With the subtropical high pressure situated over southern Nevada, the steering flow was from the northeast. Thunderstorm activity developed over the Mogollon Rim during the early afternoon hours and was steered southwestward towards Yavapai, northwestern Maricopa, and La Paz Counties.
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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 PSR wrote it up.
With the subtropical high pressure situated over southern Nevada, the steering flow was from the northeast. Thunderstorm activity developed over the Mogollon Rim during the early afternoon hours and was steered southwestward towards Yavapai, northwestern Maricopa, and La Paz Counties. The overall environment was characterized by MLCAPE values of 500-1000 J/KG, with DCAPE values near 2000 J/KG. Thus, conditions were favorable for strong to severe downburst wind gusts to materialize with any thunderstorm activity that developed.
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 Phoenix, AZ wrote its last area forecast discussion before the first event at Jul 23, 4:46 PM MST, 1 hour 43 minutes earlier.
Area Forecast Discussion National Weather Service Phoenix AZ 446 PM MST Tue Jul 23 2024 .UPDATE...Updated 00Z Aviation Discussion. && .SYNOPSIS... Daily thunderstorm activity is expected to continue through the rest of the week, with the highest chances across the AZ higher terrain areas. Storm chances will still exist across the lower deserts, with large daily fluctuations in coverage. Drier conditions are expected during the upcoming weekend. Temperatures through the next several days will remain above normal. && .DISCUSSION... The latest objective analysis depicts the center of the subtropical ridge situated over southern NV with most of the region entrenched under northeasterly flow aloft. Widely scattered and storms have already started develop along the vicinity of the Mogollon Rim. The activity through the afternoon will be steered southwestward into portions of Yavapai, Gila, and Mohave counties and eventually into the lower deserts of south-central and southwest AZ. The main question is gonna be whether or not these storms survive their trip into the lower deserts and this aspect of the forecast is not clear cut as the latest Hi-res model guidance continues to show widely varying solutions. Everything will be dependent on whether or not the storms that initially develop over the High Country can spark a deep enough outflow boundary or any sort of outflow collisions to spark new storm development across the lower deserts. Another area in which thunderstorm activity has already developed has been across western portions of Joshua Tree National Park as well as across the Peninsular Range of the northern Baja Peninsula and San Diego Mountains, which could instigate some new development across western Imperial County later on this afternoon. There is also some signal of potential new thunderstorm activity developing in portions of Riverside County from outflow collisions from activity from western AZ and the Mohave desert as well from the San Diego Mountains and western Imperial County. The main hazard with these storms as they mature will be the potential for strong gusty winds with latest HREF indicating a 30-70% chance of gusts of 35+ mph across a wide area, with a 5% chance of 58+ mph gusts, especially across western AZ and the Mohave Desert Region. With the strong winds will also be the potential for areas of blowing dust to materialize in the dust prone areas. Locally heavy rainfall will also be possible, especially near the vicinity of Joshua Tree National Park. Heading into the middle to latter half of the week, as a trough impinges across the Pacific Northwest, the subtropical ridge is expected to be displaced very slightly southeastward into western AZ while strengthening slightly as 500 mb height fields increase to between 597-600dm. The overall steering flow is not expected to change that much with the mid-level flow still remaining out of the east to northeast. The latest hi-res model guidance indicates a much more active day for convection across eastern and southeastern AZ on Wednesday. Not much thunderstorm activity is being depicted across the south-central AZ lower deserts Wednesday evening, however, if there are multiple outflow collisions, then storm chances will indeed go up. A strong outflow boundary originating from the activity across eastern and southeastern AZ is likely to migrate its way northwestward through south-central AZ and could potentially result in blowing dust issues, especially across Pinal County. What the outflows will likely do is increase the low-level moisture and setup for a better storm environment for Thursday. Guidance for the past several iterations has been hinting on the potential for better storm coverage across the south-central AZ lower deserts, including the Greater Phoenix area, for Thursday. A robust shortwave that develops along the eastern periphery of the ridge is being indicated by guidance to move in, providing larger scale forcing for ascent. In addition, with the better moisture likely to be in place, forecast soundings for Phoenix indicate MLCAPE values of 1000-1500 J/KG. Therefore, the combination of the good thermodynamic environment in addition to the larger scale forcing for ascent from the shortwave energy should be sufficient for more robust storm activity to materialize Thursday evening across the south-central AZ lower deserts. Ensemble guidance continues to be consistent in indicating an upper- level trough progressing into the Great Basin Region through the weekend. This will cause the subtropical ridge to be displaced further southward towards the international border while also weakening in the process. This pattern shift will result in some form of a drier westerly flow to settle in, dropping moisture levels. As a result, a decrease in monsoonal thunderstorm activity is likely, with activity mostly confined to far eastern and southeast AZ for Saturday and Sunday. By early