AgWeatherNet Weekly Weather Outlook Monday Update for November 16 to November 22, 2020

A warm Tuesday followed by cooling temperatures with chances for precipitation throughout

Craig Oswald, AgWeatherNet Field Meteorologist

Synopsis:

Weather conditions look to remain mostly dreary and breezy through the week with continued opportunity for precipitation, mostly light and scattered. Tuesday will be the warmest day with temperatures several degrees above normal statewide before cooling to near or a few degrees below normal.

Discussion:

Current rain showers and mountain snow showers are expected to continue to move through the state from the southwest as a warm front continues to move across the region from south to north. Snow levels will keep rising as the day progresses as warmer air continues to inundate the state from the south. Winds will remain light to breezy, with much windier conditions throughout the eastern Washington region however.

The state will briefly trend dry Monday night from south to north as the passage of the warm front places the region into the warm sector of a surface cyclone situated off the Oregon/Washington coast. Skies will remain mostly cloudy and this period of dry weather will be short lived. As the surface cyclone continues to deepen and track north/northeast along the coast, windy conditions and showers associated with a strengthening surface pressure gradient and broad cold front respectively are expected for Tuesday. Showers look to move into the state from the west/southwest beginning Tuesday morning along with windy south/southwest winds. Snow levels are again expected to lower to near 3500-4000 feet by Wednesday as colder air slowly moves in behind the frontal passage. Snow levels will generally remain around these levels for the week, trending slightly lower throughout northern Washington, approximately 3000 feet or a little less. Washington east of the Cascades is expected to briefly trend dry Wednesday night while generally scattered showers look to remain throughout western Washington.

With an environment not lacking in moisture and containing more instability thanks to cooler air aloft, a weak upper disturbance anticipated to pass through the state from the southwest Wednesday will be enough to stir up another round of scattered showers/more consistent rainfall across the state. Conditions east of the Cascades look to trend mostly dry through Wednesday night with scattered showers remaining throughout western Washington. A similar weak disturbance will also pass Thursday, bringing similar weather conditions.

Yet another shortwave, this time ejected from a closed low over the Bering Sea, looks to bring a resurgence of scattered rain showers by Friday night to western Washington. The weak and zonal trajectory of this feature within the mean flow will likely leave Washington east of the Cascades mostly dry aside for some showers near the Idaho border. This series of upper disturbances will also work to keep skies mostly cloudy to cloudy and winds generally light to breezy.

From Tuesday morning through Saturday morning, it is anticipated that liquid water equivalent precipitation totals from the week will be around 1.5 inches for lowland western Washington, 2.5 inches for coastal areas, and 3+ for the Olympics and Cascades. South central Washington and the Columbia Basin will mostly be between 0.1 and 0.25 inches, lowland northern Washington between 0.25 and 0.5 inches with more toward the east, and 0.75 to 1.5 inches in the mountains, again with more to the east. Eastern Washington will generally see between 0.25 and 0.5 inches with some locales receiving slightly more, especially north toward Spokane.

What appear to be remnant showers from a cold front associated with a strong surface cyclone over the southern shore of Alaska look to impact the state from the northwest Saturday night and linger through much of Sunday. Scattered showers and areas of more consistent rainfall can be expected for the state with the Columbia Basin and south central Washington to see scattered showers.

A strong surface cyclone is expected to move into central British Columbia Sunday night. This system will bring much windier conditions and light to moderate rainfall to western Washington with scattered rain showers and light widespread rainfall in store for Washington east of the Cascades.


Important Points About This Week's Weather

South Central Washington
Remainder of the week
  • Wind: Generally S/SW and breezy through the week beginning Tue afternoon. Windy at times as well.
  • Precipitation: Scattered rain showers Tue with a continued chance for scattered showers through most of the week between brief dry periods. Mostly dry conditions expected for Fri.
  • High Temps: Mid 50s Tue, mid 50s Wed, low 50s Thu, upper 40s Fri.
  • Low Temps: Upper 30s Mon night, mid 30s Tue night, mid 30s Wed night, near 30 Thu night.
  • Sky Cover: Cloudy to mostly cloudy. Trending to partly cloudy Wed and remaining so through the week.

