AgWeatherNet Weekly Weather Outlook for May 15 to May 21, 2020

An unsettled and wet period throughout the state

Craig Oswald, Field Meteorologist, 509-786-9256
Joe Zagrodnik, Postdoctoral Research Associate
Mark Ingalls, AgWeatherNet Intern

Discussion:

Conditions look to remain dry and continue to trend dry through the state today (Friday). However, this will be short lived as the quickly passing low amplitude ridge continues to move east. In its wake, a respectable cold core low pressure system associated with an upper level cut-off low looks to move offshore of the Pacific Northwest. This is expected to bring a band of fairly widespread rain showers from the systems decaying cold front through the state from the west beginning Saturday in far western Washington. Any shower activity likely wont reach eastern Washington until Saturday night. Rain showers and a chance for rain showers are expected to persist into Monday before likely trending dry through Monday night. However, atmospheric conditions are expected to remain rather unstable. This will give the chance for a few scattered rain showers to pop up through the day Tuesday. Temperatures also look to remain mostly seasonable through the weekend and early next week with low concern for overnight frost in fruit growing regions through the state.

Rain showers are expected to again move into the state Wednesday. This time from the south/southeast. This is a product of the aforementioned upper low being expected to move south along the west coast and into the Great Basin early next week. From here it looks to turn north and move into Montana mid-week, bringing with it more precipitation. This, paired with what appears to be another upper low moving southeast along the British Columbia coast mid-week, will create plenty of opportunity for rain showers to manifest throughout Washington and linger through Thursday as this disturbance moves into Oregon. As mentioned, temperatures look to remain seasonable early next week. However, the upper low expected to move in from the northwest mid-week looks to bring temperatures that may be concerning for growers (low 30s in colder spots) Thursday night. This will be discussed again Monday once more details are known.

The effect of these two lows interacting over Washington and southern British Columbia can be expected to bring more variable winds across the state as they track through the region. During this period, wind directions will be partially dependent on the specific location of the low and will vary depending on where the observer is in the state and may experience significant fluctuations over short amounts of time. On top of this, they are expected to bring an extended period of unsettled weather through the second half of the week as touched upon above.

With continued unsettled weather and higher snow levels, many streams across the state are expected to experience a modest rise in flow. This is especially true for rivers and streams that drain mountain areas where significant amounts of mid-elevation snowpack will melt. Unlike what we saw in February, a regional flood event is not expected, though isolated locations could see bank full or minor flooding conditions.

Paradoxically, this is occurring while parts of the state have severe drought conditions. While showers and isolated thunderstorms are expected throughout the region off and on for the next week, the rain that is falling is not expected to make a significant dent in existing precipitation deficits in the driest areas. The upcoming systems look to have just enough moisture to accelerate melting of mid-elevation mountain snow while at the same time not having enough to improve drought conditions that are in place, particularly in Central Washington.


8 to 14 Day Outlook  May 22, 2020 to May 28, 2020
  • Near to slightly above average temperatures and near to slightly below average precipitation are expected during the 8 to 14 day time frame.

Important Points about Next Week's Weather

South Central Washington
Weekend
  • Wind: SW and light to breezy. Windier through the Basin and Palouse with some gusts around 25 mph possible. Shifting SE Fri night and remining light to breezy. Becoming more variable Sat night.
  • Precipitation: Scattered rain showers to move in from the SW Sat night. Showers lingering through Sun and Sun night with the chance for a T-storm or two.
  • High Temps: Low 70s Fri, upper 70s Sat, mid 70s Sun.
  • Low Temps: Mid 40s Fri night, low 50s Sat night, upper 40s Sun night.
  • Sky Cover: Mostly sunny Fri, partly cloudy Fri night, mostly cloudy Sat, cloudy Sat night, mostly cloudy Sun, mostly cloudy Sun night.
Next Week
  • Wind: Becoming mostly S/SW and breezy Mon yet variable through much of the week. Slightly calmer Tue. Breezy and windy Wed with some gusts around 30 mph possible. Remaining breezy through the end of the week.
  • Precipitation: A few scattered rain showers to linger through Mon before trending dry. Rain showers likely to start moving in from the S again Wed and becoming more widespread Wed night. Likely trending dry Thur but conditions to remain unsettled.
  • High Temps: Low 70s Mon, low 70s Tue, low 70s Wed, low 70s Thur.
  • Low Temps: Mid 40s Mon night, upper 40s Tue night, mid 40s Wed night, mid 40s Thur night.
  • Sky Cover: Mostly sunny to mostly cloudy.

