Flash Flood Watch 1, NWS Greenville-Spartanburg, SC

721 
WGUS62 KGSP 251901
FFAGSP

Flood Watch
National Weather Service Greenville-Spartanburg SC
301 PM EDT Thu Mar 25 2021

...MULTIPLE ROUNDS OF HEAVY RAIN THROUGH TONIGHT IN THE MOUNTAINS
OF SOUTHWEST NORTH CAROLINA AND FAR NORTHEAST GEORGIA...

.The passage of a warm front will bring an exceptionally moist
subtropical airmass over the region today. An unstable atmosphere
will allow rounds of intense showers and thunderstorms producing
heavy rain. The flash flood risk is especially high in the
southern Appalachians where terrain will enhance the production
of rainfall.

GAZ010-NCZ051-052-058-059-062>064-260315-
/O.CON.KGSP.FF.A.0001.000000T0000Z-210326T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Rabun-Swain-Haywood-Graham-Northern Jackson-Macon-
Southern Jackson-Transylvania-
Including the cities of Clayton, Pine Mountain, Mountain City, 
Alarka, Almond, Bryson City, Luada, Wesser, Waynesville, 
Waterville, Canton, Cruso, Cove Creek, Robbinsville, Stecoah, 
Cullowhee, Tuckasegee, Sylva, Franklin, Rainbow Springs, Kyle, 
Highlands, Wolf Mountain, Cashiers, Brevard, Cedar Mountain, 
and Little River
301 PM EDT Thu Mar 25 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH FRIDAY MORNING...

The Flash Flood Watch continues for

* portions of northeast Georgia and western North Carolina, 
  including the following areas, in northeast Georgia, Rabun. In 
  western North Carolina, Graham, Haywood, Macon, Northern 
  Jackson, Southern Jackson, Swain, and Transylvania. 

* Now through Friday morning

* Exceptional moisture and strong southerly flow over the high 
  terrain will lead to multiple rounds of heavy rainfall. 

* Mountain terrain will become increasingly saturated with the 
  rain today and tonight. Heavy runoff could trigger isolated 
  landslides. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.

You should monitor later forecasts and be prepared to take action
should Flash Flood Warnings be issued.

&&

$$

CAC

307 
WGUS62 KGSP 260227
FFAGSP

Flood Watch
National Weather Service Greenville-Spartanburg SC
1027 PM EDT Thu Mar 25 2021

...CONTINUED HEAVY RAIN EXPECTED THROUGH THE OVERNIGHT IN THE 
MOUNTAINS OF SOUTHWEST NORTH CAROLINA AND FAR NORTHEAST GEORGIA...

GAZ010-NCZ051-052-058-059-062>064-261030-
/O.CON.KGSP.FF.A.0001.000000T0000Z-210326T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Rabun-Swain-Haywood-Graham-Northern Jackson-Macon-Southern Jackson-
Transylvania-
Including the cities of Tuckasegee, Waterville, Canton, Luada, 
Brevard, Cullowhee, Cruso, Mountain City, Clayton, Sylva, Cashiers, 
Cove Creek, Cedar Mountain, Little River, Rainbow Springs, 
Highlands, Wesser, Pine Mountain, Stecoah, Kyle, Wolf Mountain, 
Franklin, Almond, Waynesville, Bryson City, Robbinsville, and Alarka
1027 PM EDT Thu Mar 25 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 8 AM EDT FRIDAY...

The Flash Flood Watch continues for

* Portions of northeast Georgia and western North Carolina, 
  including the following areas, in northeast Georgia, Rabun. In 
  western North Carolina, Graham, Haywood, Macon, Northern Jackson, 
  Southern Jackson, Swain and Transylvania.

* Until 8 AM EDT Friday.

* Exceptional moisture and strong southerly flow over the high 
  terrain will lead to multiple rounds of heavy rainfall.

* Mountain terrain will become increasingly saturated with the 
  rain today and tonight. Heavy runoff could trigger isolated 
  landslides. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.

You should monitor later forecasts and be prepared to take action
should Flash Flood Warnings be issued.

&&

$$

ARK

150 
WGUS62 KGSP 260743
FFAGSP

Flood Watch
National Weather Service Greenville-Spartanburg SC
343 AM EDT Fri Mar 26 2021

GAZ010-NCZ051-052-058-059-062>064-260845-
/O.CAN.KGSP.FF.A.0001.000000T0000Z-210326T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Rabun-Swain-Haywood-Graham-Northern Jackson-Macon-Southern Jackson-
Transylvania-
Including the cities of Tuckasegee, Waterville, Canton, Luada, 
Brevard, Cullowhee, Cruso, Mountain City, Clayton, Sylva, Cashiers, 
Cove Creek, Cedar Mountain, Little River, Rainbow Springs, 
Highlands, Wesser, Pine Mountain, Stecoah, Kyle, Wolf Mountain, 
Franklin, Almond, Waynesville, Bryson City, Robbinsville, and Alarka
343 AM EDT Fri Mar 26 2021

...FLASH FLOOD WATCH IS CANCELLED...

