A very moisture rich atmosphere led to the formation of heavy rain producing showers and storms that crossed the same area. This build-up of rain in a localized spot helped to saturate the soil on sloped terrain.
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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 RNK wrote it up.
A very moisture rich atmosphere led to the formation of heavy rain producing showers and storms that crossed the same area. This build-up of rain in a localized spot helped to saturate the soil on sloped terrain. This process led to two separate debris flow.
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 30, 12:46 PM EST, 5 hours 14 minutes earlier.
Area Forecast Discussion National Weather Service Blacksburg VA 146 PM EDT Thu Jul 30 2020 .SYNOPSIS... Unsettled conditions are expected to continue into the weekend as a front remains stalled across the region and troughing dominates the eastern U.S. Daily chances of rain and thunderstorms are expected. && .NEAR TERM /THROUGH FRIDAY/... As of 145 PM EDT Thursday... Already starting to see some shower and thunderstorm development this afternoon. Most of this activity has been along the Blue Ridge and west. Will continue to see an uptick in the coverage of this as the afternoon evening progresses. Low-level moisture with dew points in the upper 60s and lower 70s, plus plenty of clearing from this morning has allowed for increased instability across the area. RAP analysis indicating MLCAPE values in the 1000 to 1500 j/kg range already. With this instability already in place and as the upper- level impulse over Kentucky continues to move east, will really begin to see an increase of storm coverage progressing into the evening. We have also seen an increase in deep southerly advection this afternoon ahead of the feature over Kentucky, in response to this, PWATs have also been surging upward. Morning ROAB at Blacksburg this morning indicated PWAT value around 1.3", but we have since surged to 1.7" to 1.8" over a big portion of the CWA. This will be more than enough for storms to be very efficient rainfall producers. With this said, there is some concern of localized flooding, especially in areas that may see training of storms over the same location. Fortunately, antecedent conditions are favoring against any widespread flash flooding threat this evening. Secondary threat this afternoon will be severe storms producing damaging winds/wet downbursts, especially within areas of cell mergers/cell clusters. For this risk, the entire CWA has been highlighted with a Marginal Risk. Overall the best threat for heavy rain for this evening and tonight should be in the western parts of the CWA, particularly northwest NC mountains, southwest VA mountains, and southeast WV mountains, where FFG values are lowest and convection will arrive with favorable timing and intensity. Less is expected further east with time. Friday, stationary boundary still remains in place across the northern portions of the CWA. With abundant moisture stuck over the region (i.e., dewpoints in the mid 60s mountains to mid 70s Piedmont) combining with strong diurnal heating, the front, and good upper-level support, expect renewed scattered showers and thunderstorms again by mid-day Friday. Fairly decent spread in temperatures this afternoon, but this is a product of ongoing rain/cloud cover in the west. So will see highs in the upper 70s, low 80s for areas west of the Blue Ridge. Less clouds and storms in the Piedmont will allow for upper 80s and lower 90s. Morning lows will be muggy once again with dewpoints as high as they are (e.g., 60s & 70s). Lows will range from the mid 60s in the mountains to the lower and even a few mid 70s in the lower elevations of the Piedmont. Friday, with lingering clouds and possibility of another round of rain and storms, keeping most areas under 90. Upper 70s/low 80s for the mountains, mid to upper 80s in the lower elevations east of the Blue Ridge. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... As of 1250 PM EDT Thursday... During this portion of the forecast a ridge of high pressure over the southeastern U.S. will be encroached from the west by a slow moving shortwave trough. While we will be concerned with the potential for daily chances of showers and storms, the focus for the best coverage will be along our western areas as moisture trajectories will maximize from the southwest between the interface between these two systems. It is this same region we will need to monitor for potential heavy rain also. As we progress further into the weekend, the approaching shortwave trough is expected to shift northeast into the Great Lakes region. This will take the focus for the better coverage north of the area. However, our region will maintain the potential for additional showers and storms as we continue within a typical summertime airmass. During this portion of the forecast high temperatures will average a couple of degrees below normal, and lows will average around five degrees above normal. Confidence in the above scenario is moderate to high. && .LONG TERM /MONDAY THROUGH THURSDAY/... As of 130 PM EDT Thursday... The big story in the extended forecast looks to be widespread tropical moisture especially Monday and Tuesday as Tropical Storm Isaias works up coast toward the Carolinas. At the same time we have an upper level trough and frontal boundary to the north and west suppressing this moisture overhead. Overall timing and location of heavy rainfall will depend on the track of Isaias and placement of the front with the adjacent trough in the coming days ahead. Both the GFS and Euro agree on a wet period for Monday and Tuesday as moisture from what is now Tropical Storm Isaias is drawn in. The GFS though is a bit faster with the tropical system but slower when it comes to pulling the trough through. The GFS also brings in a few more waves of energy around the base of the trough ad strengthening high Tuesday into Wednesday. The Euro on the other hand is a bit slower on Isaias with a draw up the coast through the Outer Banks Tuesday into Wednesday before pushing into the Delmarva and out to sea midweek. This would keep rain chances on the high side of things especially during the afternoon and evening hours Monday through Wednesday. Both models hint at a front by the Thursday timeframe as high pressure asserts itself over the Ohio River Valley and slides east into West Virginia later this week. Precipitation will likely drop off beyond this period with a hit at a drier and seasonable weekend ahead. Temperatures during the extended period look to remain at or slightly below average. Highs will be in the mid to upper 80s east of the Blue Ridge and upper 70s to low 80s out over the mountains. This is in trend with bot the Climate Prediction Center's 6 to 10 day and 8 to 14 day outlooks. Things look to heat up again behind the front as precipitation chances drop with high pressure later in the week. Confidence in precipitation chances remains moderate to high while temperatures remain moderate through the period. