Santa Ana Winds developed over the region on the 29th of April as a surface high settled over the Great Basin. The event was of weak to moderate strength Santa Ana, but it brought low relative humidity values that combined with two months without significant rainfall to produce an elevated fire risk.
Every event with a place to put it; 3 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.
Santa Ana Winds developed over the region on the 29th of April as a surface high settled over the Great Basin. The event was of weak to moderate strength Santa Ana, but it brought low relative humidity values that combined with two months without significant rainfall to produce an elevated fire risk. Several small wildfires occurred in the Inland Empire on the 30th.
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 Apr 29, 3:24 AM PST, 1 hour 27 minutes earlier.
Area Forecast Discussion
National Weather Service San Diego CA
424 AM PDT Sat Apr 29 2017
.SYNOPSIS...
Surface high pressure over the Great Basin will bring strong
gusty Santa Ana winds near and along the coastal slopes of the
mountains for this morning. The offshore flow and high pressure
aloft off the California coast will bring much warmer high
temperatures for coastal and western valley areas today. Weak
onshore flow will return on Sunday with the marine layer returning
for more night and morning coastal low clouds and fog for next
week. toward the end of next week...a trough of los pressure
developing near the West Coast will bring stronger onshore flow
with greater cooling spreading inland.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
A slow moving low pressure system was over the central and
southern Rockies early this morning with high pressure aloft off
the California coast. Surface high pressure over the Great Basin
will bring strong gusty northeast winds near the coastal slopes of
the mountains and below passes and canyons. The strongest and
most widespread winds are expected after sunrise...with winds
diminishing during the late morning into the afternoon. Strongest
gusts early this morning have been to around 60 mph along the
coastal slopes of the Santa Ana Mountains.
The offshore flow combined with the high pressure aloft off the
California coast will bring much warmer high temperatures today
for coastal and western valley areas with warmest high
temperatures today of around 90 in some inland coastal areas.
High pressure aloft off the California coast will weaken some for
Sunday and Monday with weak onshore flow returning. High
temperatures near the coast will bring to cool as areas farther
inland will continue to warm.
The marine layer is expected to return late Sunday night and
Monday with cooling spreading into the valleys early next week.
Toward the end of next week...a trough of los pressure developing
near the West Coast will bring stronger onshore flow with greater
cooling spreading inland.
&&
.AVIATION...
290930Z...Northeasterly wind gusts of 35-50 kt will continue this
morning along coastal mountain slopes, through mountain passes and
into adjacent valleys. Portions of Orange County Coastal areas will
be exposed to the strong winds, as well. STG-SVR UDDFS and LLWS are
likely through the afternoon just west of the mountains. Winds will
gradually weaken through the afternoon and evening.
&&
.MARINE...
Northwest wind gusts near 20 kt will develop over the waters this
afternoon through early tonight. Otherwise, no hazardous marine
conditions are expected through Wednesday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are encouraged
to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory until noon PDT today for Riverside County
Mountains-San Diego County Mountains-San Diego County
Valleys-San Gorgonio Pass Near Banning.
High Wind Warning until noon PDT today for Orange County Coastal
Areas-Orange County Inland Areas-San Bernardino County
Mountains-San Bernardino and Riverside County Valleys-The
Inland Empire-Santa Ana Mountains and Foothills.
PZ...None.
&&
PUBLIC...17
AVIATION/MARINE...JJTThe national radar mosaic for the moment the first event began.
2 wildfire, 1 high wind. Local standard time, as filed.
The Fremont Canyon mesonet reported a peak wind gust of 70 mph, along with multiple gusts into the 60 mph range between 0051 and 0851PST.
Low relative humidity and gusty winds helped the Opera Fire begin on the 30th. The fire consumed 1350 acres east of Riverside before being fully contained on May 2nd.
The Tower Fire occurred along Interstate 15 through the Cajon Pass. Approximately 150 acres of open country were consumed before the fire was contained on May 3rd.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2017Every state in 2017This day in weather historyWarnings in California, April 2017
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: 687975, 687976, 687979.