A brief resurgence of the active pattern resulted in scattered strong thunderstorms which resulted in reports of a landspout, hail, and flash flooding.
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The episode as NWS SLC wrote it up.
A brief resurgence of the active pattern resulted in scattered strong thunderstorms which resulted in reports of a landspout, hail, and flash flooding.
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 Salt Lake City, UT wrote its last area forecast discussion before the first event at Sep 13, 9:09 AM MST, 4 hours 21 minutes earlier.
Area Forecast Discussion National Weather Service Salt Lake City UT 1009 AM MDT Wed Sep 13 2023 .UPDATE... A quick update this morning to increase the PoPs across northern Utah from now through early afternoon. Satellite imagery shows a compact shortwave through moving through northern Utah this morning kicking off scattered showers along the Wasatch moving into southwest Wyoming later this morning. A few rumbles of thunder have been observed as well, and expect this isolated thunder risk to continue eastward into Wyoming as well, with an increasing chance into early afternoon with daytime heating. && .SYNOPSIS...An active couple of days are in store with scattered showers and storms through the end of the week, particularly across the southern and eastern portions of Utah. A cold front moves through midweek dropping temperatures a few degrees below average Thursday and Friday. A ridge builds into the weekend which will bring dry conditions with temperatures returning to near seasonal normals. && .SHORT TERM...(Through 12Z/6AM Friday)...Early morning analysis products depict a disorganized cluster of shortwaves extending from NW Arizona stretching eastward across the Four Corners region, with a weak shortwave situated across north-central Utah. Meanwhile an upstream, positively tilted trough extended across the PacNW. This trough, per model consensus, is forecast to undergo subtle strengthening/amplification as it approaches Utah and SW Wyoming. By 00Z this evening, the trough is forecast to stretch from central Montana southwestward to near San Fransisco. The first two features are forecast to produce some cloud cover and generally light, disorganized showers during the morning hours. Heading into the afternoon, daytime heating generated instability will be in place while the incoming trough provides some large- scale support. The result will be a gradual increase in shower and thunderstorm initiation across most high terrain areas. Ensemble mean SBCAPE values are forecast to be higher than the past couple of days, especially over southern Utah where skies will be clearer through the morning. CAMs depict convection migrating off of the terrain towards the ESE through the afternoon and evening hours. Lack of strong deep-layer shear will prove a challenge with regards to longevity of organized updrafts, so longevity challenges will need to be overcome where boundaries/cold pools collide. We have mentionable precipitation probabilities in the forecast across the entirety of the forecast area today, with the greatest probabilities over high terrain areas, generally along/east of I-15 and across southern Utah. Isolated flash flood risk continues assuming a stronger, more sustained cell and/or training cells move over vulnerable areas. A gradual reduction in activity can be expected through the evening hours, but the presence of the trough and its assist with the large-scale support will result in at least some shower activity persisting well into Wednesday night, especially over west-central, southwest and south-central Utah, per latest CAM consensus. Can't rule out isolated activity outside of these areas, however. By Thursday, the trough axis is forecast to extend from southern Wyoming to southern Utah. This will shift the axis of best forcing south and east. We once again see convective initiation occurring over high terrain areas with convection drifting southeast. Best deep-layer shear remains weak, but strongest across eastern Utah with values up to 20kts in the afternoon. CAM membership seems to be zeroing in on southeast Utah for the highest probability for most widespread heavy rainfall from late afternoon through the early evening hours, so have added 'probable' wording to the Flash Flood Potential Rating product for Glen Canyon, Grand Staircase- Escalante and Grand Gulch. Of course, eventual convection outcomes will be sensitive to the amount of instability that can be realized, which is modulated by the amount of antecedent cloud cover. The trough is forecast to exit into Colorado by Friday, with lingering convection across eastern and southeast Utah through the night Thursday night, gradually weakening as instability wanes. Modest cooling of temperatures is expected Thursday in the wake of the trough. .LONG TERM...(After 12Z/6AM Friday)...High pressure is forecast to build into the region Friday which will be the trend through the weekend and into Monday. Seasonal temperatures and dry conditions are anticipated as a result. By late Monday, eyes will turn to the how an area of low pressure from the Gulf of Alaska will progress as it tracks inland. Widely different solutions are noted between forecast models which have very different weather forecast results for Utah as a result. We will continue to monitor trends and see how forecasts adjust each day. && .AVIATION...KSLC...A rain shower or two may pass across the terminal this morning or early afternoon with very minimal impacts. VFR conditions are expected to prevail regardless of if a shower passes overhead or not. South-southeast winds will prevail this morning before shifting out of the northwest at 19z. .REST OF UTAH AND SOUTHWEST WYOMING...A chance for rain showers will exist this morning across northern Utah and southwest Wyoming terminals with minimal to no impacts expected; VFR conditions