Alert archive / Georgia / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 247, NWS Greenville-Spartanburg, SC

July 25, 2017Rabun County, Georgia; Oconee County, South Carolina

NWS Greenville-Spartanburg, SC issued this severe thunderstorm warning at Jul 25, 2017, 11:14 PM EDT for Rabun County, Georgia; Oconee County, South Carolina. It was in force for 46 min. 2 reports 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
Jul 25, 2017, 11:14 PM EDT (03:14 UTC)
Expired
Jul 26, 2017, 12:00 AM EDT
In force
46 min
Issued by
NWS Greenville-Spartanburg, SC
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Rabun County, GA, Oconee County, SC

The radar

The Greer radar (KGSP), 91 km from the middle of the area, began a volume at 03:14 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
Jul 25, 11:30 PM EDTTSTM WND DMGWestminster, SC911 CALL CENTER REPORTED NUMEROUS TREES DOWN IN WESTMINSTER WITH POWER OUTAGES.
Jul 25, 11:35 PM EDTTSTM WND DMG2 Ne Longcreek, SCSCHP REPORTED A TREE DOWN AT CHARLIE COBB RD AND CASSIDY BRIDGE RD. TIME ESTIMATED FROM RADAR.

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 2 storm reports 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

Peachtre/Fal Fld, GA (KFFC), launched 00:00Z, 3.2 hours before the alert went out and 187 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, Peachtre/Fal Fld, GA at 00:00Z on 2017-07-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1589 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, Peachtre/Fal Fld, GA at 00:00Z on 2017-07-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 14 square meters per square second.1939Sfc1 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
1589 J/kg
Mixed-layer CIN
-30 J/kg
Mixed-layer LCL
1245 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
14 m²/s²
0-3 km storm-relative helicity
37 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

017 
WUUS52 KGSP 260314
SVRGSP
GAC241-SCC073-260400-
/O.NEW.KGSP.SV.W.0247.170726T0314Z-170726T0400Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Greenville-Spartanburg SC
1114 PM EDT TUE JUL 25 2017

The National Weather Service in Greenville-Spartanburg has issued a

* Severe Thunderstorm Warning for...
  Eastern Rabun County in northeastern Georgia...
  Central Oconee County in Upstate South Carolina...

* Until midnight EDT

* At 1114 PM EDT, severe thunderstorms were located along a line
  extending from 10 miles east of Clayton to 9 miles south of
  Walhalla, moving southwest at 10 mph.

  HAZARD...60 mph wind gusts and quarter size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Minor hail damage to vehicles is expected. Expect wind 
           damage to trees and power lines. 

* Locations impacted include...
  Walhalla, Westminster, Oconee State Park, Mountain Rest, Long
  Creek, Pine Mountain and Oakway.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A few trees and power lines will be blown down in the warned area.
Hail can cause major property damage, especially to vehicles. 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 3488 8338 3498 8315 3462 8297 3453 8308
      3453 8310 3456 8313 3456 8314 3457 8314
      3458 8316 3459 8316 3459 8317 3460 8316
      3461 8316 3460 8320 3462 8324
TIME...MOT...LOC 0314Z 052DEG 8KT 3487 8322 3465 8311 

HAIL...1.00IN
WIND...60MPH
 
$$

TDP
2 follow-up statements
282 
WWUS52 KGSP 260336
SVSGSP

Severe Weather Statement
National Weather Service Greenville-Spartanburg SC
1136 PM EDT TUE JUL 25 2017

GAC241-260346-
/O.CAN.KGSP.SV.W.0247.000000T0000Z-170726T0400Z/
Rabun GA-
1136 PM EDT TUE JUL 25 2017

...THE SEVERE THUNDERSTORM WARNING FOR EASTERN RABUN COUNTY IS
CANCELLED...

The storms which prompted the warning have weakened. Therefore, the 
warning has been cancelled.

