AgWeatherNet Weekly Weather Outlook for August 16 to August 22, 2021

Much cooler temperatures this week following a cold front Monday

Mark Ingalls, AgWeatherNet Field Technician

Synopsis:

A cold front crossing Washington Monday is going to usher in a period of cooler temperatures with the coolest temperatures expected Tuesday. Some light rain is possible in Western Washington with some lingering showers possible in the mountains and areas north of Everett on Tuesday Morning. Some showers are possible in Eastern Washington, mainly in the mountains and along the Idaho border, Tuesday night into Wednesday. Otherwise, look for mainly partly cloudy skies through the end of the week. Another round of light and isolated showers are possible this weekend in the same areas as before with temperatures possibly warming into next week.

Discussion:

The ridge of high pressure that brought another heatwave and smoky skies to much of Washington over the past several days is going to slip westward to rest over the Pacific Ocean as a cold front works its way across the state Monday. A few showers are possible in Western Washington and the Okanogan Highlands with rain generally tapering off Monday night. A few showers may linger in the mountains and western lowlands north of Mount Vernon into Tuesday morning.

On Tuesday, an upper level low sweeps into the Pacific Northwest. With it will come a chance of scattered showers along the Idaho state line. Through the remainder of the work week, near average temperatures and dry conditions are likely. Prolonged troughing over the region looks poised to bring gusty winds to typically windy areas, such as through the Strait of Juan de Fuca, the Columbia Gorge and other Cascade mountain gaps, and the US 395 corridor from north of the Tri-Cities to near Spokane. This doesn’t look to be a significant wind storm event, but could bring elevated fire concerns.

Heading into the weekend, troughing continues. There is a bit of uncertainty regarding the strength, timing, and moisture load of the disturbances during this period, but it appears that a few areas of Western and Northern Washington along with along the Idaho state line could again benefit from light showers. Throughout the week, precipitation values are forecast to remain light so that no significant improvement to the drought is expected.

With a northwesterly flow regime situated over Washington, some from wildfires in British Columbia may continue to be present through much of the week. Smoke-specific modeling does not extend out very far into the future, but given the wind pattern smoke may return. This is especially true for Eastern Washington beginning Wednesday. Outside of the widespread regional smoke pattern, localized smoke will likely be observed directly downwind of large fires.

Central Washington Heat Stress:
Note: This is an experimental forecast product that may undergo changes over the coming weeks. For questions or comments please email Mark Ingalls.

Cooler temperatures this week should help to mitigate heat stress concerns for both tree fruit and agricultural workers. Tuesday is expected to be the coolest day with highs only expected to reach above 80 in the warmest parts of the Columbia Basin. Temperatures rise to the mid 80s to near 90 by Friday before moderating somewhat for the weekend. Dew points will follow a similar rise, going from the low to mid 40s to the mid 50s. Wet bulb temperatures will start in the 70s this week with warmer temperatures pulling it up toward 80 on Friday. It should be mostly clear to partly cloudy in much of Central Washington, but smoke cover Wednesday and beyond may knock a degree or two off both the daily highs and wet bulb temperatures in areas where it is particularly thick.

Based on conditions observed during the previous cool down and modeled by the fruit surface temperature model available on the AgWeatherNet website, it looks as though fruit surface temperatures should not exceed 100 at the beginning of the week. They may, however, reach as high as 115 toward the end of the week in the hottest locations (around the Tri-Cities, along the Columbia River near Wenatchee, and in the Okanogan Valley) under clear skies with little-to-no smoke.


8 to 14 Day Outlook, August 23 to August 29, 2021
  • Near average temperatures and below average precipitation are favored for the period.

Important Points About This Week's Weather

South Central Washington
Remainder of the Week
  • Wind: W becoming N with breezy areas Tue, N and light Wed, light and variable Thu, breezy areas and variable Fri.
  • Precipitation: Dry conditions expected.
  • High Temps: Near 80 Tue, mid 80s Wed, upper 80s Thu, near 90 Fri.
  • Low Temps: Mid 60s Mon night, near 60 Tue night, upper 50s Wed night, low 60s Thu night, mid 60s Fri night.
  • Sky Cover: Mostly clear, areas of smoke.
Weekend
  • Wind: Becoming W Sat, breezy conditions possible Sun.
  • Precipitation: Dry conditions expected.
  • High Temps: Upper 80s Sat & Sun.
  • Low Temps: Low 60s Sat & Sun nights,
  • Sky Cover: Mostly clear, areas of smoke.

North Central Washington
Remainder of the Week
  • Wind: W becoming N with breezy areas Tue, N and light Wed, light and variable Thu, breezy areas and variable Fri.
  • Precipitation: Low chance of showers (mainly in the mountains) Tue & Wed.
  • High Temps: Near 80 Tue, mid 80s Wed, upper 80s Thu, near 90 Fri. Cooler in higher terrain.
  • Low Temps: Low 60s Mon-Wed nights, mid 60s Thu-Fri nights. Cooler in higher terrain.
  • Sky Cover: Partly cloudy, areas of smoke.
Weekend
  • Wind: Becoming W Sat, breezy conditions possible Sun.
  • Precipitation: Low chance of showers in the mountains Sat.
  • High Temps: Upper 80s Sat & Sun. Cooler in higher terrain.
  • Low Temps: Mid 60s Sat & Sun nights. Cooler in higher terrain.
  • Sky Cover: Partly cloudy, areas of smoke.

Eastern Washington
Remainder of the Week
  • Wind: W becoming N with breezy areas Tue, N and light Wed, light and variable Thu, breezy areas and variable Fri.
  • Precipitation: Low chance of showers Tue & Wed.
  • High Temps: Upper 70s Tue-Wed, low 80s Thu, mid 80s Fri. Warmer in the Lewis & Clark Valley.
  • Low Temps: Near 60 Mon night, mid 50s Tue night, low 50s Wed night, mid 50s Thu night, upper 50s Fri night. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Partly cloudy, areas of smoke.
Weekend
  • Wind: Becoming W Sat, breezy conditions possible Sun.
  • Precipitation: Low chance of showers Sat.
  • High Temps: Low 80s Sat, mid 80s Sun. Warmer in the Lewis & Clark Valley.
  • Low Temps: Upper 50s Sat & Sun nights. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Partly cloudy, areas of smoke.

Western Washington
Remainder of the Week
  • Wind: Generally W with breezy areas Tue, N and light Wed, W and breezy south of Olympia Thu, light and variable Fri.
  • Precipitation: Rain showers tapering off Tue AM.
  • High Temps: Near 70 Tue, near 80 Wed-Fri. Cooler along the coast and in higher terrain.
  • Low Temps: Upper 50s Mon-Wed nights, near 60 Thu-Fri nights. Cooler in higher terrain.
  • Sky Cover: Decreasing clouds Tue, partly cloudy Wed-Fri.
Weekend
  • Wind: W with breezy areas Sat & Sun.
  • Precipitation: Low chance of showers Sat.
  • High Temps: Upper 70s Sat & Sun. Cooler along the coast and in higher terrain.
  • Low Temps: Near 60 Sat & Sun nights. Cooler in higher terrain.
  • Sky Cover: Partly cloudy Sat & Sun.

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Washington State University