Alert archive / Georgia / Flash Flood Warnings in 2020

Flash Flood Warning 60, NWS Greenville-Spartanburg, SC

October 11, 2020Habersham County, Rabun County, Georgia

NWS Greenville-Spartanburg, SC issued this flash flood warning at Oct 11, 2020, 2:19 AM EDT for Habersham County, Rabun County, Georgia. It was in force for 6 hr. 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
Oct 11, 2020, 2:19 AM EDT (06:19 UTC)
Expired
Oct 11, 2020, 8:15 AM EDT
In force
6 hr
Issued by
NWS Greenville-Spartanburg, SC
Area
Storm-based polygon
Flood severity
None

Counties Habersham County, GA, Rabun County, GA

The radar

The Greer radar (KGSP), 111 km from the middle of the area, began a volume at 06:20 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
Oct 11, 4:10 AM EDTFLASH FLOODClayton, GARABUN COUNTY 911 REPORTED NUMEROUS ROADS WERE FLOODED ACROSS THE COUNTY INCLUDING: SHADY LN AND OLD US 441 IN LAKEMONT AND GA 15 IN CLAYTON. A FEW MUDSLIDES OF UNKNOWN SIZE WERE ALSO REPORTED, IMPACTING ROADWAYS.

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 flash flood warning; the first came 111 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, 6.3 hours before the alert went out and 188 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 2020-10-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1465 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 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 2020-10-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 221 square meters per square second.19395878Sfc1 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
1465 J/kg
Mixed-layer CIN
-533 J/kg
Mixed-layer LCL
1573 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
221 m²/s²
0-3 km storm-relative helicity
368 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.6

Open this sounding in Storm Lab

The text

As transmitted.

496 
WGUS52 KGSP 110619
FFWGSP
GAC137-241-111215-
/O.NEW.KGSP.FF.W.0060.201011T0619Z-201011T1215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Greenville-Spartanburg SC
219 AM EDT Sun Oct 11 2020

The National Weather Service in Greenville-Spartanburg has issued a

* Flash Flood Warning for...
  Eastern Habersham County in northeastern Georgia...
  Rabun County in northeastern Georgia...

* Until 815 AM EDT.

* At 219 AM EDT, Doppler radar indicated several rounds of heavy 
  rain across the warned area. Between 2 and 3.5 inches of rain have 
  fallen over the past 2-3 hours. Flash flooding is ongoing or 
  expected to begin shortly especially across southern and eastern 
  Rabun County near Lakemont, Tiger, and the Chattooga River as well 
  as extreme eastern Habersham County near Turnerville and 
  Hollywood. Georgia Power is releasing water from Mathis Dam and 
  this additional flow along the Tallulah River will likely flood 
  portions of Shady Ln and possibly Mathis Dam Rd over the next 1-3 
  hours.  Additional releases and more significant flooding is 
  possible over the next several hours as significant flows work 
  through the Tallulah River system.  Residents on the south side of 
  Lake Rabun may have to seek an alternate route overnight into the 
  early Sunday morning hours.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Doppler radar and automated rain gauges

  IMPACT...Expect rapid rises of small streams, flooding of urban
           areas, low-lying areas adjacent to streams and
           drainage ditches, low-elevation roadways, farmland and
           parks.

* Some locations that may experience flash flooding include...
  Clayton, Mount Airy, Mountain City, Tiger, Dillard, Sky Valley, 
  Tallulah Falls, Lakemont, Black Rock Mountain State Park, Lake 
  Rabun, Tallulah Gorge State Park, Lake Burton, Seed Lake, 
  Turnerville, Hollywood and Pine Mountain.

Additional rainfall amounts of 0.5 to 1 inch are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Warning means that flooding is imminent or occurring. 
If you are in the warned area move to higher ground immediately. 
Residents living along streams and creeks should take immediate 
precautions to protect life and property.

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 3483 8366 3488 8366 3491 8360 3494 8360
      3495 8355 3499 8355 3500 8310 3494 8311
      3488 8324 3487 8324 3482 8327 3482 8331
      3473 8335 3469 8334 3468 8337 3448 8346
      3449 8351 3471 8346 3473 8352 3483 8360

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR 

$$

JMP
1 follow-up statement
146 
WGUS72 KGSP 110821
FFSGSP

Flash Flood Statement
National Weather Service Greenville-Spartanburg SC
421 AM EDT Sun Oct 11 2020

GAC137-241-111215-
/O.CON.KGSP.FF.W.0060.000000T0000Z-201011T1215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Habersham GA-Rabun GA-
421 AM EDT Sun Oct 11 2020

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 815 AM EDT THIS 
MORNING FOR EASTERN HABERSHAM AND RABUN COUNTIES...