LAT...LON 3481 8330 3482 8327 3485 8327 3485 8325
      3488 8324 3488 8320 3492 8317 3492 8316
      3460 8303 3457 8313 3459 8317 3461 8316
      3460 8320 3462 8324 3478 8332
TIME...MOT...LOC 0336Z 052DEG 8KT 3484 8326 3462 8315 

$$

SCC073-260400-
/O.CON.KGSP.SV.W.0247.000000T0000Z-170726T0400Z/
Oconee SC-
1136 PM EDT TUE JUL 25 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL MIDNIGHT EDT
FOR SOUTHWESTERN OCONEE COUNTY...

At 1136 PM EDT, severe thunderstorms were located along a line
extending from 8 miles east of Clayton to 10 miles east of Toccoa,
moving southwest at 10 mph.

HAZARD...60 mph wind gusts and nickel size hail. 

SOURCE...Radar indicated. 

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

Locations impacted include...
Westminster, Mountain Rest, Long Creek and Oakway. 

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 8330 3482 8327 3485 8327 3485 8325
      3488 8324 3488 8320 3492 8317 3492 8316
      3460 8303 3457 8313 3459 8317 3461 8316
      3460 8320 3462 8324 3478 8332
TIME...MOT...LOC 0336Z 052DEG 8KT 3484 8326 3462 8315 

HAIL...0.88IN
WIND...60MPH
 
$$

TDP
728 
WWUS52 KGSP 260350
SVSGSP

Severe Weather Statement
National Weather Service Greenville-Spartanburg SC
1150 PM EDT TUE JUL 25 2017

SCC073-260400-
/O.EXP.KGSP.SV.W.0247.000000T0000Z-170726T0400Z/
Oconee SC-
1150 PM EDT TUE JUL 25 2017

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN OCONEE COUNTY
WILL EXPIRE AT MIDNIGHT EDT...
            
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 will be allowed to expire.  However heavy rain
is still possible with these thunderstorms.

LAT...LON 3481 8330 3482 8327 3485 8327 3485 8325
      3488 8324 3488 8320 3492 8317 3492 8316
      3460 8303 3457 8313 3459 8317 3461 8316
      3460 8320 3462 8324 3478 8332
TIME...MOT...LOC 0350Z 052DEG 8KT 3483 8328 3461 8317 

$$

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 Jul 25, 10:55 PM EDT, 19 minutes earlier.

Area forecast discussion, Jul 25, 10:55 PM EDT, 19 minutes before
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1055 PM EDT Tue Jul 25 2017

.SYNOPSIS...
High pressure moving by to the north is expected to provide cooler
temperatures on Wednesday. Another front will move in from the
northwest late in the week, with cooler and drier conditions
arriving behind it for the weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 10:45pm EDT Tuesday.  Thunderstorms have mostly declined, but
one severe storm has arisen in Oconee County on a pocket of higher
CAPE/DCAPE.  Instability levels remain strong enough for more
activity with the primary threat of strong outflows, though
storms will be short-lived due to non-existent wind shear.

The pattern of events on Wednesday may be fairly similar to today,
with some widely scattered afternoon showers, with some chance for
strong to severe storms.  Instability may creep up a little bit as
better dewpoints advance northwestward. General synoptic pattern is
nearly identical on Wednesday with zonal 591 500mb height line
hardly moving, and negligible surface features.  Lack of surface
features and any upper level support will cause the pattern of
initiation over higher terrain to continue.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 200 PM EDT Tuesday: Upper-level heights will begin falling
from the Great Lakes to the Ohio River Valley Wednesday night
through Thursday. At low levels, Light southerly upslope flow could
permit isolated to scattered showers, with a thunderstorm or two, to
persist into the nightttime hours early Thursday across the southern
mountains. Otherwise, anticipate slightly better diurnal convective
coverage across the NC mountains Thursday afternoon and evening
ahead of the approaching upper support as surface-based instability
increases a bit over previous days. Improving westerly steering flow
will also likely bring scattered convection farther east of the Blue
Ridge along the I-40 corrdor into the western NC foothills/piedmont
into Thursday evening. Surface to 6 km bulk shear magnitude may rise
to 25 to 30 kt across the northern tier by Thursday afternoon as
these westerlies improve. Thus, anticipate a gradual change in the
character of the convection to more multi-cell types by late
Thursday.

