A shift in the atmospheric pattern from mid to late July brought an array of impacts to much of Utah, including severe thunderstorm wind gusts, large hail, and flash flooding.
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 SLC wrote it up.
A shift in the atmospheric pattern from mid to late July brought an array of impacts to much of Utah, including severe thunderstorm wind gusts, large 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 Jul 17, 3:04 AM MST, 11 hours 46 minutes earlier.
Area Forecast Discussion
National Weather Service Salt Lake City UT
404 AM MDT Mon Jul 17 2023
.SYNOPSIS...Very hot temperatures will continue over much of Utah
and southwest Wyoming today as a strong ridge exits the area. A
boundary moving into the area tonight into Tuesday will bring an
increase in high based moisture and allow for less warm
temperatures across the area. The potential for showers and
thunderstorms will continue into the midweek period before high
pressure returns for the weekend.
&&
.SHORT TERM (Through 12Z Wednesday)...Strong high pressure is
parked over Utah this morning. Under this airmass, saw many daily
high temperature records broken yesterday and with limited cooling
will likely see some high min records realized during the day as
well. However, a bit of relief is on the way as the ridge will
continue to be nudged east by a Pacific Northwest trough that will
move over the top of it later today. During the afternoon the
ridge axis is on track to move to the Utah/Colorado border. As a
result, many eastern Utah locations will see their hottest
temperatures of the year so far.
Meanwhile, the previously mentioned trough will eventually bring a
boundary into northern Utah late this afternoon/early this
evening. This will take the edge off of temperatures just slightly
this afternoon for northern and western portions of the forecast
area, though highs will still be plenty hot to warrant the Heat
Advisories and Excessive Heat Warnings that are in place. However,
the presence of the boundary will bring an increase in instability
as well as draw in some high based moisture. With these
ingredients in place, will see some development of high based
showers and thunderstorms late this afternoon into the evening
over portions of western Utah. Given latest output from some CAMs,
isolated POPs currently in the forecast may be on the low side.
That being said, given how dry lower levels will be, associated
rain will be limited, but there is a heightened threat of strong,
gusty microburst winds with any precip that develops.
The boundary is forecast to continue to slide south overnight
before stalling over central Utah during the day Tuesday as it
outruns any upper level support. This will allow the high based
moisture to become more widespread across the area. Additionally,
the boundary will act as a focus for shower and thunderstorm
activity Tuesday afternoon and evening, with the presence of the
boundary allowing some convection to persist during the overnight
hours. Additionally, areas behind the boundary will see a
noticeable drop in temperatures, with maxes running near seasonal
normals over northern and central portions of the forecast area.
Areas ahead of the boundary, particularly far southern Utah, will
continue to be quite unseasonably hot with HeatRisk values still
approaching the red range for portions of lower Washington county.
.LONG TERM (After 12Z Wednesday)...A trough that passes through the
northern Rockies on Tuesday will help to weaken and move the ridge
that is currently over the CWA. This ridge will continue to be
centered to the southeast of the CWA through the middle of the week.
With the passage of the trough to our north, moisture will accompany
it and stick around through much of the week. A secondary source of
moisture will be coming from the south as the first monsoonal push
of moisture comes into play due to the position of the ridge. PWAT
values for Wednesday and Thursday will be between 0.7" and 1.1". As
a result, showers and thunderstorms will be possible, especially
over higher terrain during these two days. There is a slight chance
(10% to 25%) that these storms successfully move off the terrain and
impact lower elevation valleys. Given that the majority of the
moisture is located in the mid levels, these showers and
thunderstorms should mainly have a strong wind threat due to
outflows and microbursts, while the flash flood threat remains low.
Heading into the rest of the week and into the weekend, the ridge
will move back westward and strengthen. This will result in hot and
dry conditions making a return. Ensemble guidance continues to show
the axis of this ridge to be located over the Four Corners Region.
This will help keep some moisture around, but with weak synoptic
support, these showers and thunderstorms will be isolated and mainly
over higher terrain in central and southern Utah. With the ridge
strengthening again, temperatures will climb back to near 100F and
even into the low 100s for the Wasatch Front for the weekend and
into early next week.
&&
.AVIATION...KSLC...Southeast winds expected to switch to northwest
winds between 18Z and 20Z. There is a 50% chance that wind gusts
will reach 25kts during the afternoon. Isolated showers will be
possible between 02Z and 06Z. The better chance at seeing
precipitation that effects KSLC will be after 06Z. Gusty and erratic
outflow winds will be possible with these showers. Northwest winds
expected to change to southeast drainage winds between 05Z and 07Z.