At 421 AM EDT, Heavy rainfall has ended across Rabun and Habersham 
Counties, however, significant flooding is ongoing across the 
county.  Widespread 2.5 to 4 inches of rain has fallen over the past 
4-6 hours across most of Rabun and Habersham Counties but isolated 
areas of 4-6 inches has fallen, especially from Lakemont to Clayton 
to Sky Valley and points east to the SC state line.  Storm-total 
rainfall since yesterday morning has ranged from 4 to as much as 8 
inches.  Rabun County 911 is reporting numerous roads closed and a 
few mudslides across the county.  GA 15 in Clayton is flooded in 
multiple locations and Shady Ln just below Mathis Dam is also closed 
due to flooding.  Flooding is also being reported along Old US 441 
adjacent to the Tallulah River below Mathis Dam.  Georgia Power 
continues to release significant flows out of Mathis Dam and higher 
flows are possible as the Tallulah River above Lake Burton continues 
to rise.  Therefore, residents along Old US 441 near Lakemont and 
below Mathis Dam should consider seeking higher ground immediately 
and be prepared for additional flooding over the next 2-4 hours.  
Residents on the south side of Lake Rabun will have to seek an 
alternate route overnight into the early Sunday morning hours.

HAZARD...Life-threatening flash flooding due to torrential
         rainfall.

SOURCE...Doppler radar and automated gauges.

IMPACT...Expect life-threatening flooding of small and large
         streams, urban areas, low-lying areas adjacent to
         streams and drainage ditches, low-elevation roadways,
         farmland and parks.  Life threatening flash flooding of
         creeks and streams, urban areas, highways, streets and
         underpasses. Flooding of a few structures and a few
         roadway and/or culvert washouts are still possible.
         Drivers must exercise extreme caution, avoid all flooded
         roadways, and obey all barricades.

* Some locations that are continuing to experience flash flooding 
  include...Clayton, Mount Airy, Mountain City, Tiger, Dillard, Sky 
  Valley, Tallulah Falls, Lakemont, Lake Rabun, Tallulah Gorge State 
  Park, Lake Burton, Seed Lake, Turnerville, Hollywood and Pine 
  Mountain.

Additional significant rainfall is not expected through Sunday 
morning.  Flash flooding conditions across most of Rabun County will 
gradually improve into the morning hours; however, more significant 
flooding may continue downstream of Mathis Dam for several more 
hours.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Warning means that flooding is imminent or occurring. 
If you are in the warned area move to higher ground immediately. 
Residents living along streams and creeks should take immediate 
precautions to protect life and property.

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 3483 8366 3488 8366 3491 8360 3494 8360
      3495 8355 3499 8355 3500 8310 3494 8311
      3488 8324 3487 8324 3482 8327 3482 8331
      3473 8335 3469 8334 3468 8337 3448 8346
      3449 8351 3471 8346 3473 8352 3483 8360

FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

JMP

What forecasters said that day

The local office's own words before this flash flood 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 flash flood warning went out at Oct 10, 10:48 PM EDT, 3 hours 31 minutes earlier.

Area forecast discussion, Oct 10, 10:48 PM EDT, 3 hours 31 minutes before
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1048 PM EDT Sat Oct 10 2020

.SYNOPSIS...
Abundant moisture from the remnants of Delta will continue to stream
over the southern Appalachians and surrounding areas through the
weekend. Drier air will move into the area early next week with a
cold front expected to cross our region early Tuesday. Drier high
pressure will settle in behind the front through Thursday, with
another cold front approaching from the northwest on Friday.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 1045 PM EDT Saturday: A Flash Flood Watch remains in effect
for portions of the area through Sunday evening.

Minor adjustments made to temps/PoPs/present wx to coincide with
latest trends as the rest of the near term remains on track. While a
brief, isolated tornado could not be entirely ruled out through the
overnight hours, continue to expect the primary threat to be the
rainfall, heavy at times, as moisture from the remnants of Delta
continues to infiltrate in. Flash flooding will be possible. Current
temps range from the low to mid 60s to around 70 degrees.

Previous discussion: Current weak northeasterly CAD regime will
become more southeasterly and increase moisture and precipitation,
especially in upslope areas of the Southern Appalachians.  Storm
Total QPF forecast has not changed a lot, with isolated pockets of 3
to 6 inches possible in the escarpment areas, and 1 to 3 inches
elsewhere.

Circulation from Delta will enhance wind profiles and
give some gusts at higher elevations.  Wind shear profiles will be
generally good enough for severe weather on Sunday, in areas of non-
trivial CAPE.  Chances for convection are somewhat better on Sunday
afternoon as some breaks in cloud cover allow temperatures to warm.
CAPE forecasts, and forecasts of sigtor reach notable levels with
some afternoon heating on Sunday, over basically the eastern half of
the CWA, and is consistent with some strong updrafts seen in high-
res models at that time.  This area is currently under a marginal
SPC risk category, but some part of that area may need to be raised,
and will at least bear watching.

