A slow-moving series of localized thunderstorms produced intense rainfall in excess of 11 inches during a 3- to 4-hour period of time during the evening of July 24th, 2021, which is an exceedingly rare event. 1% of occurring during any given year.
Every event with a place to put it. Tap one for its entry below.
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 RNK wrote it up.
A slow-moving series of localized thunderstorms produced intense rainfall in excess of 11 inches during a 3- to 4-hour period of time during the evening of July 24th, 2021, which is an exceedingly rare event. NOAA Atlas 14 Point Precipitation Estimates put this amount of rain for a 6-hour duration at well over an 1000-year rainfall event, or less than a 0.1% of occurring during any given year. Nearly all of the 10.1 miles^2 (per USGS Stream Stats) of the Sycamore Creek basin received heavy rain. A National Water Model simulation of streamflow at the mouth of Sycamore Creek where it empties into the James River calculated a flow of 3,979 cfs. If close to accurate, this flow would be between a 50- and 100-year flooding event per USGS Stream Stats. However, as the basin is heavily wooded and sparsely populated, and given that the rain fell on a Saturday evening when commuting would be at a minimum, very few impacts were observed and/or reported.
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 Blacksburg, VA wrote its last area forecast discussion before the first event at Jul 24, 1:25 AM EST, 4 hours 35 minutes earlier.
Area Forecast Discussion National Weather Service Blacksburg VA 225 AM EDT Sat Jul 24 2021 .SYNOPSIS... High pressure moves offshore today bringing an increase in humidity and storm chances. A cold front moves slowly into the region Sunday into Monday, pushing just south of our area Tuesday. && .NEAR TERM /THROUGH TONIGHT/... As of 205 AM EDT Saturday... ...Airmass changes back to a typical late July feel... You will notice the humidity more today than the past couple of days, and with that, a bit more cumulus forming today. Still have a storm early this morning in association with a vort and upper divergence pushing through the piedmont east of Lynchburg. Storm motion has been around 10 mph, so torrential downpours has been the main concern, though storm has pulsed enough despite limited CAPE to produce several cloud to ground strikes, with hail interrogation via radar showing potential pea size. Appears this area will remain in a favorable environment this morning for isolated showers, but the thunder should abate due to loss of instability. With the surface high moving offshore, the flow turns out of the south, and will likely see storms form along the Blue Ridge and just east along a low level theta-e ridge/gradient and moisture convergence due to the mountains by midday, spreading through the piedmont into the afternoon. At the moment expect coverage to be scattered, so not going to have pops any higher 50, with best chance in the NC mountains/foothills. Further west, warmer air aloft will likely keep convection limited over WV and adjacent VA highlands. Models indicate somewhat more cloud cover in the foothills and piedmont, but enough sun to warm it into the mid to upper 80s, but with less cloud cover/subsidence and rising heights in the west, some of those valleys could be just as warm in the mid to upper 80s. If storm coverage is greater, those areas south of the VA/NC border into the mountains/foothills could be the coolest with highs in the upper 70s to lower 80s. Not seeing threat of showers/storms past midnight tonight, though will likely see more clouds, but still partly-mostly cloudy as northwest flow aloft sends any convective debris from Ohio Valley into the area. Muggy with lows in the mid 60s to around 70 expected. The katydids should be singing in full chorus tonight. Forecast confidence is average on storm coverage today, but higher on temperatures and winds. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... As of 100 AM EDT Saturday... A cold front will slowly move into the area Sunday through Monday. In advance of this front on Sunday, a series of lee troughs will act as the focus for scattered convection across the region. However, by Monday, the front itself will be the main area of focus for a greater coverage of convection. During the peak heating of the day, the area east of the crest of the Blue Ridge may be a candidate for strong storms with MUCAPE forecast around 1500 J/kg, effective bulk shear around 25kts oriented orthogonal to the front, and 0-3km SRH numbers around 100 m2/s2. While mid-level lapse rates in the area are not expected to be relatively steep, DCAPE value in this region are expected to range from 750-1000 J/kg. Forecast precipitable water values are forecast in the 1.50 to 1.75 range which ranks them between the moving 90 percentile and the daily max moving values on the SPC sounding climatology page for KRNK. Given the above, its probable that