Weekend
  • Wind: S/SW and light to breezy.
  • Precipitation: Mostly dry Sat. Scattered rain showers Sun.
  • High Temps: Mid 40s Sat, mid 40s Sun.
  • Low Temps: Upper 20s Fri night, upper 20s Sat night, near 30 Sun night.
  • Sky Cover: Partly cloudy and becoming mostly cloudy/cloudy by Sun.

North Central Washington
Remainder of the week
  • Wind: Generally S and breezy through the week beginning Tue afternoon. Windy at times as well, mostly throughout the Basin.
  • Precipitation: Lowland rain showers and mountain snow showers beginning Tue with continued showers and scattered showers through most of the week between very brief dry periods. Mostly dry Fri. Greater activity and lingering showers to the east.
  • High Temps: Upper 40s Tue, upper 40s Wed, mid 40s Thu, low 40s Fri. Cooler in high terrain.
  • Low Temps: Mid 30s Mon night, mid 30s Tue night, low 30s Wed night, upper 20s Thu night. Cooler in high terrain.
  • Sky Cover: Cloudy to mostly cloudy. Becoming partly cloudy to mostly cloudy Fri.

Weekend
  • Wind: Generally S and light to breezy. Breezier throughout the Basin.
  • Precipitation: Mostly dry Sat. Rain showers and mountain snow showers Sun. Greater activity and lingering showers to the east.
  • High Temps: Near 40 Sat, near 40 Sun. Cooler in high terrain.
  • Low Temps: Upper 20s Fri night, upper 20s Sat night, upper 20s Sun night. Cooler in high terrain.
  • Sky Cover: Partly cloudy and becoming mostly cloudy/cloudy by Sun.

Eastern Washington
Remainder of the week
  • Wind: Generally S/SW and breezy through the week beginning Tue afternoon. Windy at times as well, especially near the Blue Mtns Tue with some gusts 55+ mph.
  • Precipitation: Lowland rain showers beginning Tue. Continued showers and scattered showers through most of the week, becoming rain/snow mix after Wed, between very brief dry periods. Mostly dry Fri. Greater activity along the Idaho border and north.
  • High Temps: Low 50s Tue, upper 40s Wed, mid 40s Thu, low 40s Fri. Cooler through the Blue Mtns.
  • Low Temps: Near 40 Mon night, near 40 Tue night, mid 30s Wed night, near 30 Thu night. Cooler through the Blue Mtns.
  • Sky Cover: Cloudy to mostly cloudy. Becoming partly cloudy Fri.

Weekend
  • Wind: S/SW and light to breezy.
  • Precipitation: Mostly dry Sat. Rain and snow showers Sun.
  • High Temps: Upper 30s Sat, upper 30s Sun. Cooler through the Blue Mtns.
  • Low Temps: Upper 20s Fri night, upper 20s Sat night, upper 20s Sun night. Cooler through the Blue Mtns.
  • Sky Cover: Partly cloudy and becoming mostly cloudy/cloudy by Sun.

Western Washington
Remainder of the week
  • Wind: Generally S and breezy through the week beginning Tue afternoon. Windy at times as well, especially near the coast and sound Tue with gusts 55+ mph along the coast in particular.
  • Precipitation: Scattered rain showers and more consistent rainfall at times through the week. Mountain snow expected.
  • High Temps: Mid 50s Tue, upper 40s Wed, upper 40s Thu, upper 40s Fri. Cooler through the Cascades and Olympics.
  • Low Temps: Mid 40s Mon night, low 40s Tue night, upper 30s Wed night, mid 30s Thu night. Cooler through the Cascades and Olympics.
  • Sky Cover: Mostly cloudy to cloudy. Becoming partly cloudy Fri.

Weekend
  • Wind: Generally S and light to breezy. Breezier near the coast and sound.
  • Precipitation: Scattered rain showers and more consistent rainfall at times through the weekend. Mountain snow expected.
  • High Temps: Upper 40s Sat, upper 40s Sun.
  • Low Temps: Mid 30s Fri night, mid 30s Sat night, upper 30s Sun night. Cooler through the Cascades and Olympics.
  • Sky Cover: Partly cloudy and becoming mostly cloudy/cloudy by Sun.

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Washington State University