A strong cold front moved south across Washington and Oregon on September 7th, 2020 producing strong northerly winds. These winds kicked up dust and reduced visibility to 1/4 mile at times.
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 PDT wrote it up.
A strong cold front moved south across Washington and Oregon on September 7th, 2020 producing strong northerly winds. These winds kicked up dust and reduced visibility to 1/4 mile at times.
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 Pendleton, OR wrote its last area forecast discussion before the first event at Sep 7, 9:50 AM PST, 40 minutes earlier.
Area Forecast Discussion
National Weather Service Pendleton OR
1050 AM PDT Mon Sep 7 2020
Updated Aviation Discussion
SHORT TERM...Cold front approaching from the north. Satellite
indicates the front is moving through northeast Washington and
northern Idaho this morning. Winds in vicinity of the front are
increasing. Large fire near Omak producing significant smoke which
is spreading into the Columbia basin. This will likely continue
possibly spreading into central Oregon by afternoon. Northerly
winds will be increasing today becoming 20-40 mph with gusts to
50 mph possible. Expect blowing dust to develop over the northern
Columbia basin and spread south by afternoon. Could have significant
reductions in visibility. May extend the wind and dust advisories
further south in Oregon. Otherwise the front will bring partly
cloudy skies. Much cooler tonight with lows in the 30s and 40s.
Winds will be decreasing. 94
AVIATION...18Z TAFs. VFR conditions with periodic degradation to
MVFR or IFR conditions will occur through the period. Today, winds
will increase ahead and behind a cold front that is currently
crossing eastern WA right now. Winds will increase to 20-30kts at
all sites, with gusts up to 35kts possible. Strong winds will also
produce areas of BLDU across portions of our CWA, mainly PSC/PDT.
Smoke from regional fires upstream may also impact vsby at times,
and create few-bkn layers 5kft to 10kft AGL. Winds will lighten
overnight to 10-15kts. Lawhorn/82
PREV DISCUSSION... /issued 437 AM PDT Mon Sep 7 2020/
SYNOPSIS...Much anticipated early season front is on track to
bring high winds and extreme fire weather conditions to much of
the region today. Winds to be a nuisance to Labor Day plans to
possibly damaging in isolated areas. Fire danger will be extensive
today before focusing toward Gorge and east Cascade slopes
Tuesday.
SHORT TERM...Overnight satellite has been impressive as WV
imagery and high cirrus reveal structure of the upper level trough
digging into N Idaho/NW Montana while extensive lower cloud deck
to east of this area and sfc temps show colder airmass taking
hold along US/Canada border. Winds are already gusty in Kittitas
Valley/I-90 corridor and to north of CWA owing in part due to
synergy between downsloping winds from WA Cascades and a response
to the system dropping southward. Lionshead fire near Mt
Jefferson is our current local smoke producer, but upper level
winds have already turned northward with OR DEQ shifting air
quality guidance with changing winds.
Today and tonight...Winds will not delay today as gradients
tighten this morning and dry airmass readily mixes winds down as
PBL lifts with daylight. Guidance for winds still shows some
variability with some statistical guidance terribly weak given
setup and GFS op as the high end outlier. Have used stat blends as
starting point and pushed toward GFS guidance as GEG to PDX
gradients remain concerning. Endpoint brings current forecast
within envelop of Euro ensemble and HREF guidance. Timing for
winds will be in morning and through afternoon for WA Basin and
foothills, near midday and through evening for OR Basin, and mid
to late afternoon into night for US-97 corridor and the Gorge. OR
Cascade Crest to peak in late evening or possibly even overnight.
Highest gusts in region will likely be on ridgelines in eastern
Kittitas/Yakima Counties and NW of Tri Cities where gusts about
60mph are likely. In the more populated valleys, expecting several
hours of sustained 35mph/gust 50mph winds. For now, have not
expanded or upgraded wind highlights but this is still possible should
first mixing down of winds at sunrise indicate reality will be on
high end of guidance. Other than gusty conditions, max temps
expected to be in 80s lower elevations/near 70 mtns with dry
surface conditions. Tonight, winds will continue their race to the
sea, with central Oregon remaining breezy to gusty much of the
evening. High Cascade ridges will be downright windy.
