AgWeatherNet Weekly Outlook for January 15 to January 21, 2021

Calmer conditions expected with occasional light precipitation

Mark Ingalls, AgWeatherNet Intern
Craig Oswald, AgWeatherNet Field Meteorologist
Joe Zagrodnik, AgWeatherNet Postdoctoral Research Associate

Note: There will be no Monday outlook on January 18 in observation of Martin Luther King, Jr. Day.

Synopsis:

A weak shortwave trough is expected to bring some light precipitation to parts of the state Saturday night and into Sunday with another around Tuesday, otherwise the dominant feature through at least Wednesday looks to be a strong upper level ridge focused on the West Coast. This will keep temperatures relatively steady with calm conditions throughout Washington and a chance of inversion-type fog layers forming in typical spots of Eastern Washington. Wednesday night into Thursday things become more interesting as surface low pressure slides south from the Yukon to the Pacific Northwest to bring a return to active conditions. There is reasonable confidence in a significant cooldown coming after this forecast period. This far out, details are few, but should become clearer over the next week.

Discussion:

As the weak cold front that brought shower activity to the Pacific Northwest Thursday night and Friday continues eastward, the upper level ridge dominating the weather pattern in the Western United States will rebuild. This is expected to allow the state to dry out Saturday before another weak shortwave trough and associated weak cold front force their way through the ridge. This is expected to bring light rain and mountain snow to Western Washington, the Palouse, and mountainous regions of Washington similar to what was seen during the day Friday. Some drizzle is possible in the Columbia Basin, but folks in that area shouldn't expect much.

By Monday, another ridge is expected to build just offshore, bringing a brief period of drier and calmer conditions. Low elevation areas of Eastern Washington may see some inversion fog Monday into Tuesday, but this is expected to be limited in scope as another weak system passes over the region Tuesday. Again, light precipitation in the form of rain and mountain snow can be expected for most of the state on Tuesday except the Columbia Basin.

Wednesday looks to be relatively calm, but by that point models show a decent surface low pressure system already pushing south from the Canadian Arctic. That should clear British Columbia and arrive in the Pacific Northwest by Thursday to bring another round of precipitation. Models also indicate that this will be part of a larger pattern change with cooler temperatures and lower snow levels leading into the following weekend. As of this writing, it is too early to provide specifics except that a period of cold, arctic air and potential lowland snow seems likely as we move into the last week of January and beyond.

All of what is expected for the next week pales in comparison to what Washington experienced Monday through Wednesday. A robust atmospheric river event dropped huge amounts of rain, as recorded by AgWeatherNet as well as NOAA MADIS sites. The windward side of the Olympic Mountains as well as the southwest Washington highlands recorded between eight and ten inches of rain, with two to three inches in the Puget Sound Region and greater Portland/Vancouver area during that three day period. East of the Cascades, precipitation amounts were subdued in comparison with about a quarter inch for the Yakima area and around an inch in Spokane.

Landslides were especially problematic in the Columbia River Gorge, where both I-84 in Oregon and SR 14 in Washington were blocked at one point, requiring those traveling to or from the Portland/Vancouver area to do a sort of zig zag across the Columbia River bridges to make it to their destination.

Rain wasn't the only notable impact, however. Tuesday evening a 990mb surface low moved across the Northwest Interior bringing strong winds to much of Washington. Some aspects of this low were anticipated, but as AgWeatherNet's Joe Zagrodnik notes in a recent blog post, the scope and coverage of the wind were not well forecasted for most of the state. Wind gusts around the greater Seattle area ranged from 45 to 60 mph overnight Tuesday into early Wednesday, but a particularly strong surge sent gusts to 70 mph in parts of the Northwest Interior. This resulted in power being cut to about half a million customers.

Eastern Washington shared in the experience. Wind gusts in excess of 60 mph were observed around the Tri-Cities, north of Wenatchee, and the Spokane area even had winds reach to around 70 mph. Power was disrupted around the entire region, but east of the Cascades Spokane bore the brunt of the system.