are forecast to prevail. This afternoon and evening, isolated showers and thunderstorms are forecast across the state and will have the potential to impact any given terminal. Lowered visibilities and gusty winds are the primary threats; outflow winds from nearby thunderstorms may impact operations as well. Improving conditions are forecast after 03z this evening. && .FIRE WEATHER...Moisture combined with an area of low pressure across the region will remain in place through Thursday, maintaining elevated relative humidity, along with a good chance for showers and thunderstorms capable of producing wetting rains. The best chances for wetting rains will be across central and southern Utah on Wednesday, especially across higher elevation areas. Best chances for wetting rains on Thursday shifts to southern and eastern Utah. High pressure will then strengthen across the region late this week through the upcoming weekend, resulting in a drying and warming trend. By the middle of next week, we are watching for a potential pattern change as an increasing number of models suggest an emerging scenario where a Canadian low pressure system and strong cold front drops into the Northern Rockies. The stronger scenarios bring a shot of cool Canadian air and moisture into at least northern Utah by the middle to latter portions of next week. There is a lot of uncertainty in the forecast beginning in this time frame, and we'll continue to monitor for this potential forecast outcome. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && Church/ADeSmet/NDeSmet For more information from NOAA's National Weather Service visit... http://weather.gov/saltlakecity
Special Weather Statement National Weather Service Salt Lake City UT 222 PM MDT Wed Sep 13 2023 UTZ123>125-132045- Southern Mountains UT-Zion National Park UT- Lower Washington County UT- 222 PM MDT Wed Sep 13 2023 ...A strong thunderstorm will impact portions of central Washington County through 245 PM MDT... At 222 PM MDT, Doppler radar was tracking a strong thunderstorm 7 miles north of Quail Creek State Park, or 22 miles west of Zion National Park, moving southeast at 15 mph. HAZARD...Penny size hail. SOURCE...Radar indicated. IMPACT...Minor damage to outdoor objects is possible. Locations impacted include... Washington, Hurricane, La Verkin, Quail Creek State Park, Toquerville and Leeds. This includes Interstate 15 between mile markers 15 and 29. 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. && LAT...LON 3727 11355 3736 11346 3729 11322 3712 11344 TIME...MOT...LOC 2022Z 308DEG 13KT 3728 11344 MAX HAIL SIZE...0.75 IN MAX WIND GUST...<40 MPH JAC
The Salt Lake City radar (KMTX), 201 km away, was scanning. The volume nearest the first event began at 21:36 UTC.
4 flash flood, 1 strong wind, 1 hail. Local standard time, as filed.
LANDSPOUT. Location: 40.33, -110.01. Multiple public photos on social media showing a landspout north of Roosevelt, UT. The location as well as time were estimated based on the photos and associated viewing angles.
Capitol Reef National Park officials reported a debris flow across state Route 24, making it impassable just east of the Visitor Center between Hickman Bridge and Grand Wash. Additionally, flash flooding was observed in Sulphur Creek, and high flows were reported in Grand Wash. This flooding was associated with a cluster of showers and thunderstorms which produced heavy rain over portions of the park, with Multi-Radar Multi-Sensor rainfall estimates of approximately 0.75 to 1.25.
Hilldale Fire Dispatch reported quarter-sized hail, lasting approximately 10 minutes. They further relayed reports of broken windshields, shredded vegetation, and accumulating hail up to 3 inches deep in places.
Grand Staircase-Escalante National Monument Kanab Visitor Center officials reported flash flooding in the town, with local streets flooded and covered with mud and debris, resulting in closure of a few streets. Creeks through town were overflowing across roads at culverts, and in one spot, Kanab Creek was overflowing across the road with water approximately 9 to 12 deep. Dirt roads on the outskirts of town were impassable. Additionally, Kane County Sheriff's office officials reported that several homes had some minor basement flooding. This flooding is the result of strong thunderstorms in the area, with Multi-Radar Multi-Sensor estimates of approximately 0.75 to 1.50 of rainfall in around 3 hours.
Flash flooding was reported on Short Creek and its tributaries through the Hilldale and Colorado City area. All creek road crossings were closed for 2 to 3 hours, and the Hilldale Street Creek crossing was heavily damaged and subsequently closed indefinitely until repairs could be made. This flooding is the result of strong thunderstorms which per Multi-Radar Multi-Sensor, produced approximately 3.00 to 4.00 of rainfall, largely within the span of 2 hours, though some of this can likely be attributed to hail contamination. At 6:25 am MST on the 14th, the downstream Fort Pearce Wash gauge recorded a spike in flow to 124 CFS associated with the flood water propagation.
The Grand Staircase-Escalante National Monument Big Water Visitor Center reported a flash flood wave along Wahweap Creek that was audible from the town of Big Water until around 8 pm MST. A survey of the creek at the Smokey Mountain Road low-water crossing the following morning revealed the flood wave was approximately 60 to 75 feet wide at some point overnight, which would roughly equate to around 3 to 4 feet of depth at this particular point. This flooding was associated with heavy rain that fell within the far headwaters from approximately 3 pm MST to 5 pm MST.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2023Every state in 2023This day in weather historyWarnings in Utah, September 2023
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: 1131401, 1131404, 1131406, 1131415, 1131412, 1131417.