at least a few storms will have the potential for gusty winds thanks to plenty of water loading within the updrafts and subsequent healthy DCAPE values. Also, given the high PW values, training of cells could lead to localized flooding issues. Monday night, the front will sag to our south, taking showers and storms with it. Coverage will decrease from north to south during the evening hours. On Tuesday, while the front remains to our south, a shortwave trough riding along the front from the Ohio Valley will cross our region. This feature, along with daytime heating, will touch off isolated to scattered showers and storms, with the best coverage across the south, nearest the departed cold front. Tuesday night, coverage will decrease thanks to the loss of sunshine, the departure of the upper shortwave, and advancement of high pressure into the region from the northwest. Temperatures during this portion of the forecast will average close to five degrees above normal. Confidence in the above forecast scenario is moderate. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... As of 130 AM EDT Saturday... High pressure will continue building into the western sections of the region on Wednesday, allowing for a dry forecast. However, building heights aloft and slightly milder 850mb temperatures will result in slightly higher temperatures. On Thursday, a weak disturbance is expected to head southeast along the eastern edge of the surface high. Currently guidance suggests the bulk of this precipitation will remain northeast of the forecast area, small fluctuations in the strength and location of the high could allow for slightly better coverage. Our current forecast continues to reflect only isolated potential for any showers or storms across northern parts of the area. By Thursday night and/or Friday, another cold front may impact the area with better coverage of showers and storms. The latest guidance offers a variety of solutions regarding the timing and expanse of any precipitation across our area. For now, our forecast will reflect increasing chances, but not too ambitious at this time. Increased cloud cover and better potential for precipitation will mean somewhat cooler temperatures as compared to Wednesday. Temperatures during this portion of the forecast will average about five degrees above normal on Wednesday, but trend to near normal Thursday and Friday. Confidence in this portion of the forecast is on the low side of moderate. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... As of 115 AM EDT Saturday... Airmass will be a little more moist this period, and with lack of clouds, should see at least MVFR to possibly IFR for toward 10-12z at LWB, but not having any in the other taf sites. There is an area of convection east of LYH toward FVX, but appears this will not impact LYH. Overall VFR through the period. Some storms are possible in the afternoon, mainly across the southern Blue Ridge and east into the VA piedmont, but with widely scattered to isolated coverage, deemed not even putting VCTS in the tafs, so removed them where we had them earlier. Winds will remain light and variable this morning, becoming south around 5 to 8 kts this afternoon. Forecast confidence is average on fog and thunderstorm coverage, but above average for the rest of the period for all other elements. Extended Aviation Discussion... VFR conditions are expected through next week. Exceptions being late night fog at LWB, perhaps BCB. Any other hazards would be from showers/storms which will become more prevalent when a frontal boundary moves into the area Sunday into Monday. Drier conditions are expected by the middle of next week. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && SYNOPSIS...WP NEAR TERM...WP SHORT TERM...DS LONG TERM...DS AVIATION...BMG/PM/WP
Hazardous Weather Outlook National Weather Service Blacksburg VA 341 AM EDT Sat Jul 24 2021 NCZ001>006-018>020-VAZ007-009>020-022>024-032>035-043>047-058-059- WVZ042>044-507-508-250745- Ashe-Alleghany NC-Surry-Stokes-Rockingham-Caswell-Watauga-Wilkes- Yadkin-Tazewell-Smyth-Bland-Giles-Wythe-Pulaski-Montgomery-Grayson- Carroll-Floyd-Craig-Alleghany VA-Bath-Roanoke-Botetourt-Rockbridge- Patrick-Franklin-Bedford-Amherst-Henry-Pittsylvania-Campbell- Appomattox-Buckingham-Halifax-Charlotte-Mercer-Summers-Monroe- Eastern Greenbrier-Western Greenbrier- 341 AM EDT Sat Jul 24 2021 This Hazardous Weather Outlook is for north central North Carolina, northwest North Carolina, central Virginia, south central Virginia, southwest Virginia, west central Virginia and southeast West Virginia. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Sunday through Friday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
Special Weather Statement
National Weather Service BLACKSBURG VA
124 AM EDT Sat Jul 24 2021
VAZ046-059-240600-
Charlotte-Appomattox-
124 AM EDT Sat Jul 24 2021
...A STRONG THUNDERSTORM WILL AFFECT
SOUTHEASTERN APPOMATTOX AND NORTHERN CHARLOTTE COUNTIES...
