AgWeatherNet Weekly Outlook for May 07 to May 13, 2021

Unsettled weekend followed by warming conditions next week

Mark Ingalls, AgWeatherNet Intern
Joe Boomgard-Zagrodnik, WSU Postdoctoral Research Associate

Synopsis:

An upper level trough is working it's way into the region. It is likely to park over the Northern Rockies for most of the weekend. Cool temperatures aloft and a few weak disturbances in the mean flow may allow for some shower activity in Western Washington, the Palouse, and mountain regions through Sunday evening. The trough remains stalled for the beginning of the week to keep northwesterly flow aloft, but a building ridge along the coast should help to dry out the state. A shortwave trough may transit British Columbia on Wednesday, bringing a few showers to areas north of US 2. Otherwise, look for dry conditions through the end of the forecast period.

Discussion:

Much cooler temperatures were observed for much of Washington Friday afternoon after the passage of a cold front. Shower activity is forecast to taper off statewide during the overnight hours, resuming again Saturday afternoon thanks to daytime heating and cold temperatures aloft. These showers will be mostly limited to Western Washington, the Palouse, and mountain areas. A weak disturbance Sunday afternoon should enhance shower activity in these areas.

Winds are forecast to be strongest in Eastern Washington on Friday afternoon. That said, a tight west to east pressure gradient is expected to keep elevated wind speeds in the Columbia Basin and adjacent areas through Saturday night. This will be most pronounced during the afternoon hours as daytime heating allows for vertical mixing to bring stronger winds aloft down to the surface.

For the beginning of the week, the upper level trough will be located in the lee of the Rocky Mountains, keeping northwesterly flow aloft. A ridge building just offshore should keep the region dry and initiate a slow warming trend. The trough progresses eastward into the Great Lakes region beginning Tuesday which will allow the ridge axis to come onshore and strengthen the warming trend.

Wednesday, the ridge is flattened somewhat by a shortwave trough transiting southern British Columbia. A few showers are possible north of US 2 on Wednesday, otherwise typical windy spots may see breezy conditions during the afternoon. The flattening ridge will turn upper level flow more zonal, giving the Pacific Ocean more influence over the region's weather to end the cooling trend. Aside from showers in northern areas Wednesday, dry conditions are forecast through Thursday.

Precipitation values are forecast to be fairly light in all of the disturbances that are forecast to move through. In most instances, most rain will remain in Western Washington, mountain areas, and/or the Palouse, but it is not expected to make an impactful difference to drought conditions around Washington.


8 to 14 Day Outlook, May 14 to May 20, 2021
  • Below average temperatures and above average precipitation are favored for the period.

Important Points About Next Week's Weather

South Central Washington
Weekend
  • Wind: Generally W. Breezy areas Fri & Sat.
  • Precipitation: Isolated showers Fri night.
  • High Temps: Upper 60s Sat, near 70 Sun.
  • Low Temps: Near 40 Fri night, mid 40s Sat & Sun nights.
  • Sky Cover: Partly cloudy.
Next Week
  • Wind: Generally W, breezy areas Wed.
  • Precipitation: Dry conditions expected.
  • High Temps: Mid 70s Mon, near 80 Tue, low 80s Wed & Thu.
  • Low Temps: Near 50 Mon night, low 50s Tue-Thu nights.
  • Sky Cover: Clear to partly cloudy.

North Central Washington
Weekend
  • Wind: Generally W. Breezy areas Fri & Sat.
  • Precipitation: Chance of upslope showers through the weekend.
  • High Temps: Mid 60s Sat, near 70 Sun. Cooler in higher terrain.
  • Low Temps: Near 40 Fri night, mid 40s Sat-Sun nights. Cooler in higher terrain and sheltered areas.
  • Sky Cover: Partly cloudy.
Next Week
  • Wind: Generally W, breezy areas Wed.
  • Precipitation: Chance of upslope showers Wed.
  • High Temps: Mid 70s Mon, upper 70s Tue-Thu. Cooler in higher terrain.
  • Low Temps: Mid 40s Mon night, near 50 Tue-Thu nights. Cooler in higher terrain and sheltered areas.
  • Sky Cover: Partly cloudy.

Eastern Washington
Weekend
  • Wind: Generally W. Breezy areas Fri & Sat.
  • Precipitation: Low chance of showers through the weekend. Best chance in upslope areas.
  • High Temps: Low 60s Sat, mid 60s Sun. Warmer in the Lewis & Clark Valley.
  • Low Temps: Mid 30s Fri night, upper 30s Sat night, near 40 Sun night. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Partly cloudy.
Next Week
  • Wind: Generally W, breezy areas Wed.
  • Precipitation: Possible upslope showers Wed.
  • High Temps: Near 70 Mon, low 70s Tue, mid 70s Wed-Thu. Warmer in the Lewis & Clark Valley.
  • Low Temps: Low 40s Mon night, mid 40s Tue-Thu nights. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Partly cloudy.

Western Washington
Weekend
  • Wind: SW Sat, NW and breezy on the Coast Sun.
  • Precipitation: Rain and mountain snow showers through the weekend.
  • High Temps: Upper 50s Sat, low 60s Sun. Cooler in higher terrain.
  • Low Temps: Mid 40s Fri night, upper 40s Sat-Sun nights. Cooler in higher terrain.
  • Sky Cover: Mostly cloudy.
Next Week
  • Wind: Generally NW. Breezy periods on the Coast and along the Strait.
  • Precipitation: Chance of rain N of Everett Wed, otherwise dry.
  • High Temps: Mid 60s Mon, upper 60s Tue, near 70 Wed-Thu. Cooler in higher terrain.
  • Low Temps: Near 50 Mon-Thu nights. Cooler in higher terrain.
  • Sky Cover: Partly cloudy Mon, mostly cloudy Tue-Thu.

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