North Central Washington
Weekend
  • Wind: SW and light. Windier through the Basin with some gusts around 25 mph possible. Shifting SE Fri night and becoming light to breezy. Becoming more variable Sat night.
  • Precipitation: Scattered rain showers to move in from the SW Sat night. Showers lingering through Sun and Sun night with the chance for a T-storm or two. Greater shower activity and a greater chance for a T-storm expected over high terrain
  • High Temps: Low 70s Fri, low 70s Sat, upper 60s Sun. Cooler through high terrain.
  • Low Temps: Mid 40s Fri night, low 50s Sat night, upper 40s Sun night. Cooler through high terrain.
  • Sky Cover: Mostly sunny Fri, mostly clear Fri night, partly sunny Sat, cloudy Sat night, mostly cloudy Sun, mostly cloudy Sun night.
Next Week
  • Wind: Becoming mostly S/SW and light to breezy Mon. Becoming N Mon night and remaining generally light. Shifting W/SW Wed night and becoming breezier again. Expect windier conditions through the Basin with some gusts near 30 mph at times.
  • Precipitation: Scattered rain showers to linger through Mon night before trending dry, especially through high terrain where a few showers may linger into mid-week. Widespread rain showers to start moving in from the SE again Wed. Likely trending dry Thur night but conditions to remain unsettled.
  • High Temps: Mid 60s Mon, near 70 Tue, low 70s Wed, upper 60s Thur. Cooler through high terrain.
  • Low Temps: Mid 40s Mon night, mid 40s Tue night, upper 40s Wed night, mid 40s Thur night. Cooler through high terrain.
  • Sky Cover: Partly sunny to mostly cloudy.

Eastern Washington
Weekend
  • Wind: SW and light to breezy. Windier through the Basin and Palouse with some gusts around 25 mph possible. Shifting SE Fri night and remining light to breezy. Becoming more variable Sat night.
  • Precipitation: Scattered rain showers to move in from the SW Sat night. Showers lingering through Sun and Sun night with the chance for a T-storm or two.
  • High Temps: Low 60s Fri, near 70 Sat, near 70 Sun.
  • Low Temps: Low 40s Fri night, near 50 Sat night, mid 40s Sun night.
  • Sky Cover: Mostly sunny Fri, mostly clear Fri night, mostly sunny Sat, mostly cloudy Sat night, cloudy Sun, mostly cloudy Sun night.
Next Week
  • Wind: Becoming mostly S/SW and breezy Mon yet variable through much of the week. Slightly calmer Tue. Breezy and windy Wed with some gusts around 30 mph possible. Remaining breezy through the end of the week.
  • Precipitation: A few scattered rain showers to linger through Mon before trending dry. Widespread rain showers to start moving in from the S again Wed. Likely trending dry Thur night but conditions to remain unsettled.
  • High Temps: Mid 60s Mon, low 60s Tue, low 60s Wed, low 60s Thur.
  • Low Temps: Low 40s Mon night, mid 40s Tue night, mid 40s Wed night, mid 40s Thur night.
  • Sky Cover: Partly sunny to mostly cloudy.

Western Washington
Weekend
  • Wind: Breezy on the coast and along the Strait of Juan de Fuca Sat with S flow and gusts to 30 mph. Shifting more E Fri night. Becoming mostly light and variable Sat night.
  • Precipitation: A chance of showers Sat with widespread rain likely Sat night through Sun.
  • High Temps: Mid 60s through the weekend. Much cooler through the Cascades and Olympics.
  • Low Temps: Near 50 Fri night, low 50s Sat night. Much cooler through the Cascades and Olympics.
  • Sky Cover: Sunny turning mostly cloudy Fri night, mostly cloudy to overcast Sat and Sun.
Next Week
  • Wind: Onshore flow Mon-Thu with breezy conditions for most of the area Wed and Thu.
  • Precipitation: Widespread rain likely Mon with a chance of showers Tue-Thu.
  • High Temps: Low 60s Mon-Thu. Much cooler through the Cascades and Olympics.
  • Low Temps: Near 50 Mon-Thu. Much cooler through the Cascades and Olympics.
  • Sky Cover: Partly cloudy to overcast.

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