The Flash Flood Watch for portions of northeast Georgia and western 
North Carolina, including the following areas, in northeast Georgia, 
Rabun. In western North Carolina, Graham, Haywood, Macon, Northern 
Jackson, Southern Jackson, Swain and Transylvania has been cancelled.

The Flood Watch is cancelled. While numerous rivers are still rising 
and some flooding of main-stem rivers is ongoing, Additional flash 
flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures.

$$

ARK

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
404 AM EDT Thu Mar 25 2021

.SYNOPSIS...
A vigorous cold front is expected to move through the area later
tonight and into Friday and could produce isolated strong to severe
convection along with significant rainfall. The active pattern
continues this weekend as another cold front slides through the
area on Sunday bringing another round of showers and thunderstorms.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 320 AM: We remain under a weak WAA regime and influence of a
subtropical ridge off the SE Coast. This ridge is downstream of an
expansive trough, within which a potent shortwave will move today,
driving development of a low pressure system over the lower MS
Valley. A significant severe outbreak is expected to our west. Ahead
of that system, a warm front is developing across central MS/AL/GA
attm, with the aid of a jet streak. Cirrus are advecting into the
CWA as that streak approaches and via convective debris. This cirrus
likely won't arrive fast enough to hinder radiational cooling that
will produce areas of fog across portions of the Piedmont. Our
normally pretty reliable LAMP guidance continues to depict an
area of dense fog west and northwest of Charlotte. Some of the
meso models depict a more typical distribution focusing on the
lower elevations of the Upstate. Careful analysis of thermal fields
suggests the most probable cause of the LAMP depiction is a shallow
cool pool remaining banked against the Escarpment, a remnant of our
longstanding wedgelike pattern which otherwise ended yesterday. Will
have to monitor for locally dense fog; a couple sites are already
1/4SM on a local scale, but that could improve when the thick
cirrus move overhead. An area of light precip assoc with the warm
front will shift into the area around daybreak, from the SW; this
will mainly affect the mtns and foothills. Hourly precip rates in
that round are expected to be light, but they will begin to set
the stage for later heavy rain to possibly cause hydrologic issues.

Forcing for precip will have an initial peak this morning as
initial band of divergence associated withe the aforementioned jet
streak translates across the mtns and then off to the north. This
effectively will put the CWA in the warm sector; low level lapse
rates are not especially good, and PoPs will be kept on the low end
in areas too far from the Escarpment for any significant terrain
boost. Fairly brisk southerly flow should continue to generate
precip over the higher terrain. The depth and strength of moisture
advection will be impressive, leading to PWATs peaking near +3 SD,
and IVT parameter values that are also anomalously large. Deep layer
hodographs will already be long and curving, but midlevel lapse
rates are not the greatest; the limited instability will keep our
severe threat comparatively small during the day, with convective
layers too shallow to realize all the shear. This does somewhat
limit our heavy rain threat as well, though there will be widespread
coverage and potential for multiple rounds thru tonight. WPC Day
1 ERO includes a portion of our SW mtns in a Moderate Risk, partly
because of the aforementioned anomalies and high probabilities for
significant rain rates from the HREF. We are hoisting a Flash Flood
Watch from 18z today to 12z Fri. The same southerly flow will lead
to rather gusty winds, and higher elevations of the mtns will be
exposed to near Wind Advisory-level conditions.