Tuesday and Tuesday night...Tuesday morning will be cold in
elevated valleys and eastern regions closer to the core of cold
airmass (Blue Mtn crest eastward). Examples of cold spots will be
mid 20s Tue morn at Seneca, the Wallowa Valley inc Joseph and
Enterprise, and possibly a few degs warmer, near freezing, at
Ukiah, Meacham, and Tollgate. Some uncertainty here as lingering
winds or clouds could prevent the forecast cooling but most model
guidance suggests excellent radiational cooling will allow these
cold temps to prevail. During day Tuesday, focus will be on the
Columbia Gorge and Oregon Cascade region as winds sharply
downslope and accelerate down west Cascade slopes. Anticipating
east side upslope flow to be weaker than on west side, but still
forecasting wide N-S oriented swath of sus20-25mph winds on east
slopes with much higher winds along crest and ridges and a
critically dry airmass in place... as such, fire highlights
continue through Tuesday. Winds will be much more reasonable
outside of Gorge and Cascades on Tuesday though some breeziness
remains. High temps into the 70s lower elevations/60s mtns before
coming back down in dry airmass Tue night/Wed morn.
LONG TERM...Wednesday through Sunday...Models are in good agreement
in showing an impressive upper level ridge over the eastern Pacific
Wednesday. The upper high slowly moves to southern OR/northern CA
by late Friday. This will result in continued dry, northerly flow
through the work week. By the weekend, models begin to diverge in
their handling of the break down/flattening of the ridge as an upper
level low begins to make it's way closer to the Pacific Northwest.
GFS shows the low approaching the Oregon coast early next week
before diving southward to northern CA while the ECMWF lifts it
northeastward into Washington. At this time, will continue the dry
forecast through the period. Daytime highs will remain above
normal. Earle
FIRE WEATHER...Today, humidity will be seasonably dry with min
RHs 12-20 pct in lower elevations up to mid elevation slopes.
Some model guidance has suggested minRH today might be a bit above
this 12-20 pct number as cold air moves in but thinking is well-mixed
surface layer and encroaching bone dry airmass aloft will still
promote a drying trend through the day. From fire perspective,
winds today will be extreme as they race through mid-Columbia late
morning, lower Columbia by afternoon, and over the Cascade Crest
overnight with extensive red flag warnings in place into the night
tonight. Expect cold temperatures Tuesday morning and cool to
cold temps Wednesday morning, especially in areas from Blue Mtns
eastward. Tuesdays fire weather: surface min humidity may be at
its lowest yet this season in the Oregon Cascades as incoming
airmass fully takes hold, even as max temps are depressed. Min RHs
will range from single digits along US-20 east of Bend to maybe a
meager 20 pct on highest peaks and ridges of OR Cascades. Winds
will still be high over Cascade crest Tuesday morning. On the mid-
elevation slopes, Tuesday's sun will bring mixing and renewed
gustiness. Intersection of these winds and critical RHs means red
flag warnings will be maintained for Gorge and OR east slopes
until Tuesday evening. Break in winds but continued dry conditions
expected in mid-week period.
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 78 41 73 39 / 0 0 0 0
ALW 78 43 74 43 / 0 0 0 0
PSC 81 46 76 41 / 0 0 0 0
YKM 81 44 74 43 / 0 0 0 0
HRI 82 43 76 38 / 0 0 0 0
ELN 76 43 71 43 / 0 0 0 0
RDM 83 35 75 32 / 0 0 0 0
LGD 75 36 69 36 / 0 0 0 0
GCD 80 35 72 38 / 0 0 0 0
DLS 85 49 78 45 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning until 11 PM PDT Tuesday for ORZ610-611-639.
Red Flag Warning until 11 PM PDT this evening for ORZ640>642.
Blowing Dust Advisory until 8 PM PDT this evening for ORZ044.
Wind Advisory until 8 PM PDT this evening for ORZ044.
WA...Red Flag Warning until 11 PM PDT Tuesday for WAZ639-681.
Red Flag Warning until 11 PM PDT this evening for WAZ641-675.
Blowing Dust Advisory until 8 PM PDT this evening for WAZ026>028.
Wind Advisory until 8 PM PDT this evening for WAZ026>028.
&&
SHORT TERM...94
AVIATION...82The national radar mosaic for the moment the first event began.
1 dust storm. Local standard time, as filed.
Pendleton ASOS (KPDT) reported a visibility of 1/4 mile or less due to blowing dust and smoke. Visibilities were low for much of the day into the early evening.
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, September 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: 909172.