Weather Historic Wind Event to Hit PNW Monday through Wednesday

marsh

TB Fanatic
RogueWeather.Com

3h ·
HISTORIC WIND EVENT TO HIT PACIFIC NORTHWEST MONDAY THROUGH WEDNESDAY. THIS TYPE EVENT OCCURS "2 TO 4 TIMES" IN A 100 YEAR PERIOD

WINDS MORE TYPICALLY ASSOCIATED WITH WINTER STORM SYSTEMS WILL BE SEEN. THESE WINDS ARE LIKELY TO REACH ABOVE 50 MILES AN HOUR IN THE SOUTHERN OREGON CASCADES, AND ABOVE 70 MILES AN HOUR FOR THE CENTRAL AND NORTHERN OREGON CASCADES. RARE TO SEE IN SEPTEMBER HIGH WIND WARNINGS AND WATCHES HAVE BEEN ISSUED FOR NORTHERN AND EASTERN OREGON.

UNPRECENDENTED ISSUANCE OF RED FLAG WARNINGS FOR ALL AREAS WEST OF THE CASCADES FROM NORTHERN CALIFORNIA TO THE CANADIAN BORDER.

After much looking, I found a source that describes this coming event very well. Portland NWS has the best layout of it with the most common language in it. Even down here in Southern Oregon and Northern California, we need to be taking advance warning of this. While our winds will be lighter in the valleys, they will still meet critical fire weather criteria.

From Portland NWS -

Looking at the big picture, the longwave upper level pattern is beginning to amplify over the Pacific as a very strong upper level ridge noses north toward Alaska. This upper ridge is presently a sprawling area of 500 mb heights above 590 dam which extends from the Four Corners region northwest to Oregon, then westward into the Pacific out to about 150W. The western portion of this upper ridge had already been displaced northward as part of a Rex Block, with a dry upper low to its south in the general vicinity of 35N/135W. Further west, a vigorous upper low south of the Aleutians is becoming part of an amplifying upper trough as jet stream energy from the Kamchatka Peninsula digs into its west side.

This amplifying pattern is something we often look for to diagnose winter arctic/modified arctic high pressure systems digging down through western Canada and into the Interior Northwest. These systems are often responsible for our winter cold east wind events, with strong high pressure establishing east of the Cascades and driving strong east winds through the Columbia Gorge and occasionally downslope winds spilling over the Cascade Crest if the cold pool is deep enough. Well, it appears the atmosphere hasn`t looked at the calendar because models show excellent agreement that this overall setup will occur Monday and Tuesday, resulting in a potentially historic East Wind event. "September Arctic" high pressure squares off against a very strong inverted pressure trough along the coast, which is strengthening as exceptionally hot weather over California expands northward.

This is probably about as close to a continental-style "clash of the air masses" as we can get, especially in early September. And models have been very consistent the past 48 hours in saying the battle ground between these two air masses will set up right over our forecast area as both air masses advance on one another. Pressure and thermal gradients will intensify to levels more typical of a December or January arctic air mass banking up against the east slopes of the Cascades, with the 06z NAM/GFS maintaining an astounding 22 to 26 mb pressure gradient between Spokane and North Bend late Mon night/early Tue morning. If anything, these forecasted MSLP gradients have strengthened a bit over the past 24 hours. In addition to the pressure gradients, there will be an extremely strong east-west thermal gradient packed against the Cascades, with 06z NAM 850 mb temps around +5 deg C near The Dalles to near +19 deg C at Detroit Lake.

The end result is an early September weather pattern that probably occurs in this magnitude only 2-4 times a century. Compared to 1979-2009 climatology, 00z NAEFS and EPS ensemble means suggest this offshore wind event is literally off the charts for this time of year, and by many measures. As mentioned above, the 00z ensemble mean easterly wind component of both models are in the neighborhood of 7 to 8 standardized anomalies for this time of year (late Aug-mid Sept). With all this in mind, east to northeast winds Monday night and Tuesday will be exceptional for this time of year. This comes after a prolonged period of drying of fuels, save the exception of Saturday`s brief switch to onshore flow.

There are many concerns regarding this event; chief among them is the extreme fire danger that results from desiccating offshore winds of near record strength for late summer. Since this AFD is already ridiculously long and late, I won`t get into the weeds regarding specifics except for one: Just after midnight Monday night, the 06z NAM continues to show two rather broad maxima of 70-80 kt east winds extending down to 900 mb over the western portions of the Columbia Gorge, across much of the PDX metro area, and again along the northern Oregon Coast. These magnitudes would be worth of a high-end east wind event any time of year. Plus, mixing Tuesday will be more efficient than in winter due to the stronger early September sun.

So... here`s what we are going to do for now: We will be issuing a High Wind Watch for elevations above 2000 feet in the S WA/N OR Cascades, and above 1000 feet in the adjacent foothills. The North Oregon Coast and Coast Range will also be getting High Wind Watch for elevations above 1000 feet, where terrain will be most exposed to the strong winds. The Greater Portland and Vancouver metro area will be getting a Wind Advisory. Timing for all zones will be 8 PM Monday to 1 PM Tuesday. Winds should back off a bit Tuesday afternoon as diurnal heating weakens cold pool high pressure over the Columbia Basin.

This is all in addition to the numerous Fire Weather highlights we have. We will be extending the Red Flag Warning which begins at noon Monday out to Wednesday evening for all zones. Given these historic and threatening fire weather conditions, it is imperative to be EXTREMELY careful with fire leading up to and during this wind event, as any existing fires will very likely spread quickly once these strong winds set in. Please visit your local fire agency`s webpage for actions you can take to help mitigate the threat of fast-spreading fire in your area.
Not to be lost in all this talk of wind are the exceptionally hot temperatures expected along portions of the Oregon Coast due to this extreme offshore wind event. Areas Tillamook southward will likely reach the 90s during this event, and it isn`t out of the question that a location or two along Oregon`s central coast reaches the triple digits. Meanwhile, usually-warmer Hood River will be enjoying much cooler temperatures in the 70s and 80s. Exceptional weather pattern, indeed."

Exceptional.......good way to term this. And, what else would we expect from 2020 now?
 

Double_A

TB Fanatic
They've put out Alerts for these winds as far south as the SF Bay Area Hills
& Mountains. NOT GOOD! We still have smoldering fires in several areas and these are dry winds.
 

naturallysweet

Has No Life - Lives on TB
We had an early warm up followed by a rainy period. This caused lots of extra brush growth. Then months of no rain.

People need to be careful and not even think hot thoughts outside .
 

Babs

Veteran Member
We had terrible winds today. It picked up our grill and tossed it into the landscaping off of our porch, and all our wicked porch furniture was in the yard. We are still without power and phone, due to downed power poles etc...in the highest fire danger time of the year. Horrible fire ranging to the south of us with evacuation orders now, and I am told there is a fire on a ridge about a mile from us. Scary day.
 

parsonswife

Senior Member
Town of Talent looks like a war zone. Winds gave died down, Alot calmer. But still surrounded on 3 sides with different fires. Happy Camp, Cave Junction, Eagle Point and Phoenix. As long as the wind stay down we will all make it. Northern Oregon is bad too.
 
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