Severe Thunderstorm Warning 33, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
654 AM EDT Fri Apr 19 2019

.SYNOPSIS...
A strong cold front will move through the forecast area today
bringing showers and thunderstorms to the region. There is a
good chance that some of these storms could become severe as
the front moves through the area. Cooler temperatures and
lingering showers are expected behind the front. Temperatures
will warm again by early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 650 AM...Latest radar imagery showed a well defined line
thunderstorms extending north out of the Gulf fo Mexico into the
Southern Appalachians. Some thunderstorms have been strong to severe
with a couple of warnings already issued this morning (no damage
reports so far). Rainfall rates of 1 to 3 inches per hour raise some
hydro concerns, but the line is moving just fast enough to alleviate
these concerns somewhat. However, there is the potential that this
line will slow down or training of storms could become more
prevalent, increasing this risk. Have tweaked PoPs and other avn
grids to match the latest trends.

Otherwise, the big story continues to be the dynamic upper low
pressing east into the Deep South and the associated severe weather
potential for our area later today. The latest radar showed an
organized line of convection (QLCS) stretching north to south from
the Gulf of Mexico into eastern TN. The upper low responsible for
this line of convection is expected to close off across northern MS
this afternoon before curling east and then northeast into the
southern to mid Appalachian mtns tonight. The closed low will slow
down somewhat while beginning to acquire a negative tilt. This will
likely do two things. One, it will provide a significant couplet of
strong synoptic ascending and descending air associated with a 120
kt jet streak overhead. Two, the slowing should allow for diurnal
instability (especially for the I-77 corridor) to be able to tap
into strong shear (0-1 km BS of 40+ kts) just above the surface (two
key ingredients for severe weather). The leading line of convection
(QLCS) looks to have the greatest widespread severe threat after 11
am with severe winds (in excess of 58 mph) the primary threat due to
the potential for a strong rear inflow jet associated with the QLCS
with a secondary threat for both tornadoes and severe hail. In fact
SPC has issued an moderate risk of severe weather for the I-77
corridor including Charlotte meaning that scattered severe
thunderstorms are likely. The severe risk gradually decreases
heading west across the FA. The mode of convection is more up for
debate after the initial line as model guidance does show a
secondary frontal feature following the main one, but the question
remains as to how much instability will be left and how any
convection may organize along or out ahead of it. Leaning towards
more disorganized convection moving generally SW to NE as llvl flow
veers to the SW with the upper low nearing the FA later this
afternoon. Can't rule out a few supercell thunderstorms developing
ahead or along the main line of convection (if there are breaks) or
mini super cells behind the system (mini due to the relative lack of
instability. The slow moving nature of convection with the main line
of convection in particular will likely cause at least some hydro
issues to small streams and roadways (WPC slight risk for excessive
rainfall across the region). The strong southerly winds along and
ahead of this system will support gusty winds across the high
elevations, especially SW mountains where a wind advisory has been
posted and continues through noon.

