A warm plume of moist tropical air brought a very active period of weather to the area between the evening of March 20 and the evening of March 22. This resulted in widespread heavy rainfall across the area on March 21 and 22 which produced flooding at many locations with rock slides and debris flows closing several roads across the area.
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 warm plume of moist tropical air brought a very active period of weather to the area between the evening of March 20 and the evening of March 22. This resulted in widespread heavy rainfall across the area on March 21 and 22 which produced flooding at many locations with rock slides and debris flows closing several roads across the area. The most impacted areas being around Mariposa as a result of the Detwiler Fire burn scar and Springville as a result of the Pier Fire burn scar. In addition, thunderstorms developed during the afternoon of March 22 producing flash flooding at many locations as well as funnel clouds. A Flash Flood Emergency was issued for most of western Mariposa County where several buildings were flooded and some areas were evacuated. A small tornado briefly touched down near Dinuba in Tulare County. In addition, several feet of new snow fell above 9000 feet. Below the snow line, much of the Southern Sierra Nevada measured between 4 and 8 inches of rainfall while most of the San Joaquin Valley picked up between 1 and 3 inches of rainfall.
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 Mar 20, 12:34 PM PST, 6 hours 26 minutes earlier.
Area Forecast Discussion National Weather Service San Joaquin Valley - Hanford CA 134 PM PDT Tue Mar 20 2018 .SYNOPSIS... Clouds will continue to increase tonight with the approach of a storm over the Eastern Pacific. This storm will bring substantial precipitation to the district through Thursday along with very mild temperatures over the higher elevations. Friday through the weekend will be unseasonably cool, but relatively dry. && .DISCUSSION... Precipitation will continue to move inland over Central California through tonight. Latest radar imagery shows light to moderate rain over the San Joaquin Valley into the Sierra Nevada foothills mainly Tulare and Kings Counties and northward. This will be the beginning of an active weather period that will continue until Thursday evening. Precipitation will begin in earnest tonight over much of the forecast area, and short-term high resolution models also show a significant increase in precipitation over the southern portion of the forecast area, mainly over Kern County during Wednesday afternoon into Thursday. Areas north of Kern County will likely see significant precipitation during this period. The bulk of the precipitation is also expected during this same period. The main impacts will be due to heavy rainfall over the Sierra Nevada below 8,000 feet and into the foothills. Several inches of rain can be expected in much of the Sierra Nevada and the Kern County mountains through Thursday night. Burn scar areas due to wildfires could experience debris flows and flash flooding. Locations above 8,000 feet can expect heavy snow, especially in the Sierra Nevada north of Kern County. In addition, locations in the San Joaquin Valley can expect around one to two inches from this system during the next 48 hours (tonight through Thursday night), including at the south end. Areas of poor drainage could experience minor flooding or at least ponding on roadways. Another potential concern is periods of heavy rainfall rates during the peak of the event on Wednesday afternoon into Thursday morning, especially over the mountains and foothills. Rainfall amounts in March so far, especially in the Central Valley, are already around the average totals for the entire month. Locations in the San Joaquin Valley could see significant increases in total precipitation since the beginning of this month (possibly near double for the month of March by the time precipitation ends), as well as the beginning of the wet season (or water year beginning on Oct 1st). By Friday, the best moisture and dynamics associated with the low pressure system will be east of the area. However, another upper- level low will bring a slight chance for precipitation over the weekend. At this time, this system is expected to pass over mainly northern California; however, some moisture could move as far south as Fresno County. After the weekend, models continue to show high pressure ridging beginning to develop, so a dry period is at least in store during early next week. Otherwise, cooler than average temperatures will continue. && .AVIATION... Mountain obscuration due to clouds/precipitation in the Sierra Nevada and Tehachapi Range. Otherwise, MVFR/IFR conditions in low ceilings and precipitation will prevail for 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.php for additional information an/or to provide feedback. && .HNX Watches/Warnings/Advisories... Winter Storm Warning from 5 PM this afternoon to 11 PM PDT Thursday ABOVE 8000 FEET FOR THE CAZ096-097. Flash Flood Watch from Wednesday afternoon through Thursday evening CAZ093>097. && public...BSO avn/fw...BSO synopsis...BSO weather.gov/hanford
The San Joaquin Valley radar (KHNX), 113 km away, was scanning. The volume nearest the first event began at 13:05 UTC.
14 flood, 8 debris flow, 3 flash flood, 3 funnel cloud, 1 heavy snow, 1 heavy rain, 1 tornado. Local standard time, as filed.
Tuolumne Meadows (8694 feet) measured 31 inches of new snow during the 2 and a half day event as precipitation mainly fell as snow above 8500 feet.
