Public Information Statement
Issued by NWS Pocatello, ID
Issued by NWS Pocatello, ID
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128 NOUS45 KPIH 120113 PNSPIH IDZ051>075-121315- Public Information Statement National Weather Service Pocatello ID 713 PM MDT Tue Jun 11 2024 ...NWS STORM SURVEY CONFIRMS DAMAGING THUNDERSTORM OUTFLOW WINDS OF 60 MPH AND A WET MICROBURST WITH WINDS OF 65 TO 80 MPH IN EASTERN JEFFERSON COUNTY, IDAHO ON FRIDAY, JUNE 7, 2024... The National Weather Service in Pocatello conducted a storm damage survey in eastern Jefferson County, Idaho on Saturday, June 8, 2024 to investigate reports, photos, and videos of significant damage that occurred in association with a thunderstorm during the afternoon of Friday, June 7, 2024. SURVEY START: The survey began in Roberts just off of I-15, finding no obvious damage. Working eastward, the first signs of organized downed leaf litter/twigs was found in the N 3300 E corridor near and south of ID-48, just west of Menan and Lewisville, suggesting stronger sub-severe winds had occurred in this area. All litter and twigs were strewn to the south of their parent trees and vegetation. A slight increase in the size and coverage of downed leaf litter, twigs, and small branches was noted eastward across the Menan, Midway, Lewisville, and Barlow corridor, but the survey still did not locate any significant wind damage (although there were public reports of one tree uprooted in Menan and small tree limbs down in Lewisville, and Rocky Mountain Power reported wind-related power outages across these areas). MAIN CORRIDOR OF DAMAGE: As the survey continued east, a corridor of significant wind damage was noted stretching from just northwest of Annis, southeast between Rigby and Lorenzo, ending between North Yellowstone Highway and the Labelle community. The most significant damage stretched as far west as N 3700 E, as far north as the Snake River, as far south as the northern edge of Rigby proper near E 400 N, and as far east as just west of N 4200 E. Within this corridor, an estimated 50 to 100 trees were either snapped off or uprooted, multiple trees fell on top of or through homes with varying degrees of damage, the roofs of several barns and outbuildings were damaged or blown off, at least a dozen vehicles were significantly damaged and approximately 20 sheep were killed due to falling trees, power poles were damaged, multiple roads were blocked, and power outages were widespread. Some highlights working northwest to southeast down this corridor...a livestock outbuilding constructed of wooden beams, wooden poles, and sheet metal was found destroyed along N 3800 E south of E 800 N just north of Annis, along with multiple trees and large tree limbs down in the area. Damage is this area was all laying to the south or southeast, although one large tree limb was observed to be laying to the northeast not far from the outbuilding, and the outbuilding itself largely collapsed to the east. A very large tree was down along E Menan Lorenzo Highway just east of Annis, and a tree was snapped off at Annis Little Butte Cemetery, both also laying southeast. The public also reported 4 trees snapped off and down at the intersection of E 700 N and N 3700 E, with several pieces of siding removed from a residence and small twigs and branches impaled into the siding on one side of the residence. Further southeast, two very large trees were uprooted and laying to the southeast along N 3950 E just north of Long Island Canal, one measured at 4 feet in diameter, one measured at 3.5 feet in diameter, along with 1 power pole down. At least 7 additional trees were down along Long Island Canal, and a local farmer reported that approximately 20 sheep were killed due to falling trees in this area. The survey observed other trees down in the distance on inaccessible private property at several locations in the area. The most severe damage of the event was found next along E 600 N between N 3950 E and N 4062 E, about half way between Lorenzo and Rigby. Speaking with residents and repair crews from Rocky Mountain Power, as well as assessing damage visually: 10 power poles were down, numerous power pole cross arms were broken, and at least 15 large trees were down...some snapped at various heights and some uprooted...in this area. Debris covered roads and yards. One large tree fell through the bedroom of a residence and another split a mobile home into two sections, with no injuries in either case. All damage was laying to the east or southeast. Multiple roads in this area were blocked. Crossing over US-20...an area of significant tree damage was found at the intersection of N Yellowstone Highway and E 550 N where at least 4 large