Most areas will see rain and thunderstorms come to an end by this
evening as the main forcing exits NE of the region. However, the
cold core upper low will support snow levels falling to around 4K
feet and potential for accumulating snows at this level with several
inches possible above 5K feet, especially where the best upslope
flow (from the SW) overlaps with good synoptic lift and moisture
across the SW mtns. As of now the main winter weather impacts appear
to be above 5K feet so any winter products will be shelved for now,
but considered on future shifts. Temps for most areas will only fall
into the 40s and 50s (30s higher mtn elevations) due to continued
breezy conditions, so frost should not be an issue.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 235 AM EDT Friday: the short-term fcst picks up at 12z on
Saturday with an impressive upper low centered just to our north
as steep upper ridging spreads over the Western CONUS. Because
this system is essentially cut-off from the northern-stream upper
flow, it will push eastward very slowly and is not expected to
move off the Atlantic Coast until the very end of the period on
Monday. At the sfc, a substantial low pressure system will be
centered to our NNW and over the Ohio River Valley as the cold
front associated with it moves offshore. Over the next 24hrs or
so, the low will remain nearly stationary as a substantial plum
of deep-lyr moisture spreads over much of the CWFA from the west.
The latest model guidance continues to open up the low by Sunday
morning as the system gradually lifts NE of the fcst area and
drier air moves back over the area. For the rest of the period,
drier high pressure centered over the Northern Gulf of Mexico
will persist over the Southeast. As for the sensible fcst, we
will likely have some lingering precip on Sat with the remainder
of the period being dry. With the impressive cold-air advection
expected across the region and unusually low thickness values,
some snow flurries are expected over the higher elevations early
Sat and early Sun. Some accumulating snow is possible above 3500
ft, with a better chance above 5000ft. At this time, I do not
anticipate any winter hazard products will be needed, but if
expected snow amounts trend upwards then hazards cannot be ruled
out. The resulting windy conditions should help inhibit any frost
formation across the active zones (which is everywhere except the
Northern NC Mountains). Temps should warm back into the upper 60s
to low 70s across the lower elevations on Sunday, with more warming
as we move into the extended period.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 245 PM EDT Thursday: Upper low over the Mid-Atlantic will
continue to lift north, with high pressure building in and
increasing thicknesses. Temperatures will increase through the
extended, 5 to maybe even 10 degrees above seasonal. A shortwave
spinning around the upper low may bring some showery activity or
even possible thunderstorms Tuesday afternoon, GFS a little stronger
with this idea than ECMWF. Next system gearing up over the Rockies
will push off into the Plains sometime midweek, but there are some
very significant timing differences between the global models, so
frankly opted to keep a fairly generic blend through the end of the
period and into the new day 7. As a note to readers, depending on
how near-term activity shapes up tonight, the extended forecast may
not be updated until Friday afternoon.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Rapidly deteriorating conds expected between
12Z and 18Z associated with a dynamic storm system to move through
the region. Model guidance shows that the strong line of showers and
thunderstorms (QLCS) approaching across the deep south will hold
together and even intensify east of I-26 and especially near the I-
77 corridor, including KCLT. Brief SW/W gusts in excess of 40 kts
is possible with the QLCS. Light to occasionally moderate LLWS is
possible, especially between 15Z and 20Z. LLWS issues may linger at
KAVL behind this time as winds veer to the SW. A secondary impulse
of showers and embedded thunderstorms associated with the leading
edge of the upper low are possible just about anywhere between 18Z
and 00Z.

Outlook: Improving conditions are expected early Saturday. Spotty
restrictions cannot be ruled out over the mtns as an upper low
passes by on Saturday.

Confidence Table...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       High 100%     High  81%     Med   75%     High  93%
KGSP       High  85%     Low   56%     Med   75%     Med   71%
KAVL       High  93%     High  94%     High  87%     High  85%
KHKY       High 100%     High  87%     High  87%     Med   64%
KGMU       Med   71%     Low   56%     High  81%     Med   71%
KAND       Med   71%     High  87%     High  81%     High  85%

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...Wind Advisory until noon EDT today for NCZ033-048>052-058-059-
     062>064.
SC...None.

&&

SYNOPSIS...JPT
NEAR TERM...Munroe
SHORT TERM...JPT
LONG TERM...TDP
AVIATION...Munroe

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
804 AM EDT Fri Apr 19 2019

NCZ033-048>053-058-059-062>064-201215-
Avery-Madison-Yancey-Mitchell-Swain-Haywood-Buncombe-Graham-
Northern Jackson-Macon-Southern Jackson-Transylvania-
804 AM EDT Fri Apr 19 2019

...WIND ADVISORY IN EFFECT UNTIL NOON EDT TODAY ABOVE 3500 FEET...

This Hazardous Weather Outlook is for 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.

   Wind Advisory.

