A low pressure system dropped southward along the California coast on April 16 then slowly moved inland over southern California on April 17. This system provided enough moisture for widespread showers and scattered thunderstorms to develop by the afternoon of April 17 and continue through the morning of April 18.
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 HNX wrote it up.
A low pressure system dropped southward along the California coast on April 16 then slowly moved inland over southern California on April 17. This system provided enough moisture for widespread showers and scattered thunderstorms to develop by the afternoon of April 17 and continue through the morning of April 18. The showers and thunderstorms produced locally heavy precipitation in some areas and some areas of flooding were observed. Rainfall amounts varied due to the convective nature of the precipitation, but a few locations measured close to an inch of rainfall during this period while most stations picked up between a tenth and a half inch of rain. Above 7000 feet, the precipitation mainly fell in the form of snow; and several stations in the higher elevations of the Sierra Nevada picked up between 2 and 5 inches of new snowfall.
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 Hanford, CA wrote its last area forecast discussion before the first event at Apr 17, 1:04 PM PST, 2 hours 5 minutes earlier.
Area Forecast Discussion National Weather Service Hanford CA 204 PM PDT Fri Apr 17 2020 .SYNOPSIS... Spotty, mainly light precipitation can be expected over the district tonight into Saturday. Much of this weekend will be dry. A weak storm system will bring scattered showers and a slight chance of thunderstorms to the district Monday into Monday night. Dry weather can be expected for the remainder of next week. && .DISCUSSION...A substantially cooler air mass moved into the central California interior last night as evidenced by current 24-hour temperature trends which are running 8 to as much as 20 degrees lower than Thursday. The cool change was brought in by an offshore storm system which is now tracking inland through southern California. This storm has also been producing scattered showers and isolated thunderstorms over the southern half of our CWA today, mainly throughout Kern county, Tulare county and Kings county as well as the Sierra between Yosemite and Kings Canyon NP. A few of those thunderstorms brought frequent lightning and brief heavy rain, but so far there've been no reports of any significant hydrological impacts. Meanwhile, convection has been rather sparse in Merced county and in the valley portion of Madera county and Fresno county although these areas could receive some precipitation in addition to the Sierra foothills and mountains tonight into Saturday as an upper level disturbance drops in from the north while the storm system exits southern California and moves into Arizona. A drier air mass should begin to infiltrate the CWA by late in the day Saturday as the upper level disturbance moves east of the state and a weak ridge of high pressure settles into central California. This high pressure ridge will keep our weather dry for the remainder of the weekend. Temperatures will remain cooler than normal Saturday before recovering to seasonable levels Sunday afternoon. Another storm system, most likely the last one for quite some time, will approach from the northwest Sunday night and bring another round of showers into much of our CWA Monday. Isolated thunderstorms are possible Monday afternoon into Monday evening as the cold core of this storm moves over the central California interior. Precipitation totals with this early week system will be rather light...generally less than a tenth of an inch in the San Joaquin Valley and Kern county mountains to as much as a quarter of an inch in the foothills and higher elevations of the Sierra. Up to a few inches of snow could fall in the Sierra above 8000 feet. Little if any rain is expected in the Kern county desert. The models do have some timing differences with the early week storm system. For example, the ECM rushes this storm eastward into northern Arizona Monday night while the GFS is a good 12 hours slower. If the GFS is right, showers could linger into Tuesday, especially over the mountains. Whatever the case, Tuesday will likely be a transition day to drier weather as an Eastern Pacific ridge of high pressure begins to build into the Golden State. As for Monday, the presence of clouds and showers will keep high temperatures cooler than normal. A notable day to day warming trend can be expected for the remainder of next week as the eastern pacific ridge builds more strongly into central CA. By Wednesday, highs could top 80 degrees again in the San Joaquin Valley, lower foothills and the Kern county desert. Next Friday could end up as the warmest day yet this year with highs well into the 80s in parts of the San Joaquin Valley and the Kern county desert. && .AVIATION... MVFR conditions will occur in areas of precipitation through 19z Saturday in the foothills and higher elevations of the Sierra. Additionally, isolated thunderstorms can be expected until 03z Saturday. VFR conditions will prevail over the remainder of the central California interior during the next 24 hours. && .AIR QUALITY ISSUES... None. && .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.html for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... None. && synopsis...Durfee public/aviation/fw...Durfee PIO/IDSS...DS weather.gov/hanford
Special Weather Statement National Weather Service San Joaquin Valley CA 127 PM PDT Fri Apr 17 2020 CAZ192-172115- Central Sierra CA- 127 PM PDT Fri Apr 17 2020 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN MARIPOSA COUNTY UNTIL 215 PM PDT... At 126 PM PDT, Doppler radar was tracking a strong thunderstorm 7 miles southeast of Yosemite National Park, or 8 miles north of Yosemite South Entrance, moving north at 10 mph. Half inch hail and winds in excess of 40 mph will be possible with this storm. Locations impacted include... Ostrander Lake, Bridalveil Creek Campground and Badger Pass Ranger Station. PRECAUTIONARY/PREPAREDNESS ACTIONS... 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. && LAT...LON 3761 11954 3756 11962 3768 11969 3773 11958 TIME...MOT...LOC 2026Z 167DEG 8KT 3762 11960 DS
Special Weather Statement National Weather Service San Joaquin Valley CA 218 PM PDT Fri Apr 17 2020 CAZ192-172215- Central Sierra CA- 218 PM PDT Fri Apr 17 2020 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN MARIPOSA... SOUTHWESTERN TUOLUMNE AND NORTH CENTRAL MADERA COUNTIES UNTIL 315 PM PDT... At 217 PM PDT, Doppler radar was tracking strong thunderstorms along a line extending from 11 miles northwest of Yosemite National Park to 7 miles northeast of Yosemite South Entrance. Movement was northeast at 10 mph. Half inch hail and winds in excess of 40 mph will be possible with these storms. Locations impacted include... Yosemite Valley, Yosemite National Park, Tamarack Flat Campground, Little Yosemite Valley Campground, Badger Pass Ranger Station, North Pines Campground, Camp 4 Campground, Yosemite Glacier Point, Ostrander Lake, Gin Flat, Bridalveil Creek Campground, Little Yosemite Valley Ranger Station, Crane Flat Campground, Yosemite Valley Visitor Center, Lower Pines Campground and Upper Pines Campground. PRECAUTIONARY/PREPAREDNESS ACTIONS... Torrential rainfall is also occurring with these storms, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. Frequent cloud to ground lightning is occurring with these storms. Lightning can strike 10 miles away from a thunderstorm. Seek a safe shelter inside a building or vehicle. && LAT...LON 3768 11943 3754 11960 3781 11987 3792 11976 TIME...MOT...LOC 2117Z 233DEG 9KT 3784 11981 3760 11958 DS
Special Weather Statement
National Weather Service San Joaquin Valley CA
253 PM PDT Fri Apr 17 2020
CAZ192-172245-
Central Sierra CA-
253 PM PDT Fri Apr 17 2020
...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL MARIPOSA AND NORTH
CENTRAL MADERA COUNTIES UNTIL 345 PM PDT...