The winds reached the Tri-Cities just after midnight and the enhanced vertical mixing caused a surge in temperatures. Kennewick recorded a temperature of 67 degrees, breaking the old daily record of 62 which was set in 1895. The 1 am report from the Tri-Cities Airport noted a temperature of 66, which ties the record warmest overnight January temperature recorded there since hourly observations started in 1973. The full force of the wind reached Spokane to start the Wednesday morning rush hour. A tree fell on a traveling motorist, tragically killing the driver. Elsewhere, local media reported a large tree limb crashing through a roof and landing on a woman's arm while she was lying in bed. She was successfully extracted by emergency crews and is expected to recover.


8 to 14 Day Outlook, January 22 to January 29, 2021
  • Below average temperatures and near average precipitation are favored for the period.

Important Points About Next Week's Weather

South Central Washington
Weekend
  • Wind: Light and variable Fri-Sat, W and breezy Sun.
  • Precipitation: Dry conditions expected.
  • High Temps: Low 40s Sat, near 50 Sun.
  • Low Temps: Near 30 Fri night, low 30s Sat & Sun nights.
  • Sky Cover: Mostly cloudy. Areas of fog.
Next Week
  • Wind: Light and variable Mon, S and breezy Tue, light and variable Wed, SW Thu.
  • Precipitation: Dry conditions expected.
  • High Temps: Mid 40s Mon-Wed, low 40s Thu.
  • Low Temps: Near 30 Mon & Tue nights, low 30s Wed & Thu nights.
  • Sky Cover: Partly cloudy Mon-Wed, mostly cloudy Thu. Areas of fog.

North Central Washington
Weekend
  • Wind: Light and variable Fri-Sat. W and breezy Sun.
  • Precipitation: Low chance of rain/snow Sat night and Sun AM.
  • High Temps: Upper 30s Sat, mid 40s Sun. Cooler in higher terrain.
  • Low Temps: Upper 20s Fri night, low 30s Sat & Sun night. Cooler in higher terrain.
  • Sky Cover: Mostly cloudy Fri-Sat, clearing Sun. Patchy fog.
Next Week
  • Wind: S and breezy Tue, primarily across the Basin. Otherwise light and variable through the week.
  • Precipitation: Chance of mountain rain/snow Tue, low chance of lowland snow Thu with higher chances in the mountains.
  • High Temps: Mid 40s Mon, Low 40s Tue-Wed, upper 30s Thu. Cooler in higher terrain.
  • Low Temps: Near 30 Mon-Thu nights. Cooler in higher terrain.
  • Sky Cover: Partly cloudy Mon, mostly cloudy Tue, partly cloudy Wed, mostly cloudy Thu. Areas of fog.

Eastern Washington
Weekend
  • Wind: Light and variable Fri-Sat. SW and breezy Sun.
  • Precipitation: Low chance of rain/snow Sat night and Sun AM.
  • High Temps: Near 40 Sat & Sun. Warmer in the Lewis & Clark Valley.
  • Low Temps: Near 30 Fri night, low 30s Sat night, upper 20s Sun night. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Mostly cloudy with areas of fog.
Next Week
  • Wind: Light and variable Mon, S and breezy Tue, light and variable Wed, SW and potentially breezy Thu.
  • Precipitation: Low chance of rain/snow Thu.
  • High Temps: Near 40 Mon-Wed, upper 30s Thu. Warmer in the Lewis & Clark Valley.
  • Low Temps: Mid 20s Mon-Thu nights. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Partly cloudy Mon, mostly cloudy Tue, partly cloudy Wed, mostly cloudy Thu. Areas of fog.

Western Washington
Weekend
  • Wind: E and light Fri night, light and variable Sat, S and light Sun.
  • Precipitation: Rain and mountain snow showers Sat night, tapering off Sun.
  • High Temps: Upper 40s Sat, near 50 Sun. Cooler in higher terrain.
  • Low Temps: Upper 30s Fri night, low 40s Sat night, near 40 Sun night. Cooler in higher terrain.
  • Sky Cover: Mostly cloudy to overcast.
Next Week
  • Wind: W and potentially breezy Tue, otherwise light and variable except on the Coast where periodically breezy conditions are expected all week.
  • Precipitation: Rain and mountain snow showers Tue and Thu.
  • High Temps: Upper 40s Mon & Tue, mid 40s Wed & Thu. Cooler in higher terrain.
  • Low Temps: Upper 30s Mon-Thu nights. Cooler in higher terrain.
  • Sky Cover: Mostly cloudy to overcast.

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