AgWeatherNet Weekly Outlook for March 12 to March 18, 2021

Mostly dry and seasonal weather with light precipitation on Sunday

Mark Ingalls, AgWeatherNet Intern
Joe Boomgard-Zagrodnik, AgWeatherNet Postdoctoral Research Associate

Special note:

AgWeatherNet will begin providing daily spring frost forecasts on Monday March 15. This service is aimed at tree fruit growers in Central Washington and will be available to the public online under the Spring Frost Program section at weather.wsu.edu. AgWeatherNet thanks WSTFA for financially supporting the Spring Frost Program.

Synopsis:

Dry conditions lasting into Saturday are expected to erode away Sunday as pattern change brings a return to moist, onshore flow. A cold front crossing the state on Sunday is expected to bring rain and mountain snow to much of the region, though arid regions like the Columbia Basin and Yakima Valley shouldn't expect any significant amount of precipitation. A few lingering showers are likely in the mountains and Western Washington on Monday, otherwise dry weather should resume and last through at least Wednesday. Late next week, models indicate another frontal system moving into the Pacific Northwest. There is a bit of uncertainty with this disturbance, with most solutions bringing it ashore either Thursday or Friday with wet weather continuing into next weekend.

Discussion:

Upper level ridging over the Pacific Northwest can be expected to keep the region dry through Saturday. Sunday, a cold front moves across Washington from west to east bringing with it rain and mountain snow showers. Snow levels are expected to start around 3000-4000 feet Sunday, decreasing to around 1000-2000 feet by Monday morning. This disturbance does not have a ton of moisture embedded with it, though, with only a few inches of snow at most expected in the mountains. For arid parts of Washington, isolated light rain showers or drizzle are possible, but the most notable impact will be an uptick in wind on Monday.

A few showers may linger in and west of the Cascades through the day Monday, but a weak ridge is expected to build over the Western United States during the first half of the week. This ridge, while weak, should be the dominant weather pattern in Washington by keeping conditions dry throughout at least Wednesday. Toward the end of the week, another frontal passage is possible. The jury's still out on when the front can be expected, but most ensemble models place it over the region either Thursday or Friday.

High temperatures Saturday should be around 5-10 degrees above average statewide, but will moderate following Sunday's cold front to be within a few degrees of average for the remainder of the forecast period. Clear skies will help most of Eastern Washington to reach below average low temperatures Saturday morning with colder spots reaching the low 20s again Saturday morning, similar to most of the past week. Next week, the coldest mornings are expected to be Monday through Wednesday with clear skies and radiative inversions formation in the overnight hours. Current projections suggest that low-to-mid 20s can be expected in the colder spots of eastern and central Washington with near-freezing conditions elsewhere.

In Western Washington, colder spots can expect another hard freeze on Saturday morning. Rural areas also have a chance of getting below freezing during the first half of next week. This is especially true along I-5 between Olympia and the Columbia River as well as between I-5 and the coastal lowlands.


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

Important Points About Next Week's Weather

South Central Washington
Weekend
  • Wind: Light and variable through Sat, S and light Sun.
  • Precipitation: Low chance of light rain Sun night.
  • High Temps: Near 60 Sat, upper 50s Sun.
  • Low Temps: Upper 20s Fri night, low 30s Sat night, upper 30s Sun night.
  • Sky Cover: Clear to partly cloudy through Sat. Mostly cloudy Sun.
Next Week
  • Wind: W and breezy Mon, light and variable the remainder of the week.
  • Precipitation: Dry conditions expected.
  • High Temps: Mid 50s Mon, upper 50s Tue, low 60s Wed, mid 60s Thu.
  • Low Temps: Mid 30s Mon-Tue nights, upper 30s Wed-Thu nights.
  • Sky Cover: Partly cloudy Mon-Wed, mostly cloudy Thu.

North Central Washington
Weekend
  • Wind: Light and variable.
  • Precipitation: Low chance of rain and mountain snow Sun & Sun night. Highest chance in the mountains.
  • High Temps: Mid 50s Sat, low 50s Sun. Cooler in higher terrain.
  • Low Temps: Upper 20s Fri night, low 30s Sat-Sun nights. Cooler in higher terrain.
  • Sky Cover: Partly cloudy through Sat night, mostly cloudy Sun.
Next Week
  • Wind: W and breezy Mon, light and variable the remainder of the week.
  • Precipitation: Low chance of rain and mountain snow Thu.
  • High Temps: Near 50 Mon, low 50s Tue, mid 50s Wed-Thu. Cooler in higher terrain.
  • Low Temps: Low 30s Mon-Tue nights, mid 30s Wed-Thu nights. Cooler in higher terrain.
  • Sky Cover: Clear to partly cloudy Mon-Tue, mostly cloudy Wed-Thu.

Eastern Washington
Weekend
  • Wind: Light and variable.
  • Precipitation: Low chance of rain and mountain snow Sun night.
  • High Temps: Upper 50s Sat & Sun. Warmer in the Lewis & Clark Valley.
  • Low Temps: Upper 20s Fri night, low 30s Sat-Sun night. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Clear to partly cloudy Fri-Sat. Mostly cloudy Sun.
Next Week
  • Wind: W and breezy Mon, light and variable the remainder of the week.
  • Precipitation: Low chance of rain and mountain snow Mon.
  • High Temps: Upper 40s Mon, near 50 Tue, mid 50s Wed-Thu. Warmer in the Lewis & Clark Valley.
  • Low Temps: Low 30s Mon-Tue nights, mid 30s Wed-Thu nights. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Mostly cloudy Mon, partly cloudy Tue, mostly cloudy Wed-Thu.

Western Washington
Weekend
  • Wind: S and generally light Sat, S becoming W and windy Sun with gusts to 45 mph in the San Juans.
  • Precipitation: Chance of rain and mountain snow Sun-Sun night.
  • High Temps: Near 60 Sat, low 50s Sun. Cooler in higher terrain.
  • Low Temps: Upper 30s Fri night, low 40s Sat night, near 40 Sun night. Cooler in higher terrain.
  • Sky Cover: Partly cloudy Fri & Sat, mostly cloudy to overcast Sun.
Next Week
  • Wind: Light and variable Mon-Tue, E and light Wed, turning S and possibly breezy Thu. Breezy through the week on the coast.
  • Precipitation: Chance of upslope rain & mountain snow Mon, chance of rain & mountain snow Thu.
  • High Temps: Near 50 Mon, low 50s Tue, upper 50s Wed & Thu. Cooler in higher terrain.
  • Low Temps: Upper 30s Mon night, near 40 Tue night, low 40s Wed-Thu nights. Cooler in higher terrain.
  • Sky Cover: Mostly cloudy.

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