A frontal system brought heavy snow to the Cascades from Snoqualmie Pass northward, with snowfall totals of 12 to 20 inches. Snoqualmie Pass (I-90) was closed in both directions for several hours due to snow and avalanche risk, stranding motorists (including children in ski buses).
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 frontal system brought heavy snow to the Cascades from Snoqualmie Pass northward, with snowfall totals of 12 to 20 inches. Snoqualmie Pass (I-90) was closed in both directions for several hours due to snow and avalanche risk, stranding motorists (including children in ski buses).
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 6, 9:25 PM PST, 4 hours 35 minutes earlier.
Area Forecast Discussion
National Weather Service Seattle WA
925 PM PST Mon Mar 6 2017
.SYNOPSIS...A series of low pressure systems will keep the weather
pattern over the area wet and unsettled this week. Temperatures are
expected to remain below normal for this time of the year.
&&
.SHORT TERM...Current radar shows scattered showers over portions of
W WA this evening with a convergence zone over central Snohomish
County and light echoes over the Cascades indicating continued
snowfall. Temperatures around the area generally at or above
freezing with dewpoints right around or just below that same
mark...resulting in varying forms of precip for locations that
happen to see one of these scattered showers. Obs from PAE shows
precip in convergence zone mostly light snow...but with ground
temperatures there still fairly warm...not too terribly worried
about accumulation there. Radar trends show CZ thinning and moving
northward...so will be worthwhile to monitor obs out of AWO. That
being said however...temps there bumped up 2 degrees in past
hour...so may just end up being liquid or mixed there...should
anything happen at all. Lastly...with snowfall continuing over the
Cascades at the time of this writing...will leave inherited winter
weather headlines for the Cascade zones alone.
Looking at short term...those hoping for spring need to do so harder
because current efforts are not working...as evidenced by above
discussion of mixed precip and snow. A combination of moist zonal
upper level flow with an embedded shortwave disturbance and an
approaching surface low from off the coastal waters will bring
another round of precip to the area Tuesday with the potential for
another round of heavy snowfall in the Cascades. General trend of
snow levels rising in the daytime then falling at night will also
look to continue as 1000-850 mb heights look to fall below 1300m yet
again overnight Tue and into early Wed AM. Thankfully...models
progging that precip will be winding down during that time frame but
the risk for mixed precip or occasional flakes of that other four
letter s-word may still be present. Not much difference in forecast
high temps for Tue and Wed although some very gradual warming is
possible starting Thu. Even with that...temps still look to be below
climo. Wed and Thu progs look to have precip more scattered...but
still present as active pattern continues.
Inherited forecast is on track. No evening updates required at this
time. SMR
.LONG TERM...from previous discussion...Confidence in this period
was low due to inconsistencies in the models and disagreements
between the models. Decided to compromise between the GFS and ECMWF
solutions with a nudge towards persistence.
There may or may not be a significant wind event late Thursday
night and/or Friday. Also, snow levels may or may not rise to 4000
feet (or higher) the end of this week.
Overall, anticipate wet and unsettled conditions along with below
normal temperatures during this period.
&&
.AVIATION...W flow aloft will continue through 12Z with areas of
showers still offshore heading inland across the area. Conditions
are predominantly good VFR, often with SCT clouds or CIGS above
10000 feet. However, CIGS drop all the way down to MVFR around
BKN020 around shower activity. This should continue through 12Z. A
warm front just W of the Oregon coast at 05Z will spread rain up
over W WA after 12Z. Cigs will lower down to MVFR as the -RA spreads
north with MVFR CIGS over central Puget Sound by 14Z. The rain will
continue into Tuesday evening.
KSEA...Good VFR conditions through 12Z. Showers around the area
could drop CIGS briefly down to around BKN020. Warm front rain
should spread N over the area by 14Z with CIGS dropping down to MVFR
BKN-OVC025, then BKN-OVC015 by 18Z. Surface winds will remain
southerly around 10 KT. Kam
&&
.MARINE...S to SE flow will increase tonight as a warm front
approaches the region from the SW. SCA winds are expected over the
coastal waters and over north interior in the E entrance and N
inland waters. The warm front will move inland across W WA Tuesday
afternoon. An associated 1006 MB surface low approaching from the W
will move inland across SW WA Tuesday afternoon. Onshore flow will
increase behind the low with gale force winds possible in the Strait
of Juan de Fuca Tuesday night. The ARW-west indicates potential gale
winds. The 18Z Canadian meso model remains below gale except for a
tiny area for one hour. The GFS and NAM UIL-BLI gradient Tuesday
night is 3.6 to 3.9 MB which certainly grabs the attention. A weak
surface ridge builds over W WA Wednesday so winds should diminish
quickly. The ridge hangs around through Thursday.
The 00z GFS and 12z ECMWF are in poor agreement for Thursday night
and Friday. The GFS shows a 998 MB low crossing Cape Flattery 12Z
Friday. The ECMWF has a broader 1013 MB low crossing W WA 06z
Friday. Sigh. Kam
&&
.HYDROLOGY...
River flooding is not expected the next 7 days.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory until midnight PST tonight for Cascades
of Pierce and Lewis Counties-Cascades of Snohomish and King
Counties-Cascades of Whatcom and Skagit Counties.
Winter Storm Watch from 6 AM PST Tuesday through Tuesday
afternoon for Cascades of Pierce and Lewis Counties.
PZ...Small Craft Advisory until 4 AM PST Tuesday for Coastal Waters
From Cape Flattery To James Island 10 To 60 Nm-Coastal
Waters From Cape Flattery To James Island Out 10 Nm-Coastal
Waters From James Island To Point Grenville 10 To 60 Nm-
Coastal Waters From James Island To Point Grenville Out 10
Nm-Coastal Waters From Point Grenville To Cape Shoalwater
10 To 60 Nm-Coastal Waters From Point Grenville To Cape
Shoalwater Out 10 Nm.
Gale Watch from Tuesday evening through Wednesday morning for
Central U.S. Waters Strait Of Juan De Fuca-East Entrance
U.S. Waters Strait Of Juan De Fuca.
Small Craft Advisory from 1 AM to 4 PM PST Tuesday for East
Entrance U.S. Waters Strait Of Juan De Fuca-Northern Inland
Waters Including The San Juan Islands.
Small Craft Advisory until 10 PM PST this evening for Puget
Sound and Hood Canal.
&&
www.weather.gov/seattle
You can see an illustrated version of this discussion at
www.weather.gov/seattle/gafd/latest_webafd.html2 heavy snow. Local standard time, as filed.
Mt Baker NWAC station reported 20 inches snow during 24 hours ending 2 am Mar 8.
Stevens Pass NWAC station reported 11 inches snow during warning period. Alpental and Snoqualmie Pass NWAC stations both reported 13 inches snow during warning period. The snowfall and avalanche risk closed I-90 in both directions, trapping many motorists (including children in ski buses).
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Washington in 2017Every state in 2017This day in weather historyWarnings in Washington, March 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: 677909, 677910.