Any severe weather is likely to be on the tail end of the event as
the system that was Delta pulls out to the northeast, with clouds
and rain in decline Sunday evening outside of isolated convective
storms.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 200 pm Saturday: Trough axis associated with the remnants of
T.C. Delta will be lifting across the forecast area at the start of
the period, with lingering potential for locally excessive rainfall.
Additionally,  continued moderate sbCAPE aligned with adequate shear
in the warm sector will support a persistent threat for isolated
severe convection across the Piedmont. Likely to categorical pops
are warranted across much of the forecast area through the evening.

The remainder of the short term will be characterized by rising
heights, supporting unseasonably warm weather, max temps expected to
average around 5 degrees above climo, and mins 10-15 degrees above
normal. Conditions will otherwise become increasingly dry, although
some lingering showers will be possible into Monday morning.
Northern stream height falls Monday night and early Tuesday will
allow a frontal boundary to approach the area from the TN Valley.
With the Gulf of Mexico expected to be more or less closed for
business during this time, small pops (20-30%) with the front will
be primarily confined to the Tennessee border.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 225 pm Saturday: Although the front that will cross the area
late in the short term will advect drier air into the region,
conditions will generally remain unseasonably warm through about the
first half of the period. By late in the week, global models agree
that a major trough will take shape across the eastern Conus, with
associated strong frontal zone expected to push into the area on
Friday. The models are not in the best agreement regarding the
magnitude of the moisture/forcing associated with the front, so only
token small pops are carried from late Thu night through Friday.
However, guidance does agree that a major cooling trend will occur
for the Fri/Sat time frame, when temps will likely dip to 10 degrees
below climo...at least. Widespread frost and perhaps some freeze
concerns can therefore be expected across the mountains.

&&

.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: A mixture of MVFR/IFR/LIFR prevails at the
TAF sites tonight as the remnants of TC Delta allows for periods of
SHRA/TSRA, low cigs and patchy fog to affect the FA. Expect this
trend to continue through the overnight hours and through Sunday as
the center of circulation passes to the west, with another window of
opportunity for TSRA late Sunday morning/Sunday afternoon. Could not
entirely rule out brief improvement within lull in precip at times.
NE winds will become ENE/ESE on Sunday AOB 10 kts, with SSE at KAVL.

Outlook: Expect gradually improving conditions Monday into Tuesday
as the remnants of TC Delta moves away from the area and drier air
infiltrates into the area.

Confidence Table...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       Low   54%     Med   70%     High  93%     High  93%
KGSP       Low   55%     High 100%     High  83%     High  91%
KAVL       High  95%     High  97%     High  90%     High  80%
KHKY       High 100%     High  95%     High  97%     High  89%
KGMU       Med   66%     High  83%     Med   70%     High  90%
KAND       High  91%     High  97%     High  85%     High  82%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Flash Flood Watch through Sunday evening for GAZ010-017.
NC...Flash Flood Watch through Sunday evening for NCZ033-049-050-
     052-053-059-062>065-501>510.
SC...Flash Flood Watch through Sunday evening for SCZ001>003.

&&

SYNOPSIS...DEO/SGL
NEAR TERM...SGL/WJM
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...SGL
Hazardous weather outlook, Oct 10, 5:46 PM EDT, 8 hours 33 minutes before
Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
546 PM EDT Sat Oct 10 2020

NCZ048-051-058-112200-
Madison-Swain-Graham-
546 PM EDT Sat Oct 10 2020

This Hazardous Weather Outlook is for western North Carolina.

.DAY ONE...Tonight.

Periods of heavy rainfall associated with the remnants of tropical
cyclone Delta will impact the area tonight. Streams and main stem
rivers will see considerable rises. In addition, winds may gust to 30
to 40 mph along the highest ridge tops of the mountains tonight.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Heavy rainfall associated with the Delta remnants will continue
Sunday before gradually tapering off Sunday night. Despite the recent
dry weather, isolated flooding will be possible, especially in
locations closer to the Blue Ridge mountains where 2 to 4 inches of
rain are most likely.

.SPOTTER INFORMATION STATEMENT...

None.

GAZ010-017-NCZ033-049-050-052-053-059-062>065-501>510-SCZ001>003-
112200-
Rabun-Habersham-Avery-Yancey-Mitchell-Haywood-Buncombe-
Northern Jackson-Macon-Southern Jackson-Transylvania-Henderson-
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-
546 PM EDT Sat Oct 10 2020

...FLASH FLOOD WATCH IN EFFECT THROUGH SUNDAY EVENING...

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

.DAY ONE...Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Flash Flood Watch.