trees measured at 3 to 4 feet in diameter were uprooted and down across Yellowstone Highway with multiple other smaller trees and wires down across the area. All damage in this area was observed to be laying again to the southeast, or to the east-southeast. Other public reports from this area were generally comprised of trees down, including on homes and vehicles, with multiple vehicles damaged at a wedding at The Millhouse Venue. Little to no damage was located by the survey heading north of this corridor across the Snake River along the Menan Buttes, and damage southward across the City of Rigby generally decreased to just downed leaf litter, twigs, and small tree branches. SURVEY END: Continuing east, the survey found additional large tree limbs down as far as Labelle along with significant downed leaf litter and twigs in residential yards, all strewn to the southeast or east, but damage decreased quickly further south and east of Labelle. Some downed leaf litter was still evident as far southeast as the area of ID-48 and 4500 E, which is where the survey concluded as no larger downed tree limbs or other damage was found southeast of Labelle. FINDINGS: The damage from this severe thunderstorm is believed to have come from two sources or components. First, an outflow boundary was visible on doppler radar emanating from the south side of the thunderstorm moving south-southeast, and a couple of the first reports of small tree limbs down and power outages received by NWS Pocatello came in timed with this outflow boundary. In addition, video received via social media showed very strong winds occurring ahead of the storm itself with no active rainfall. Thus, some damage across the area was likely due to thunderstorm outflow winds estimated at 60 MPH. However, multiple videos were also received showing large trees actively falling during heavy rainfall, and one resident interviewed during the survey described a "white wall of water and wind" overtaking his residence which produced the damage along N 3950 E including the two large uprooted trees on his property. In addition, damage was strewn to the south out west toward Menan and Lewisville, then largely to the southeast down the main damage corridor, and then east-southeast on the eastern edges of this corridor east of US-20. In addition, the one tree limb laying to the northeast north of Annis was near the northern edge of the main damage corridor. While not perfect by textbook standards, this all suggests a slightly divergent wind damage pattern. Thus, much of the damage across the area was likely due to a wet microburst with winds estimated at 65 to 80 MPH. Winds across the impacted area usually originate out of the southwest, so it should be noted here that both the outflow and microburst winds were from a direction abnormal for the area (north and northwest), which likely exacerbated the degree of damage as the trees are not "hardened" against winds from these directions. The overall body of damage reports, photos, and videos received via social media also support the above findings. Finally, evidence collected during the survey and via other reports, photos, and videos does not support occurrence of a tornado. One resident interviewed suggested that the trees downed along Long Island Canal had actually fallen northward and had been moved prior to the arrival of the survey team, but additional corroborating evidence and damage indicators suggesting a tornado were not found, no photos or videos were received by NWS Pocatello showing rotation or anything that resembled a tornado, and no resident accounts of the storm included descriptions of tornadic activity. All damage is estimated to have occurred between 530 PM (northwest) and 600 PM (southeast). No injuries or fatalities were reported. ACKNOWLEDGEMENTS: The National Weather Service in Pocatello would like to thank Jefferson County Emergency Management for coordination on storm impacts and locations to survey, the residents interviewed during the survey for their time, valuable accounts of the event, and for granting access to private property, and the public for submitting hundreds of extremely valuable reports, photos, and videos of the damage via the US National Weather Service Pocatello Idaho Facebook page. Regardless of whether you have attended SKYWARN Spotter Training or not, we would like to remind all residents of southeast Idaho that any reports and photos of tornadoes, hail, wind damage, and flooding during or after any weather event play an extremely valuable role in our warning operations to protect life and property and for post-storm verification, and are always encouraged and appreciated as long as they can be obtained safely. $$ KSmith