Flash Flooding and Flooding in Georgia, October 11, 2020

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
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.

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