AgWeatherNet Weekly Outlook for April 09 to April 15, 2021

Larger pattern change leading to sunny skies and warming temperatures

Mark Ingalls, AgWeatherNet Intern

Synopsis:

Clouds will be on the increase Friday afternoon ahead of a cold front that will cross Washington overnight and into Saturday. Breezy conditions are likely in typical windy spots, with rain and mountain snow showers in the mountains and western half of the state. Showers taper off Saturday as the cold front progresses eastward. Sunday through Thursday, Washington looks to be placed between a closed low to the south and upper ridge to the north resulting in dry conditions under east-northeasterly flow aloft.

Discussion:

A cold front is forecast to cross Washington Friday night into Saturday, bringing with it gusty winds, mountain snow, as well as rain to the west of the Cascades. Precipitation values with the frontal passage are expected to be light, with daytime highs Saturday being a few degrees lower than Friday. This front is very similar to the one that crossed the state Wednesday.

Precipitation is expected to taper off from west to east Friday night into Saturday for a generally dry day across Washington. The exception to this is the Puget Sound Convergence Zone, which should last to near sunset. Model guidance suggests that the convergence zone will bring enhanced precipitation along Interstate 90 from Seattle to near Cle Elum, which could bring significant travel impacts to the Snoqualmie Pass corridor.

Saturday night should be dry and clear, allowing for widespread frost in lowland areas statewide. Sunday through Thursday, a rex block pattern builds across the Western United States and Canada. A rex block refers to a scenario where a ridge of high pressure is located directly north of a closed low. In next week's case, the closed low is expected to spend a significant amount of time over the Great Basin while an upper level ridge builds across British Columbia and Alberta.

The position of the closed low and upper level high should place Washington under east to northeasterly flow aloft – a reversal of the typical westerlies that occur at this latitude. The near-meridional flow coming from the continent's interior will keep the state dry through this portion of the forecast period with the exception of some possible upslope showers on the eastern sides of mountain ranges in the state.

Mostly sunny skies across the region are likely to lead to a warming trend. By midweek, daytime highs in the Puget Sound Region should reach to the mid 60s, with the warmest parts of Eastern Washington possibly getting back into the 70s. Eastern Washington lowlands may be breezy for much of the week. Steep environmental lapse rates with warm temperatures at the surface but cold air aloft allowing for enhanced vertical mixing to bring down strong winds from several thousand feet above. Overnight lows are also expected to slowly rise through the week. If winds ease during the overnight hours, frosting may be a concern for agricultural interests, but it remains to be seen whether or not this will happen.


8 to 14 Day Outlook, April 16 to April 22, 2021
  • Above average temperatures and below average precipitation are favored for the period.

Important Points About Next Week's Weather

South Central Washington
Weekend
  • Wind: SW and breezy becoming NW and breezy Sat. SW and light Sun.
  • Precipitation: Dry conditions expected.
  • High Temps: Mid 50s Sat, upper 50s Sun.
  • Low Temps: Upper 30s Fri night, Near 30 Sat night, low 30s Sun night. Cooler in sheltered areas.
  • Sky Cover: Partly cloudy Fri night, mostly clear Sat & Sun.
Next Week
  • Wind: Generally NE and breezy to windy most days.
  • Precipitation: Dry conditions expected.
  • High Temps: Mid 60s Mon-Tue, upper 60s Wed, near 70 Thu.
  • Low Temps: Mid 30s Mon night, upper 30s Tue-Thu nights. Cooler in sheltered areas.
  • Sky Cover: Clear.

North Central Washington
Weekend
  • Wind: SW and breezy becoming NW and breezy Sat. SW and light Sun.
  • Precipitation: Low chance of rain and mountain snow showers Fri night.
  • High Temps: Near 50 Sat, upper 50s Sun. Cooler in higher terrain.
  • Low Temps: Mid 30s Fri night, upper 20s Sat night, near 30 Sun night. Cooler in higher terrain.
  • Sky Cover: Mostly cloudy Fri night, decreasing clouds Sat, clear Sun.
Next Week
  • Wind: Generally NE and breezy to windy in the Basin most days.
  • Precipitation: Dry conditions expected.
  • High Temps: Low 60s Mon, mid 60s Tue, upper 60s Wed & Thu. Cooler in higher terrain.
  • Low Temps: Mid 30s Mon night, upper 30s Tue-Thu nights. Cooler in higher terrain.
  • Sky Cover: Clear.

Eastern Washington
Weekend
  • Wind: SW and breezy becoming NW and breezy Sat. SW and light Sun.
  • Precipitation: Low chance of rain/snow Sat.
  • High Temps: Upper 40s Sat, low 50s Sun. Warmer in the Lewis & Clark Valley.
  • Low Temps: Mid 30s Fri night, mid 20s Sat night, upper 20s Sun night. Warmer in the Lewis & Clark Valley.
  • Sky Cover: Mostly cloudy Sat, partly cloudy Sun.
Next Week
  • Wind: Generally NE and breezy to windy most days.
  • Precipitation: Dry conditions expected.
  • High Temps: Mid 50s Mon, upper 50s Tue, low 60s Wed, mid 60s 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 clear.

Western Washington
Weekend
  • Wind: W and breezy Sat, N and generally light Sun.
  • Precipitation: Rain and mountain snow tapering off Sat.
  • High Temps: Near 50 Sat, low 50s Sun. Cooler in higher terrain.
  • Low Temps: Upper 30s Fri night, low 30s Sat night, mid 30s Sun night. Cooler in higher terrain.
  • Sky Cover: Mostly cloudy Sat, mostly clear Sun.
Next Week
  • Wind: Generally NE with breezy areas during the afternoons.
  • Precipitation: Dry conditions expected.
  • High Temps: Upper 50s Mon, low 60s Tue, mid 60s Wed-Thu. Cooler in higher terrain.
  • Low Temps: Near 40 Mon night, low 40s Tue night, mid 40s Wed-Thu nights. Cooler in higher terrain.
  • Sky Cover: Mostly clear.
Washington State University