next week, the ensembles indicate that the subtropical ridge will quickly rebound and move back into the Four Corners region. At the same time, there are indications from both the GFS and ECMWF deterministic model solutions of a potent inverted trough moving into the region from Mexico. If the model guidance is correct with the depiction of the inverted trough and with moisture increasing, then a more active thunderstorm pattern is likely to setup. High temperatures today will continue to remain similar to yesterday with highs between 108-113 degrees across the lower deserts. As the subtropical ridge strengthens Wednesday and Thursday, hotter temperatures can be expected with highs of 109-114 degrees across the AZ lower deserts to between 115-118 degrees across southeast CA. An Excessive Heat Warning is in effect for areas along the Colorado River Valley westward through all of southeast CA through Friday as the combination of the hotter temperatures along with dewpoints in the mid 60s to mid 70s will cause heat indices to approach or in some cases exceeding 120 degrees, making for oppressive conditions. Heading into the weekend, as the subtropical ridge weakens, temperatures will be cooling off with highs across many of the lower desert communities likely staying near to just below 110 degrees. && .AVIATION...Updated at 2345Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Westerly winds will continue into the evening. Guidance has backed off on the outflow potential this evening, however, it still does show a couple weak outflows trying to move into the Phoenix Metro around 02-03Z this evening. Given that there is not much activity off to the NE at this time and there is more activity/more robust activity off to the NW, the current thinking that any outflow that does survive into the Phoenix Metro will come from those storm from the NW. So have reflected that in the TAFs by making the wind direction 350-360 with speeds around 10 kt. There may be some very brief gusts up around 20 kt, but these are not expected to last long, if they occur at all. The outflow is expected to wash out prior to reaching KIWA, so the wind shift from any outflows has been removed from their TAF. VCSH/VCTS is also no longer expected and has also been removed from the TAFs. Behind the potential outflow this evening winds are expected to return to their typical diurnal tendencies, going easterly overnight and returning to westerly tomorrow afternoon. Tomorrow evening we will once again have to watch for outflow potentials and possible VCSH/VCTS, but this would occur after 00Z. There will be fluctuating mid and high clouds throughout the period with bases down to around 10 kft with convection. Southeast California/Southwest Arizona including KIPL and KBLH: In the area, isolated storms have fired up around SE CA and on the AZ side of the CO River. We will have to continue to monitor these storms this evening and if any additional activity tries to fire up near or over the terminals, however, at this time no activity is expected to directly impact the terminals. A complex of storms currently in west-central AZ will continue to move to the SW through the evening. This activity is expected to push an outflow boundary through KBLH, with gusts up around 20-25 kt around 05Z this evening. This outflow could be accompanied by VCSH and could cause some BLDU with a slight drop in visibility to around 6SM. Otherwise winds will continue to follow their typical diurnal trends and tend to be southeasterly at KIPL and southerly at KBLH. Mid and high cloud coverage will fluctuate with convective development with bases down to around 10 kft. && .FIRE WEATHER... Widely scattered afternoon and evening thunderstorms will be common over higher terrain locations of eastern districts through the majority of the week with storms occasionally propagating into lower elevations. While only a few areas are expected to receive beneficial wetting rainfall, the main impacts from these storms will be strong, gusty outflow winds which could affect any ongoing wildfires and the possibility of new starts due to lightning. Winds outside of thunderstorms will generally exhibit typical afternoon upslope tendencies with gusts commonly around 20 to 25 mph. Otherwise, minimum afternoon humidity levels will mostly fall in a 20-35% range with a potential for modest drying towards the end of the week and weekend. Overnight recovery should be highly variable from 30-40% in lower elevations to 40-80% in higher terrain of eastern districts. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Excessive Heat Warning until 8 PM MST Friday for AZZ530-532. CA...Excessive Heat Warning until 8 PM PDT Friday for CAZ560>570. && DISCUSSION...Lojero AVIATION...Berislavich FIRE WEATHER...Salerno
Special Weather Statement
National Weather Service Phoenix AZ
357 PM PDT Tue Jul 23 2024
CAZ561-570-232345-
Chuckwalla Valley CA-Joshua Tree NP East CA-
357 PM PDT Tue Jul 23 2024
...A STRONG THUNDERSTORM WILL IMPACT SAN BERNARDINO AND RIVERSIDE
COUNTIES THROUGH 445 PM PDT...
At 357 PM PDT, Doppler radar was tracking a strong thunderstorm 13
miles north of Eagle Mtn, or 22 miles north of Desert Center. This
thunderstorm was nearly stationary. Additional storm development was
seen just east of SR-177.
HAZARD...Wind gusts of 50 to 55 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
This storm will remain over mainly rural areas of San Bernardino and
Riverside Counties.
This includes CA Route 177 between mile markers 19 and 27.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 3407 11532 3408 11504 3393 11498 3392 11546
3407 11556 3408 11554 3411 11552
TIME...MOT...LOC 2257Z 135DEG 2KT 3404 11539
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...55 MPH
SDBSpecial Weather Statement
National Weather Service Phoenix AZ
422 PM PDT Tue Jul 23 2024
CAZ560-561-240000-
Joshua Tree NP West CA-Joshua Tree NP East CA-
422 PM PDT Tue Jul 23 2024
...A STRONG THUNDERSTORM WILL IMPACT SAN BERNARDINO AND RIVERSIDE
COUNTIES THROUGH 500 PM PDT...
