What forecasters said that day
The local office's own words before the first event, 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 the first event at May 24, 6:38 PM EST, 52 minutes earlier.
Area forecast discussion, May 24, 6:38 PM EST, 52 minutes before
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
738 PM EDT Thu May 24 2018
.SYNOPSIS...
Unsettled weather will persist over the next week, with chances for
showers and thunderstorms each afternoon. As low pressure develops
over the Gulf of Mexico, deep tropical moisture will overspread the
area over the weekend and persist into next week, bringing
potentially heavy rainfall for Memorial Day weekend and beyond.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 735 PM: Line of showers and isolated thunderstorms moving WNW
across the Upstate and into NE GA and the Southern NC Piedmont this
evening. Storms have shown a weakening trend, but gust front ahead
of the line will bring gusts around 25 mph. Rainfall rates have been
dropping as well, which is good as some of the storms are moving
toward the Southern NC Foothills which don't need any more heavy
rainfall. Other convection continues across the SW NC mountains. All
this convection should continue to weaken with loss of heating. That
said, brief heavy rainfall is possible through early evening. In
addition, lighter showers may continue through the evening into the
overnight on the moist southeasterly flow into the area. Expect low
clouds and patchy fog to develop as well. Forecast lows look on track.
Tonight, the upper pattern progresses slightly and the sfc high
to our north will begin to shift off the East Coast. In response
low-level flow will veer, returning us to a more typical regime,
albeit still resulting in terrain-induced lift. Above the boundary
layer, thermodynamic profiles essentially do not change, and with
temps/dewpoints remaining elevated, sfc-based (or near-sfc based)
instability will linger and the aforementioned mechanical lift may
be enough to maintain some convection thru the night. Forcing may
also be enhanced by a lobe of vorticity rotating around the weak
upper low centered over Georgia. Thus, we will retain a high chance
to likely range PoP over the western half of the area, though the
focus shifts back to the south-facing Escarpment. Any cells that
develop will still be possible of intense rainfall rates and will
move very slowly...so the heavy rain remains our biggest concern.
Realistically there is little change in the expectations for
tomorrow versus today. Though the flow will be southerly and not
easterly, lapse rates remain mediocre, and we will again deal with
low clouds that will have to dissipate during the morning, before
we can really destabilize. PWATs are expected to be higher overall,
given that we will see less influence from the continental high
currently to our north. Heavy rain may be slightly easier to come
by as a result.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 230 PM EDT Thursday: In this part of the forecast we start
with trouble. The upper level ridge from the eastern Great Lakes to
the Caribbean either breaks down or shifts slightly east. This
allows the old upper level low pressure system in GA to shift
northeast into our forecast area (FA) Friday night. This feature has
had a history of nocturnal heavy rain. Indeed all guidance is
suggestive that Friday night may become active with a locally heavy
rainfall potential. Precipitable waters rise to between 1.7 and 1.9
inches, which is about the 90th percentile. Very soupy. We
entertained a Flash Flood Watch for Friday night, but will wait one
more cycle before pulling that trigger. Overall the model QPF does
not appear drastic, however other players at work may have this
underdone. We would like to see an uptick before moving forward, and
we have a bit more time.
As the upper level low moves northeast we remain in the soupy like
atmosphere Saturday. Meanwhile the ridge from the Caribbean starts
to reestablish itself back to the west, into our FA. Nevertheless,
an unstable atmosphere, meso scale boundaries and some mid level
support, should lead to scattered or numerous showers and
thunderstorms. Heavy rain possible.
Somewhat of a lull (relatively speaking ) for Saturday night as
upper level ridging, and nearby confluence zone, may allow for
lowering POPS until better forcing arrives.
As precipitable water values Sunday shift into the 1.5 to 2.00 inch
range, and the initial arrival of some forcing ( outer banding )
from the system in the Gulf of Mexico, it would be seem prudent to
ramp POPS back up.
