Two rounds of thunderstorms developed across portions of southeast California, one round during the very early morning hours, between midnight through 4 am local time and another round during the mid to late afternoon hours. The early morning round was instigated by outflow boundaries that moved westward into southeast California from the decaying storm complex across southwest Arizona during…
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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.
Two rounds of thunderstorms developed across portions of southeast California, one round during the very early morning hours, between midnight through 4 am local time and another round during the mid to late afternoon hours. The early morning round was instigated by outflow boundaries that moved westward into southeast California from the decaying storm complex across southwest Arizona during the evening hours on the 12th. The environment was characterized by high moisture content (PWATs in excess of 2 inches) and moderate instability (MLCAPE of around 1000 J/KG). The mid to late afternoon round, was a more typical diurnal instigator and the environment once again was conducive, with very high moisture content (PWATs of 2+inches) and high instability (MLCAPE of 1500-2000 J/KG).
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 Aug 13, 2:28 AM PST, 14 minutes earlier.
Area Forecast Discussion National Weather Service Phoenix AZ 328 AM MST Sat Aug 13 2022 .SYNOPSIS... The weather pattern will continue to support ample monsoonal moisture across the region and daily chances for thunderstorms into next week. Best coverage for storms today should exist across southeast California and across the far eastern Arizona high terrain. For Sunday, the chances for more widespread storms is likely to affect the south-central Arizona deserts. Strong winds, heavy rainfall, and localized flooding will all be possible with any thunderstorm activity. Temperatures near to slightly below normal are anticipated over the next several days. && .DISCUSSION... Yesterday ended up being another active monsoon day with showers and widespread thunderstorms across central and western Arizona. The westward moving outflow from the storms across western Arizona during first half of the evening was then enough to trigger additional thunderstorms across southeast California starting around 10 pm leading to more areas of heavy rainfall and flooding. The current area of showers and thunderstorms to the north and northwest of the El Centro area is expected to gradually wind down by sunrise. The atmosphere over most of the area has been "worked over" from convection over the past 18 hours and this will largely limit afternoon development today. The 00Z HREF and recent HRRR runs show only isolated storms developing this afternoon, focused over higher terrain areas well north and east of the Phoenix area and potentially again across southeast California and southwest Arizona. The current storm activity in southeast California should hinder storm development across much of Riverside County later today, but it still seems likely there will be some isolated to scattered storms across Imperial Co. and possibly into far southwest Arizona if there is enough destabilization. The Flood Watch for southeast California and southwest Arizona through this evening generally looks good, but there is some doubt whether there will be enough redevelopment of storms later today given the current activity. The large scale sub-tropical high is forecast to remain centered near the panhandle of Texas through at least early next week with overall weak southerly flow persisting over the Desert Southwest. After today's more of a down day for storms for Arizona, Sunday is looking like another potential active day. Plenty of monsoon moisture will still be in place and the atmosphere should recover by Sunday leaving ample instability for thunderstorm activity. There also could be decent forced ascent moving into the area associated with a mid level PV anomaly which is currently seen within water vapor imagery across southeast New Mexico. Models have picked up on this disturbance and are in good agreement it will continue to track westward reaching southeast Arizona sometime Sunday morning. Given the anticipated recovered atmosphere on Sunday and this additional forcing from the disturbance, it seems fairly likely scattered to numerous thunderstorms will develop over the eastern Arizona high terrain Sunday afternoon. There is still some question on how much of this activity will progress into the south-central Arizona lower deserts later on Sunday, but it could end up being another organized MCS. Given the current forecast soundings, strong winds, blowing dust, heavy rainfall, and localized flooding all will be possible. WPC's Day2 ERO shows a slight risk of excessive rainfall for most of eastern Arizona westward through Maricopa County. Another Flood Watch may be needed on Sunday given this potential excessive rainfall. For southeast California into southwest Arizona, hi-res CAMs also show at least isolated storms developing Sunday afternoon. Forecast confidence then drops Sunday night into Monday as additional shower and storm potential could occur as models hint at the disturbance stalling out over central Arizona. However, due to the anticipated active day on Sunday, instability may be limited into Monday leading to more of a localized heavy rainfall threat. Monday's storm potential will likely be contingent on how widespread Sunday's activity is and whether or not the atmosphere is again work over. Looking into the extended period, the weather pattern is not likely to vary all that much with the sub-tropical high either remaining centered to our east