A lee surface trough was present across the Appalachian mountains of western North Carolina. Widely isolated showers and storms developed in the vicinity of this surface trough in the late afternoon and early evening over Guilford and Forsyth Counties, producing one report of a downed tree over northern Forsyth County.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS RAH wrote it up.
A lee surface trough was present across the Appalachian mountains of western North Carolina. Widely isolated showers and storms developed in the vicinity of this surface trough in the late afternoon and early evening over Guilford and Forsyth Counties, producing one report of a downed tree over northern Forsyth County.
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 Raleigh, NC wrote its last area forecast discussion before the first event at Aug 26, 3:00 PM EST, 25 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Raleigh NC 400 PM EDT Thu Aug 26 2021 .SYNOPSIS... Strong high pressure building in from Bermuda will bring hot temperatures through the weekend, along with relatively dry weather. && .NEAR TERM /THROUGH TONIGHT/... As of 340 PM Thursday... No changes from the morning forecast update. Areas of stratus and fog will be possible late tonight-Fri morning mainly over srn NC, with low temperatures in the upr 60s to lwr 70s. .PREV DISCUSSION... /ISSUED 1045 AM EDT Thu Aug 26 2021/ 12Z upper air data indicate the low level airmass has changed little over NC during the past day (or really all week) - stagnant within a degree C difference at 925-850 mb. As such, temperatures are likely to be near those of recent days again this afternoon - generally 89- 95 F and adjusted up from the previous forecast cycle. Additionally, the subsidence inversion that was present at GSO for the past couple of days has eroded and deep moisture increased (precipitable water up to 1.7" from 1.4" since this time Wed, at least temporarily until the offshore mid level ridge exerts greater subsidence/drying influence later today through the weekend, and which was already evident on the 12Z MHX sounding to the east. These thermodynamics may prove more favorable, than has been indicated by CAM guidance, for the development of isolated to widely scattered cells over the nrn and nw Piedmont this afternoon, in the vicinity of a lee surface trough analyzed at 1430Z from CHO to DAN to GSO. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... As of 355 PM Thursday... An anomalously-strong sub-tropical ridge --595-596 dm at 500 mb and already near the max moving average for upper air sites along the middle Atlantic and NC coasts this morning-- will continue to drift wwd across the far wrn Atlantic and ern Carolinas through 12Z Sat. On the nwrn and nrn periphery of that ridge, a weak mid level trough and vorticity max over WV will be advected slowly ewd across the nrn Virginias, MD, and srn PA Fri afternoon, then to the middle Atlantic coast through 12Z Sat. Related to the sub-tropical ridge, a subsidence inversion and pocket of low to mid-level dry air characterized by precipitable water values of around 1.2 to 1.4", already nosing wwd into the coastal Carolinas this afternoon, will become centered squarely over cntl NC on Fri. At the surface, high pressure beneath and just downstream of the ridging aloft will extend wwd across the Carolinas, while an Appalachian-lee trough will extend across the middle Atlantic Piedmont and Foothills. A weak lee low will likely develop across nrn VA during the afternoon, then migrate east to the middle Atlantic coast Fri night. Point forecast soundings indicate the subsidence inversion that had already become evident on the 12Z Thu MHX sounding will strengthen and lower across cntl NC on Fri, which along with the related dry air in place and probable mixing out of surface dewpoints into the mid-upr 60s (locally lwr 60s) will result in very little instability across cntl NC. And what little MLCAPE there will be, it will be capped by the subsidence inversion aloft. As such, it will be a rare dry day devoid of even general thunder. The boundary layer dryness will also curb heat index values resulting from high temperatures again mostly in the lwr-mid 90s, with apparent temps likely only a degree or three higher than air temps. Areas of fog and/or stratus will again be possible, especially across srn NC late Fri night, with lows in the upr 60s to around 70 F. && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 330 PM Thursday... In the upper-levels, strong high pressure, two standard deviations above normal, will build across the Carolinas this weekend. The ridge will then break down and push south early next week as, what is currently Tropical Depression 9, moves north across the lower Mississippi Valley. The upper low will then weaken and become a trough across the Mid-Atlantic by the middle of next week. At the surface, high pressure will linger off the coast of the Carolinas for the weekend, then a Piedmont trough will develop across the area for early next week. Confidence in the location of surface features for the middle of next week is low at the time, and will depend