At 422 PM PDT, Doppler radar was tracking a strong thunderstorm 13
miles south of Twentynine Palms Airport, or 13 miles south of
Twentynine Palms. This thunderstorm was nearly stationary.
HAZARD...Wind gusts up to 50 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
This storm will remain over mainly rural areas of San Bernardino and
Riverside Counties.
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 3406 11601 3403 11600 3403 11591 3395 11585
3383 11600 3393 11620 3408 11602 3407 11600
TIME...MOT...LOC 2322Z 135DEG 2KT 3395 11599
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH
SDBSpecial Weather Statement
National Weather Service Phoenix AZ
520 PM PDT Tue Jul 23 2024
CAZ560-561-568-240100-
Chiriaco Summit CA-Joshua Tree NP West CA-Joshua Tree NP East CA-
520 PM PDT Tue Jul 23 2024
...A STRONG THUNDERSTORM WILL IMPACT SAN BERNARDINO AND RIVERSIDE
COUNTIES THROUGH 600 PM PDT...
At 520 PM PDT, Doppler radar was tracking a strong thunderstorm 10
miles northwest of Cottonwood Visitor, or 17 miles northwest of
Chiriaco Summit. This thunderstorm was nearly stationary.
HAZARD...Wind gusts up to 40 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
This storm will remain over mainly rural areas of San Bernardino and
Riverside Counties.
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 3384 11555 3375 11587 3389 11607 3404 11575
3403 11570
TIME...MOT...LOC 0020Z 135DEG 2KT 3389 11586
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH
SDBSpecial Weather Statement
National Weather Service Phoenix AZ
540 PM MST Tue Jul 23 2024
AZZ531-536-240115-
Gila River Valley AZ-Kofa AZ-
540 PM MST Tue Jul 23 2024
...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN LA PAZ AND NORTH
CENTRAL YUMA COUNTIES THROUGH 615 PM MST...
At 540 PM MST, Doppler radar was tracking a strong thunderstorm 13
miles northeast of Yuma Proving Ground, or 22 miles northeast of
Martinez Lake. This thunderstorm was nearly stationary.
Strong, gusty winds will be capable of producing areas of blowing
dust with reduced visibilities below 6 miles.
HAZARD...Wind gusts up to 40 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
This storm will remain over mainly rural areas of southwestern La Paz
and north central Yuma Counties.
This includes AZ Route 95 between mile markers 56 and 77.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 3330 11403 3313 11391 3296 11429 3326 11439
TIME...MOT...LOC 0040Z 068DEG 4KT 3319 11419
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH
SDBSpecial Weather Statement
National Weather Service Phoenix AZ
600 PM MST Tue Jul 23 2024
AZZ531-533-240145-
Kofa AZ-Central La Paz AZ-
600 PM MST Tue Jul 23 2024
...A STRONG THUNDERSTORM WILL IMPACT SOUTHERN LA PAZ AND NORTH
CENTRAL YUMA COUNTIES THROUGH 645 PM MST...
At 559 PM MST, Doppler radar was tracking a strong thunderstorm 12
miles south of Kofa Wildlife Refuge, or 38 miles northeast of
Martinez Lake. This thunderstorm was nearly stationary.
Strong, gusty winds will be capable of producing areas of blowing
dust with reduced visibilities below 6 miles.
HAZARD...Wind gusts of 50 to 55 mph and half inch hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Palm Canyon.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 3343 11390 3326 11382 3314 11405 3339 11416
TIME...MOT...LOC 0059Z 068DEG 4KT 3332 11394
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...55 MPH
SDBSpecial Weather Statement
National Weather Service Phoenix AZ
601 PM MST Tue Jul 23 2024
AZZ534-240145-
Aguila Valley AZ-
601 PM MST Tue Jul 23 2024
...A STRONG THUNDERSTORM WILL IMPACT MARICOPA COUNTY THROUGH 645 PM
MST...
At 601 PM MST, Doppler radar was tracking a strong thunderstorm 8
miles west of Wickenburg, moving southwest at 5 mph.
HAZARD...Wind gusts up to 50 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Wickenburg.
This includes US Highway 60 between mile markers 89 and 108.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 3397 11275 3375 11288 3392 11314 3401 11302
3400 11280
TIME...MOT...LOC 0101Z 038DEG 5KT 3397 11290
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH
SDBThe Yuma radar (KYUX), 73 km away, was scanning. The volume nearest the first event began at 01:28 UTC.
2 thunderstorm wind. Local standard time, as filed.
A Yuma Proving Ground Mesonet site west of US Highway 95 measured a 61 mph wind gust.
A mesonet station in Aguila measured a 58 mph wind gust.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2024Every state in 2024This day in weather historyWarnings in Arizona, July 2024
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: 1202309, 1202308.