or shifting more across the Four Corners area/Great Basin. Either way, it should remain in a good position for continued southerly moist flow into much of the region. There are some indications Tuesday may see some drier air briefly work into eastern Arizona and this may keep storm activity more limited. Model ensembles then indicate a potential eastern wave tracking off the Gulf of Mexico close to our region by Wednesday or Thursday. Since this potential disturbance is around 5 days out, we can't infer much, but it will definitely be something to watch for later next week. && .AVIATION...Updated 0520Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Some variability in wind direction will occur overnight, but in general, N/NW winds will gradually veer to the typical easterly as abundant mid/high clouds prevail from the leftovers of earlier storms. Chances for any additional storms overnight through Saturday early afternoon is less than 10%. Confidence is moderately good that thunderstorms will remain well removed from terminal locations Saturday afternoon and evening (direct TS impact 20% or less) with somewhat better chances of a muted, distant outflow bringing an E/SE wind shift later Saturday evening. Southeast California/Southwest Arizona including KIPL and KBLH: With periodic mid/high clouds streaming through the region from decaying storms, S/SE winds will be preferred into Saturday afternoon. Some occasional gustiness from distant outflows will be possible. Chances for storms and impacts to aviation will begin to increase markedly Saturday afternoon, particularly at KIPL where direct TS impact chances increase around 30%. Even higher probabilities exist that erratic gusty winds affect either terminal location. && .FIRE WEATHER... Ample monsoonal moisture is expected to persist through at least the first half of next week keeping the fire danger threat low. This moist airmass will continue to yield elevated humidities with afternoon minimum RH values mostly in a 30-35% range, locally higher, and good overnight recovery. Chances for wetting rains will continue for most areas almost daily, especially through Monday. Winds for the most part will remain light, with the exception of thunderstorm outflows generating stronger gusts. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Flood Watch through this evening for AZZ530>533-535-536. CA...Flood Watch through this evening for CAZ560>570. && DISCUSSION...Kuhlman AVIATION...18 FIRE WEATHER...Kuhlman
Special Weather Statement
National Weather Service Phoenix AZ
1155 PM PDT Fri Aug 12 2022
CAZ560-561-130730-
Joshua Tree NP East CA-Joshua Tree NP West CA-
1155 PM PDT Fri Aug 12 2022
...A strong thunderstorm will impact portions of Riverside County
through 1230 AM PDT...
At 1155 PM PDT, Doppler radar was tracking a strong thunderstorm 11
miles northeast of Coachella. This storm was nearly stationary.
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.
This storm will remain over mainly rural areas of Riverside County.
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.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.
&&
LAT...LON 3397 11612 3398 11592 3389 11590 3377 11589
3374 11595 3374 11600 3384 11613 3386 11614
TIME...MOT...LOC 0655Z 150DEG 2KT 3380 11601
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH
INSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
1200 AM MST SAT AUG 13 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0440 PM TSTM WND DMG 11 ESE CENTENNIAL 33.52N 113.16W
08/12/2022 MARICOPA AZ UTILITY COMPANY
POWER LINE(S) DOWN.
&&
SBPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
1213 AM MST SAT AUG 13 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0305 AM TSTM WND DMG 6 N EAST MESA 33.51N 111.67W
08/12/2022 MARICOPA AZ UTILITY COMPANY
POWER LINES DOWN.
&&
SBPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
1215 AM MST SAT AUG 13 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0322 PM TSTM WND DMG 2 NNW MESA 33.44N 111.84W
08/12/2022 MARICOPA AZ UTILITY COMPANY
POWER LINES DOWN IN AREA.
&&
SBPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
1216 AM MST SAT AUG 13 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0305 PM TSTM WND DMG 6 N EAST MESA 33.51N 111.67W
08/12/2022 MARICOPA AZ UTILITY COMPANY
CORRECTS PREVIOUS TSTM WND DMG REPORT FROM 6
N EAST MESA. POWER LINES DOWN IN AREA.
&&
SBPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PHOENIX AZ
1243 AM MST SAT AUG 13 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0245 PM TSTM WND DMG 2 N PHOENIX MESA GATEWA 33.34N 111.65W
08/12/2022 MARICOPA AZ PUBLIC
POWER LINES DOWN IN AREA.
&&
SBThe Yuma radar (KYUX), 154 km away, was scanning. The volume nearest the first event began at 10:43 UTC.
4 flash flood, 1 thunderstorm wind. Local standard time, as filed.
SR-177, just north of Desert Center, was closed due to flooding. No damages or injuries were reported.
Highway 78 near Milepost 53 was flooded, with multiple vehicles stuck in the floodwaters. No damages or injuries were reported.
Highway 78 was flooded at Milpitas Wash with debris across the road. A vehicle was reported to have been damaged by the rocks on the road. No injuries were reported.
A thunderstorm microburst that moved through Winterhaven resulted in 49 downed power poles in the Quechan Tribe area. No injuries were reported.
Ogilby Road closed near the intersection with Sidewinder Road due to flooding. Vehicles were stranded between two washes pushing sediment and debris onto roadways. No injuries were reported.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2022Every state in 2022This day in weather historyWarnings in California, August 2022
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: 1053841, 1053842, 1053844, 1053866, 1053843.