AgWeatherNet Weekly Weather Outlook for July 6 to July 11, 2021

Unsettled to start with temperatures remaining above average for many

Mark Ingalls, AgWeatherNet Intern

Synopsis:

A shortwave trough will pass through the region Tuesday evening, bringing with it a chance of dry thunderstorms in and east of the Cascades and breezy conditions for typical windy spots lasting into Wednesday afternoon. Marine air may send low clouds as far as the I-5 corridor both Wednesday and Thursday, limiting afternoon highs in Western Washington lowlands both days. Highs in Eastern Washington will also be moderated somewhat but remain above average. Friday and Saturday, ridging building over the Southwest raises temperatures statewide, but another trough passing through is forecast to bring highs down a bit (though still above average) Sunday.

Discussion:

Parts of Eastern Washington are likely to reach above 100 degrees again Tuesday afternoon. By early evening, winds should be picking up thanks to a shortwave trough making its way through the Pacific Northwest. This shortwave is forecast to inject enough energy and moisture into the environment to initiate isolated thunderstorm development along and east of the Cascades. These are likely to start during the afternoon hours in Central Oregon, moving into southeast Washington for the evening and to the north of I-90 overnight.

Due to low relative humidity at the surface, any thunderstorms that form are likely to be dry thunderstorms which have most or all of their precipitation evaporate before making it to the ground. Tightening pressure gradients are forecast to bring increased wind speeds through the Cascade mountain gaps Tuesday evening and overnight, with more widespread breezy conditions in Eastern Washington on Wednesday.

A marine push is likely on Wednesday that should bring low clouds as far as the I-5 corridor with some drizzle along the coast. Interior locations may see these clouds evaporate by noon. Thursday looks similar, but the low clouds may last well into the afternoon for much of Western Washington limiting afternoon highs there. This marine influence should make it into Eastern Washington as well, resulting in moderated temperatures with highs in the upper 80s to mid 90s in the lowlands.

Temperatures begin to climb again Friday and Saturday as the ridge of high pressure over the Southwest builds over the region. Highs are not currently forecast to be nearly as extreme as what was seen last week, but this does look to be what one may consider a normal heatwave for the Pacific Northwest. Sunday, a shortwave trough transiting the northern edge of the ridge weakens its influence in Washington state, lowering highs modestly for Sunday.

Drought conditions have resumed their worsening trend in Eastern Washington. In last week's update from the National Drought Mitigation Center, extreme drought (D3/4) conditions were noted to have spread throughout the Palouse, around Spokane, and north to the point where Washington, Idaho, and British Columbia meet. Other cities such as Goldendale, the Tri-Cities, Moses Lake, and Walla Walla remain in extreme drought with severe drought (D2/4) for Yakima, Wenatchee, and Vancouver.


8 to 14 Day Outlook, July 12 to July 18, 2021
  • Above average temperatures and below average precipitation are favored for the period.

Important Points About Next Week's Weather

South Central Washington
Remainder of the Week
  • Wind: W with breezy areas Tue night, W and breezy Wed, SW with breezy areas Thu, light and variable Fri.
  • Precipitation: Isolated (mainly dry) thunderstorms Tue night/Wed AM.
  • High Temps: Mid 90s Wed-Thu, upper 90s Fri.
  • Low Temps: Mid 60s Tue night, near 60 Wed night, low 60s Thu night, mid 60s Fri night. Cooler in sheltered areas.
  • Sky Cover: Decreasing clouds Wed, mostly clear Thu-Fri.
Weekend
  • Wind: Generally W. Breezy Sat with breezy areas Sun.
  • Precipitation: Dry conditions expected.
  • High Temps: Mid 100s Sat, upper 90s Sun.
  • Low Temps: Mid 60s Sat-Sun nights.
  • Sky Cover: Mostly clear.

North Central Washington
Remainder of the Week
  • Wind: W with breezy areas Tue night, W and breezy Wed, SW with breezy areas Thu, light and variable Fri.
  • Precipitation: Isolated (mainly dry) thunderstorms Tue night/Wed AM.
  • High Temps: Mid 90s Wed, low 90s Thu, upper 90s Fri. Cooler in higher terrain.
  • Low Temps: Low 70s Tue night, low 60s Wed night, mid 60s Thu night, near 70 Fri night. Cooler in higher terrain and sheltered areas.
  • Sky Cover: Decreasing clouds Wed, mostly clear Thu-Fri.
Weekend
  • Wind: Generally W. Breezy Sat with breezy areas Sun.
  • Precipitation: Dry conditions expected.
  • High Temps: Low 100s Sat, upper 90s Sun. Cooler in higher terrain.
  • Low Temps: Upper 60s Sat night, mid 60s Sun night. Cooler in higher terrain and sheltered areas.
  • Sky Cover: Mostly clear.

Eastern Washington
Remainder of the Week
  • Wind: W with breezy areas Tue night, W and breezy Wed, SW with breezy areas Thu, light and variable Fri.
  • Precipitation: Isolated (mainly dry) thunderstorms Tue night/Wed AM.
  • High Temps: Mid 90s Wed, near 90 Thu, mid 90s Fri. Warmer in the Lewis & Clark Valley.
  • Low Temps: Mid 60s Tue night, near 60 Wed-Thu nights, mid 60s Fri night. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Decreasing clouds Wed, mostly clear Thu-Fri.
Weekend
  • Wind: Generally W. Breezy Sat with breezy areas Sun.
  • Precipitation: Dry conditions expected.
  • High Temps: Near 100 Sat, mid 90s Sun. Warmer in the Lewis & Clark Valley.
  • Low Temps: Mid 60s Sat night, low 60s Sun night. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Mostly clear.

Western Washington
Remainder of the Week
  • Wind: Generally W with breezy areas Wed, W and light Thu, light and variable Fri.
  • Precipitation: Some drizzle along the coast Wed & Thu.
  • High Temps: Mid 70s Wed-Thu, low 80s Fri. Cooler in higher terrain and along the coast.
  • Low Temps: Near 60 Tue night, upper 50s Wed-Thu nights, near 60 Fri night. Cooler in higher terrain.
  • Sky Cover: Decreasing clouds Wed, mostly cloudy Thu, mostly clear Fri inland. Mostly cloudy Wed-Fri on the coast.
Weekend
  • Wind: Generally NW. Breezy areas Sat, breezy along the coast and strait Sun.
  • Precipitation: Dry conditions expected.
  • High Temps: Mid 80s Sat, low 80s Sun. Cooler in higher terrain and along the coast.
  • Low Temps: Near 60 Sat-Sun nights. Cooler in higher terrain.
  • Sky Cover: Mostly clear.

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