Tornado Warning 9, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
639 AM EST Thu Feb 6 2020

.SYNOPSIS...
Abundant moisture will impact the region today into tonight ahead of
an approaching cold front and strong upper-level disturbance.
Colder, but drier, conditions will develop behind the front through
Friday. A swiftly moving system will cross the region on Saturday,
before dry high pressure sets up by Sunday. Another moist cold front
will approach the area slowly from the west during the early to
middle part of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 640 AM EST: The ingredients are firmly in place for a very wet
and stormy day across the western Carolinas and northeast Georgia.
Water vapor imagery reveals a prominent 500 mb trough moving across
TX/OK this morning. A tremendous fetch of moisture is evident east
of the trough across the lower MS River Valley and stretching up the
Appalachian mountain chain. Precipitable water values in this plume
are running 1.5 to 1.75 inches, with anomalies some 3+ standard
deviations above normal. A Flash Flood Watch is already in place
across the entire forecast area, with several Warnings now issued as
hydro conditions continue to deteriorate. No changes to the Flash
Flood Watch are planned with the expiration still set at midnight
tonight.

As the base of the trough moves east over the lower MS River Valley
today, lobes of stronger DPVA will shuttle northeast across the
southern Appalachians and adjacent foothills/piedmont. This will
combine with robust upper level divergence associated with the
subtropical jet streak reaching 170+ kt at times to produce
impressive forcing. Waves of better sfc-6km bulk shear will cross
the region ahead of the associated surface cold front, with values
around 70 kt at times. Instability was looking to be the main
limiting factor for widespread severe weather, with sbCAPE values
generally just a few hundred J/kg during the daytime hours, and mid-
level lapse rates rather modest. However, recent RAP runs are now
suggesting some sbCAPEs in the 500 to 1000 J/kg range at times
midday as mid 60s dewpoints approach. Overall, the dynamics are so
strong, and the low-level wind shear so abundant, that the existing
Marginal west to Enhanced east gradient of severe threat looks well
placed for today into this evening. Improving updraft helicity on
the mesoscale models will arrive in the southwest mountains before
daybreak, but better organization seems likely over the eastern half
from 16Z onward as the low-level jet ramps up to 50 to 60 kt. Strong
to severe discrete activity will be possible through the morning
hours, but the pre-frontal line should sharpen up through the day as
mesolows move up the frontal boundary to pose the greatest severe
risk through the afternoon hours, perhaps into the early evening
across I-77.

Anticipate a late evening fropa across the mountains, with the
boundary moving east across the piedmont overnight. Snow levels will
fall from the west through daybreak Friday, with light accumulations
most likely along the higher ridges around the Smokies. Winds will
be gusty through the period, both on the warm advection side today
and the cold advection side tonight, but with gusts generally below
advisory levels (30 to 40 mph) at all but the highest peaks.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
As of 255 AM EST Thursday: With the cold front east of the region by
Friday morning, colder air will continue to spill across the
mountains, with 850 mb temperatures bottoming out at minus 6 or
colder along the spine of the southern Appalachians. Although the
low-level flow will be a less favorable westerly direction for
upslope, orographic lift will still wring out snow showers through
the day, with some high elevations in and around the Smokies seeing
possibly 2 to 4 inches of snow by Friday evening. Accumulations will
be quite terrain dependent, with Advisory or greater snow amounts
limited to mainly above 4000 feet, and very little in the lower
valleys. Will mention in the HWO, but hold off on any Advisories at
present. A brief lull in the moisture is expected on Friday night.
Temperatures will return to below climo values during the period.

