AgWeatherNet Weekly Weather Outlook Monday Update for November 9 to November 15, 2020

A series of systems to keep weather active with more cold and snow expected

Craig Oswald, AgWeatherNet Field Meteorologist

Synopsis:

A series of modest disturbances are expected to pass through the Pacific Northwest this week with two robust low pressure systems likely by weeks end and the weekend. This will keep weather active through the period with temperatures generally remaining much cooler than average. Snow is expected at pass levels through the period with snow levels lowering to as low as 2000 feet or slightly less through the northern half of the state and around 2500 feet through the southern half of the state (east of the Cascades) during the night.

Discussion:

The first disturbance expected tonight (Monday night) will begin moving into the state form the west/northwest. This is primarily thanks to an upper trough moving into the region from the northwest along the Pacific coast. Widespread mountain snow and low land rain showers are expected throughout western Washington. East of the Cascades, northern and far eastern Washington will see mountain snow and lowland rain/snow showers. The Columbia Basin and south central Washington to see mostly scattered precipitation, especially toward the south with more consistent precipitation northward, that looks to be mostly rain with some rain/snow mix along higher elevation ridgelines. Additionally, an upper disturbance is anticipated to move across the state from the north along the upstream potion of the trough axis after the passage of the leading edge of this feature. The main thing to expect from this is a continuation of precipitation through the day Tuesday and into Tuesday night before trending dry for Wednesday. Breezy conditions can also be expected statewide. It is likely that areas in the western part of the state and the southeast corner of the state will cling to a few scattered showers through the day Wednesday. Precipitation type will trend toward rain during the day in lowland areas with snow levels rising several hundred feet during the day Tuesday. Liquid equivalent totals from this event look to be around 0.25 to 0.5 inches for low land western Washington while approaching an inch for some spots along the coast. The Cascades will likely be between 1.5 to 2 inches through the high mountains. East of the Cascades, northern Washington looks to be between 0 and 0.15 inches toward the west and 0.25 to 0.5 inches near the Idaho border with higher totals in upland areas. South Central and eastern Washington are expected to be between 0 and 0.15 inches total, but again with higher totals to the east where locations along the Idaho border are expected to reach near 0.5 inches with some spots in the southeast corner of the state reaching closer to 0.75 inches.

Aside from a few lingering scattered showers in certain parts of the state, as mentioned during the day Wednesday, Wednesday and Wednesday night are expected to be mostly dry state wide.

After Wednesdays brief reprieve, weather is again to turn quite active Thursday. It appears that a precursor shortwave will move through the Pacific Northwest early Thursday before a robust low pressure system tied to a strong jet stream arrives Friday afternoon from the west. Thursday’s event will see a renewed surge of widespread and light precipitation throughout the state with more scattered type precipitation throughout the Columbia Basin. Overnight and daytime snow levels look to remain near where they had been for the event early in the week. Conditions are expected to briefly trend dry Friday morning for much of eastern Washington aside from high elevation areas that will likely cling to a few light snow showers. Western Washington will also have lingering and scattered low land rain and mountain snow showers through the day Friday. With a significant low pressure system impacting the southern coast of British Columbia sometime Friday afternoon/evening, widespread, consistent, and moderate rain/snow showers are expected through the state Friday night and into Saturday morning. Along with this, conditions are expected to be quite windy Friday night through Saturday as strong surface gradients will be present, in conjunction with the robust low pressure center anticipated to traverse west to east along the U.S./Canadian border. Wind gusts in excess of 55 mph are possible throughout the Columbia Basin and Palouse with quite gusty conditions in many other regions. Conditions look to slowly trend dry through the day Saturday along with rising snow levels as a short lived ridge moves across the Pacific Northwest, bringing modestly warmer surface and upper air temperatures. Washington east of the Cascades looks to be fully dry by Saturday night, aside from a few lingering snow showers over the high terrain of the Blue Mountains and the northeast corner of the state. Western Washington and the Cascades/Olympics are expected to cling to scattered rain and snow showers respectively into Sunday with more activity through high terrain. Liquid equivalent precipitation totals between Thursday’s event and Friday’s low pressure system are estimated to be as follows. Around 1 to 2 inches for low land western Washington with possibly greater totals to the south, with around 3 inches for some spots along the coast. The Cascades will likely receive around 3 inches as well through the high mountains. East of the Cascades, northern Washington looks to be between 0.5 and 1 inches with totals closer to 1 to 1.5 inches in upland areas. South Central and eastern Washington are expected to be between 0.15 and 0.5 inches with totals between 1 and 1.5 inches in the Blue Mountains as well. The majority of these estimated totals are anticipated to accumulate with Friday’s event.

Sunday looks to see another strong surface low pressure system impact southern British Columbia as a long wave trough moves in from the west, displacing the modest upper ridge to the east. This will bring more widespread precipitation and windy conditions. More detail will be provided in Fridays outlook, but be aware that another round of widespread lowland rain and mountain snow are likely


Important Points About This Week's Weather

South Central Washington
Remainder of the week
  • Wind: S/SW and breezy. Becoming W and light Wed. S and light Thu. Breezier Fri and becoming windy Fri night with some gusts 40+ mph.
  • Precipitation: A few scattered rain/upland snow showers beginning Mon night. Trending mostly to rain Tue, and back to rain/upland snow Tue night before trending dry for Wed. Return of scattered rain/upland snow showers Thu night. Trending dry Fri. Widespread rain/upland snow Fri evening through Fri night.
  • High Temps: Near 50 Tue, upper 40s Wed, mid 40s Thu, upper 40s Fri.
  • Low Temps: Low 30s Mon night, near 30 Tue night, near 30 Wed night, low 30s Thu night.
  • Sky Cover: Partly cloudy to mostly cloudy Tue. Becoming mostly sunny Wed before trending back to mostly cloudy for Thu. Remaining mostly cloudy through Fri.