A band of heavy rain showers and embedded thunderstorms will also
move over the mountains. The primary threat from these showers and
storms will be from very heavy rainfall leading to rapid water rises
on small streams and in areas of poor drainage. Localized flash
flooding will be possible. In addition, brief, damaging wind gusts
cannot be ruled out during any heavier showers or thunderstorms.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

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

GAZ010-017-018-026-028-029-NCZ035>037-056-057-065-068>072-082-
501>510-SCZ001>014-019-201215-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Alexander-Iredell-
Davie-Catawba-Rowan-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-
804 AM EDT Fri Apr 19 2019

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

.DAY ONE...Today and tonight.

A band of heavy rain showers and embedded thunderstorms is expected
to move across the foothills and Piedmont today. Isolated severe
thunderstorms capable of producing locally damaging wind gusts and
isolated brief tornadoes will be possible, especially across the
Piedmont, and especially in the late morning and afternoon. In
addition, localized excessive rainfall may cause flash flooding of
small streams and urban areas.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

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

Wimberley

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
903 AM EDT Fri Apr 19 2019

NCZ036-191330-
Iredell NC-
903 AM EDT Fri Apr 19 2019

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN IREDELL COUNTY
UNTIL 930 AM EDT...

At 903 AM EDT, Doppler radar was tracking a strong thunderstorm 11
miles north of Statesville, or 5 miles southeast of Love Valley,
moving northeast at 50 mph.

Locations to be impacted include...
Harmony, Union Grove and Olin.

Wind gusts up to 40 mph, pea size hail and very heavy rainfall rates
up to 2 inches per hour will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio and tv
stations, as well as local cable tv outlets for additional
information and possible warnings from the National Weather Service.

&&

LAT...LON 3605 8070 3586 8088 3594 8100 3606 8094
TIME...MOT...LOC 1303Z 209DEG 42KT 3595 8090

MOORE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
917 AM EDT Fri Apr 19 2019

NCZ036-056-191345-
Iredell NC-Catawba NC-
917 AM EDT Fri Apr 19 2019

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN CATAWBA AND CENTRAL
IREDELL COUNTIES UNTIL 945 AM EDT...

At 916 AM EDT, Doppler radar was tracking a strong thunderstorm 11
miles northwest of Huntersville, or near Lake Norman, moving
northeast at 50 mph.

Locations to be impacted include...
Statesville, Troutman, Lake Norman, Lake Norman State Park,
Mooresville, Sherrills Ford, Terrell, Doolie and Cool Springs.

Wind gusts up to 45 mph, pea size hail and very heavy rainfall rates
up to 2 inches per hour will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio and tv
stations, as well as local cable tv outlets for additional
information and possible warnings from the National Weather Service.

Lake Norman is in the path of this storm. Cloud to ground lightning
and gusty winds will create dangerous boating conditions.
Move to shore immediately.

&&

LAT...LON 3586 8071 3566 8078 3553 8089 3549 8095
      3551 8096 3552 8096 3553 8095 3553 8094
      3555 8096 3555 8105 3556 8106 3590 8093
TIME...MOT...LOC 1316Z 203DEG 41KT 3557 8094

MOORE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
922 AM EDT Fri Apr 19 2019

GAZ018-026-SCZ001-004-191400-
Franklin GA-Stephens GA-Greater Oconee SC-Oconee Mountains SC-
922 AM EDT Fri Apr 19 2019

...A STRONG THUNDERSTORM WILL IMPACT NORTHERN FRANKLIN...SOUTHEASTERN
STEPHENS AND SOUTH CENTRAL OCONEE COUNTIES UNTIL 1000 AM EDT...

At 922 AM EDT, Doppler radar was tracking a strong thunderstorm 5
miles north of Carnesville, or 4 miles southwest of Martin, moving
northeast at 40 mph.

Locations to be impacted include...
Carnesville, Gumlog, Martin, Avalon, Tugaloo State Park, Lavonia,
Eastanolee and Oakway.

Wind gusts up to 50 mph 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 3442 8337 3468 8314 3454 8297 3449 8304
      3449 8305 3447 8307 3433 8325
TIME...MOT...LOC 1322Z 222DEG 35KT 3444 8324

KRENTZ

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