The upstream shortwave energy will cross the forecast area from the
northwest Thursday night through Friday ahead of much stronger
heights falls carving out a more prominent trough from the Great
Lakes to the Appalachians. The best moisture and forcing will occur
around the passing cold front, but the numerical models still
exhibit quite a bit of spread on the timing. The faster NAM/ECM
camps bring clouds and moisture into the region very early Friday
and thus limit instability, while the GFS timing is much later in
the day. Indeed, the slower GFS would keep precipitation going well
into Friday night across the southeast half of the area. This will
play havoc will instability around the fropa and also shear
profiles, but an uptick in storm organization is certainly possible
Friday afternoon and evening. For now, will blend the timing
slightly toward the faster solutions which is preferred given the
push from the rapidly falling upstream heights.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 200 PM EDT Tuesday: A trend toward drier and cooler conditions
seen in the previous forecast was continued with this forecast
package. By Saturday morning, a surface cold front should have moved
through our area and settled to our south. The GFS/ECMWF remain in
agreement on maintaining an amplified pattern and sweeping this
front through towards the Gulf coast, with an upper longwave trough
deepening over the eastern CONUS over the weekend and into early
next week. There is also better agreement in the global models with
respect to drier air arriving behind the front...and with basically
all convection remaining suppressed Saturday and Sunday over our
area in yet another guidance cycle, have lowered pops even more to
below climo over the weekend. The Bermuda high reasserts itself a
bit more over the southeast early next week, and gradual moistening
of the column will lead to pops returning closer to average by
Tuesday and Wednesday.

With the above-mentioned upper trough expected to deepen
dramatically over the eastern CONUS over the weekend and into early
next week, maintained the downward trend in temperatures through the
period. Large adjustments weren't made with this package, but
temperatures more than 5 degrees below climo and dew points in the
mid to low 60s could make for some...dare I say it...rather pleasant
conditions for late July.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere:  Relatively stable weather pattern will
continue through Wednesday with some widely scattered afternoon
convective showers and light to variable winds.  Some patchy fog and
possible low OVC in the morning could affect some sites, especial KAVL.
Probability of getting convection at any give site is low enough to
not be worth mention in the TAFS at this time.  Some fog and stratus
overnight are possible as boundary layer cools.  How much is
difficult to be precise about, but will be less likely at KCLT and
KGSP which have slightly lower forecast relative humidity levels.

Outlook: Scattered diurnal convection can be expected each day
thru Friday across the region. Then drier air will filter in from
the north behind a passing cold front this weekend. Chances for
morning fog and stratus will also be possible each day in the
mountain valleys.

Confidence Table...

            03-09Z        09-15Z        15-21Z        21-00Z
KCLT       High 100%     High  90%     Med   70%     High 100%
KGSP       High 100%     High 100%     High  83%     High 100%
KAVL       High  94%     Low   34%     High  96%     High 100%
KHKY       High 100%     Med   72%     High  89%     High 100%
KGMU       High 100%     High 100%     High  94%     High 100%
KAND       High 100%     High  83%     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...Carroll
NEAR TERM...WJM
SHORT TERM...HG
LONG TERM...Carroll
AVIATION...WJM
Hazardous weather outlook, Jul 25, 2:45 PM EDT, 8 hours 29 minutes before
Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
245 PM EDT Tue Jul 25 2017

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-261845-
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-
245 PM EDT Tue Jul 25 2017

This Hazardous Weather Outlook is for northeast Georgia, the
foothills and piedmont of western North Carolina and Upstate South
Carolina.

