AgWeatherNet Weekly Weather Outlook for June 19 to June 25, 2020

Unsettled conditions this weekend with a heat wave expected mid week

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

Discussion:

A shortwave trough is expected to move across Washington this weekend. This will bring an end to the sunny skies of the past few days to areas west of the Cascades. While some shower activity is possible east of the Cascade Crest, it looks like this will be limited to mountainous regions such as the Blues and the Okanogan. For the rest of Eastern Washington, the trough will just be bringing increased cloudiness Friday night into Saturday and periodic breezy conditions.

The best chance of rain will be Saturday into Saturday night. Areas west of the Cascades can expect frequent showers on the coast and in mountainous areas with scattered showers elsewhere. East of the Cascades, there may be some showers in the Blues, Okanogan, and Palouse, but these should be fairly isolated. A few showers here might generate some lightning strikes. Rain chances come to an end on Sunday across the entire state. Along with this will be periodic breezy conditions on the coast and along the Strait of Juan de Fuca. The strong breeze expands to include the Kittitas Valley, eastern Columbia Gorge, and Columbia Basin on Sunday with gusts to 40 mph in places.

Following an unsettled weekend, a weak ridge is expected to build centered on the Inland Northwest beginning Sunday night into Monday. The ridge will degrade into more zonal flow Tuesday evening, but will be the preamble to widespread dry conditions with highs reaching into the mid-90s in the Columbia Basin midweek. Temperatures will be warm in other lowland non-coastal areas, with highs near 80 along the I-5 corridor and well into the 80s on the Palouse. With the zonal flow that is expected to be in place across Washington, periodically breezy conditions in and downwind of mountain gap areas such as the Strait of Juan de Fuca, Kittitas Valley (downwind of Snoqualmie Pass), and the east end of the Columbia Gorge can be expected.

Weak shortwave troughs embedded in the mean flow should cross the state on Tuesday night and Thursday. Model guidance indicates that these should not have copious amounts of moisture within them, which would geographically restrict whatever showers they will produce to mountainous areas. Tuesday's weak shortwave appears to focus showers in mountain areas west of the Cascade Crest while Thursday's highest chance is in mountain areas near the Idaho border. With both, there is a chance of a stray thunderstorm along I-5 or in lowland Eastern Washington, but this won't be a widespread thunderstorm event because of the lack of moisture (among other things).

There is increasing agreement among models that the Pacific Northwest will return to unsettled conditions beginning next weekend (beginning June 26). Model guidance indicates a couple of strong upper-level lows tracking from Alaska across British Columbia and into Alberta. This biggest impact from this seems to be cooler temperatures, but the extent to which this occurs will be dependent on where these lows end up moving. More details on this as we get closer to that time period.


8 to 14 Day Outlook  June 26, 2020 to July 2, 2020
  • Near average temperatures and near to slightly above average precipitation are expected during the 8 to 14 day time frame.

Important Points about Next Week's Weather

South Central Washington
Weekend
  • Wind: Generally light SW winds becoming breezier Saturday with gusts near 25 mph possible. Trending lighter Sunday night.
  • Precipitation: Low chance for a stray rain shower Saturday afternoon and night. Otherwise dry conditions expected.
  • High Temps: Upper 80s Fri, low 80s Sat, mid 80s Sun.
  • Low Temps: Low 60s Fri night, mid 50s Sat night, low 50s Sun night.
  • Sky Cover: Mostly cloudy through Saturday. Becoming partly cloudy Saturday night and sunny by Sunday. Mostly clear Sunday night.
Next Week
  • Wind: Mostly light and S yet variable. Winds shifting W/NW Wednesday night and becoming windy with some gusts near 35 mph possible. Winds expected to remain elevated and breezy through the end of the week.
  • Precipitation: Dry conditions expected.
  • High Temps: Upper 80s Mon, mid 90s Tue, mid 90s Wed, low 90s Thu.
  • Low Temps: Near 60 Mon night, low 60s Tue night, upper 50s Wed night, mid 50s Thu night.
  • Sky Cover: Sunny and mostly clear.

