Heavy Snow, Central Sierra
- When
- May 18, 7:00 AM PST to May 19, 7:00 AM PST
- Where
- Central Sierra forecast zone
- Reported by
- SNOTEL
The Ostrander Lake SNOTEL (8200 feet) picked up an estimated 7.0 inches of new snow.
Flooding and Heavy Snow in California, May 18 to 19, 2020
A low pressure system dropped southward off the northern California coast on May 17 than moved inland across central California on May 18. As a result, precipitation spread southward across the area north of Fresno County during the evening of May 17 and became widespread across our area on May 18.
Where it happened
Every event with a place to put it. Tap one for its entry below.
- Tornadoes
- Tropical storms and surge
- Floods
- Wind
- Hail
- Winter weather
- Heat and drought
- Cold
- Fire, smoke and dust
- Marine and coastal
- Other
The toll
- Deaths
- 0
- Injuries
- 0
- Property damage
- None recorded
- Crop damage
- None recorded
- Events
- 9
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.
What happened
The episode as NWS HNX wrote it up.
A low pressure system dropped southward off the northern California coast on May 17 than moved inland across central California on May 18. As a result, precipitation spread southward across the area north of Fresno County during the evening of May 17 and became widespread across our area on May 18. Several stations in the Sierra Nevada picked up between an inch and 2.50 inches of liquid precipitation while a few stations from Madera County northward picked up between 2.50 and 3.25 inches of liquid precipitation. Snow levels were between 8000 to 9000 feet early on, but lowered to around 6000 feet by the afternoon of May 18. Several higher elevation SNOTEL stations picked up between 2 and 6 inches of new snowfall while a few stations picked up 7 inches or more. As a cooler airmass pushed into the area during the afternoon of May 18, thunderstorms developed during the afternoon. One thunderstorm produced nuisance roadway flooding near Riverdale while another produced nuisance roadway flooding near Parlier. A third thunderstorm produced a funnel cloud near North Fork. Finally, This system produced a period of strong winds over the Kern County Deserts as well as over the Lake Isabella and Tehachapi areas between the evening of May 18 and the morning of May 19. Several stations in these areas reported wind gusts between 45 and 60 mph. A few low impact indicator sites reported gusts between 60 and 70 mph. The winds diminished by late morning on May 19 as the storm moved out of the area.
What forecasters said that day
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 May 18, 2:35 AM PST, 4 hours 25 minutes earlier.
Area forecast discussion, May 18, 2:35 AM PST, 4 hours 25 minutes before
Area Forecast Discussion National Weather Service Hanford CA 335 AM PDT Mon May 18 2020 .SYNOPSIS... A Pacific storm system will spread precipitation throughout Central California. High elevation mountain snow and valley rain will persist into Tuesday. A few strong thunderstorms are possible this afternoon and evening north of Kern County. Dry weather is expected Wednesday through Monday. && .DISCUSSION... Strong Pacific storm system is making its way into the CENCAL interior this morning as showers are breaking out over the region. Showers are increasing in the Sierra attm. Regional radar and satellite are indicating a line of heavy showers making its way onshore across Monterey Bay. The front is pushing through the CWA and embedded troughs will bring enhanced showers and possibly thunderstorms through the day as the main center of low pressure will sit off the NORCAL coast before moving inland later today. Significantly cooler temperatures are expected today with periods of showers and thunderstorms. Winds will be strong along the west side of the SJV through this morning. Convection will decrease after sunset this evening. We will see additional precip across the Sierra with continued onshore flow and orographic lift. However the bulk of the moisture will be over and only spotty showers are expected overnight. Unsettled weather is expected across the region again on Tuesday as onshore flow will continue with embedded shortwaves that will trigger showers. Afternoon convection is possible once again in the Sierra on Tuesday, mainly north of Kings Canyon. The main upper level trough will move through on Tuesday morning with the coldest day expected. NW flow aloft will keep the region dry and seasonable Wednesday through Saturday. Weak embedded shortwaves will progress through the NW flow through Friday. Weak ridging will bump temps up on Sunday and Monday with a rex block pattern setting up in the EPAC for early next week. && .AVIATION... Areas of mountain obscurations and IFR conditions are expected in the Southern Sierra Nevada through 1200z Tuesday. IFR or lower conditions are likely in and near thunderstorms north of Kern County this afternoon. && .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 high. 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... Winter Storm Warning until 5 AM PDT Tuesday for CAZ192-193. Wind Advisory until 5 AM PDT Tuesday for CAZ179-180-182. Winter Weather Advisory until 5 AM PDT Tuesday for CAZ194-195. && public/FW...JDB aviation/IDSS/PIO....Molina weather.gov/hanford
The radar
The San Joaquin Valley radar (KHNX), 25 km away, was scanning. The volume nearest the first event began at 00:13 UTC.
