A surface low funneled moisture into the region and increased QPF values, and with snow levels around 3000 feet, moderate snow accumulations were likely. Winter weather advisories were posted for all Cascade Zones.
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 SEW wrote it up.
A surface low funneled moisture into the region and increased QPF values, and with snow levels around 3000 feet, moderate snow accumulations were likely. Winter weather advisories were posted for all Cascade Zones.
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 Seattle, WA wrote its last area forecast discussion before the first event at Mar 9, 8:34 PM PST, 2 hours 26 minutes earlier.
Area Forecast Discussion
National Weather Service Seattle WA
834 PM PST Thu Mar 9 2023
.SYNOPSIS...A vertically-stacked low offshore will slowly work its
way eastward through the remainder of the day, moving onshore later
tonight. Precipitation will expand in coverage through tonight with
lowland rain and mountain snow. A brief break Saturday into early
Sunday as a weak surface high moves across Oregon. A warmer frontal
system will bring another round of lowland rain and mountain snow
late Sunday into Monday followed by a weaker system Tuesday and
Tuesday night.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY/...An upper low over the Oregon
offshore waters is on track to move onshore over Western Oregon
early Friday. Moisture wrapping around the low will take its time to
get into the interior of Western Washington. Easterly cross Cascade
gradients are doing an effective job at keeping the lower levels of
the atmosphere on the drier side this evening around Puget Sound.
The easterly gradient is progged to quickly weaken after 09Z tonight
and the rain will likely begin to spread into central/north interior
soon after. After a wet morning, much of the interior lowlands
should dry out by mid-afternoon Friday into the overnight hours.
There's little in the way onshore flow behind the upper trough so a
convergence zone is unlikely to factor into the equation. Following
shifts may want to nudge PoPs downward a smidge tomorrow afternoon
and night, otherwise the forecast looks on track. Previous
discussion follows. 27
Rain continues along the coast this afternoon with the occluded
surface low still offshore. The rain has struggled to make much
progress inland north of Tacoma and Bremerton so far today thanks to
the slow progress of the low and dry air over the central and
northern Puget Sound Lowlands. Snow also continues over the Olympics
this afternoon but has yet to really get going over the Cascade
passes. The bigger news in these areas is the gusty winds this
afternoon thanks to the increasing pressure gradient between the
high to our east and the low offshore. Wind gusts should remain
below advisory levels with gusts generally from 40 to 45 mph in the
usual wind-prone areas such as North Bend. Highs today shouldn't
nudge much higher in the upper 40s to perhaps 50 for a few lowland
locations.
QPF has increased slightly with the latest forecast, so opted to
extend the Winter Weather Advisory. Expanded it through the
remainder of the Cascades for elevations over 3000 feet from 10 pm
this evening through 10 pm Friday evening. With snow having started
a little early over the Olympics and expected to continue through
the early afternoon Friday. While not the most impressive snow event
for these regions by any means, HREF guidance does suggest some
areas in the western Cascades may see snowfall exceed 6 inches in 12
hours. Some travel disruption over the passes may occur, especially
with and drifting due to the easterly gap wind in the Cascade
advisories.
Rain and snow should gradually taper off through the late morning
and especially into the afternoon Friday with lingering light snow
in the mountains. In total, 10 to 15 inches of new snow looks to
fall in the Olympics, with the higher totals on the eastern slopes
thanks to the upslope component with this system. Over the
Cascades, the higher totals look to occur over eastern Pierce and
Lewis Counties with 8 to 14 inches and slightly less from King
County northward where 5 to 10 inches may occur. Long-range
ensemble guidance is in fairly good agreement with these totals
with roughly 80% of members forecasting 5 to 10 inches of snow at
Snoqualmie and Stevens Passes.
An overall quiet day Saturday with a few lingering post-frontal and
convergence-zone showers, especially in the morning. Highs will be
closer to normal for most locations in the low 50s. Meanwhile, the
trough will begin to amplify to our west as a shortwave trough digs
southward offshore. As this trough taps in to the southern stream,
it also allows for deeper almost sub-tropical moisture to stream
northward ahead of the front. As a surface low forms along this front
Sunday, we may see rain move onshore as early as Sunday afternoon
along the coast, though some members are not this progressive in
timing of the front.