Temperatures should exhibit a minimum diurnal trend in this type of
atmospheric structure.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 230 PM EDT Thursday: The medium range forecast is made very
interesting by the presence of what is looking more and more likely
to be a tropical/subtropical low pressure system moving inland from
the Gulf of Mexico. Guidance is coming into better agreement on the
track of the system, though a word of of warning...all models are
being initialized on a system that has not yet been able to form
even a weak closed center of circulation. This renders any model
output on the track/intensity of the system especially uncertain.
Going off what we have to work with, though, it appears that this
very wet low pressure system will be steered northward into the
central Gulf coast between upper subtropical ridges to its east and
west, transporting with it a plume of deep tropical moisture that
will swing northward towards the Carolinas on Monday. This will be
aided by southerly flow off the Atlantic induced by the surface
Bermuda high, resulting in PW values that well exceed the 90th
percentile in the CFSR climatology across the entire area, with some
zones approaching record max values Monday and Tuesday.
To further complicate matters, a sideways omega-type blocking
pattern will persist across the central CONUS in the upper levels,
morphing into more of a Rex block by Tuesday. The tropical low,
which will likely be inland over the Gulf states by this point, will
therefore make little progress through the southeastern CONUS
through Wednesday until an upper trough is able to absorb it on
Thursday. This means that there will be a relatively uninterrupted
flow of deep tropical moisture into our area through Thursday before
the upper trough is able to hopefully clear the system remnants from
our area. At this point, it should be noted that regardless of
development of this system, "spaghetti model" type plots and others
that emphasize just the track of the system's center will do a very
poor job of demonstrating where the heavy rain threat will occur.
With the likely asymmetrical nature of the system after it moves
inland early next week, it looks increaingly likely that very heavy
rainfall will occur over portions of our area at times despite the
center of the system remaining hundereds of miles to our southeast.
Wind impacts in our area seem unlikely at this point with the heavy
rainfall threat the most concerning potential impact, especially
along the Blue Ridge zones. It is currently almost impossible to pin
down an exact number as far as QPF goes through the next week (we
are currently forecasting 3-5" across the area, though that will
likely change going forward as more banding features may develop),
though with the heavy rainfall we've received over the previous week
or so creating very wet antecedent conditions, interests across the
entire area are advised to stay tuned to forecast updates.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Line of showers and scattered thunderstorms
is drifting WNW across the area. The SC sites look to be the most
likely to see TSRA, so have included a TEMPO there. KCLT the next
likely, but winds likely not as strong there. Have a TEMPO there but
without the gusty winds. Convection least likely at KAVL/KHKY but
SHRA will likely develop overnight in the moist southeasterly flow.
Expect MVFR then IFR cigs overnight in that moist flow, with MVFR
vsby. IFR vsby possible if heavier showers develop. Vsby
restrictions end by mid morning MVFR cigs linger into early
afternoon. Expect another round of showers and thunderstorms, so
PROB30s are in place. Showers and low VFR will linger into Friday
evening at KCLT with restrictions possible late in the period. Winds
already ESE at KCLT and they will continue to slowly move through SE
to S through the period. Elsewhere outside of the mountains NE wind
becomes SE after daybreak and SSE during the afternoon. KAVL sees S
to SSE wind through the period.
Outlook: The unsettled pattern will continue into next week,
with flight restrictions possible each day under diurnal showers
and thunderstorms. Tropical moisture will increase by the late
weekend, further increasing frequency/intensity of SHRA. Morning
stratus/fog are possible each day, especially following heavy rain
the previous day.
Confidence Table...
23-05Z 05-11Z 11-17Z 17-18Z
KCLT High 100% High 89% Med 61% Med 64%
KGSP Med 62% Low 55% High 83% Med 64%
KAVL High 87% Med 72% Med 72% Med 78%
KHKY High 100% Med 72% Low 41% Med 78%
KGMU Med 62% High 83% Low 58% Med 64%
KAND High 100% High 83% Med 72% Med 64%
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...None.
SC...None.
&&
SYNOPSIS...Carroll
NEAR TERM...RWH/Wimberley
SHORT TERM...TS
LONG TERM...Carroll
AVIATION...RWHHazardous weather outlook, May 24, 4:30 PM EST, 3 hours before
Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
530 PM EDT Thu May 24 2018
GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-251230-
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-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-
530 PM EDT Thu May 24 2018
This Hazardous Weather Outlook is for northeast Georgia, piedmont
North Carolina, western North Carolina and upstate South Carolina.