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... As of 130 PM EDT Thursday... Ongoing rain and thunderstorms will continue through the remainder of the afternoon and evening hours. Greatest coverage and intensity of convection appears to be across the western areas into the New River, Shenandoah, and Greenbrier Valleys this afternoon/evening. Thus, expect brief periods of MVFR-IFR in showers/thunderstorms at the TAF sites during this time frame. Confidence in convection impacting the TAF sites decreases as one goes further eastward, but opted to leave in VCTS for DAN and LYH through around midnight. Otherwise, conditions outside afternoon convection should generally be VFR. Patchy fog is expected again tonight, with the highest confidence being at LWB, BCB, and BLF where LIFR/IFR conditions are likely after midnight through sunrise. Elsewhere, also added in some mention of fog, but not nearly as confident at those locations. Winds will be light and generally SSW/SW at speeds of 5 mph or less, outside of brief variable and gusty wind in/near thunderstorms. Extended Aviation Discussion... Low pressure aloft deepening across the eastern U.S. and a stalled frontal boundary in/near the region will keep an unsettled pattern in place through much of next week. This will result in daily rounds of afternoon/evening showers/thunderstorms and abundant low clouds, fog, and even some rain showers at night. Certainly not the best period for aviation overall. Several periods of sub-VFR conditions are likely. && .CLIMATE... As of 430 AM EDT Thursday... ROA 90F+ streak now at Day 29. Through the 29th, ROA still maintaining position as 2nd warmest month on record at 81.8F after August 2007 at 82.1F. Could be a photo finish on the last day given warm forecast but likely falls just short of the record. Warmest July is inevitable however, with previous record a full 1.0F lower at 80.8F in July 2012. Lynchburg currently on track for 3rd warmest month on record at 81.2F and very close to 2nd place which was 81.3F way back in August 1900. With a forecast high of 92 at LYH today, still time to come closer to the 2nd place record. Not only has it been hot but very dry in some places. Bluefield, WV currently sitting at 3rd driest July on record with 1.68 inches through the 29th, after picking up 0.54 Tuesday. Blacksburg NWS office still holding at 2nd driest July at 1.29 inches, behind only the 0.93 inches in the midst of the Great Drought of 1930. However, unlike the temperature records, which are likely to hold, the precipitation records may fall with substantial rainfall predicted for many locations today and tomorrow the 31st. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && SYNOPSIS...BMG NEAR TERM...BMG SHORT TERM...DS LONG TERM...ET AVIATION...BMG/RAB CLIMATE...PC/RAB
Hazardous Weather Outlook National Weather Service Blacksburg VA 231 PM EDT Thu Jul 30 2020 NCZ003>006-019-020-VAZ022>024-032>035-043>047-058-059-311845- Surry-Stokes-Rockingham-Caswell-Wilkes-Yadkin-Roanoke-Botetourt- Rockbridge-Patrick-Franklin-Bedford-Amherst-Henry-Pittsylvania- Campbell-Appomattox-Buckingham-Halifax-Charlotte- 231 PM EDT Thu Jul 30 2020 This Hazardous Weather Outlook is for north central North Carolina, northwest North Carolina, central Virginia, south central Virginia, southwest Virginia and west central Virginia. .DAY ONE...This afternoon and tonight. Scattered thunderstorms are expected this afternoon and evening. Some thunderstorms could become strong to severe with damaging wind gusts the main threat. Locally heavy rainfall is also expected, which could lead to isolated areas of flooding and/or flash flooding. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. Scattered to numerous showers and thunderstorms are expected each day. The main and increasing concern during this time period will be heavy rainfall leading to flooding and flash flooding. Areas that see repeated rainfall and areas with mountainous terrain will be the most susceptible to flooding. While a few storms could become strong to severe each day, flooding remains the main concern. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed. NCZ001-002-018-VAZ007-009>020-WVZ042>044-507-508-311845- Ashe-Alleghany NC-Watauga-Tazewell-Smyth-Bland-Giles-Wythe-Pulaski- Montgomery-Grayson-Carroll-Floyd-Craig-Alleghany VA-Bath-Mercer- Summers-Monroe-Eastern Greenbrier-Western Greenbrier- 231 PM EDT Thu Jul 30 2020 This Hazardous Weather Outlook is for northwest North Carolina, southwest Virginia, west central Virginia and southeast West Virginia. .DAY ONE...This afternoon and tonight. Scattered thunderstorms are expected this afternoon and evening. Some thunderstorms could become strong to severe with damaging wind gusts the main threat. Locally heavy rainfall is also expected, which could lead to areas of flooding and/or flash flooding. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. Scattered to numerous showers and thunderstorms are expected each day. The main and increasing concern during this time period will be heavy rainfall leading to flooding and flash flooding. Areas that see repeated rainfall and areas with mountainous terrain will be the most susceptible to flooding. While a few storms could become strong to severe each day, flooding remains the main concern. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed.
The national radar mosaic for the moment the first event began.
2 debris flow. Local standard time, as filed.
A mudslide occurred along Dry Fork Road. Damage values are estimated.
A mudslide occurred along Lick Branch Road. Damage values are estimated.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2020Every state in 2020This day in weather historyWarnings in Virginia, July 2020
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: 912933, 912934.