A long fetch off the coast of northern California provided the moisture for a significant snow storm which dumped from six inches up to nearly a foot of snow across Eastern Oregon.
Every event with a place to put it; 1 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 BOI wrote it up.
A long fetch off the coast of northern California provided the moisture for a significant snow storm which dumped from six inches up to nearly a foot of snow across Eastern Oregon.
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 Boise, ID wrote its last area forecast discussion before the first event at Nov 13, 3:21 AM MST, 6 hours 39 minutes earlier.
Area Forecast Discussion
National Weather Service Boise ID
321 AM MST Fri Nov 13 2020
.SHORT TERM...Today through Sunday night...Leading edge of
precipitation associated with storm system moved inland off the
Pacific overnight and is approaching eastern Oregon early this
morning. The precip will start off as snow at all elevations as it
spreads into southeast Oregon early this morning and southwest
Idaho by late morning/early afternoon. Little or no snow
accumulations are expected in most of the valleys before changing
to rain by early-mid afternoon, except for areas north of a
Burns-Ontario line...including Baker County. Locations from
Burns-Ontario could receive around an inch of snow, with 1-3
inches along the Ontario-Baker City interstate corridor. The
heaviest snow is still expected to occur late this morning through
this evening in the higher elevations of central Idaho where
Winter Storm Warnings and Winter Weather Advisories are in effect.
Strong low-mid level flow will also lead to very windy conditions
across southern areas, including Harney County, Malheur County,
Owyhee County, and Southern Twin Falls County where a Wind
Advisory is in effect from late this morning through this evening.
It will also be breezy in central Idaho resulting in
blowing/drifting snow. The precipitation will transition to
showers tonight in an unstable post-frontal regime along with the
passage of an upper trough. Additional snow accumulations are
expected in the higher elevations of central Idaho.
Another moist Pacific system will move into the area late Saturday
and continue through Sunday. This system will not be as potent as
the current one but the mountains could see moderate snow totals
on the order of 3 to 6 inches with locally higher amounts. Snow
levels will be near valley floors Saturday night before rising to
around 5500 feet on Sunday with little snow accumulation expected.
.LONG TERM...Monday through Friday...A ridge will build over the
Intermountain West into the beginning of next week, allowing
temperatures to increase roughly 5 to 8 degrees above normal on
Monday and Tuesday. An upper low will cross the region later on
Tuesday, spreading precipitation across the area through Thursday
and returning temperatures to near-normal. Snow levels will remain
fairly high as the system moves through, hovering between
5000-7000 ft MSL. Models are hinting at another incoming system
sometime next weekend, but the GFS is bringing moisture inland
faster than other models. A slight chance remains in the forecast
for Friday but confidence remains low.
&&
.AVIATION...Mostly VFR this morning. Showers entering from the
west this morning causing MVFR to localized LIFR conditions
starting near KBNO/KBKE/KBNO and becoming widespread across the
region by mid-day. Mountains obscured. Snow levels: at valley
floors this morning, rising above 4000 ft MSL in the afternoon and
dropping back to valley floors overnight Saturday. Surface winds:
generally S to SE 5- 15 kts increasing this afternoon to 10-20
kts, except 20-30 kts with gusts up to 40 kts across SE Oregon and
the Southwest Highlands/Owyhees of Idaho. Low level wind shear
possible this evening. Winds aloft near 10kft MSL: southwest 30-50
kts, becoming west 45 to 65 kts after 13/21z.
.Weekend Outlook...Conditions gradually improving from the west
Friday night, with precipitation ending in the valleys by
Saturday morning but continuing over the higher elevations.
Precipitation becoming widespread Saturday night and continuing
through Sunday morning, then decreasing to isolated showers at
lower elevations Sunday afternoon. Snow levels 2k-4k feet MSL,
rising to 4k-5k feet MSL Sunday afternoon.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Warning until 5 AM MST Saturday IDZ011-013.
Wind Advisory from 11 AM this morning to 7 PM MST this evening
IDZ015-029-030.
Winter Weather Advisory until 5 AM MST Saturday IDZ028-033.
OR...Wind Advisory from 11 AM MST /10 AM PST/ this morning to 7 PM
MST /6 PM PST/ this evening ORZ061-063.
Winter Weather Advisory until 4 AM PST Saturday ORZ062.
&&
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SHORT TERM...BW
LONG TERM....AL
AVIATION.....ALThe national radar mosaic for the moment the first event began.
1 heavy snow. Local standard time, as filed.
The COOP observer at Halfway reported 6 inches of new snow and the public reported 10 inches at Sumpter.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2020Every state in 2020This day in weather historyWarnings in Oregon, November 2020
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: 932877.