.LONG TERM /MONDAY THROUGH THURSDAY/...Heading into next week, there
is growing disagreement on how progressive the trough and associated
cold front will be. While ensemble clusters suggest the trough will
weaken with the Aleutian Low, there is disagreement on just how much
weakening will occur. Wednesday looks to be the drier day in the
extended. Highs look to trend in the low 50s into much of next week.
Davis
&&
.AVIATION...An upper low over the Offshore Waters will move to
near the mouth of the Columbia River Friday morning and then push
inland on Friday. An associated frontal system will move through
the area later tonight and Friday. Southerly flow aloft tonight
will ease and become mostly westerly on Friday. At the surface,
easterly flow will peak this evening then ease and turn more
southerly Friday morning. The air mass will be stable.
Mid clouds for most of the interior tonight. There will
be some lower ceilings near the coast and over the south interior
and west of Puget Sound in areas of rain. Low clouds into the
interior Friday morning as the front moves through with ceilings
lifting and improving a bit in the afternoon.
KSEA...Mid and high clouds tonight with easterly winds, gusty at
times this evening. Low clouds will arrive Friday morning
and winds will ease and turn more southerly. Ceilings should lift
a bit in the afternoon behind the front. 16/27
&&
.MARINE...A frontal system will move through the area tonight and
Friday. Gale force east to southeast winds over the outer Coastal
Waters should ease this evening. Otherwise, small craft advisory
strength winds for most waters tonight will ease on Friday.
There will be a brief period of onshore flow behind the
front Friday night. A low will develop well offshore over the
weekend, turning the flow easterly again. A frontal system will
move into the area Sunday night, then slowly push inland Monday
and Tuesday.
Combined seas 10 to 13 feet over the Coastal Waters tonight will
subside below 10 feet Friday. 16
&&
.HYDROLOGY...No river flooding is expected through the next seven
days, though heavy rain in the Olympics late Sunday into Monday will
bring a sharp rise on the Skokomish River to within a foot of flood
stage.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory until 4 PM PST Friday for Olympics.
Winter Weather Advisory from 10 PM this evening to 10 PM PST
Friday for West Slopes North Cascades and Passes-West
Slopes North Central Cascades and Passes.
Winter Weather Advisory until 10 PM PST Friday for West Slopes
South Central Cascades and Passes.
PZ...Small Craft Advisory until 10 AM PST Friday for Coastal Waters
From Cape Flattery To James Island Out 10 Nm-Coastal Waters
From James Island To Point Grenville Out 10 Nm-Coastal
Waters From Point Grenville To Cape Shoalwater Out 10 Nm-
West Entrance U.S. Waters Strait Of Juan De Fuca.
Gale Warning until 2 PM PST this afternoon for Central U.S.
Waters Strait Of Juan De Fuca.
Small Craft Advisory until 10 AM PST Friday for Central U.S.
Waters Strait Of Juan De Fuca.
Small Craft Advisory until 4 AM PST Friday for East Entrance
U.S. Waters Strait Of Juan De Fuca.
Small Craft Advisory from 10 PM this evening to 10 AM PST Friday
for Coastal Waters From Cape Flattery To James Island 10 To
60 Nm-Coastal Waters From James Island To Point Grenville
10 To 60 Nm-Coastal Waters From Point Grenville To Cape
Shoalwater 10 To 60 Nm-Northern Inland Waters Including The
San Juan Islands.
Small Craft Advisory from 6 PM this evening to 4 AM PST Friday
for Puget Sound and Hood Canal.
Gale Warning until 10 PM PST this evening for Coastal Waters
From Cape Flattery To James Island 10 To 60 Nm-Coastal
Waters From James Island To Point Grenville 10 To 60 Nm-
Coastal Waters From Point Grenville To Cape Shoalwater 10
To 60 Nm.
&&3 winter weather. Local standard time, as filed.
Observations depict light snow started to fall in the late evening hours of March 9th and continued through the day on March 10th, with advisory amount snow accumulations of around 5 to 7 inches through 12 hours.
Light to moderate snow started to accumulate March 10th around 3pm and continued onwards until March 11th. During this time, around 8 to 10 inches of snow fell within 12 hours, verifying the Winter Weather Advisory that was out at that time.
Observations at Snoqualmie Pass and Stevens Pass only depict minor accumulations in the Central Cascades, around 4 to 6 inches.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2023Every state in 2023This day in weather historyWarnings in Washington, March 2023
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: 1091413, 1091418, 1091421.