Weekend
  • Wind: S/SW Sat and windy. Some gusts 55+ mph. Trending lighter through Sat night, S and light to breezy by Sun.
  • Precipitation: Precipitation slowly trending dry through Sat. More widespread rain/upland snow to arrive Sun night.
  • High Temps: Low 50s Sat, low 50s Sun.
  • Low Temps: Mid 30s Fri night, mid 30s Sat night, low 30s Sun night.
  • Sky Cover: Partly cloudy to mostly cloudy.

North Central Washington
Remainder of the week
  • Wind: S/SW and light to breezy. Becoming W/NW and light Wed. S yet variable and light Thu. Breezier Fri and becoming windy Fri night with some gusts 40+ mph throughout the Basin.
  • Precipitation: Rain/snow showers beginning Mon night with greater chances for snow north. Trending more toward rain Tue, and back toward snow Tue night before trending dry for Wed. Return of rain/snow showers Thu night. Trending dry Fri with upland snow showers lingering near the Cascade crest and far eastern part of the region. Widespread rain/snow Fri evening through Fri night.
  • High Temps: Mid 40s Tue, mid 40s Wed, near 40 Thu, mid 40s Fri. Cooler in high terrain.
  • Low Temps: Mid 20s Mon night, mid 20s Tue night, low 20s Wed night, upper 20s Thu night. Cooler in high terrain.
  • Sky Cover: Partly cloudy to mostly cloudy Tue. Becoming mostly sunny Wed before trending back to mostly cloudy/cloudy for Thu. Remaining mostly cloudy/cloudy through Fri.

Weekend
  • Wind: S/SW Sat and windy. Some gusts 55+ mph possible throughout the Basin. Trending lighter through Sat night, S and light to breezy by Sun.
  • Precipitation: Precipitation slowly trending dry through Sat with a few snow showers likely to linger near the Cascade crest and upland areas along the eastern part of the region. More widespread rain/snow to arrive Sun night.
  • High Temps: Mid 40s Sat, mid 40s Sun. Cooler in high terrain.
  • Low Temps: Near 30 Fri night, upper 20s Sat night, upper 20s Sun night. Cooler in high terrain.
  • Sky Cover: Mostly cloudy to cloudy.

Eastern Washington
Remainder of the week
  • Wind: S/SW and breezy. Becoming W and light Wed. S and light Thu. Breezier Fri and becoming windy Fri night with some gusts 40+ mph.
  • Precipitation: Rain/snow showers beginning Mon night. Trending mostly to rain Tue, and back to rain/snow Tue night before trending dry for Wed with the chance for a stray shower or two to the south. Return of rain/snow showers Thu night. Trending dry Fri. Widespread rain/snow Fri evening through Fri night.
  • High Temps: Upper 30s Tue, upper 30s Wed, upper 30s Thu, low 40s Fri. Cooler through the Blue Mtns.
  • Low Temps: Low 20s Mon night, mid 20s Tue night, low 20s Wed night, mid 20s Thu night. Cooler through the Blue Mtns.
  • Sky Cover: Mostly cloudy Tue. Becoming partly cloudy Wed before trending back to mostly cloudy/cloudy for Thu. Remaining mostly cloudy/cloudy through Fri.

Weekend
  • Wind: S/SW Sat and windy. Some gusts 55+ mph. Trending lighter through Sat night, S and light to breezy by Sun.
  • Precipitation: Precipitation slowly trending dry through Sat with a few snow showers likely to linger over the Blue Mtns. More widespread rain/snow to arrive Sun night.
  • High Temps: Mid 40s Sat, low 40s Sun. Cooler through the Blue Mtns.
  • Low Temps: Low 30s Fri night, near 30 Sat night, upper 20s Sun night. Cooler through the Blue Mtns.
  • Sky Cover: Mostly cloudy to cloudy.

Western Washington
Remainder of the week
  • Wind: S and breezy. Trending W/SW and light by Wed. S/SE and light Thu. S and breezier Fri and becoming windy Fri night with some gusts 40+ mph near the coast.
  • Precipitation: Rain/mountain snow showers beginning Mon night. Trending mostly dry for Wed with a few showers lingering, especially through the mountains. Return of rain/mountain snow showers Thu. Trending more scattered in nature Fri. Resurgence of widespread rain/mountain snow Fri afternoon through Fri night.
  • High Temps: Upper 40s Tue, upper 40s Wed, upper 40s Thu, upper 40s Fri. Cooler through the Cascades and Olympics.
  • Low Temps: Low 40s Mon night, upper 30s Tue night, upper 30s Wed night, low 40s Thu night. Cooler through the Cascades and Olympics.
  • Sky Cover: Mostly cloudy Tue. Becoming partly cloudy Wed before trending back to mostly cloudy/cloudy for Thu. Remaining mostly cloudy/cloudy through Fri.

Weekend
  • Wind: W/SW Sat and windy. Some gusts 55+ mph near the coast and through the straight. Trending lighter through Sat night, S and light to breezy by Sun.
  • Precipitation: Precipitation slowly trending more scattered in nature through Sat with more consistent activity remaining through the mountains. More widespread rain/mountain snow to arrive Sun.
  • High Temps: Near 50 Sat, near 50 Sun.
  • Low Temps: Low 40s Fri night, low 40s Sat night, near 40 Sun night. Cooler through the Cascades and Olympics.
  • Sky Cover: Mostly cloudy to cloudy.

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