At 252 PM PDT, Doppler radar was tracking a strong thunderstorm near
Yosemite South Entrance, moving north at 10 mph.
Half inch hail and winds in excess of 40 mph will be possible with
this storm.
Locations impacted include...
Yosemite South Entrance, Fish Camp, Wawona, Poison Ridge, Mariposa
Grove and Wawona Vistor Center.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
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.
&&
LAT...LON 3738 11963 3755 11967 3761 11958 3763 11949
3738 11951
TIME...MOT...LOC 2152Z 173DEG 8KT 3746 11959
DSSpecial Weather Statement National Weather Service San Joaquin Valley CA 318 PM PDT Fri Apr 17 2020 CAZ179-172300- West Side Hills CA- 318 PM PDT Fri Apr 17 2020 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN FRESNO COUNTY UNTIL 400 PM PDT... At 318 PM PDT, Doppler radar was tracking a strong thunderstorm 15 miles northwest of Coalinga, or 46 miles north of Paso Robles, moving northwest at 5 mph. Pea size hail and winds in excess of 40 mph will be possible with this storm. This storm will remain over mainly rural areas of southwestern Fresno County. PRECAUTIONARY/PREPAREDNESS ACTIONS... 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. && LAT...LON 3623 12045 3631 12061 3636 12057 3632 12040 TIME...MOT...LOC 2218Z 119DEG 6KT 3630 12052 DS
Special Weather Statement
National Weather Service San Joaquin Valley CA
334 PM PDT Fri Apr 17 2020
CAZ195-196-198-172315-
Indian Wells Valley CA-Lake Isabella CA-Tehachapi Area CA-
334 PM PDT Fri Apr 17 2020
...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN KERN AND
SOUTHEASTERN TULARE COUNTIES UNTIL 415 PM PDT...
At 331 PM PDT, Doppler radar was tracking a strong thunderstorm 9
miles northeast of Inyokern, or 11 miles northwest of Ridgecrest,
moving northwest at 10 mph.
Pea size hail and heavy rainfall is also occurring with this storm,
and may lead to localized flooding.
Locations impacted include...
China Lake Acres and Inyokern.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
&&
LAT...LON 3571 11766 3568 11765 3562 11772 3580 11805
3584 11801 3579 11801 3579 11793 3580 11792
3580 11764 3571 11763
TIME...MOT...LOC 2231Z 129DEG 9KT 3578 11775
mvSpecial Weather Statement
National Weather Service San Joaquin Valley CA
406 PM PDT Fri Apr 17 2020
CAZ179-182-172345-
Western San Joaquin Valley CA-West Side Hills CA-
406 PM PDT Fri Apr 17 2020
...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL FRESNO COUNTY UNTIL
445 PM PDT...
At 404 PM PDT, Doppler radar was tracking a strong thunderstorm near
Cantua Creek, or 38 miles southwest of Madera, moving northeast at 20
mph.
Heavy rainfall up to one inch per hour is occurring with this storm,
and may lead to localized flooding. Winds in excess of 30 mph will
be possible with this storm.
Locations impacted include...
Cantua Creek.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
&&
LAT...LON 3665 12035 3646 12017 3627 12052 3637 12060
3647 12060
TIME...MOT...LOC 2304Z 236DEG 17KT 3646 12040
mvThe national radar mosaic for the moment the first event began.
2 flood, 1 heavy rain. Local standard time, as filed.
California Department of Transportation measured 0.34 inches and 0.28 inches of rainfall in a 15 minute period along SR 140 in the Ferguson Burn scar area prompting closure of the highway during the afternoon.
California Highway Patrol reported roadway flooding at the intersection of W. Shields Ave. and N. Russell Ave.
California Highway Patrol reported roadway flooding on SR 99 at the Prosperity Ave. exchange in Tulare.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2020Every state in 2020This day in weather historyWarnings in California, April 2020
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: 877245, 877243, 877244.