California Highway Patrol reported a rock slide covering half of the roadway on State Route 168 at Huntington Lake Rd.
California Highway Patrol reported rocks fallen onto the roadway at the middle of a 4 lane section of State Route 168 below Shaver Lake.
California Highway Patrol reported debris covering one lane on the westbound side of State Route 180 and partially the other lanes at Snow Line Lodge near Dunlap.
California Highway Patrol reported closure of Malaga Rd. between Digiorgio Rd. and Panama Rd. due to roadway flooding.
California Highway Patrol reported two boulders in the roadway of State Route 155 near Alta Sierra Rd. with heavy rainfall in the area.
California Highway Patrol reported a mud slide along northbound State Route 41 at Jackson Rd. near Fish Camp after brief heavy rain moved over the area.
A trained spotter measured 0.91 inches of rainfall between 900 pm on March 21 and 700 am on March 22 with periods of heavy rain during this time frame.
Media report of minor flooding at the intersection of Champlain and Perrin in north Fresno with several inches of water covering the roadway.
California Highway Patrol reported a mud slide onto the roadway on Road 274 at Marina View Dr. near the southeast side of Bass Lake.
Madera County Public Works reported Road 417 was closed just west of Huron Rd. due to flooding.
California Highway Patrol reported a rock slide partially blocking State Route 178 in Kern Canyon.
California Highway Patrol reported a rock slide covering the entire westbound lane and partial blocking of the eastbound lane of State Highway 140 at Briceburg.
California Highway Patrol reported Redrock-Randsburg Rd. at State Route 14 closed due to water over the road.
California Highway Patrol reported large boulders at State Route 140 and Colorado Rd.
California Highway Patrol reported the entire roadway flooded at the intersection of Roadway J59 and Fields Rd.
California Highway Patrol reported major flooding across the roadway at State Route 59 and Nevada St.
California Highway Patrol reported Fowler Ave. just north of Elkhorn Ave. completely flooded.
California Highway Patrol reported State Route 49 completely closed due to mudslides between State Route 120 and Bear Valley Rd. The road was closed for several days due to erosion from a massive amount of water which washed out the roadway.
Mariposa Office of Emergency Services reported several homes flooded and roadways washed out. While many roadways were washed out across Northwestern Mariposa County, the homes were generally impacted near Lake Don Pedro, Hornitos, and the City of Mariposa. The two fatalities that did occur in the area were both related to a person driving into a flooded roadway. One was along highway 132 west of Coulterville and the other was near Cathey's Valley where a 72 year old woman was found dead nearly four months later.
A brief cold air funnel was reported by an NWS employee at the corner of Houston Ave. and Mooney Blvd. in north Visalia.
A storm chaser intercepted a small tornado between Yettem and Seville on State Route 201. The tornado was on the ground for a minute or less and no damage was reported.
California Highway Patrol reported State Route 140 sliding into the Merced River and a large crack in the road.
Public report of a funnel cloud in the vicinity of Ave 384 and Road 156 in the Seville area.
Report of a funnel cloud received on Facebook near the intersection of State Route 201 and Road 140 near Yettem.
Cal Trans reported a road closure due to a mudslide on State Route 190 about 8.4 miles west of Camp Nelson.
Several media and social media reports of numerous cars hitting each other or getting stuck because of high water on Champlain Dr. in north Fresno.
Public reports of road flooding with about 10 cars stuck in high water on Clovis Ave near the State Route 168 underpass in Clovis.
California Highway Patrol reported road closure due to rocks and mud on State Route 223 at State Route 58. Several vehicles were stuck in mud.
A television station broadcast indicated that 6 campers were trapped in high water from the San Joaquin River in Woodward Park. 2 were able to escape and 4 were rescued by the Fresno Fire Department in 2-3 feet of water.
Public report of around a foot of water from Miles Creek flooding parts of Planada Elementary School. This report was later confirmed by the Merced County OES official.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Flash Flood, Mariposa | 2018-03-22 | 72 | Female | Vehicle/Towed Trailer | Direct |
| Flash Flood, Mariposa | 2018-03-22 | 67 | Male | Vehicle/Towed Trailer | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2018Every state in 2018This day in weather historyThe tornado archive for California, 2018Warnings in California, March 2018
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: 737987, 737990, 737991, 737996, 737998, 737999, 738043, 738023, 738000, 738006, 738009, 738042, 738040, 738010, 738039, 737988, 738037, 738012, 738034, 740496, 738019, 738025, 738032, 738020, 738022, 738013, 738015, 738016, 738031, 737989, 738017.