Upper level high pressure brought record heat to the area. A plume of subtropical moisture promoted the growth of isolated afternoon thunderstorms with large hail.
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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 STO wrote it up.
Upper level high pressure brought record heat to the area. A plume of subtropical moisture promoted the growth of isolated afternoon thunderstorms with large hail.
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 Sacramento, CA wrote its last area forecast discussion before the first event at Aug 1, 7:54 AM PST, 4 hours 6 minutes earlier.
Area Forecast Discussion National Weather Service Sacramento CA 854 AM PDT Tue Aug 1 2017 .SYNOPSIS... Heatwave this week peaking today and Wednesday. Isolated late-day thunderstorms possible mainly near the Sierra crest. && .UPDATE... Latest Hi-Res guidance suggest some late-day convection developing along the Sierra Nevada crest north to about Lassen National Park today. Therefore, have updated PoPs to include a slight chance of thunderstorms and/or showers generally through 03z Wednesday. No other updates were needed as the current forecast remains on track. && .DISCUSSION... Delta Breeze continues, but it's influence inland is waning as onshore gradients slacken and the marine layer becomes a little more compressed. Current temperatures are milder across the region compared to 24 hours ago and generally range from the 50s in the mountain valleys to the upper 70s and lower 80s across the mildest portions of the Central Valley. Today and Wednesday looks to be the peak of this heatwave with hottest readings around 115 expected across the northern Sacramento Valley. Smoke from area wildfires may be enough to shave several degrees off highs from what they otherwise would be. Records the next several days are listed below: RECORDS: Today Wednesday Thursday Redding Airport.........113 1993....111 1993....112 1998 Red Bluff Sacramento....111 1993....111 1977....112 1998 Sacramento Exec.........106 1993....106 1975....106 1975 Sacramento..............109 1993....108 1987....107 1998 Stockton................109 1980....105 1993....108 1998 Modesto.................106 2014....104 1980....106 1998 Temperatures begin to trend downward on Thursday as a disturbance approaches from the south and cloud cover increases. While it is expected to cool off a bit, it will still be hot for the remainder of the week with most of the Valley remaining in triple digits. Moisture spreading northward late this week, along with a more favorable upper flow could lead to late-day convection. There are model differences at this point, but will have to monitor the potential for convection. && .EXTENDED DISCUSSION (Saturday THROUGH Tuesday) Strong upper ridge centered over Nevada weakens and shifts east through the extended forecast period as upper trough approaches. Above normal temperatures continue into early next week with highs from the upper 90s to around 106 in the Central Valley and 80s to 90s in the foothills and mountains. Monsoonal flow will keep a threat of afternoon thunderstorms over the mountains. && .AVIATION... High pres conts ovr Intr NorCal with VFR conds nxt 24 hrs exc isold IFR vcnty of Delta in ST til arnd 17z and lcl MVFR poss in FU vcnty of Minerva Fire. Isold aftn tstms poss ovr Siernev btwn 22z-03z. SWly sfc wnd gsts to arnd 25 kts poss thru Delta btwn 02-15z. && .STO WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 8 PM PDT Thursday for Burney Basin / Eastern Shasta County-Motherlode-Northern San Joaquin Valley-Southern Sacramento Valley-West Slope Northern Sierra Nevada-Western Plumas County/Lassen Park. Excessive Heat Warning until 8 PM PDT Thursday for Central Sacramento Valley-Clear Lake/Southern Lake County-Mountains Southwestern Shasta County to Northern Lake County-Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Shasta Lake Area / Northern Shasta County. &&
The national radar mosaic for the moment the first event began.
1 excessive heat, 1 hail. Local standard time, as filed.
A 13-year-old was hospitalized Tuesday after suffering heat stroke during tryouts for the freshman football team at Lincoln High School on August 1. Temperatures at Lincoln Airport reached 100 degrees between 4 and 7 pm PDT.
Golf ball hail was reported southeast of Quincy, in the vicinity of the Minerva Fire.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2017Every state in 2017This day in weather historyWarnings in California, August 2017
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: 720356, 720267.