VFR conditions to expected to prevail for TAF period.
.REST OF UTAH AND SOUTHWEST WYOMING...Diurnal winds expected for TAF
period. Gusty and erratic outflow winds will be possible with
showers and thunderstorms. Precipitation chances will continue for
northern Utah and southwest Wyoming through Monday night and into
Tuesday morning. VFR conditions to expected to prevail for TAF
period.
&&
.FIRE WEATHER...High pressure centered over Utah this morning will
shift east and flatten this afternoon as a trough moves over the
ridge, bringing a mostly dry boundary into northern Utah. Because
of this boundary and movement of the ridge, northern and western
Utah high temperatures will be a couple of degrees less warm than
Sunday, but still rather unseasonably warm, as eastern Utah sees
the hottest temperatures of the year so far. High based moisture
accompanying the boundary will introduce a threat of showers and
thunderstorms capable of producing gusty winds to western Utah
late this afternoon and into the evening. The boundary is expected
to move into central Utah on Tuesday, allowing the moisture to
spread farther south and acting as a focus for another round of
high based convection. Temperatures will also continue to become
less warm, with high temperatures Tuesday into Wednesday staying
within 5F of seasonal normals except over far southern Utah. By
late in the week, high pressure will return to the area, bringing
another warming and drying trend.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Excessive Heat Warning until 9 PM MDT this evening for UTZ101-
102-104>106-123-124-129-131.
Heat Advisory until 9 PM MDT this evening for UTZ103-114>116-
118>122-128-130.
WY...None.
&&
SHORT TERM/FIRE WEATHER...Traphagan
LONG TERM/AVIATION...Cecava
For more information from NOAA's National Weather Service visit...
http://weather.gov/saltlakecityThe Cedar City radar (KICX), 92 km away, was scanning. The volume nearest the first event began at 21:48 UTC.
30 thunderstorm wind, 3 flash flood, 1 hail. Local standard time, as filed.
The Milford Municipal Airport/Ben and Judy Briscoe Field ASOS recorded an initial wind gust of 58 mph at 2:50 pm MST, followed by wind gusts to 70 mph through 3:05 pm MST. These gusts were the result of outflow winds associated with a line of showers and thunderstorms moving through the area.
The I-15 @ MP 169 mesonet station recorded an initial peak gust of 71 mph at 3:00 pm MST, and subsequent strong gusts of 69 mph at 3:10 pm MST and 3:20 pm MST. These gusts were a result of outflow winds associated with a cluster of showers and thunderstorms moving through the area.
Strong crosswinds associated with outflow from nearby showers and thunderstorms resulted in multiple overturned semitrailers on Interstate 15 at milepost 163. Around this time, the UTCIR mesonet sensor recorded a wind gust of 71 mph. Video from broadcast media showed a semitrailer rolling at speed, with subsequent articles indicating multiple semitrailers were rolled. Additionally, the video showed a substantial dust plume as a result of the strong winds.
The Simpson Springs mesonet station recorded a wind gust of 62 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Nephi West mesonet station recorded a wind gust of 68 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The I-15 @ Scipio Summit mesonet station recorded a wind gust of 70 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Scipio Summit mesonet station recorded a wind gust of 61 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Groome mesonet station recorded an initial wind gust of 71mph and a subsequent peak wind gust of 76 mph as a result of outflow winds associated with a nearby cluster of thundershowers moving through the area.
Capitol Reef National Park officials reported multiple flows and waterfalls associated with heavy rain and thunderstorms moving through the park. At approximately 11:46 am MST, multiple waterfalls were noted on cliffs. By 11:55 am MST, water was reported to be coming over state Route 24, and by 11:59 am MST, debris, in addition to water, was noted. At approximately 12:30 pm MST, the wash south of Hickman Bridge through Neil Johnson Bridge was reported to be flowing high, and the Hickman Bridge area was reported to be flooded.
The Wendover Airport AWOS recorded a wind gust of 64 mph as a result of outflow winds associated with a line of showers and thunderstorms moving through the area.
