Flash Flood Warning 40, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
346 AM EDT Thu Aug 8 2024

.SYNOPSIS...
Tropical Cyclone Debby will gradually track northwest today with
the center expected to be near Charlotte, North Carolina by this
evening. Considerable rainfall is anticipated roughly along and
east of Interstate 77 today and tonight. The remnants of Debby
are expected to eventually move north of our area on Friday with
drier high pressure spreading over the region in its wake through
the weekend.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 345 AM Thursday: The leading edge of the rain shield
associated with Debby continues to spread westward across the
western Piedmont of NC and Charlotte metro area. The better rainfall
rates were starting to push into Union County, with some 1-1.5
inch per hour seen there. Sooner or later, this rain will start
to pile up and we will have to move into warning mode. We could
see a rapid development of flooding toward daybreak. Fortunately,
the ongoing forecast has this in hand and only a few tweaks were
made through daybreak.

With Debby now moving northward and back over land, we should
witness a transition toward a more extra-tropical low with the
precip shield shifting gradually to the left of the track. All
signs point to a continued westward expansion of the precip shield
across western NC and the nrn Upstate through the morning and
into the afternoon, so the precip probs follow accordingly. Minor
adjustments were made to handle this. The QPF has come down
again with this package...still sufficient to suggest a flooding
problem over the wrn Piedmont and especially the urban areas...but
less expansive. Thus, the Flood Watch will be left as-is for
now. Meanwhile, frequent gusts will continue into the afternoon in
advance of the center of Debby. We are looking a situation where
continued rain saturates the soil and makes it easier for the gusty
winds to start blowing down trees here and there. A Wind Advisory
is being contemplated and might be issued for all or part of the
area mainly east of the mtns and northeast of I-26 where it would
rain the most. The most uncertainty remains over the western half
of the fcst area later today, both in terms of how far west the
precip shield will make it, and how much instability/low level
convergence on the western periphery will be available to create
scattered showers. We allow for almost all the fcst area to get
at least a chance at a shower or thunderstorm for the time being,
but some of the CAMs are not as optimistic with the coverage or
generous with the amounts. Lots of folks over the mtns/northeast
GA/western Upstate are going to be left wondering what happened to
the storm. Temps will show a sharp difference between the below
normal areas east and the above normal areas west, depending on
where the rain shield stops. The new guidance seems to be in order
with taking the center of the circulation northward just to our
east during the late afternoon and evening. Once that passes, we
should see the main area of rain start to pull northward and out
of the fcst area, perhaps as early as midnight, but probably by
daybreak Friday. Wind should have diminished by then as well. Once
the remnants are off to the north on Friday, a developing westerly
flow favors some upslope enhancement for showers near the TN
border through the afternoon. Leftover convergence/moisture east
of the mtns suggest keeping a token slight chance/chance thru
peak heating. Temps should rebound back to normal in the east,
but should also end up hot again over northeast GA.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 3:10 am Thursday: The short-term fcst picks up at 00z on
Saturday with the remnants of TC Debby already well north of our
area and drier Canadian high pressure spreading into the region
from the NW. There could be some lingering hydro/flood threats
over our eastern zones on Saturday, but they should be limited.
Otherwise, Saturday should be mostly dry with just a slight chance
for some diurnal convection over our southern zones as a weak, low-
level convergence zone is expected to set up just to our south and
southeast. Temperatures should be slightly cooler than Fri, with
highs near climatology across most of our CWA and values a few
degrees above climo over our SW zones.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 2:45 am Thursday: The extended forecast picks up at 12z on
Sunday with very broad upper trofing centered well to our north
and broad upper ridging over the Western CONUS. At the surface,
Canadian high pressure will be centered to our NW as the period
begins. By early next week, the high will begin to weaken but
remains centered to our NW. At the same time, weak SLY return
flow begins to spread further north into our area. With the high
lingering to our NW, this will set up a broad area of weak low-
level convergence over our area thru the middle of next week.
As a result, the chances for diurnally-driven showers and thun-
derstorms is increasing for the first half of next week. From
Monday onward, I have slight to solid chance PoPs each day/
evening with marginally higher values over the mtns each day.
Otherwise, temperatures are expected to be near-normal thru the
period with our SW zones likely being slightly above normal and
our NE zones being slightly below normal.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: And here we go!  The leading edge of the
precip associated with Debby was moving west and should reach KCLT
by 07Z at the latest, bringing an initial MVFR ceiling restriction,
then it all goes downhill E-to-W from there. KCLT will bear the
brunt of the restrictions, with IFR cigs arriving around the start
of operations and the lower vis restrictions by 12Z. Wind should
also pick up from the NE by then. There could be occasional LLWS at
KCLT, but the forecast wind difference between the sfc and 2k ft
doesn't technically meet the criteria, so it was left out of the
TAF. There will no doubt be some MVFR or even VFR holes, but for
the most part IFR is expected to prevail there, and also at KHKY.
The other terminals will be more on the edge of the precip shield
later today, so the confidence is lower, particularly over the
Upstate. Will use a TEMPO for the mid/late afternoon when it
would be most likely that some showers would wrap around from
the north. Otherwise, MVFR should prevail, and the gusts should
be frequent from the N. Farther to the W, KAND might end up VFR
through the whole day. What's left of the storm should pull out
to the N/NE this evening and take the precip with it, but a low
cloud restriction is likely to persist well into the overnight
hours early Friday morning.