North Central Washington
Weekend
  • Wind: Mostly S yet variable and light. Becoming a bit breezier Saturday, particularly through the Basin with gusts near 25 mph possible. Trending lighter Sunday night.
  • Precipitation: A few scattered rain showers likely for Saturday afternoon and night with greater activity through upland areas. Only a low chance for a shower through the Basin. Showers possibly lingering in upland areas through Sunday, particularly to the east, with dry conditions expected elsewhere.
  • High Temps: Near 80 Fri, near 80 Sat, low 80s Sun. Cooler in high terrain.
  • Low Temps: Low 60s Fri night, mid 50s Sat night, mid 50s Sun night. Cooler in high terrain and deep valleys.
  • Sky Cover: Mostly cloudy through Saturday. Becoming partly cloudy Saturday night and sunny by Sunday. Mostly clear Sunday night.
Next Week
  • Wind: Mostly light and S yet variable. Winds shifting NW Wednesday night and becoming windy with some gusts near 35 mph possible, particularly through the Basin. Winds expected to remain elevated and breezy through the end of the week.
  • Precipitation: Low chance for a light mountain rain shower Tuesday night near the Cascade crest. Another low chance for a light mountain rain shower Thursday, this time to the east. Otherwise dry conditions expected.
  • High Temps: Mid 80s Mon, upper 80s Tue, upper 80s Wed, mid 80s Thu. Cooler in high terrain.
  • Low Temps: Mid 50s Mon night, upper 50s Tue night, low 60s Wed night, near 60 Thu night. Cooler in high terrain and deep valleys.
  • Sky Cover: Partly cloudy to sunny.

Eastern Washington
Weekend
  • Wind: Generally light SW winds becoming breezier Saturday with gusts near 25 mph possible. Trending lighter Sunday night.
  • Precipitation: A passing rain shower or two likely Saturday afternoon and night. Otherwise dry conditions expected.
  • High Temps: Mid 70s Fri, low 70s Sat, low 70s Sun.
  • Low Temps: Mid 50s Fri night, low 50s Sat night, upper 40s Sun night.
  • Sky Cover: Mostly cloudy through Saturday night. Becoming mostly sunny Sunday. Mostly clear Sunday night.
Next Week
  • Wind: Mostly light and S yet variable. Winds shifting W/NW Wednesday night and becoming windy with some gusts near 35 mph possible. Winds expected to remain elevated and breezy through the end of the week.
  • Precipitation: Low chance for a light rain shower or two Thursday. Otherwise dry conditions expected.
  • High Temps: Upper 70s Mon, low 80s Tue, low 80s Wed, low 80s Thu.
  • Low Temps: Low 50s Mon night, mid 50s Tue night, mid 50s Wed night, mid 50s Thu night.
  • Sky Cover: Sunny and mostly clear.

Western Washington
Weekend
  • Wind: Light and generally S/SW yet variable. Becoming breezier Saturday with winds shifting W. Winds to trend lighter and more variable Sunday night.
  • Precipitation: Scattered rain showers Saturday with greater activity through the Olympics and Cascades. Showers slowly trending dry through Sunday with only a few light rain showers likely to linger through the mountains by Sunday night.
  • High Temps: Low 80s Fri, upper 60s Sat, low 70s Sun. Much cooler through the Cascades and Olympics.
  • Low Temps: Upper 50s Fri night, low 50s Sat night, upper 40s Sun night. Much cooler through the Cascades and Olympics.
  • Sky Cover: Mostly cloudy. Becoming partly sunny Sunday. Mostly clear Sunday night.
Next Week
  • Wind: Mostly light and W yet variable. Winds shifting mostly NW Wednesday night and becoming breezier. Winds expected to remain breezy through the end of the week.
  • Precipitation: Chance for a light rain shower or two in the northern half of the region Tuesday with a slightly greater chance for a shower over the northern half of the Cascades. Otherwise dry conditions expected.
  • High Temps: Upper 70s Mon, low 80s Tue, low 80s Wed, near 80 Thu. Much cooler through the Cascades and Olympics. Cooler near the coast.
  • Low Temps: Low 50s Mon night, mid 50s Tue night, mid 50s Wed night, mid 50s Thu night. Much cooler through the Cascades and Olympics.
  • Sky Cover: Partly cloudy to sunny.

Like us on Facebook at https://www.facebook.com/AgWeatherNet
Follow us on Twitter at https://www.twitter.com/AgWeatherNet
Washington State University