A potent late season storm system brought widespread rainfall to the region. Locations in Sonoma County received over 4 inches of rain in 24 hours.
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 MTR wrote it up.
A potent late season storm system brought widespread rainfall to the region. Locations in Sonoma County received over 4 inches of rain in 24 hours. The system caused some minor roadway flooding as well as wind damage from falling trees.
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 Francisco Bay Area, CA wrote its last area forecast discussion before the first event at May 15, 4:03 PM PST, 4 hours 17 minutes earlier.
Area Forecast Discussion
National Weather Service San Francisco Bay Area
503 PM PDT Wed May 15 2019
.SYNOPSIS...Unsettled weather conditions will persist through the
first half of Thursday resulting in widespread rainfall and the
potential for thunderstorms. After a break break Thursday night into
Friday, another storm system will move through the region Saturday
into early Sunday morning. Wet and unsettled conditions may
potentially continue into next week as well.
&&
.DISCUSSION...as of 02:18 PM PDT Wednesday...Much of the region
is getting a brief break from precipitation after widespread
rainfall moved inland earlier in the day. Rainfall amounts range
from a few hundredths of an inch for most areas outside of the
North Bay and Santa Cruz Mountains where totals are in the 0.25"
to 0.75" range. Meanwhile, Santa Rosa has picked up 0.50" in the
past 12 hours with more than 1.00" in one of the region's wetter
locations, Venado. The next band of precipitation can be seen
offshore and is beginning to approach the North Bay at this hour.
Rain will spread inland and steward throughout the afternoon as a
cold front approaches the coast. This band will likely produce
moderate to locally heavy rainfall, especially over the North Bay
and along the coastal ranges where isentropic lift will be best.
It is just ahead of and along this frontal boundary when breezy to
locally gusty winds will develop as well. Additional rainfall of
0.25" to 0.50" can be expected for many locations with locally
higher amounts in the aforementioned favorable locations.
Meanwhile, inland valley locations will likely be rain shadowed
and see lesser amounts as typical with winter-like systems.
In wake of the frontal passage late this evening, lingering showers
will be possible with the potential for a few thunderstorms. Another
renewed chance of showers and thunderstorms are expected late in the
night into early Thursday morning as the core of the mid/upper level
low pushes inland over northern California. The main focus for
precipitation on Thursday will be over the North Bay, yet there will
be plenty of low level moisture and support for isolated to
scattered rain showers over much of the region. Weather conditions
begin to dry out by Thursday night as the system shifts inland.
Dry conditions are likely for much of the region on Friday as weak
short-wave ridge develops in wake of the exiting system. The region
may even see a few breaks in the cloud cover along with slightly
warmer daytime temperatures. However, unsettled conditions quickly
return on Saturday as another mid/upper level trough approaches the
West Coast. Another modest plume of moisture will advect inland and
result in widespread rainfall Saturday into Saturday night before
the core of the upper level system shifts inland on Sunday. Rainfall
from this system will be less than the current one, yet still
impressive for this time of year. Cannot rule out an additional
0.10" to 0.50" for most urban areas with amounts of 0.50" to 1.00"
in the North Bay and along the coastal ranges. Lingering showers
will potentially continue into Sunday, at least for the first half
of the day. Those with travel or outdoor plans this weekend should
be aware of the unsettled weather conditions.
Drier weather looks to return late Sunday into Monday. However,
ensembles maintain unsettled conditions into next week with a zonal
flow early in the week and a deepening trough along the West Coast
late in the forecast period. Given low confidence in details beyond
this weekend's weather, folks are urged to stay up to date with the
latest forecast information.
&&
.AVIATION...as of 5:03 PM PDT Wednesday...An upper level trough
and surface low pressure system will bring widespread rain showers
and gusty southerly winds tonight along with low level wind shear
(LLWS) into early this evening. Latest guidance and models show
winds at 2000 ft peaking between 35-45 kt until 06z with lighter
winds at the surface. LLWS is mainly unidirectional shear although
some directional shear will be possible, particularly at
KSNS/KSJC this evening, as the front moves through. SE winds will
continue ahead of the front and transition to SW/W late this
evening behind the front. Winds will be breezy with localized
gusts around 30 kt possible. Strongest winds still expected around
the time of the frontal passage late this afternoon through this
evening. Guidance still supports timing of the frontal passage
between 04z-06z. Rain/showers mainly light but brief periods of
moderate to heavy rainfall will be possible, during which time
conditions may be reduced to MVFR/IFR. Latest HRRR/WRF models show
a line of heavier precipitation moving through between around
00z-06z. Current cigs range from 2,000 to around 4,500 ft AGL with
the exception of locally lower IFR cigs at KSTS. Generally expect
borderline VFR/MVFR cigs to prevail with FEW-SCT cigs around
1,500 to 3,000 ft. Cigs/vis may lower during heavier showers.
Showers will begin to dissipate tonight and become more widely
scattered and less frequent overnight, but models show another
round of more widespread showers around sunrise tomorrow along
with the potential for thunderstorms.
Vicinity of KSFO...Borderline VFR/MVFR cigs 3,000 to 5,000 ft with
SCT cigs currently at 2,000 ft. Gusty S/SE winds to develop over
the next few hours. Hi res models show heavier precipitation
arriving around 00z-01z and lasting through around 05z-06z. During
this time lower cigs and reduced vis will be possible. LLWS will
be a potential hazard into early this evening with winds at 2000
ft between 30-45 kt. These winds may occasionally mix down to the
surface bringing infrequent gusts around 35 kt to the surface.
Anticipate winds shifting to more SW between 04z-06z tonight.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...Borderline MVFR/VFR. SE winds with
showers through much of the period. Hi-res models show heavier
precip late this afternoon and through the early evening. Gusty
SE winds early this evening, particularly at KSNS with LLWS a
concern. Winds to shift more SW between 04z-06z.
&&
.MARINE...as of 4:47 PM PDT Wednesday...Expect gusty southerly
winds this afternoon and evening across the coastal waters as a
frontal boundary gets set to move through. Gale force gusts will
be possible along the coast and over much of the outer waters
through early tonight. Winds will turn more westerly tomorrow as
the system moves through. These strong winds will bring steep
fresh swell from the south/southwest today and west tomorrow
creating hazardous seas condition, especially for smaller vessels.
Isolated thunderstorms will also be possible with this system
starting late tonight.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...GLW...Mry Bay until 9 PM
GLW...Pt Arena to Pt Reyes 0-10 nm until 9 PM
GLW...Pt Reyes to Pigeon Pt 0-10 nm until 9 PM
GLW...Pigeon Pt to Pt Pinos 0-10 nm until 9 PM
GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm until 9 PM
GLW...Pt Arena to Pigeon Pt 10-60 nm until 9 PM
GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 9 PM
SCA...SF Bay until 2 AM
&&
PUBLIC FORECAST: RGass
AVIATION: AS/Canepa
MARINE: AS
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www.youtube.com/nwsbayareaThe national radar mosaic for the moment the first event began.
4 strong wind, 2 flood. Local standard time, as filed.
Roadway flooding reported at 53 San Clemente Dr, 6 to 8 inches deep and 40 feet across.
Roadway flooding on SB 280 at Saratoga Ave off ramp.
Trees down on SR 35 and Page Mill Rd.
Tree down blocking both lanes at Happy Valley Rd and Bear Creek Rd.
Two trees down blocking roadway at Trenton Rd and River Rd.
Downed tree on car in Windsor on Shira Street west of Old Redwood Hwy, exact time unknown.
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: 818684, 818685, 818689, 818690, 818691, 818692.