on the location of the remnants of Tropical Depression Nine. The aforementioned pattern will create continued hot and dry weather across central NC this weekend into early next week. Highs will increase into the mid to upper 90s, but luckily dewpoints will lower into the 60s, limiting the heat index from rising very much above the actual temperature. Monday looks to be the hottest day, with highs around 10 degrees above seasonal normals. The drier air and subsidence will limit the coverage of showers and thunderstorms through the period, with only a slight chance of showers and thunderstorms near the VA border Saturday afternoon and a slight chance of showers and thunderstorms across the region Sunday and Monday afternoons. Although temps will soar during the day, radiational cooling should allow temps to drop into the upper 60s to low 70s each night. The remnants of Tropical Depression 9 look to remain to our west for the time being, however tropical moisture will likely make it to central NC by the middle of next week, increasing the precipitable water from 1-1.50" this weekend to 2-2.25" by Wednesday. Over half of the GEFS and EPS ensemble members show precipitation across our area for the middle of next week, and confidence is increasing that central NC will have a break from the dry pattern. Stay tuned for further updates. With the increasing chances of precip, lower heights and increased cloud cover, highs will lower to just above seasonal normals (mid-80s to low 90s) for the middle of next week, with lows remaining mostly the same as the weekend. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... As of 200 PM Thursday... Scattered showers and storms around INT/GSO this afternoon should dissipate by early this evening, with both nocturnal and outflow cooling, and also increasing sinking motion and stability caused by ridging aloft building toward the NC coast. Areas of LIFR stratus and fog are expected to develop across nrn SC and srn NC, including at FAY, late tonight-Fri morning. Shorter-lived, less restrictive sub-VFR conditions will also be possible throughout cntl NC around 12Z Fri, with the relative highest probability of those at RWI and RDU. Outlook: Areas of stratus and fog will be possible each morning, particularly at FAY, with otherwise mainly dry and VFR conditions expected through early-mid next week. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && SYNOPSIS...BSD/Green NEAR TERM...MWS SHORT TERM...MWS LONG TERM...JJT AVIATION...MWS
Hazardous Weather Outlook National Weather Service Raleigh NC 846 AM EDT Thu Aug 26 2021 NCZ008>011-024>028-040>043-073>078-083>086-088-089-271300- Granville-Vance-Warren-Halifax-Orange-Durham-Franklin-Nash-Edgecombe- Chatham-Wake-Johnston-Wilson-Stanly-Montgomery-Moore-Lee-Harnett- Wayne-Anson-Richmond-Scotland-Hoke-Cumberland-Sampson- 846 AM EDT Thu Aug 26 2021 This Hazardous Weather Outlook is for central North Carolina. .DAY ONE...Today and tonight. Heat index values between 100 and 105 degrees are expected this afternoon. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. Hazardous weather is not expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. NCZ007-021>023-038-039-271300- Person-Forsyth-Guilford-Alamance-Davidson-Randolph- 846 AM EDT Thu Aug 26 2021 This Hazardous Weather Outlook is for central North Carolina. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
Special Weather Statement
National Weather Service Raleigh NC
328 PM EDT Thu Aug 26 2021
NCZ021-022-262030-
Guilford NC-Forsyth NC-
328 PM EDT Thu Aug 26 2021
...A cluster of strong thunderstorms will impact portions of
northeastern Forsyth and northern Guilford Counties through 430 PM
EDT...
At 326 PM EDT, Doppler radar was tracking a cluster of strong
thunderstorms across the northern half of Forsyth and Guilford
Counties. These storms were nearly stationary.
HAZARD...Winds in excess of 30 mph and local flooding.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Local flooding may result in ponding on
roadways.
Locations impacted include...
Greensboro, Winston-Salem, Kernersville, McLeansville, Summerfield,
Stokesdale, Walkertown, Rural Hall, Pfafftown and Lake Jeanette
Marina.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.
Very heavy rain can be expected due to the slow movement of this
storm. Prolonged heavy rain will result in ponding of water on
roadways, standing water in low lying areas, and minor flooding of
creeks and streams. Drivers are urged to slow down and use extra
caution to avoid hydroplaning.
&&
LAT...LON 3626 8028 3624 7959 3607 7966 3607 7989
3613 8031
TIME...MOT...LOC 1926Z 259DEG 4KT 3616 7987
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...30 MPH
JJTThe Roanoke radar (KFCX), 90 km away, was scanning. The volume nearest the first event began at 20:24 UTC.
1 thunderstorm wind. Local standard time, as filed.
A tree and power lines were reported down near the 3900 block of Grubbs Road.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in North Carolina in 2021Every state in 2021This day in weather historyWarnings in North Carolina, August 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 982040.