AgWeatherNet Weekly Outlook for October 30 to November 05, 2020

A dry weekend followed by unsettled conditions throughout next week

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

Synopsis:

A cold front crossing Washington Friday is bringing scattered showers to mountain regions and part of the west side of the state as well as gusty winds in the lee of the Cascades. Both the precipitation and the wind are expected to taper off Friday evening as the front and associated shortwave trough progress eastward into the Northern Rockies. A ridge builds over the region to dominate conditions Saturday through Monday, bringing mainly dry conditions statewide and possible inversion conditions for basins and valleys east of the Cascades. By Tuesday, zonal flow replaces the ridge. These westerlies should bring moisture from the Pacific across the state, resulting in showers in the mountains and west of the Cascades, with breezy conditions resuming east of the Cascades for the remainder of the forecast period.

Discussion:

A shortwave trough and associated cold front crossed Washington on Friday, bringing some rain showers and to Western Washington and breezy conditions to Eastern Washington with gusts over 40 mph in spots, and with the strongest being observed on the Palouse. Rain showers should be finished by sunset. Breezy conditions will linger into the evening, diminishing as the atmosphere stabilizes following sunset.

Behind the trough, a strengthening ridge will move into the Pacific Northwest. Overall, dry conditions are expected under the ridge for the weekend. Temperatures west of the Cascades will be near average Saturday, rising to around five degrees above average by Monday. A temperature inversion is expected to build in the Columbia Basin and adjacent valleys under the ridge, keeping temperatures a few degrees below average in that region with warmer conditions on the Palouse and around Spokane. On top of the cooler temperatures, hazy conditions, and comparatively high surface pressure. With a forecasted sea level pressure difference of approximately 5 mb between KHRI (Hermiston) and KPDX (Portland) by Sunday afternoon, breezy easterlies should develop in the west end of the Columbia Gorge as well as other spots on the western fringe of the Cascades.

A transition to zonal flow is anticipated, bringing wet weather into Western Washington and the mountains as early as Monday night with the ridge moving eastward. Widespread rain in those areas is expected Tuesday and Wednesday with showers possible Thursday. Most of the lowlands in Eastern Washington will remain dry through Wednesday except a stray shower or two near the Idaho border, but breezy conditions in association with this pattern are possible. Temperatures will remain steady during this period in Western Washington, but the breezy conditions east of the Cascades should mix out the inversion and produce temperatures around 10 degrees above average for Wednesday.

An upper level disturbance is projected to drop into the Pacific Northwest toward the end of the week, bringing a chance of showers for everyone in Washington Thursday and a drop in temperatures. Models are indicating that this disturbance is likely to linger over the Western United States through the following weekend. This could bring some unsettled weather and below average temperatures, though those looking for specifics on precipitation timing, location, and snow levels will have to wait for Mondays outlook.


8 to 14 Day Outlook, October 23 to October 29, 2020
  • Below average temperatures and near average precipitation are favored for the period.

Important Points About Next Week’s Weather

South Central Washington
Weekend
  • Wind: W Fri and breezy with gusts to 35 mph. Light and variable Sat & Sun.
  • Precipitation: Dry conditions expected.
  • High Temps: Mid 50s Sat & Sun.
  • Low Temps: Low 30s Fri-Sun nights.
  • Sky Cover: Partly to mostly cloudy. Patchy fog.
Next Week
  • Wind: Light and variable Mon & Tue. S/SW Wed & Thu with breezy conditions possible.
  • Precipitation: A chance of rain Thu, otherwise dry.
  • High Temps: Mid 50s Mon, near 60 Tue, mid 60s Wed, near 60 Thu.
  • Low Temps: Mid 30s Mon night, mid 40s Tue & Wed night, near 40 Thu night.
  • Sky Cover: Clear to partly cloudy Mon, mostly cloudy Tue-Thu.

North Central Washington
Weekend
  • Wind: W/NW and breezy Fri with gusts to 40 mph. Light and variable Sat & Sun.
  • Precipitation: Dry conditions expected.
  • High Temps: Mid 50s Sat, upper 50s Sun. Cooler in higher terrain.
  • Low Temps: Low 30s Fri & Sat night, mid 30s Sun night. Cooler in higher terrain.
  • Sky Cover: Clear to partly cloudy. Patchy fog.
Next Week
  • Wind: Light and variable Mon & Tue. S/SW Wed & Thu with breezy conditions possible.
  • Precipitation: Rain showers possible Tue-Thu, mainly in the mountains.
  • High Temps: Near 60 Mon, upper 50s Tue, near 60 Wed, mid 50s Thu. Cooler in higher terrain.
  • Low Temps: Near 40 Mon night, mid 40s Tue & Wed night, low 40s Thu night. Cooler in higher terrain.
  • Sky Cover: Partly cloudy Mon, mostly cloudy to overcast Tue-Thu.

Eastern Washington
Weekend
  • Wind: W and breezy Fri with gusts to 40 mph. Light and variable Sat & Sun.
  • Precipitation: Dry conditions expected.
  • High Temps: Near 50 Sat, mid 50s Sun. Warmer in the Lewis & Clark Valley.
  • Low Temps: Near 30 Fri & Sat night, low 30s Sun night. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Clear to partly cloudy. Patchy fog.
Next Week
  • Wind: Light and variable Mon & Tue. S/SW Wed & Thu with breezy conditions possible.
  • Precipitation: Stray rain shower possible Tue night-Thu.
  • High Temps: Mid 50s Mon-Wed, low 50s Thu. Warmer in the Lewis & Clark Valley.
  • Low Temps: Mid 30s Mon night, mid 40s Tue night, near 40 Wed night, upper 30s Thu night. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Clear to partly cloudy Mon, mostly cloudy to overcast Tue-Thu.

Western Washington
Weekend
  • Wind: W Fri, breezy through the Strait. Light & variable Sat, E and locally breezy Sun.
  • Precipitation: Showers tapering off Fri, otherwise dry.
  • High Temps: Mid 50s Sat, upper 50s Sat. Cooler in higher terrain.
  • Low Temps: Mid 40s Fri-Sun nights.
  • Sky Cover: Partly to mostly cloudy. Patchy fog.
Next Week
  • Wind: S/SW through the week. Breezy Wed.
  • Precipitation: Rain showers beginning Mon night, widespread rain Tue & Wed, rain showers Thu.
  • High Temps: Near 60 Mon, upper 50s Tue-Wed, mid 50s Thu.
  • Low Temps: Near 50 Mon night, low 50s Tue night, upper 40s Wed night, mid 40s Thu night.
  • Sky Cover: Increasing clouds Mon, mostly cloudy to overcast Tue-Thu.

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