Event by event
3 heavy snow, 3 high wind, 2 flood, 1 funnel cloud. Local standard time, as filed.
Heavy Snow, North Kings River
- When
- May 18, 7:00 AM PST to May 19, 7:00 AM PST
- Where
- North Kings River forecast zone
- Reported by
- SNOTEL
The Blackcap Basin SNOTEL (10300 feet) picked up an estimated 9.0 inches of new snow.
Heavy Snow, Sequoia Kings
- When
- May 18, 7:00 AM PST to May 19, 7:00 AM PST
- Where
- Sequoia Kings forecast zone
- Reported by
- SNOTEL
The Crabtree Meadow SNOTEL (10700 feet) picked up an estimated 6.0 inches of new snow.
Flood, Fresno
- When
- May 18, 4:14 PM PST to 6:00 PM PST
- Where
- Fresno County, Riverdale to 0.12 mi E of Riverdale
- Cause
- Heavy Rain
- Reported by
- NWS Employee
- Coordinates
- 36.430, -119.870
An NWS Employee observed roadway flooding just west of Riverdale at the intersection of |W. Mount Whitney Ave and S. Brawley Ave.
Funnel Cloud, Madera
- When
- May 18, 4:43 PM PST to 4:45 PM PST
- Where
- Madera County, 1.6 mi E of South Fork
- Reported by
- Public
- Coordinates
- 37.230, -119.471
Public observation of a funnel cloud near North Fork.
Flood, Fresno
- When
- May 18, 5:00 PM PST to 6:00 PM PST
- Where
- Fresno County, 0.93 mi S of Parlier to 1.14 mi S of Parlier
- Cause
- Heavy Rain
- Reported by
- Public
- Coordinates
- 36.607, -119.522
Public report of roadway flooding and half inch hail in Parlier.
High Wind, Lake Isabella
- When
- May 18, 9:18 PM PST
- Where
- Lake Isabella forecast zone
- Measured
- 53 kt (61 mph) measured gust
- Reported by
- RAWS
The Squirrel Valley Lynch Canyon RAWS measured a peak wind gust of 61 mph.
High Wind, Indian Wells Valley
- When
- May 19, 3:26 AM PST
- Where
- Indian Wells Valley forecast zone
- Measured
- 58 kt (67 mph) measured gust
- Reported by
- RAWS
The Indian Wells Canyon RAWS measured a peak wind gust of 67 mph.
High Wind, Tehachapi Area
- When
- May 19, 6:27 PM PST
- Where
- Tehachapi Area forecast zone
- Measured
- 59 kt (68 mph) measured gust
- Reported by
- RAWS
The Bird Springs Pass RAWS measured a peak wind gust of 68 mph.
What these are
- Heavy Snow
- Snowfall reaching the local warning threshold without the other hazards of a winter storm.
- Flood
- Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.
- Funnel Cloud
- A rotating column of cloud extending from a thunderstorm that did not reach the ground.
- High Wind
- Sustained non-thunderstorm winds of 40 mph or more for an hour, or gusts of 58 mph or more.
After NWS Directive 10-1605, the rules offices file Storm Data by.
The same day elsewhere
- Tornado and Flash Flooding in Ohio, May 18 to 19, 2020
- Flash Flood and Flooding in Virginia, May 18 to 27, 2020
- Flash Flood and Flooding in Michigan, May 18 to 22, 2020
- Flooding in Michigan, May 18, 2020
- Lakeshore Flood in Michigan, May 18 to 19, 2020
- Flash Flood and Flooding in Florida, May 18, 2020
- Flash Flooding and Flooding in Kentucky, May 18 to 20, 2020
- Flash Flood and Flooding in Ohio, May 18 to 21, 2020
- Flash Flooding and Flood in Kentucky, May 18 to 19, 2020
- Flood in Missouri, May 18 to 31, 2020
- Hail and Damaging Winds in Montana, May 18 to 21, 2020
- Marine Thunderstorm Winds in Gulf of Mexico, May 18, 2020
More
Every storm in California in 2020Every state in 2020This day in weather historyWarnings in California, May 2020
Sources
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: 881927, 881928, 881930, 881935, 881936, 885466, 881920, 881923, 881919.