The latest model runs continue to show the development of weak low
pressure on Saturday morning as a strong short wave drops down
across the TN Valley into the base of the long wave trof across the
eastern US. The models have shown good run-to-run continuity with
this peculiar feature, blowing up precip over the mtns early in the
day and then moving it slowly off to the E/NE, but the recent trend
is toward lower precip amts possibly because the sfc low looks more
like it will be moving over the OH Valley region on Saturday. It is
worth noting, however, that the operational GFS continues to run at
the low end of the GEFS distribution. The fcst is interesting
because partial thickness remains rather low, the boundary layer
rather cool to start with at onset, and the fcst soundings showing
wet bulb profiles that would support all snow at onset across the
mtns. Eventually, warming takes place in the valleys, but not before
we might get a few hours of light snow, especially if the NAM is
correct. Elevations above about 3k feet would be likely to stay snow
for the duration. Because the QPF has come down in the operational
model guidance, present indications are for an Advisory-level event,
but if we end up closer to the ensemble mean, we could push Warning
criteria at elevations above 3500 feet by Saturday afternoon. East
of the mtns, if the precip can begin early enough in the day, it
could begin as a period of light snow, before an eventual changeover
to rain. This would be somewhat similar to what transpired last
Friday, but the amounts this time would be much less. However, the
latest trend was also to delay the onset by a few hours outside the
mtns. This system lifts out Saturday evening and precip pares back
to the NW flow upslope areas by late evening, and then ends by
daybreak Sunday. Temps should be below normal for this period.

The rest of the weekend should be quiet and dry as a flat upper
ridge moves overhead Sunday, pushing high pressure past, then off
the Mid-Atlantic Coast Sunday night. Temperatures should return
to normal. The moisture associated with the next front is not
expected to arrive before daybreak Monday.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 327 AM EST Thursday: Fcst confidence starts out decent on
Monday morning with the models in general agreement that another
frontal boundary will gradually sag down across the fcst area as
the upper flow slowly goes WSW under a low amplitude trof/ridge
pattern. This system is not expected to have nearly the same
benefit of moisture flux from the Gulf as our current event,
but there should be enough forcing and deep moisture to afford a
likely precip probability ramping up Monday and then continuing into
Tuesday while the front stalls against the WSW flow aloft. Temps
should be warm enough...about 5-10 deg above normal...that it
should be all rain. Confidence plummets dramatically beyond
Tuesday. The op GFS has a stronger short wave coming through
the nrn stream which develops a stronger frontal wave that lifts
out Tuesday. Because the wave is stronger, the flow amplifies an
eastern trof which drives the front through and we dry out for
the middle of the week, until a srn stream wave ejects and brings
moisture and precip back from the SW for Thursday. Meanwhile, the
ECMWF remains more low amplitude and keeps the frontal boundary
stalled across our region right through the end of the period,
with another wave on Thursday. For the time being, we lean toward
the ECMWF solution, which makes for another wet week with fairly
high precip probs. But, again, confidence beyond Tuesday is low.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
At KCLT and Elsewhere: Cannot rule out rogue cloud-to-ground
lightning with just about any convective elements passing over the
airfields today. However, will try to target the prime thunder
periods this afternoon with a TEMPO group, and use VCTS otherwise
where permitted. Cigs should quickly settle down into the IFR range
throughout as the heavier rainfall become widespread, with mainly
MVFR visibility except IFR in the heaviest downpours. LIFR
conditions should develop through the day from time to time as the
stronger forcing and very deep moisture move overhead. Anticipate a
sharp uptick in south to southwesterly gusts. Low-level wind shear
will be possible at all sites as the low-level jet continues to ramp
up this morning, but with less confidence at KCLT. Very little
improvement is expected until the fropa moves through the region
later tonight, and even then low clouds may remain.

Outlook: Northwest flow may persist near KAVL, but drying is
possible elsewhere through Friday. A system will move through the
region on Saturday, with brief restrictions possible, before drying
returns on Sunday.

Confidence Table...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       High  90%     Med   68%     High  82%     Low   58%
KGSP       Med   60%     Med   63%     Med   77%     Med   65%
KAVL       Med   70%     Med   72%     Med   77%     Med   65%
KHKY       High  80%     Med   72%     Med   61%     Med   70%
KGMU       Med   65%     Med   72%     Med   77%     High  95%
KAND       High  85%     High  91%     High  82%     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 are available at
the following link:

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Flash Flood Watch through this evening for GAZ010-017-018-026-
     028-029.
NC...Flash Flood Watch through this evening for NCZ033-035>037-
     048>053-056>059-062>065-068>072-082-501>510.
SC...Flash Flood Watch through this evening for SCZ001>014-019.

