AgWeatherNet Weekly Weather Outlook Monday Update for October 26 to November 1, 2020

Slow warming trend through the week with mostly dry conditions

Craig Oswald, AgWeatherNet Field Meteorologist

Synopsis:

Overnight low temperatures will continue to be quite cold for the beginning of the week. However, a slow warming trend has already started and temperatures will slowly warm as the week progresses. A return to near seasonable temperatures still looks to be in store by weeks end. Skies will generally be mostly sunny/clear with light winds early in the week, making overnight inversions a concern for most fruit growing regions. Patchy valley fog and freezing fog are also likely by mid week.

Conditions look to be mostly dry early in the week aside from some recurring rain and high mountain snow showers in the far northwest portion of the state starting Tuesday. A weak system is expected to move in from the west/northwest Thursday night, bringing rain and high mountain snow to western Washington, and to a lesser extent, parts of northern and eastern Washington. Weather conditions are anticipated to remain dry and seasonable for the weekend.

Discussion:

The surge of cold and dry arctic air that has influenced the state over the weekend continues to slowly move out of the area to the east as the large scale wave pattern continues its eastward propagation. A low amplitude broad ridge and associated high pressure off the Oregon coast will continue to build into the region through the week. Two important weather patterns look to be associated with this. First, warming temperatures mostly clear and sunny skies, and light winds will dominate early in the week. This will help promote inversion formation throughout many fruit growing regions, creating a continued threat for cold overnight lows, even though temperatures aloft are already slowing warming. Second, Washington State is expected to continue to transition to mostly zonal flow aloft, additionally, placing the state under strong, moist flow as moist tropical air is drawn from near Hawaii and transported around the top of the ridge and funneled into the state. The effect of this will be a few recurring light rain showers and high mountain snow showers throughout the far northwest portion of the state starting Tuesday. The northern portions of the Cascade crest, Olympics, and some coastal areas of the Olympic Peninsula are expected to see the bulk of the shower activity but a few showers can't be ruled out for other low land areas as well. Relatively moist air paired with overnight inversions are also expected to be enough to produce some valley fog and freezing fog throughout western and eastern Washington as well.

Clouds are anticipated to build into the state by Thursday as a modest weather system moves into Washington from the west/northwest thanks to an upper level feature transiting across the north Pacific. Widespread rain showers and high mountain snow showers are expected throughout western Washington Thursday night with rain totals generally under a half inch throughout the low lands. A few scattered rain showers and high mountain snow showers can be expected across upland areas of northern Washington with more activity near the Cascade crest and and the far northeast corner of the state. Eastern Washington also stands to see a few passing rain showers with the Columbia Basin likely to remain dry with only a low chance for a stray shower or two. Any low elevation rain fall totals look to be minimal. Conditions are to trend dry through Friday night as the system continues east. Unlike the last system that passed through the Pacific Northwest, a significant cold air surge is NOT expected behind Thursday night/Fridays weather.

The weekend's weather looks to be seasonable and pleasant for outdoor work with dry conditions expected statewide. This is thanks to renewed residence under a broad ridge after Thursday night/Fridays weather system passes.


Important Points About This Week's Weather

South Central Washington
Remainder of the week
  • Wind: Light and variable through most of the week. Becoming SW and windy Fri with some gusts near 35mph possible.
  • Precipitation: Dry conditions through most of the week with the low chance for a stray rain shower or two Fri.
  • High Temps: Upper 40s Tue, low 50s Wed, mid 50s Thu, near 60 Fri.
  • Low Temps: Upper teens Mon night, mid 20s Tue night, mid 20s Wed night, upper 20s Thu night.
  • Sky Cover: Sunny and mostly clear. Becoming partly cloudy Thu night with mostly sunny to partly cloudy conditions Fri. Patchy valley fog mid week.