LLJ is expected to precede the cold front into our area in the early
evening, again enhancing precip generation along the srn end of the
Appalachians; a narrow tongue of sfc based instability will linger
until the front itself enters in the late evening. A convective
line, likely with some embedded rotation--likely supercellular
structures if NAM instability verifies--will make a run at our
area. The dynamic lift provided by the shortwave will mostly miss
our area to the NW as the wave tracks north of the OH River; this
coupled with the unfavorable timing, and diminishing instability,
should begin to impact the convection particularly as it crosses
the mountains. Nevertheless, a narrow line of strong showers with
a few embedded tstms could progress across the area overnight. Prog
soundings reveal that the line will encounter poor low to midlevel
lapse rates, and this would limit sfc based updrafts and thus
tornado risk. The SPC slight risk extending only into the mtns
looks well-placed.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 320 AM EDT Thursday: the short-term fcst picks up at 12z on
Friday with upper ridging amplifying to our south as an upper trof
rides up and over the ridge. The trof will eventually move off the
New England Coast early Saturday as the upper ridge remains in place
over the Southeast CONUS. By the end of the period early Sunday,
another upper trof will be digging down over the Great Lakes. At
the surface, a robust cold front will be exiting the CWFA as the
period begins. High pressure will build in behind the front Friday
afternoon as low-lvl flow shifts to more WLY direction and the
frontal zone stalls out across south-central GA and SC. We'll see
a brief period of drying in the wake of the front, however SLY
return flow will spread back over the region during the day on
Saturday as another low develops to our west and lifts northward
towards the Great Lakes. That low will move another cold front
to our doorstep by the end of the period early Sunday. Temps will
remain well-above normal thru the period.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 305 AM EDT Thursday...the extended fcst picks up at 12z on
Sunday with a closed upper low separating from the southern stream
upper flow as the main trof lifts NE towards the Great Lakes. By
late Sunday, the upper trof axis is expected to pass just to our
north and then move off the Atlantic Coast early Monday. Heights
will recover as the trof moves offshore and upper ridging begins
to amplify again over the Gulf of Mexico and remains over our region
thru mid-week. At the sfc, another robust cold front will be at our
doorstep as the period begins early Sunday. The front will move thru
our CWA Sunday morning/afternoon with broad high pressure drying
things out in the front's wake by early Monday. The sfc high appears
to be fairly transitory and will linger over the region on Monday
and then slide eastward and off the coast later on Tuesday. By the
end of the period on Wednesday, warm SLY flow will spread over the
Southeast and bring increased chances for showers and thunderstorms.
The environment is still looking favorable for another round of
convection with the Sunday front. The timing remains consistent
and the amount of instability looks decent across most of the CWFA
for Sunday afternoon/evening.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Weak warm advection in the low levels will
maintain patches of low VFR cloud early this morning; cirrus will
increase as a jet streak approaches from the south. This feature
is also associated with a developing warm front that will bring a
chance of precip mainly to KAVL and the Upstate sites by around
daybreak. Guidance is hitting low cigs hard across portions of
the Piedmont seemingly along a weak boundary; questions are how
much the invading cirrus will inhibit radiative cooling and also
confidence in the placement of the apparent boundary. Thus, with
limited confidence, have used TEMPOs to highlight the most severe
impacts (and to capture precip chances with the warm front). Cigs
should lift thru MVFR to low VFR by early aftn. Slightly unstable
soundings this aftn most likely will be capped, so abundant cu field
is expected with PoPs too low to mention east of the mtns (where
upslope and WAA will remain in place thru the aftn). A weakening
convective line is expected to traverse the region tonight; with
the impacts earlier in the period have not focused on these too
closely yet, but have made a mention of worsened flt cat and VCSH
near the end of the respective periods. VCTS at KAVL/KAND where
line may stil have some oomph; damaging wind risk is nonzero with
those storms or any stronger showers.

Outlook: Active weather will continue until a cold front pushes
through the region Friday. Another system may bring rain and
associated restrictions late Saturday into Sunday.

Confidence Table...

            08-14Z        14-20Z        20-02Z        02-06Z
KCLT       High  96%     High  86%     High 100%     High 100%
KGSP       High  92%     High  83%     High 100%     High  92%
KAVL       Low   57%     Med   71%     High  82%     High  85%
KHKY       High  81%     High  80%     High 100%     High  86%
KGMU       High  81%     Med   79%     High 100%     High  94%
KAND       High  92%     High  95%     High 100%     High  92%

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 from 2 PM EDT this afternoon through Friday
     morning for GAZ010.
NC...Flash Flood Watch from 2 PM EDT this afternoon through Friday
     morning for NCZ051-052-058-059-062>064.
SC...None.

&&

SYNOPSIS...JPT
NEAR TERM...Wimberley
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...Wimberley

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
417 PM EDT Wed Mar 24 2021

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>070-501>510-SCZ001>008-010>012-019-252030-
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-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-Anderson-Abbeville-Laurens-
Greenwood-
417 PM EDT Wed Mar 24 2021

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

.DAY ONE...Tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Showers and thunderstorms will move into the area from west to east
Thursday afternoon through Friday morning. Areas in far Western North
Carolina and parts of Northeast Georgia will see some storms Thursday
afternoon and evening, with storms initiating or entering other
areas early Friday morning. Strength of storms will be in decline by
daybreak on Friday. Some of these storms may reach severe limits
with the primary threat of strong straight- line winds.

.SPOTTER INFORMATION STATEMENT...

None.

NCZ071-072-082-SCZ009-013-014-252030-
Mecklenburg-Cabarrus-Union NC-York-Union SC-Chester-
417 PM EDT Wed Mar 24 2021

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

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.