In addition, winds may gust to 30 to 40 mph along the highest ridge
tops of the mountains tonight.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Flash Flood Watch.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any information about
observed flooding to the NWS while following all local, state, and
CDC guidelines.

NCZ035>037-056-057-068>072-082-SCZ007>009-013-014-112200-
Alexander-Iredell-Davie-Catawba-Rowan-Cleveland-Lincoln-Gaston-
Mecklenburg-Cabarrus-Union NC-Spartanburg-Cherokee-York-Union SC-
Chester-
546 PM EDT Sat Oct 10 2020

This Hazardous Weather Outlook is for piedmont North Carolina and
upstate South Carolina.

.DAY ONE...Tonight.

Periods of heavy rainfall associated with the remnants of tropical
cyclone Delta will impact the area tonight. Streams and main stem
rivers will see steady rises.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Heavy rainfall associated with the Delta remnants will continue
Sunday before gradually tapering off Sunday night. Despite the recent
dry weather, isolated flooding will be possible, especially in
locations closer to the mountains where 1 to 3 inches of rain are
likely.

Strong thunderstorms may also develop on Sunday, especially during
the afternoon hours. Isolated severe thunderstorms could develop,
especially in locations along and southeast of Interstate 85, with
damaging winds the primary threat. A brief tornado cannot be ruled
out.

.SPOTTER INFORMATION STATEMENT...

None.

GAZ018-026-028-029-SCZ004>006-010>012-019-112200-
Stephens-Franklin-Hart-Elbert-Greater Oconee-Greater Pickens-
Greater Greenville-Anderson-Abbeville-Laurens-Greenwood-
546 PM EDT Sat Oct 10 2020

This Hazardous Weather Outlook is for northeast Georgia and upstate
South Carolina.

.DAY ONE...Tonight.

Periods of heavy rainfall associated with the remnants of tropical
cyclone Delta will impact the area today through tonight. Streams
and main stem rivers will see steady rises. Isolated thunderstorms
are also possible tonight, with cloud to ground lightning and locally
heavy rainfall the mains threats. However, a severe thunderstorm with
damaging winds cannot be ruled out.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Heavy rainfall associated with the Delta remnants will continue
Sunday before gradually tapering off Sunday night. Despite the recent
dry weather, isolated flooding will be possible, especially in
locations closer to the mountains where 1 to 3 inches of rain are
likely.

Stronger thunderstorms may also develop on Sunday, especially during
the afternoon hours. Isolated severe thunderstorms could develop,
especially in locations southeast of Interstate 85, with damaging
winds the primary threat. A brief tornado cannot be ruled out.

.SPOTTER INFORMATION STATEMENT...

None.

In the hours before

Special weather statement, Oct 11, 12:56 AM EDT, 1 hour 23 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1256 AM EDT Sun Oct 11 2020

GAZ010-017-018-SCZ001-110545-
Rabun GA-Stephens GA-Habersham GA-Oconee Mountains SC-
1256 AM EDT Sun Oct 11 2020

...STRONG THUNDERSTORMS WILL IMPACT STEPHENS...EASTERN HABERSHAM...
CENTRAL RABUN AND SOUTHWESTERN OCONEE COUNTIES UNTIL 145 AM EDT...

At 1255 AM EDT, Doppler radar was tracking a strong thunderstorm 4
miles northwest of Toccoa, moving northeast at 25 mph.

Locations to be impacted include...
Toccoa, Westminster, Tallulah Falls, Tallulah Gorge State Park,
Lakemont, Lake Rabun, Hollywood, Mountain Rest, Long Creek and
Boydville.

Wind gusts up to 40 mph and very heavy rainfall rates up to 2 inches
per hour will be possible in these areas. Isolated flooding of low
lying areas may also occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The combination of gusty winds and saturated soil conditions will
cause scattered trees and power lines to fall. Seek shelter inside an
interior room.

&&

LAT...LON 3496 8319 3469 8305 3460 8316 3460 8317
      3459 8317 3459 8316 3458 8315 3448 8344
      3470 8352
TIME...MOT...LOC 0455Z 242DEG 22KT 3463 8337

HG

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 10, 11:33 PM EDTAreal Flood AdvisoryGSPHabersham3 hr
Oct 11, 12:48 AM EDTFlash Flood WarningGSPHabersham8 hr
Oct 11, 12:56 AM EDTSpecial Weather StatementGSPStephens49 min
Oct 11, 1:31 AM EDTAreal Flood AdvisoryGSPRabun83 min
Oct 11, 2:01 AM EDTAreal Flood AdvisoryGSPStephens8 hr
Oct 11, 7:59 AM EDTAreal Flood WarningGSPHabersham16 hr
Oct 11, 8:13 AM EDTAreal Flood WarningGSPHabersham, Rabun57 hr

Nearby

Flash Flood Warnings in Georgia, 2020Every flash flood warning in 2020

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.