Weekend
  • Wind: Returning to light and variable by Sat morning.
  • Precipitation: Dry conditions expected.
  • High Temps: Near 60 Sat, upper 50s Sun.
  • Low Temps: Mid 30s Fri night, mid 30s Sat night, mid 30s Sun night.
  • Sky Cover: Mostly sunny to partly cloudy.

North Central Washington
Remainder of the week
  • Wind: Light and variable through most of the week. Becoming generally W/SW and breezy Fri. Windier through the Basin with a few gusts near 35mph possible.
  • Precipitation: Dry through most of the week with a few upland rain showers and high mountain snow showers beginning Thu night and trending dry Fri night. Greatest activity near the Cascade crest and north of Spokane. A few stray low land rain showers expected as well with greater chances to the north, and a low chance through the Basin.
  • High Temps: Mid 40s Tue, low 40s Wed, near 50 Thu, low 50s Fri. Cooler in high terrain.
  • Low Temps: Upper teens Mon night, upper 20s Tue night, low 30s Wed night, low 30s Thu night. Cooler in high terrain and deep valleys.
  • Sky Cover: Mostly cloudy to partly sunny. With mostly sunny and mostly clear conditions through the Basin while becoming partly cloudy Thu night and remaining so for Fri. Patchy valley fog mid week.

Weekend
  • Wind: Returning to light and variable by Sat morning.
  • Precipitation: Dry conditions expected.
  • High Temps: Mid 50s Sat, mid 50s Sun. Cooler in high terrain.
  • Low Temps: Mid 30s Fri night, mid 30s Sat night, mid 20s Sun night. Cooler in high terrain and deep valleys.
  • Sky Cover: Mostly cloudy to partly sunny. Mostly sunny to partly cloudy across the Basin.

Eastern Washington
Remainder of the week
  • Wind: Light and variable through most of the week. Becoming SW and windy Fri with some gusts near 35mph possible.
  • Precipitation: Dry through most of the week with a few light rain showers Friday night. Greater shower activity along the Idaho border and Blue Mtns. Lower chance for rain further west.
  • High Temps: Low 40s Tue, low 50s Wed, mid 50s Thu, upper 50s Fri. Cooler through the Blues.
  • Low Temps: Upper teens Mon night, near 30 Tue night, low 30s Wed night, upper 30s Thu night. Cooler through the Blues.
  • Sky Cover: Mostly sunny and mostly clear early in the week. Trending to partly cloudy mid week with mostly cloudy to partly cloudy conditions by Fri.

Weekend
  • Wind: Returning to light and variable by Sat morning.
  • Precipitation: Dry conditions expected.
  • High Temps: Mid 50s Sat, mid 50s Sun. Cooler through the Blues.
  • Low Temps: Upper 30s Fri night, mid 30s Sat night, mid 30s Sun night. Cooler through the Blues.
  • Sky Cover: Partly sunny and partly cloudy.

Western Washington
Remainder of the week
  • Wind: Light and variable through most of the week, breezier near the sound. Becoming S/SW and breezy Thu night and Fri.
  • Precipitation: Dry through most of the week other than a few light rain showers and high mountain snow showers throughout the northern part of the region and northern part of the Olympic Peninsula starting Tue. Rain showers and high mountain snow showers Thu night and Fri, trending dry Fri night.
  • High Temps: Mid 50s Tue, upper 50s Wed, near 60 Thu, upper 50s Fri. Cooler through the Cascades and Olympics.
  • Low Temps: Low 30s Mon night, near 40 Tue night, low 40s Wed night, low 40s Thu night. Cooler through the Cascades and Olympics.
  • Sky Cover: Partly sunny and partly cloudy. Becoming mostly cloudy Thu night and remaining so through Fri. Cloudier to the north.

Weekend
  • Wind: Returning to light and variable Fri night.
  • Precipitation: Dry conditions expected.
  • High Temps: Upper 50s Sat, upper 50s Sun.
  • Low Temps: Low 40s Fri night, low 40s Sat night, low 40s Sun night. Cooler through the Cascades and Olympics.
  • Sky Cover: Mostly cloudy.

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Washington State University