A closed upper low brought showers and thunderstorms to Southern California on May 10-11. 50 inch of rain, and some mountain areas received up to an inch of rain.
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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 SGX wrote it up.
A closed upper low brought showers and thunderstorms to Southern California on May 10-11. Coastal areas received 0.10-0.25 inch of rain, valley areas received up to 0.50 inch of rain, and some mountain areas received up to an inch of rain. Thunderstorms were observed across valley and mountain areas. Flash flooding was reported in the Coachella Valley. A rock slide was reported on I-8 near Jacumba. Rocks were approximately the size of basketballs. Penny sized hail was reported in Apple Valley.
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 May 10, 8:30 AM PST, 2 hours 30 minutes earlier.
Area Forecast Discussion National Weather Service San Diego CA 930 AM PDT Fri May 10 2019 .SYNOPSIS... A deep marine layer will continue to bring widespread low clouds from the coast to the mountain crests through Saturday. A slow moving low pressure system will bring scattered showers and a slight chance of thunderstorms through Saturday and possibly into Sunday with Saturday the most likely time for more widespread rainfall. Dry and warmer weather will return Monday and Tuesday except for some low clouds near the coast during the nights and mornings, then another low pressure system late Wednesday and Thursday could bring more clouds, cooling, gusty winds in the mountains and deserts, and a chance of precipitation. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Mostly cloudy conditions prevailed across the region due to the 5500 foot deep marine layer combined with moisture moving up from the south due to the upper level low pressure system. Some showers were occurring, mostly in San Bernardino County and coastal areas of San Diego County. The upper low is currently along the central coast of California, and some lightning occurred a few hours ago in a dynamically favorable area of northern Ventura County and Kern County. That upper low should move almost straight south today, with southwest to south flow prevailing here today. Instability will be somewhat modest, but shower activity will still be favorable over most of the area this afternoon and evening, with mostly light precipitation amounts, less than one-quarter inch. The upper low will shift east Saturday and move into northern Baja California, about 200 miles south of San Diego. This is a farther south track than the models showed Thursday, though we will still be in favorable moisture under the east flow on the north side of the low. Models show generally 400-800 J/kg CAPE Saturday, which should result in showers and a few thunderstorms given the approximately 1 inch of precipitable water. While around a 20-knot mid-level wind from the east should keep the activity moving, if there is training of cells, there could be local flooding due to a longer duration of heavier rainfall. Any flooding that occurs should be fairly isolated. See the hydrology section for projected precipitation amounts, which are slightly lower than those from Wednesday or Thursday. Some moisture and instability remain Sunday as the upper low shifts east, but shower/thunderstorm chances due decrease versus Saturday. Despite the east to northeast flow aloft around the upper low, little or now east or northeast flow will occur at the surface as the MSLP gradient will remain onshore. The marine layer stratus should decrease some Saturday/Saturday night due to the cooling aloft from the upper low, though it should increase again near the coast by Sunday night, which is typical of warming aloft at this time of year. Daytime temperatures will be lowest today and Saturday, partly due to the cloud cover, but warming should begin Sunday, with slightly above normal temperatures Monday and Tuesday under the ridge which follows the upper low. Another system could bring more clouds, cooling and possible precipitation the second half of next week. && .AVIATION... 101525Z...Coasts/Valleys...Variable bases between 2000-4000 feet MSL with tops to 6500 feet, cloud bases expected to lift to 3000 FT MSL and above in most places after 18Z. Areas of -DZ/-SHRA are possible throughout the day today, with chances of SCT -SHRA across the entire region increasing after 01Z. Vis reduced 2-5SM and cigs reduced to 700 feet MSL in precip. Areas of lower cigs 2000-3000 feet redeveloping after 01Z in the coastal basin. Mountains/Deserts...Cumulus clouds developing at around 8000 feet in desert locations. TSRA possible over SBD mountains and high desert between 20-07Z with cloud bases/tops around 8000/30000 feet. Terrain will be obscured at elevations between cloud bases and tops expected. && .MARINE... There is a chance of thunderstorms Saturday afternoon and evening. Otherwise, no hazardous marine weather is expected through Tuesday. && .HYDROLOGY... Upper level low pressure is still expected to be centered near Point Conception late this afternoon. The difference in the forecast from 24 hours ago is it now forecast to track a little farther to the south before moving inland across northern Baja Saturday night, and then move inland a little faster, moving across northern Mexico on Sunday and Monday into the Texas Big Bend on late Monday. The impact of this track change on southwest California is to limit the potential for heavier rainfall mainly to Saturday, and to shift the areas more likely to receive more widespread showers and thunderstorms on Saturday toward the south with more impact on San Diego County and less for the high desert. As the upper low moves east, there is still a chance of showers and thunderstorms on Sunday afternoon and early evening for the mountains, inland valleys, and deserts. Forecast rainfall through Sunday evening is as follows... Mountains.....0.50 to 1 inch, locally to 1.5 inch. Valleys.......0.25 to 0.50 inch. Coast.........0.15 to 0.35 inch. High desert...0.35 to 0.65 inch. Low desert....less than one third inch. The rainfall on Saturday is expected to be sufficient to cause some urban and small stream flooding, with isolated flash flooding possible if thunderstorms or stronger showers track across the same area. Isolated rainfall of one half inch or more per hour is possible Saturday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. Skywarn activation may be needed on Saturday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && PUBLIC/HYDROLOGY...Maxwell AVIATION/MARINE...CO
The Santa Ana Mts radar (KSOX), 123 km away, was scanning. The volume nearest the first event began at 18:57 UTC.
1 flash flood, 1 debris flow, 1 hail. Local standard time, as filed.
Newspaper reported flooding on Dillion Road at Thousand Palms Canyon Road in Sky Valley.
CalTrans reported a rock slide on I-8 near Jacumba. Rocks were approximately the size of basketballs.
Spotter reported penny sized hail near town hall in Apple Valley.
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, May 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: 830646, 830639, 830641.