.DAY ONE...Tonight.
Clusters of showers and thunderstorms will continue into the night
before fading later on. Localized heavy rain with flash flooding, and
cloud to ground lightning will be the primary threats. Small hail and
gusty winds will also be possible. The gusty winds from thunderstorms
could blow down a few trees due to saturated soils.
.DAYS TWO THROUGH SEVEN...Friday through Wednesday.
..Friday...Heavy rain possible.
..Saturday...Heavy rain possible.
..Sunday...Heavy rain with flooding possible. Tropical moisture
interacting with a frontal zone may bring organized heavy rainfall
back to the region.
..Monday...Heavy rain with flooding possible.
..Tuesday...Heavy rain with flooding possible.
..Wednesday...Heavy rain with flooding possible.
.SPOTTER INFORMATION STATEMENT...
Skywarn spotters are requested to forward any reports of large hail,
damaging winds, or flash flooding to our office.
ACS
In the hours before
Special weather statement, May 24, 5:47 PM EST, 1 hour 43 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
647 PM EDT THU MAY 24 2018
SCZ006-007-012-013-242315-
Laurens SC-Union SC-Spartanburg SC-Greater Greenville SC-
647 PM EDT THU MAY 24 2018
...THUNDERSTORMS WITH TORRENTIAL RAINFALL WILL IMPACT NORTHWESTERN
LAURENS...SOUTHEASTERN GREENVILLE...SOUTHEASTERN SPARTANBURG AND
UNION COUNTIES UNTIL 715 PM EDT...
At 647 PM EDT, Doppler radar indicated thunderstorms with torrential
rainfall along a line extending from near Union to 7 miles southwest
of Laurens, and moving northwest at 10 mph.
Locations to be impacted include...
Laurens, Union, Woodruff, Monarch Mill, Buffalo, Gray Court,
Jonesville, Waterloo, Rose Hill State Park and Princeton.
Wind gusts up to 40 mph and very heavy rainfall rates up to 2 inches
per hour will be possible in these areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.
&&
LAT...LON 3442 8226 3443 8226 3444 8228 3445 8228
3447 8231 3448 8231 3450 8234 3476 8208
3486 8156 3463 8144 3454 8187 3432 8209
TIME...MOT...LOC 2247Z 141DEG 10KT 3468 8162 3461 8196 3445 8213
ARKSpecial weather statement, May 24, 6:09 PM EST, 1 hour 21 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
709 PM EDT THU MAY 24 2018
SCZ009-014-242345-
York SC-Chester SC-
709 PM EDT THU MAY 24 2018
...A THUNDERSTORM WITH TORRENTIAL RAINFALL WILL IMPACT NORTHERN
CHESTER AND SOUTHERN YORK COUNTIES UNTIL 745 PM EDT...
At 709 PM EDT, Doppler radar was tracking a thunderstorm with
torrential rainfall 7 miles southeast of Rock Hill, or near Lesslie,
moving west at 30 mph.
Locations to be impacted include...
Rock Hill, Lesslie, Sharon, Mcconnells, Lowrys, Catawba and Edgemoor.
Very heavy rainfall rates up to 2 inches per hour will be possible in
these areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.
&&
LAT...LON 3484 8088 3483 8090 3482 8090 3479 8088
3473 8088 3476 8139 3496 8139 3490 8088
3487 8088 3486 8087 3484 8087
TIME...MOT...LOC 2309Z 088DEG 25KT 3485 8098
ARKSpecial weather statement, May 24, 6:35 PM EST, 55 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
735 PM EDT THU MAY 24 2018
SCZ007-013-250000-
Union SC-Spartanburg SC-
735 PM EDT THU MAY 24 2018
...A THUNDERSTORM WITH TORRENTIAL RAINFALL WILL IMPACT SOUTHEASTERN
SPARTANBURG AND CENTRAL UNION COUNTIES UNTIL 800 PM EDT...