.DAY ONE...This Afternoon and Tonight.

Isolated to scattered thunderstorms will develop around the region
late this afternoon into this evening. Cloud-to-ground lightning
will be the main threat from any storm that develops. Some of the
thunderstorms may also produce brief but strong wind gusts.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

..Wednesday...No hazardous weather is expected at this time.
..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.

.SPOTTER INFORMATION STATEMENT...

None.

HG

In the hours before

Special weather statement, Jul 25, 8:57 PM EDT, 2 hours 17 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
857 PM EDT TUE JUL 25 2017

NCZ504-260145-
Greater Burke NC-
857 PM EDT TUE JUL 25 2017

...A STRONG THUNDERSTORM WILL IMPACT SOUTHERN BURKE COUNTY UNTIL 945
PM EDT...

At 857 PM EDT, Doppler radar was tracking a strong thunderstorm 4
miles southeast of Morganton, or near Drexel, moving southwest at 5
mph.

Locations to be impacted include...
Morganton, Valdese, Icard, Drexel, Connelly Springs, Rutherford
College, Glen Alpine, South Mountains State Park, Lake Rhodhiss and
Hildebran.

Wind gusts up to 40 mph 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 3581 8158 3578 8156 3578 8153 3573 8142
      3556 8157 3557 8160 3556 8164 3557 8167
      3558 8169 3558 8170 3561 8172 3560 8174
      3561 8176 3568 8186 3583 8163
TIME...MOT...LOC 0057Z 041DEG 6KT 3571 8162

TDP
Special weather statement, Jul 25, 10:32 PM EDT, 42 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1032 PM EDT TUE JUL 25 2017

SCZ001-004-260315-
Greater Oconee SC-Oconee Mountains SC-
1032 PM EDT TUE JUL 25 2017

...A CLUSTER OF THUNDERSTORMS WILL IMPACT CENTRAL OCONEE COUNTY UNTIL
1115 PM EDT...

At 1031 PM EDT, Doppler radar indicated the leading edge of a cluster
of thunderstorms along a line extending from 8 miles north of
Walhalla to 3 miles west of Seneca. These storms were nearly
stationary.

Locations to be impacted include...
Seneca, Walhalla, Westminster, Oconee State Park, Lake Keowee,
Mountain Rest and Oakway.

Wind gusts up to 40 mph 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.

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 8317 3460 8317 3460 8316 3461 8318
      3484 8327 3485 8327 3485 8325 3488 8324
      3488 8321 3489 8320 3492 8316 3493 8316
      3493 8311 3495 8313 3497 8312 3495 8305
      3461 8290 3456 8312
TIME...MOT...LOC 0231Z 091DEG 3KT 3489 8311 3468 8302

TDP

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 25, 10:34 PM EDTSevere Thunderstorm WarningGSPRabun41 min
Jul 25, 11:47 PM EDTSpecial Weather StatementGSPHabersham, Stephens28 min
Jul 26, 3:14 PM EDTSpecial Weather StatementGSPElbert61 min
Jul 26, 5:34 PM EDTSpecial Weather StatementGSPElbert, Franklin, Hart, Stephens56 min
Jul 26, 6:11 PM EDTSpecial Weather StatementGSPElbert64 min
Jul 26, 6:38 PM EDTAreal Flood AdvisoryGSPElbert52 min
Jul 26, 7:04 PM EDTSpecial Weather StatementGSPFranklin26 min
Jul 25, 10:32 PM EDTSpecial Weather StatementGSPOconee43 min
Jul 25, 11:22 PM EDTAreal Flood AdvisoryGSPOconee113 min
Jul 26, 4:41 PM EDTSpecial Weather StatementGSPGreenwood34 min
Jul 26, 5:16 PM EDTSpecial Weather StatementGSPAbbeville, Greenwood44 min

Nearby

Severe Thunderstorm Warnings in Georgia, 2017Severe Thunderstorm Warnings in South 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.