The combination of abundant low-level moisture along with MLCAPE of greater than 1000 J/KG led to the development of terrain-induced thunderstorm activity across portions of Joshua Tree National Park during the early to mid-afternoon hours.
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The episode as NWS PSR wrote it up.
The combination of abundant low-level moisture along with MLCAPE of greater than 1000 J/KG led to the development of terrain-induced thunderstorm activity across portions of Joshua Tree National Park during the early to mid-afternoon hours.
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 1, 12:34 PM PST, 1 hour 56 minutes earlier.
Area Forecast Discussion National Weather Service Phoenix AZ 134 PM MST Mon Aug 1 2022 .SYNOPSIS...Sparse thunderstorm coverage will be the theme through the middle of the week with activity more focused over higher terrain areas. In response to lesser storm coverage, temperatures are expected to warm back to near normal values, resulting in a moderate heat risk for most of the lower desert communities. A return to a more active monsoon storm pattern still appears likely as we head towards the end of the week and into the upcoming weekend. .DISCUSSION... Latest water vapor satellite imagery as well as the 500 mb streamline RAP analysis depict a strengthening subtropical high pressure across New Mexico. The center of this high pressure is expected to migrate into Arizona through the middle of the week, resulting in subsidence aloft across the area with any easterly wave action expected to remain south towards the international border. With the increasing subsidence, some drier air will also be mixing in with PWATs dropping to below 1.5 inches. As a result, thunderstorm activity across the area is likely to be sparse with any activity expected to be confined mainly to the higher terrain areas. With the expected decrease in storm coverage, temperatures are expected to rebound to near normal levels through the middle of the week with highs in the Phoenix area topping out between 104-106 degrees and between 105-109 degrees across the western deserts. In addition, with surface dewpoints likely to remain in the 60s, it will be rather humid as well making it for uncomfortable conditions, especially at night. With this increase in temperatures, the HeatRisk across most of the lower desert communities will increase to moderate levels and thus the necessary precautions will need to be taken to avoid any heat-related illnesses. As we head towards the latter end of the week into next weekend, the overall pattern will once again become more conducive for more widespread thunderstorm activity. Ensembles are in excellent agreement that the center of the aforementioned high pressure will shift towards the Plains and Midwest while a cutoff low over the eastern Pacific combines with the remnant circulation of Tropical Storm Frank to form a stationary low off the west coast. This pattern configuration will place the SW CONUS in deep southeast flow, which will help pump in moisture resulting in an increase in PWAT values above 1.7 inches as well as allow for the migration of easterly wave energy into the area. Therefore, another active thunderstorm period is likely during this time frame with all monsoon thunderstorm hazards on the table. At this point in time, it is difficult to pin point exactly which days are likely to be the most active with activity as it will all be dependent on mesoscale features that are difficult to predict this far in advance. && .AVIATION...Update 1753Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Storm activity today over the higher terrain to the north and east of the Valley is expected to be isolated. With southeasterly steering flow, they are not expected to advect to the Valley. Outflows from them are not anticipated to reach the TAF sites. Storms over southeast AZ will have a better chance of producing outflow that reaches the metro area. KIWA would be the most likely TAF site to experience the wind shift. But anticipate it will be weak. The other TAF sites are not expected to have a discernible wind shift at this time. Thus westerly winds will be the predominant direction the rest of the day and well into the night before downvalley drainage winds develop. As for sky cover, anticipate a period of increased cloudiness AOA FL150 after 02Z tonight before thinning out again. Southeast California/Southwest Arizona including KIPL and KBLH: A small and weak weather disturbance over far northern Baja Mexico is generating considerable mid and high clouds over far southeast CA. Anticipate this will thin out during the early afternoon. KIPL: There is potential for KIPL to be indirectly affected by storms over the Baja and San Diego Mountains. But confidence in the occurrence of outflow, let alone TSRA, at the airfield is too low to reflect in the TAFs. Otherwise, expect southeasterly winds to prevail though there may be a period of variability during the late afternoon/early evening hours as winds waffle between southeast and west. KBLH: There is potential for storms over La Paz County to affect the airfield. But confidence in the occurrence of outflow, let alone TSRA, at the airfield is too low to reflect in the TAFs. Otherwise, expect southerly winds to prevail except for a period of late night light westerly winds. && .FIRE WEATHER... Somewhat drier air will spread into the region through the middle of the week with thunderstorm and rainfall chances becoming more focused over higher terrain areas of eastern districts. Eventually by the end of the week, thunderstorms will migrate back into lower elevations. Regardless, the fire threat will remain low given elevated humidity levels and recent rainfall. Minimum humidity levels will range mostly from 20-30%, except 30-40% over higher terrain of eastern areas. Recovery will vary widely between 30-90% depending on thunderstorm and rainfall locations any given day. Winds will generally remain light with some occasional afternoon upslope gusts, and stronger gusts resulting from thunderstorm outflows. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && DISCUSSION...Lojero/18 AVIATION...AJ FIRE WEATHER...18
The Santa Ana Mts radar (KSOX), 141 km away, was scanning. The volume nearest the first event began at 22:27 UTC.
1 flash flood. Local standard time, as filed.
Big Horn Pass road was closed due to flooding and debris on the roads. No damages or injuries were reported. Timing based from radar.
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: 1051671.