At 735 PM EDT, Doppler radar was tracking a thunderstorm with
torrential rainfall over Union, moving west at 15 mph.
Locations to be impacted include...
Union, Monarch Mill, Buffalo, Jonesville, Croft State Park, Cross
Keys, Pauline, Cross Anchor, Sedalia and Adamsburg.
Very heavy rainfall rates up to 2 inches per hour will be possible in
these areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.
&&
LAT...LON 3460 8188 3460 8189 3486 8188 3481 8154
3463 8154 3460 8184 3460 8185 3459 8185
3459 8188
TIME...MOT...LOC 2335Z 091DEG 14KT 3473 8163
ARKSpecial weather statement, May 24, 6:39 PM EST, 51 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
739 PM EDT THU MAY 24 2018
NCZ051-059-062-250015-
Swain NC-Northern Jackson NC-Macon NC-
739 PM EDT THU MAY 24 2018
...A THUNDERSTORM WITH TORRENTIAL RAINFALL WILL IMPACT NORTH CENTRAL
MACON...NORTHWESTERN JACKSON AND SOUTHEASTERN SWAIN COUNTIES UNTIL
815 PM EDT...
At 738 PM EDT, Doppler radar was tracking a thunderstorm with
torrential rainfall 6 miles west of Sylva, or 4 miles west of
Dillsboro. This storm was nearly stationary.
Locations to be impacted include...
Sylva, Bryson City, Cherokee, Dillsboro, Webster, Smoky
Mountains-Oconaluftee, Luada, Alarka, Whittier and Savannah.
Very heavy rainfall rates up to 2 inches per hour will be possible in
these areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.
&&
LAT...LON 3538 8319 3524 8333 3533 8355 3554 8334
TIME...MOT...LOC 2338Z 130DEG 3KT 3536 8333
ARK
Special weather statement, May 24, 7:08 PM EST, 22 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
808 PM EDT THU MAY 24 2018
NCZ051-059-062-250045-
Swain NC-Northern Jackson NC-Macon NC-
808 PM EDT THU MAY 24 2018
...A THUNDERSTORM WITH TORRENTIAL RAINFALL WILL IMPACT NORTH CENTRAL
MACON...WEST CENTRAL JACKSON AND SOUTH CENTRAL SWAIN COUNTIES UNTIL
845 PM EDT...
At 808 PM EDT, Doppler radar was tracking a thunderstorm with
torrential rainfall 6 miles southeast of Bryson City, moving west at
5 mph.
Locations to be impacted include...
Bryson City, Smoky Mountains-Deep Creek, Luada, Burningtown, Alarka,
Cowee, Whittier and Almond.
Very heavy rainfall rates up to 2 inches per hour will be possible in
these areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.
&&
LAT...LON 3540 8328 3523 8332 3522 8359 3549 8353
TIME...MOT...LOC 0008Z 099DEG 5KT 3534 8339
ARK
Special weather statement, May 24, 7:11 PM EST, 19 minutes before
Special Weather Statement
National Weather Service Greenville-Spartanburg SC
811 PM EDT THU MAY 24 2018
SCZ007-008-012-013-250045-
Cherokee SC-Laurens SC-Union SC-Spartanburg SC-
811 PM EDT THU MAY 24 2018
...STRONG THUNDERSTORMS WILL IMPACT NORTHEASTERN LAURENS...CENTRAL
SPARTANBURG...SOUTHWESTERN CHEROKEE AND WESTERN UNION COUNTIES UNTIL
845 PM EDT...
At 811 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 7 miles east of Spartanburg to 14 miles northwest
of Newberry, and moving west at 25 mph.
Locations to be impacted include...
Spartanburg, Laurens, Clinton, Woodruff, Pacolet, Roebuck, Joanna,
Buffalo, Jonesville and Pacolet Mills.
Wind gusts up to 35 mph will be possible in these areas.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.
&&
LAT...LON 3444 8203 3504 8204 3496 8166 3450 8167
3446 8170 3445 8172 3437 8178 3436 8180
TIME...MOT...LOC 0011Z 108DEG 23KT 3493 8179 3442 8179
ARK