&&

SYNOPSIS...HG
NEAR TERM...HG
SHORT TERM...HG/PM
LONG TERM...PM
AVIATION...HG

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
1017 AM EST Thu Feb 6 2020

GAZ018-026-028-029-NCZ036-037-056-057-068>072-082-507>510-SCZ001>014-
019-071530-
Stephens-Franklin-Hart-Elbert-Iredell-Davie-Catawba-Rowan-Cleveland-
Lincoln-Gaston-Mecklenburg-Cabarrus-Union NC-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-Union SC-Chester-Greenwood-
1017 AM EST Thu Feb 6 2020

...FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING...
...TORNADO WATCH 27 IN EFFECT UNTIL 5 PM EST THIS AFTERNOON...

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

.DAY ONE...Today and tonight.

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

   Tornado Watch.
   Flash Flood Watch.

Scattered to numerous thunderstorms are also expected to develop
across the region today through this evening ahead of an advancing
cold front. Some of the thunderstorms may well become strong to
severe, with damaging wind gusts possible in addition to cloud to
ground lightning. A few brief, isolated tornadoes will be possible,
especially along and southeast of Interstate 85 this afternoon and
evening. Plan now for the actions that you will take if Severe
Thunderstorm or Tornado Watches or Warnings are issued today. This
is especially important if you in a mobile home. Make arrangements
now to flee quickly to a nearby, sturdier structure if warnings are
issues for your location.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to forward any reports of large hail,
damaging winds, tornadoes, or flash flooding to our office.

GAZ010-017-NCZ033-035-048>053-058-059-062>065-501>506-071530-
Rabun-Habersham-Avery-Alexander-Madison-Yancey-Mitchell-Swain-
Haywood-Buncombe-Graham-Northern Jackson-Macon-Southern Jackson-
Transylvania-Henderson-Caldwell Mountains-Greater Caldwell-
Burke Mountains-Greater Burke-McDowell Mountains-Eastern McDowell-
1017 AM EST Thu Feb 6 2020

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

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

.DAY ONE...Today and 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.

Scattered thunderstorms are also expected to develop across the
region today ahead of an advancing cold front. Some of the
thunderstorms may become strong to severe, with damaging wind gusts
possible in addition to cloud to ground lightning.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Snow showers will develop behind the departing cold front late
tonight through Friday. Light snow accumulations are expected across
the mountains, especially at elevations above 3500 feet where a
couple of inches will be possible. Two to four inches of snow will
be possible along the highest ridge tops around the Great Smoky
Mountains.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to forward any reports of large hail,
damaging winds, tornadoes, or flash flooding to our office.

ARK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
824 AM EST THU FEB 6 2020

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

0815 AM     HEAVY RAIN       1 N GRANITE FALLS       35.82N 81.43W
02/06/2020  M3.11 INCH       CALDWELL           NC   PUBLIC

&&

OUTLAW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
843 AM EST THU FEB 6 2020

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

0830 AM     HEAVY RAIN       4 NW SALEM              34.94N 83.02W
02/06/2020  E3.50 INCH       OCONEE             SC   PUBLIC

            IN THE LAST 2 HOURS.

&&

OUTLAW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
905 AM EST THU FEB 6 2020

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

0901 AM     FLASH FLOOD      DACUSVILLE              34.94N 82.56W
02/06/2020                   PICKENS            SC   AMATEUR RADIO

            FREEMAN ROAD,NEAR THE INTERSECTION WITH HIGHWY 186, UNDER
            WATER WITH PART OF THE ROAD WASHED OUT.

&&

SWILKINS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
919 AM EST THU FEB 6 2020

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

0910 AM     FLASH FLOOD      MARIETTA                35.03N 82.49W
02/06/2020                   GREENVILLE         SC   AMATEUR RADIO

            STREAMS FLOWING OUT OF THEIR BANKS ALONG PACE BRIDGE
            ROAD.

&&

SWILKINS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
959 AM EST THU FEB 6 2020

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

0920 AM     HEAVY RAIN       3 NW TIGERVILLE         35.09N 82.41W
02/06/2020  M5.89 INCH       GREENVILLE         SC   COCORAHS

            STORM TOTAL RAIN REPORT.

&&

SWILKINS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1002 AM EST THU FEB 6 2020

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

0956 AM     FLASH FLOOD      PICKENS                 34.88N 82.71W
02/06/2020                   PICKENS            SC   AMATEUR RADIO

            ROUTE 178 AND FLEETWOOD DRIVE ARE BOTH FLOODED.

&&

SWILKINS