AgWeatherNet Weekly Outlook for October 16 to October 22, 2020

Unsettled conditions to dominate the week

Mark Ingalls, AgWeatherNet Intern
Craig Oswald, AgWeatherNet Field Meteorologist
Joe Zagrodnik, AgWeatherNet Postdoctoral Research Associate

Synopsis:

For the next week, Washington will continue to be situated between a strong ridge over the Northeast Pacific and a robust trough centered over the Canadian Prairies. This will keep upper level flow over the state northwesterly. A few weak weather systems will pass through the region over the week, bringing intermittent chances of rain and breezy conditions. None of these systems seem particularly strong, keeping the bulk of the precipitation limited to Western Washington and mountainous parts of the state. These shortwave systems are expected Friday, Sunday, and Wednesday.

Discussion:

The upper level flow will continue to be northwesterly for the time being as the jet stream negotiates the ridge centered over the Northeast Pacific and the trough over the North American interior. A shortwave and associated cold front is impacting Washington Friday, bringing with it gusty winds. The strongest winds will be Friday afternoon on the Palouse and in the northern Columbia Basin, where gusts to 50 mph are possible. Elsewhere throughout the state, breezy conditions are still likely, though this system is not likely to meet the bar set during the wind storm that was seen earlier this week.

Rain showers are expected with this system beginning Friday afternoon as it progresses from the central British Columbia coast toward Montana. This should mainly be observed in and west of the Cascades, with lighter rainfall spreading into the Okanogan and Blues overnight and into Saturday. Snow levels during this period will be well above pass level - roughly around 8,000 feet by Friday afternoon. A few stray showers may wander into the basin, but those that do will be light. Friday should be the warmest day of the forecast period, with highs near to slightly below average.

Upslope showers in the Olympics and Cascades (generally north of I-90) are possible Saturday. By this point, snow levels will be down to the North Cascades Highway, but precipitation should be limited. Look for highs to be cooler on Saturday in Eastern Washington. This is especially true on the Palouse and north of US 2, where highs may approach 10 degrees below average.

The next precipitation event arrives Saturday night ahead of another shortwave on Sunday. Snow levels should be around 5,000 feet, making this a rain event for everywhere except the High Cascades (including the North Cascades Highway). This system looks to have a little bit more moisture in it, allowing for slightly higher chances of rain even for the Columbia Basin. Still, the bulk of the precipitation will be limited to western and mountainous portions of the state. While a light breeze is expected to be observed on Saturday, winds will pick up again Sunday afternoon, with gusts to 35 mph in the Cascade mountain gaps and the Strait of Juan de Fuca.

Shower activity is forecasted to remain in and west of the Cascades through Monday, with some drying Monday night into Tuesday before the next shortwave on Wednesday. This third one should have much less moisture embedded within it, bringing widespread rain only to the Cascades and points west. Some rain is possible in the Okanogan and Blues, but rainfall values statewide out of this system look to be much lower than the ones expected over the weekend. Temperatures through Wednesday should be near to a few degrees below average, but regionally active conditions keep mild overnight temperatures in the forecast until Wednesday night, except in northeast Washington where temperatures may be near or below freezing much of the week. Parts of the upper Yakima Valley may also experience near to below freezing temperatures. Overnight inversions may bring freezing temperatures to some of the typical cold spots of southeast Washington Wednesday night.


8 to 14 Day Outlook, October 23 to October 29, 2020
  • Below average temperatures and below average precipitation are favored for the period, except on the coast where near normal temperatures are favored.

Important Points About Next Week’s Weather

South Central Washington
Weekend
  • Wind: W with breezy conditions. Strongest winds Fri with gusts to 35 mph.
  • Precipitation: Low chance of showers Sat night & Sun, otherwise dry.
  • High Temps: Near 70 Fri, mid 60s Sat, near 60 Sun.
  • Low Temps: Near 50 Fri night, upper 40s Sat night & Sun night.
  • Sky Cover: Partly cloudy to overcast.
Next Week
  • Wind: S/SW wind. Breezy conditions possible Mon & Wed.
  • Precipitation: No precipitation expected.
  • High Temps: Near 60 Mon-Wed, mid 50s Thu.
  • Low Temps: Mid 40s Mon night & Tue night. Upper 30s Wed night & Thu night.
  • Sky Cover: Partly to mostly cloudy Mon-Wed. Clear to partly cloudy Thu.

North Central Washington
Weekend
  • Wind: W with breezy conditions. Strongest winds Fri with gusts to 35 mph.
  • Precipitation: Rain showers possible Fri, Sat night, and Sun. Highest chances in the mountains.
  • High Temps: Near 70 Fri, mid 60s Sat, near 60 Sun. Cooler in higher terrain.
  • Low Temps: Upper 40s Fri night, mid 40s Sat & Sun night. Cooler in higher terrain.
  • Sky Cover: Partly to mostly cloudy.
Next Week
  • Wind: W/SW wind. Breezy conditions possible Mon & Wed.
  • Precipitation: Mountain showers possible Wed, otherwise dry.
  • High Temps: Near 60 Mon-Wed, mid 60s Thu. Cooler in higher terrain.
  • Low Temps: Mid 40s Mon night-Wed night, upper 30s Thu night. Cooler in higher terrain.
  • Sky Cover: Partly to mostly cloudy Mon-Wed. Clear to partly cloudy Thu.

Eastern Washington
Weekend
  • Wind: W with breezy conditions. Strongest winds Fri with gusts to 50 mph.
  • Precipitation: Rain showers possible Fri, Sat night, and Sun.
  • High Temps: Low 60s Fri, mid 50s Sat, near 50 Sun. Warmer in the Lewis and Clark Valley.
  • Low Temps: Near 40 Fri night, mid 30s Sat night, low 30s Sun night. Warmer in the Lewis and Clark Valley.
  • Sky Cover: Mostly cloudy to overcast.
Next Week
  • Wind: W/SW wind. Breezy conditions possible Mon & Wed.
  • Precipitation: Stray shower possible Wed, otherwise dry.
  • High Temps: Mid 50s Mon-Wed, near 50 Thu. Warmer in the Lewis and Clark Valley.
  • Low Temps: Low 30s Mon night-Wed night, near 30 Thu night. Warmer in the Lewis and Clark Valley.
  • Sky Cover: Partly to mostly cloudy Mon-Wed, clear to partly cloudy Thu.

Western Washington
Weekend
  • Wind: W with breezy conditions. Strongest winds Fri with gusts to 35 mph.
  • Precipitation: Rain likely Fri. Scattered showers Fri night, Sat night, and Sun. Otherwise upslope showers.
  • High Temps: Mid 60s Fri, mid to upper 50s Sat & Sun. Cooler in higher terrain.
  • Low Temps: Near 50 Fri night-Sun night. Cooler in higher terrain.
  • Sky Cover: Mostly cloudy to overcast.
Next Week
  • Wind: W/SW wind. Breezy conditions possible Mon & Wed.
  • Precipitation: Upslope showers possible through the week. Lowland showers possible Tue-Thu.
  • High Temps: Mid 50s Mon-Wed, low 50s Thu. Cooler in higher terrain.
  • Low Temps: Upper 40s Mon night-Tue night. Mid 40s Wed night-Thu night. Cooler in higher terrain.
  • Sky Cover: Partly cloudy to overcast.

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Washington State University