 500 PM
EDT...

At 418 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 12 miles northwest of Spartanburg to 4 miles
north of Easley, and moving southeast at 10 mph.

Locations to be impacted include...
Greenville Downtown, Spartanburg, Easley, Pickens, Greenville
Eastside, West Greenville, Greer, Mauldin, Taylors and Berea.

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...

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 3478 8245 3482 8248 3476 8262 3489 8274
      3496 8257 3514 8206 3502 8178 3496 8177
      3472 8246
TIME...MOT...LOC 2018Z 308DEG 11KT 3507 8208 3489 8261

TDP
Special weather statement, May 31, 4:32 PM EDT, 1 hour 10 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
432 PM EDT WED MAY 31 2017

NCZ037-057-312100-
Rowan NC-Davie NC-
432 PM EDT WED MAY 31 2017

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL DAVIE AND NORTH CENTRAL
ROWAN COUNTIES UNTIL 500 PM EDT...

At 432 PM EDT, Doppler radar was tracking a strong thunderstorm 4
miles southeast of Mocksville, or near Cooleemee, moving east at 20
mph.

Locations to be impacted include...
Mocksville, Cooleemee, High Rock Lake, Fork Church, Advance and
Woodleaf.

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...

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 3575 8061 3593 8060 3595 8038 3589 8037
      3588 8042 3587 8039 3585 8039 3585 8042
      3583 8043 3583 8046 3584 8047 3583 8049
      3581 8047 3579 8048 3577 8045 3574 8045
      3573 8040 3572 8034 3571 8032
TIME...MOT...LOC 2032Z 273DEG 17KT 3584 8052

TDP
Special weather statement, May 31, 5:15 PM EDT, 27 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
515 PM EDT WED MAY 31 2017

NCZ071-072-312145-
Cabarrus NC-Mecklenburg NC-
515 PM EDT WED MAY 31 2017

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN CABARRUS AND
MECKLENBURG COUNTIES UNTIL 545 PM EDT...

At 515 PM EDT, Doppler radar was tracking a strong thunderstorm 4
miles north of Uptown Charlotte, or near Northwest Charlotte, moving
southeast at 20 mph.

Locations to be impacted include...
Uptown Charlotte, Huntersville, Downtown Concord, Central Charlotte,
Northeast Charlotte, East Charlotte, Northwest Charlotte, West
Concord, Matthews and Mint Hill.

Wind gusts up to 45 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.

&&

LAT...LON 3516 8061 3507 8072 3523 8101 3535 8095
      3536 8092 3536 8094 3537 8094 3545 8090
      3537 8048
TIME...MOT...LOC 2115Z 297DEG 18KT 3529 8087

TDP
Local storm report, May 31, 5:18 PM EDT, 24 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
518 PM EDT WED MAY 31 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0435 PM     TSTM WND DMG     2 NNW LOWESVILLE        35.45N 81.02W
05/31/2017                   LINCOLN            NC   COUNTY OFFICIAL

            COUNTY OFFICIAL REPORTS MULITIPLE TREES DOWN ON HWY 73.

&&

KRENTZ
Local storm report, May 31, 5:28 PM EDT, 14 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
528 PM EDT WED MAY 31 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0424 PM     TSTM WND DMG     2 NE IRON STATION       35.47N 81.13W
05/31/2017                   LINCOLN            NC   COUNTY OFFICIAL

            LARGE TREE ON HOUSE AND CARPORT BLOWN DOWN ON TWO CARS AT
            RYYNEHEART ROAD AND OLIVE CIRCLE.

&&

KRENTZ
Local storm report, May 31, 5:36 PM EDT, 6 minutes before
PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
536 PM EDT WED MAY 31 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0424 PM     TSTM WND DMG     2 NE IRON STATION       35.47N 81.13W
05/31/2017                   LINCOLN            NC   COUNTY OFFICIAL

            LARGE TREE ON HOUSE AND CARPORT BLOWN DOWN ON TWO CARS AT
            REINHARDT CIRCLE ON HWY 73.

&&

KRENTZ

The office that day

Everything else NWS Greenville-Spartanburg, SC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 31, 3:35 PM EDTSpecial Weather StatementGSPCleveland25 min
May 31, 3:40 PM EDTSpecial Weather StatementGSPCatawba, Lincoln35 min
May 31, 4:12 PM EDTSpecial Weather StatementGSPGaston33 min
May 31, 4:29 PM EDTSevere Thunderstorm WarningGSPGaston, Lincoln, Mecklenburg46 min
May 31, 4:32 PM EDTSpecial Weather StatementGSPDavie28 min
May 31, 5:15 PM EDTSpecial Weather StatementGSPMecklenburg30 min
May 31, 5:21 PM EDTSevere Thunderstorm WarningGSPCabarrus, Mecklenburg39 min
May 31, 6:01 PM EDTSpecial Weather StatementGSPMecklenburg29 min
May 31, 6:45 PM EDTSpecial Weather StatementGSPUnion30 min
May 31, 7:35 PM EDTAreal Flood AdvisoryGSPMecklenburg, Union115 min

Nearby

Severe Thunderstorm Warnings in North Carolina, 2017Every severe thunderstorm warning in 2017

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.