Outlook: IFR and LLWS potential will not end in some areas until
early Friday morning. Diurnal convection and associated restrictions
may return for the weekend into early next week.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Flood Watch through Friday morning for NCZ035>037-056-057-
     069>072-082.
SC...Flood Watch through Friday morning for SCZ009-014.

&&

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

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
655 PM EDT Wed Aug 7 2024

NCZ033-048>050-053-064-065-068-501>510-SCZ008-012-013-102-103-
105>109-082300-
Avery-Madison-Yancey-Mitchell-Buncombe-Transylvania-Henderson-
Cleveland-Caldwell Mountains-Greater Caldwell-Burke Mountains-
Greater Burke-McDowell Mountains-Eastern McDowell-
Rutherford Mountains-Greater Rutherford-Polk Mountains-Eastern Polk-
Cherokee-Laurens-Union SC-Pickens Mountains-Greenville Mountains-
Greater Pickens-Central Greenville-Southern Greenville-
Northern Spartanburg-Southern Spartanburg-
655 PM EDT Wed Aug 7 2024

This Hazardous Weather Outlook is for 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.

Tropical Cyclone Debby is expected to impact the western Carolinas
Thursday and Friday. The main impacts would be an increased risk for
heavy rain, flooding, and gusty winds Thursday and Friday, with the
greatest risk along and east of I-77. However, the track this storm
takes as it moves over the Carolinas will determine what locations
have the higher threat for flooding rain. The combination of
persistent gusty winds and wet soils from heavy rainfall will lead to
scattered trees and powerlines down. Check hurricanes.gov for the
latest updates on this system.

.SPOTTER INFORMATION STATEMENT...

None.

GAZ010-017-018-026-028-029-NCZ051-052-058-059-062-063-SCZ010-011-019-
101-104-082300-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Swain-Haywood-Graham-
Northern Jackson-Macon-Southern Jackson-Anderson-Abbeville-Greenwood-
Oconee Mountains-Greater Oconee-
655 PM EDT Wed Aug 7 2024

This Hazardous Weather Outlook is for northeast Georgia, western
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.

NCZ035>037-056-057-069>072-082-SCZ009-014-082300-
Alexander-Iredell-Davie-Catawba-Rowan-Lincoln-Gaston-Mecklenburg-
Cabarrus-Union NC-York-Chester-
655 PM EDT Wed Aug 7 2024

...FLOOD WATCH IN EFFECT FROM 2 AM EDT THURSDAY THROUGH FRIDAY
MORNING...

This Hazardous Weather Outlook is for piedmont 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.

   Flood Watch.

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

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

   Flood Watch.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
341 AM EDT Thu Aug 8 2024

NCZ057-071-072-082-080845-
Rowan NC-Union NC-Cabarrus NC-Mecklenburg NC-
341 AM EDT Thu Aug 8 2024

...STRONG WIND GUSTS FROM TROPICAL STORM DEBBY WILL IMPACT
CABARRUS...SOUTHEASTERN MECKLENBURG... SOUTHEASTERN ROWAN AND UNION
COUNTIES THROUGH 445 AM EDT...

At 339 AM EDT, Doppler radar was tracking a strong rain band along a
line extending from 11 miles southeast of Salisbury to 10 miles
south of Downtown Concord to 7 miles north of Lancaster. Movement
was west at 15 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Downtown Concord, Monroe, Kannapolis, Salisbury, South Charlotte,
East Charlotte, West Concord, Matthews, Mint Hill, and Indian Trail.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with these storms and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3550 8030 3519 8051 3516 8044 3518 8037
      3517 8036 3519 8028 3481 8032 3482 8080
      3494 8078 3504 8088 3529 8075 3572 8039
      3572 8034 3568 8033 3558 8021 3551 8018
TIME...MOT...LOC 0739Z 111DEG 14KT 3559 8029 3526 8058 3483 8080

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

ARK