At 123 AM EDT, a strong thunderstorm was located over Pamplin City,
or 7 miles northeast of Red House, moving south at 20 mph.
Winds in excess of 30 mph and pea size hail are possible with this
storm.
Locations impacted include...
Charlotte Court House...
Phenix...
Red House...
Pamplin City...
Madisonville...
Abilene...
and Cullen.
Locally heavy rain will quickly reduce visibility and result in
ponding of water on roadways, standing water in low lying areas, and
minor flooding of creeks, streams, and areas of poor drainage.
Drivers are urged to slow down and use extra caution to avoid
hydroplaning.
LAT...LON 3702 7882 3736 7880 3737 7860 3734 7860
3732 7863 3726 7868 3720 7869 3719 7868
3719 7864 3717 7864 3714 7859 3715 7855
3714 7854 3714 7852 3707 7848
TIME...MOT...LOC 0523Z 349DEG 15KT 3727 7870
WPSpecial Weather Statement
National Weather Service BLACKSBURG VA
158 AM EDT Sat Jul 24 2021
VAZ059-240630-
Charlotte-
158 AM EDT Sat Jul 24 2021
...A STRONG THUNDERSTORM WILL AFFECT
NORTHEASTERN CHARLOTTE COUNTY...
At 158 AM EDT, a strong thunderstorm was located over Madisonville,
or near Red House, moving southeast at 10 mph.
Heavy rain, winds in excess of 30 mph and pea size hail are possible
with this storm.
Locations impacted include...
Charlotte Court House...
Phenix...
Madisonville...
Abilene...
and Cullen.
Locally heavy rain will quickly reduce visibility and result in
ponding of water on roadways, standing water in low lying areas, and
minor flooding of creeks, streams, and areas of poor drainage.
Drivers are urged to slow down and use extra caution to avoid
hydroplaning.
LAT...LON 3695 7872 3721 7880 3723 7876 3722 7873
3724 7872 3725 7868 3720 7869 3719 7868
3719 7864 3717 7864 3714 7859 3715 7855
3713 7851 3710 7849 3708 7847
TIME...MOT...LOC 0558Z 327DEG 8KT 3717 7870
WPThe Roanoke radar (KFCX), 160 km away, was scanning. The volume nearest the first event began at 11:01 UTC.
1 heavy rain, 1 flash flood. Local standard time, as filed.
A trained CoCoRaHS observer recorded a 24-hour total rainfall amount of 11.00 inches. Most of this rain fell within a 3- to 4-hour period on the evening of the 24th. This amount was well over a 1000-year rainfall event at the 6-hour duration per a NOAA Atlas 14 Point Precipitation Estimate.
Runoff from several inches of rain caused Sycamore Creek to rise out of its banks and flow across Sycamore Creek Road near the intersection of Woodlawn Church Road. At around 9:40 pm EST, the rainfall triggered at least one debris flow nearby. The flooding left large amounts of debris along the bridge crossing the creek and across the roadway. Structural damage to the road was also observed and required repair.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2021Every state in 2021This day in weather historyWarnings in Virginia, July 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: 962692, 971468.