AgWeatherNet Weekly Weather Outlook Monday Update for March 15 to March 21, 2021

Dry first half of the week followed by a Pacific system Thursday

Mark Ingalls, AgWeatherNet Intern
Craig Oswald, AgWeatherNet Field Meteorologist

Synopsis:

A ridge of high pressure will build into the region early in the week providing dry weather and slightly warmer temperatures. By Thursday a robust Pacific system will begin moving into Washington form the southwest bringing generally widespread lowland rain and mountain snow showers throughout the state. Conditions look to remain generally unsettled through the weekend with lowland rain and mountain snow showers throughout the Cascades and west. Scattered lowland rain and mountain snow showers look to prevail through locations east of the Cascades with a lower chance for precipitation across the Columbia Basin. Slightly cooler temperatures are also to be realized by Friday and the weekend.

Discussion:

A few lingering rain and mountain snow showers are expected to continue to diminish throughout the day and overnight with dry weather state wide by Tuesday morning. This is thanks to a ridge of high pressure building in from the west that will maintain dry weather and gradually warm temperatures through the first half of the week. Daytime highs as warm as the mid 60s are possible for portions of south central Washington by Thursday.

It is anticipated that a robust Pacific system and its associated cold front will begin moving into the state from the southwest Thursday morning. With strong southwesterly flow ahead of and along the frontal boundary, plenty of moisture should be available to produce precipitation statewide, including the Columbia Basin, where precipitation is expected to be generally light yet fairly widespread. Precipitation isnt expected to reach east of the Cascades until Thursday afternoon/evening in the northern mountains/valleys. The Basin may see a few stray rain showers by Thursday afternoon but it is likely that the bulk of the showers wont move in until Thursday night. Snow levels are expected to be very near pass levels and the most likely scenario is that precipitation will begin as rain throughout the Cascades passes during the day Thursday and trend to snow by the evening with snow remaining through the overnight.

The initial frontal passage looks to be exited from the state to the east by Friday morning. However, the low pressure system looks to continue to influence the region as it weakens and stalls along the Washington coast before moving into southern British Columbia. Cooler air aloft promoting unstable conditions will also help to produce rain showers and mountain snow showers primarily throughout the Cascades and western Washington throughout Friday and the weekend with snow levels generally remaining below pass levels. The northern mountains/valleys and Palouse will also likely see a resurgence of precipitation by Friday afternoon with a lower chance for a stray rain shower across the Columbia Basin. Another similar enhancement of precipitation Saturday afternoon is also possible as some guidance indicates the passage of a shortwave.


Important Points About Next Week's Weather

South Central Washington
Remainder of the Week
  • Wind: Light to calm and W/SW yet variable. SW and breezy to windy Thu night/Fri, gusts around 40mph possible.
  • Precipitation: Low chance for a stray rain shower Thu afternoon. Light rain showers Thu night. Low chance for a stray rain shower Fri, otherwise dry conditions expected.
  • High Temps: Mid 50s Tue, upper 50s Wed, mid 60s Thu, low 60s Fri.
  • Low Temps: Upper 20s Mon night, low 30s Tue night, mid 30s Wed night, upper 30s Thu night.
  • Sky Cover: Partly cloudy to mostly sunny.
Weekend
  • Wind: SW and breezy to windy. Trending slightly calmer Sun, yet remaining breezy at times.
  • Precipitation: Low chance for a stray rain shower, mostly dry conditions expected.
  • High Temps: Upper 50s Sat, upper 50s Sun.
  • Low Temps: Mid 30s Fri night, mid 30s Sat night, low 30s Sun night.
  • Sky Cover: Partly cloudy to mostly sunny.

North Central Washington
Remainder of the Week
  • Wind: Light to calm and generally varying between SW and N. S and breezy Thu. S/SW and breezy Thu night/Fri, windier through the Basin with gusts 40+ mph possible.
  • Precipitation: Dry early in the week. Rain showers and mtn snow showers moving in Thu afternoon form the SW to NE. Scattered rain showers and mtn snow showers Fri.
  • High Temps: Mid 50s Tue, mid 50s Wed, upper 50s Thu, mid 50s Fri. Cooler in high terrain.
  • Low Temps: Near 30 Mon night, low 30s Tue night, mid 30s Wed night, near 40 Thu night. Cooler in high terrain.
  • Sky Cover: Mostly sunny to partly cloudy early in the week, becoming mostly cloudy to partly cloudy by Wed.
Weekend
  • Wind: SW and breezy to windy. Trending slightly calmer Sun, yet remaining breezy at times.
  • Precipitation: Continued on/off scattered rain and mtn snow showers. Trending dry Sat night and into Sun.
  • High Temps: Mid 50s Sat, low 50s Sun. Cooler in high terrain.
  • Low Temps: Mid 30s Fri night, low 30s Sat night, near 30 Sun night. Cooler in high terrain.
  • Sky Cover: Mostly cloudy to partly sunny.

Eastern Washington
Remainder of the Week
  • Wind: Light to calm and W/SW yet variable. SW and breezy to windy Thu night/Fri, gusts around 40mph possible.
  • Precipitation: Dry early in the week. Rain showers and mtn snow showers moving in Thu evening. Scattered rain showers and mtn snow showers Fri.
  • High Temps: Mid 40s Tue, mid 50s Wed, low 60s Thu, near 50 Fri. Cooler through the Blue Mtns.
  • Low Temps: Low 30s Mon night, low 30s Tue night, upper 30s Wed night, near 40 Thu night. Cooler through the Blue Mtns.
  • Sky Cover: Mostly cloudy to mostly sunny.
Weekend
  • Wind: SW and breezy to windy. Trending slightly calmer Sun, yet remaining breezy at times.
  • Precipitation: Continued on/off scattered rain and mtn snow showers. Trending dry Sat night.
  • High Temps: Upper 40s Sat, upper 40s Sun. Cooler through the Blue Mtns.
  • Low Temps: Mid 30s Fri night, low 30s Sat night, low 30s Sun night. Cooler through the Blue Mtns.
  • Sky Cover: Mostly cloudy to partly sunny.

Western Washington
Remainder of the Week
  • Wind: Light to calm and S/SW yet variable. S and breezy to windy Thu night/Fri, gusts 50+ mph possible near the coast and sound.
  • Precipitation: Dry early in the week. Rain showers and mtn snow showers moving in Thu morning from SW to NE. Scattered showers remaining Fri.
  • High Temps: Low 50s Tue, upper 50s Wed, mid 50s Thu, low 50s Fri. Cooler through the Cascade and Olympic Mtns.
  • Low Temps: Mid 20s Mon night, near 30 Tue night, mid 30s Wed night, upper 30s Thu night. Cooler through the Cascade and Olympic Mtns.
  • Sky Cover: Partly cloudy to mostly sunny early in the week, becoming cloudy to mostly cloudy by Wed night.
Weekend
  • Wind: SW and breezy to windy. Trending slightly calmer Sun, yet remaining breezy at times.
  • Precipitation: Scattered rain showers and mtn snow showers.
  • High Temps: Low 50s Sat, low 50s Sun. Cooler through the Cascade and Olympic Mtns.
  • Low Temps: Mid 30s Fri night, mid 30s Sat night, mid 30s Sun night. Cooler through the Cascade and Olympic Mtns.
  • Sky Cover: Cloudy to mostly cloudy.

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