The I-70 at Richfield mesonet station recorded a wind gust of 64 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Hansel Valley mesonet station recorded a wind gust of 59 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Chaulk Hill mesonet station recorded a wind gust of 66 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Nephi West mesonet station recorded a wind gust of 58 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The US-189 at Deer Creek Dam mesonet station recorded a wind gust of 63 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The East Bearlake mesonet station recorded a wind gust of 62 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Groome mesonet station recorded a wind gust of 62 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
A cluster of thunderstorms produced heavy rain during the early afternoon hours through portions of Capitol Reef National Park, with Multi-Radar/Multi-Sensor estimates of around 0.50 to 0.75 inches of rain. Subsequently, Capitol Reef National Park reported that state Route 24 east of the visitor center was impassable due to high water and debris. Additionally, minor flooding was reported in the campground.
The Simpson Springs mesonet station recorded an initial peak gust of 61 mph at 4:00 pm MST, and an additional strong gust of 58 mph at 4:05 pm MST. These gusts were a result of outflow winds associated with a cluster of showers and thunderstorms moving through the area.
The SR-36 at MP 49 Stockton Bar mesonet station recorded a wind gust of 58 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Camel Back MTN mesonet site recorded a period of wind gusts to 69 mph between 4:15 pm MST and 4:25 pm MST. These gusts were the result of outflow winds associated with a line of showers and thunderstorms moving through the area.
Multiple public reports and pictures indicated hailstones with diameters ranging from approximately 1 to 1.5 inches in Tooele.
An emergency manager reported 4 manhole covers removed along state Route 36 between 200N and 600N, with heavy rain and thunderstorms noted in the area. As a result, there were multiple reports of residential flooding in the area.
The KF6RAL-6 Salt Lake Marina mesonet station recorded a wind gust of 60 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Grantsville South mesonet station recorded a wind gust of 60 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Marina mesonet station recorded a wind gust of 70 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The SR-201 at I-80 mesonet station recorded a wind gust of 61 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Provo Canyon mesonet station recorded a wind gust of 71 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Arrowhead Summit mesonet station recorded an initial strong wind gust of 59 mph at 6:00 pm MST as a result of outflow winds associated with a line of showers and thunderstorms moving through the area. A second peak wind gust of 64 mph was recorded at 6:10 pm MST before winds began to subside.
The US-189 at Deer Creek Dam mesonet station recorded an initial peak gust of 74 mph at 6:10 pm MST, and an additional strong gust of 59 mph at 6:20 pm MST. These gusts were a result of outflow winds associated with a cluster of showers and thunderstorms moving through the area.
The UofU Playa Research Site mesonet station recorded an initial peak gust of 70 mph at 6:14 pm MST, followed by strong gusts to 59mph, 60mph, and 58 mph at 6:15 pm MST, 6:16 pm MST, and 6:19 pm MST respectively. These gusts were a result of outflow winds associated with a cluster of showers and thunderstorms moving through the area.
Strong thunderstorms and associated outflow winds moved through the area during the early evening. At approximately 6:18 pm MST, a witness saw a tree fall onto a 68-year-old bicyclist riding along the Denver and Rio Grande Western Rail paved multiuse trail. Law enforcement arrived on scene, finding the woman unconscious and pinned beneath the felled 40 to 50 ft tree. After being removed, life saving measures were preformed and she was transported to a local hospital in critical condition, where she later died from her injuries. The nearest observation in the area is from Hill AFB, which measured a gust of 67 mph at 6:26 pm MST. Other supporting wind gusts are noted from these strong storms in the area.
The Hill Air Force Base AWOS recorded a period of wind gusts to 67 mph between 6:26 pm MST and 6:47 pm MST. These gusts were the result of outflow winds associated with a line of showers and thunderstorms moving through the area.
The Ogden-Hinckley Airport ASOS recorded a period of wind gusts to 61 mph between 6:33 pm MST and 6:45 pm MST. These gusts were the result of outflow winds associated with a line of showers and thunderstorms moving through the area.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Thunderstorm Wind, Davis | 2023-07-19 | 68 | Female | Under Tree | Direct |
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, July 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: 1121153, 1121154, 1121155, 1121162, 1121163, 1121164, 1121165, 1121175, 1121168, 1121166, 1121167, 1121169, 1121170, 1121171, 1121172, 1121173, 1121174, 1121176, 1121179, 1121180, 1121181, 1121177, 1121178, 1121182, 1121183, 1121185, 1121186, 1121188, 1121189, 1121193, 1121191, 1121192, 1121196, 1121195.