AgWeatherNet Weekly Outlook for June 11 to June 17, 2021

Atmospheric river to bring rain for the weekend, drying midweek

Mark Ingalls, AgWeatherNet Intern

Note: Starting next week, outlooks will only be issued on Mondays. This allows our team to focus more on network maintenance. Friday outlooks will resume this fall.

Synopsis:

Southwesterly flow aloft resulting from a trough to the west and ridge to the east is expected to inject warmer temperatures and increased moisture into the Pacific Northwest through the weekend. This will result in widespread rain in and west of the Cascades with periodic rain showers to the east. Afternoons in Eastern Washington are expected to warm to near 90 in places. Next week, rain and possible thunderstorm chances continue through Tuesday before the ridge moves westward to cut off the moisture flow leading to a drying trend toward the end of the forecast period.

Discussion:

An impressive atmospheric river will take aim at the Pacific Northwest as a subtropical moisture plume navigates between an upper level trough offshore and an upper level ridge over the Great Plains. This will bring a modest amount of rain to the state with fairly consistent rain in and west of the Cascades through the weekend. In Eastern Washington, rain is likely in many areas Friday night with lower chances Saturday and Sunday nights. The foothills of the Cascades and Blues may also see some showers during the afternoon hours.

Moisture isn't the only thing this flow pattern is expected to bring. In southeastern Washington where there will be limited cloud cover outside of shower activity, highs are likely to near 90 degrees for the warmest spots Sunday. Statewide, temperatures aloft will be warming. This mid and upper level warming should limit thunderstorm chances because thunderstorms are more likely to form in environments where the temperature decreases significantly with height. Still, a few rumbles of thunder may be heard near mountains.

Rain chances lower in Eastern Washington Monday but folks in and west of the Cascades can look for much of the same. As the trough axis passes over the region Tuesday temperatures aloft may cool enough to allow for scattered thunderstorms across Western Washington. This will be dependent on when showers form, however. If they form earlier, cloud cover will limit surface heating and decrease how high the clouds reach.

A few lingering showers are possible in the mountains and Western Washington Wednesday, but the trough helping provide the active conditions is expected to move toward Edmonton and beyond. This is forecast to be replaced by a ridge of high pressure with clearing skies and warmer temperatures for the western half of the state. Temperatures in Eastern Washington are likely to cool somewhat Tuesday and Wednesday before rising under the influence of the ridge on Thursday.

With the exception of the Olympic Mountains rain shadow (Sequim and the San Juan Islands), much of the Western Washington lowlands stand a chance at nearing an inch of rain over the next week. Higher amounts are possible in the Olympics and Cascades with parts of Eastern Washington lowlands looking at between a tenth and a quarter inch of rain.

The drought being experienced throughout the region won't be cured by one single weather pattern, but modest improvement is possible in southwestern Washington where moderate (D1/4) to severe (D2/4) drought is being observed. In this week's update from the National Drought Mitigation Center, extreme drought (D3/4) conditions were noted as having spread to include the Palouse, Spokane area, and southern Columbia Basin. This is unlikely to improve significantly with this week's weather pattern.


8 to 14 Day Outlook, June 18 to June 24, 2021
  • Above average temperatures and below average precipitation are favored for the period.

Important Points About Next Week's Weather

South Central Washington
Weekend
  • Wind: Light and variable Sat, E with breezy areas Sat night, NW with breezy areas Sun.
  • Precipitation: Showers likely Fri night, isolated showers Sat & Sun nights.
  • High Temps: Near 80 Sat, upper 80s Sun.
  • Low Temps: Mid 50s Fri night, near 60 Sat night, low 60s Sun night.
  • Sky Cover: Partly to mostly cloudy.
Next Week
  • Wind: Light and variable Mon, W with breezy areas Tue, windy Wed, breezy areas Thu.
  • Precipitation: Dry conditions expected.
  • High Temps: Near 90 Mon, upper 80s Tue, mid 80s Wed, low 90s Thu.
  • Low Temps: Low 60s Mon night, mid 50s Tue-Wed nights, near 60 Thu night.
  • Sky Cover: Clear to partly cloudy.

North Central Washington
Weekend
  • Wind: Light and variable Sat, E with breezy areas Sat night, NW with breezy areas Sun.
  • Precipitation: Chance of rain, higher chances in upslope areas.
  • High Temps: Near 80 Sat & Sun. Cooler in higher terrain.
  • Low Temps: Low 50s Fri night, low 60s Sat-Sun nights. Cooler in higher terrain.
  • Sky Cover: Partly cloudy Sat, mostly cloudy Sun.
Next Week
  • Wind: Light and variable Mon, W with breezy areas Tue, windy Wed, breezy areas Thu.
  • Precipitation: Chance of upslope showers Mon-Tue.
  • High Temps: Near 80 Mon, low 80s Tue-Wed, upper 80s Thu. Cooler in higher terrain.
  • Low Temps: Near 60 Mon night, mid 50s Tue-Wed nights, near 60 Thu night. Cooler in higher terrain.
  • Sky Cover: Clear to partly cloudy.

Eastern Washington
Weekend
  • Wind: Light and variable Sat, E with breezy areas Sat night, NW with breezy areas Sun.
  • Precipitation: Rain Fri night, rain showers Sat & Sun nights.
  • High Temps: Upper 70s Sat, mid 80s Sun. Warmer in the Lewis & Clark Valley.
  • Low Temps: Low 50s Fri night, mid 50s Sat night, upper 50s Sun night. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Partly to mostly cloudy.
Next Week
  • Wind: Light and variable Mon, W with breezy areas Tue, windy Wed, breezy areas Thu.
  • Precipitation: Low chance of rain showers Tue.
  • High Temps: Mid 50s Mon night, low 50s Tue night, near 50 Wed night, mid 50s Thu night. Warmer in the Lewis & Clark Valley.
  • Low Temps: Mid 50s Mon night, low 50s Tue night, near 50 Wed night, mid 50s Thu night.
  • Sky Cover: Clear to partly cloudy.

Western Washington
Weekend
  • Wind: S & breezy along the Coast and N Sound Sat, generally light and variable Sun.
  • Precipitation: Rain showers.
  • High Temps: Low 70s Sat, near 70 Sun. Cooler in higher terrain.
  • Low Temps: Mid 50s Fri night, upper 50s Sat-Sun nights. Cooler in higher terrain.
  • Sky Cover: Mostly cloudy to overcast.
Next Week
  • Wind: Light and variable Mon, SW with breezy areas Tue, S with breezy areas Wed, W with breezy areas Thu.
  • Precipitation: Rain Mon-Tue, leftover showers Wed, dry Thu.
  • High Temps: Low 70s Mon, near 70 Tue, low 70s Wed, mid 70s Thu. Cooler in higher terrain.
  • Low Temps: Mid 50s Mon-Thu nights. Cooler in higher terrain.
  • Sky Cover: Mostly cloudy Mon-Tue, partly cloudy Wed-Thu.

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