A low pressure system moved through Southern California March 20th and 21st and brought heavy rain, thunderstorms, and mountain snow to the area. The heaviest rainfall and snowfall occurred on the 20th, with just light showers on the 21st.
Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. 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 SGX wrote it up.
A low pressure system moved through Southern California March 20th and 21st and brought heavy rain, thunderstorms, and mountain snow to the area. The heaviest rainfall and snowfall occurred on the 20th, with just light showers on the 21st. Rainfall totals of 0.25 to 0.50 inch fell in the coastal areas (particularly San Diego County coastline), and up to an inch of rain fell in the valley and mountain areas. Snowfall amounts ranged from 1-4 inches above 5500 feet. Small hail and lightning occurred in thunderstorms on the 20th. Urban street flooding occurred in Orange County and at the Holy Fire Burn Scar. Rainfall rates of 0.70/hr occurred at the burn scar.
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 San Diego, CA wrote its last area forecast discussion before the first event at Mar 20, 7:59 AM PST, 1 minute earlier.
Area Forecast Discussion
National Weather Service San Diego CA
859 AM PDT Wed Mar 20 2019
.SYNOPSIS...
Through Thursday night, a low pressure system will move slowly
inland across California and northern Baja bringing periods of
showers along with a slight chance of thunderstorms for this
afternoon and early evening. The most widespread precipitation is
expected into this evening. Friday will be dry and a little
warmer, then a low pressure system will create a chance of mostly
light showers on Saturday. Sunday through Tuesday will be dry
with a warming trend. Spring begins this afternoon at 2:58 PM.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
At 8 AM, water vapor satellite showed an upper-level trough along
the West Coast, and an upper-level ridge stretching from New
Mexico into Montana. Radar displayed light showers across the
coastal basin. The first wave from the associated trough will move
across the area this afternoon, with showers spreading across the
region late morning through this evening. An unstable atmosphere
aloft will create the possibility of isolated thunderstorms this
afternoon and evening. A second shortwave will move across the
region Thursday morning, creating another round of more
widespread showers Thursday afternoon and evening.
Through Thursday evening, rainfall will range from 0.10-0.25
inches for the coast and valleys, with up to 0.50 inches possible
in the San Diego County valleys, and 0.50-0.75 inches in the
mountains with locally greater amounts in San Bernardino County
mountains. Rainfall in the deserts will mostly be less than 0.10
inch. The snow level will be mostly around 5500 feet with a few
inches of snowfall between 5500 and 6500 feet with 3 to 6 inches
of snowfall above 6500 feet and up to 10 inches on the highest
peaks. A Winter Weather Advisory remains in effect for the San
Bernardino and Riverside County mountains from 5 pm this afternoon
through 8 PM Thursday.
The trough will also create cooler and breezy weather across the
area, with highs 10 to 20 degrees below normal by Thursday and
west to southwest wind gusts of 40-50 mph across portions of the
mountains an deserts.
Dry, but still cooler weather will develop on Friday, then a
trough moving by to our north will create the possibility of light
showers and breezy westerly winds over the mountains and deserts
Saturday. Snow levels will be mostly above 6000, with just a
tenth or two of accumulations expected.
High pressure aloft will strengthen over the western states for
Sunday through Tuesday as a large, slowly moving closed upper
level low pressure system develops over the eastern Pacific. For
southwest California, this will create dry weather and a warming
trend for Sunday through Tuesday with high temperatures above
average for Monday and Tuesday. Precipitation could return around
Wednesday of next week.
&&
.AVIATION...
201500Z...Coasts/Valleys...BKN low clouds with bases around 1800-
2500 FT MSL becoming more widespread this morning into the
afternoon. Periods of -SHRA, most likely during late morning/early
afternoon. -TSRA possible along immediate coast including
KSAN/KCRQ/KSNA 19-03Z, with low-moderate confidence. Vis may be
locally reduced to 3-5 SM in heavier showers, obscuring some coastal
slopes. Showers subsiding at TAF sites overnight, with variable SCT-
BKN skies persisting through the period.
Mountains/Deserts...SCT -SHRA in mountains through sunrise tomorrow
with low clouds obscuring slopes. West SFC winds 15-20 kts gusting
to 30-40 kts over mountain crests, desert mountain slopes, and
through the passes into this evening. MOD UDDFTS likely over and
east of the mtns at times. -SHRA unlikely to make it to KPSP/KTRM,
with BKN high clouds AOA 10000 FT MSL and variable SCT clouds near
4000 FT in the deserts.
.MARINE...
A weak storm will bring west winds gusting 15-20 kt and higher seas,
along with showers through Thursday. Isolated thunderstorms are
possible this afternoon and evening. Otherwise, no hazardous marine
weather is expected through Sunday.
&&
.BEACHES...
A new long period west swell will build today, generating high surf
at the beaches this afternoon through Friday morning, with sets
reaching up to 8 FT in favorable locations in San Diego County.
Highest surf will be Thursday in southern San Diego County, with
marginal high surf in Orange County. Swell and surf will gradually
subside late Friday, with large swell rebuilding over the weekend,
potentially bringing another round of high surf.
With the possibility of a thunderstorm making it onshore, isolated
lightning is possible at the beaches this afternoon, though
confidence is low.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Winter Weather Advisory from 5 PM this afternoon to 8 PM PDT
Thursday for Riverside County Mountains-San Bernardino
County Mountains.
High Surf Advisory from 1 PM this afternoon to 1 PM PDT Friday
for Orange County Coastal Areas-San Diego County Coastal
Areas.
PZ...NONE.
&&
PUBLIC...JJT
AVIATION/MARINE/BEACHES...RodriguezThe Santa Ana Mts radar (KSOX), 20 km away, was scanning. The volume nearest the first event began at 23:02 UTC.
3 winter weather, 2 high surf, 2 hail, 1 debris flow, 1 heavy rain. Local standard time, as filed.
In Orange County, lifeguards reported widespread 6 ft surf on the coast.
In San Diego County, lifeguards reported widespread 6 ft surf along the coast.
Spotters reported 1-2 inches storm total snow in Idyllwild between March 20th and 21st.
A CoCoRaHS observer reported 1.5 inches of snow at Lake Arrowhead, and another CoCoRaHS observer reported 1.2 inches of snow near Big Bear Lake.
Spotter reported dime-sized hail in Yorba Linda around 1500 PST on March 20th.
Spotter reported 4 inches of snow at Snow Valley (7800 ft elevation).
CalTrans reported roadway flooding and debris in the road on Grand Ave and Blackwell Blvd.
CalTrans reported accidents on Highway 241 northbound due to hail on the road.
Rainfall rates of 0.71/hr were reported at Temescal Canyon, which is the highest hourly rainfall rate of the winter season for that canyon. In 30 minutes, 0.59 fell over Temescal Canyon. Lanes were flooded and debris was on the roadway on Temescal Canyon Road near the intersection on I-15.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2019Every state in 2019This day in weather historyWarnings in California, March 2019
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: 814905, 814906, 814902, 814903, 814899, 814907, 814901, 814908, 814900.