AgWeatherNet Weekly Weather Outlook for January 14 to January 20, 2012

Much More Active Weather Pattern Beginning This Weekend

Nic Loyd, Meteorologist, 509-786-9357
Gerrit Hoogenboom, Director, 509-786-9371

Colder weather in the lowlands at the end of this week was the result of strong wintertime temperature inversions that did not break in the afternoon. Despite temperatures in the 20s and 30s in eastern Washington, temperatures in the mountains were in the 40s and 50s.

The ever-present ridge of high pressure over the Northwest will finally break down on Saturday night as colder air enters the area. This will mark a major pattern change that will usher in more unsettled weather beginning this weekend. This pattern is likely to feature numerous storm systems that will bring increasing amounts of moisture by next week. Though the details regarding the timing of individual fronts and exact temperatures are unclear, several things are certain. Western Washington will be stormy and windy for much of next week, while the mountains will receive some much needed snow and cold weather early in the week.

While the precipitation forecast will be more problematic in eastern Washington, even typically rain shadowed areas stand a good chance of precipitation at times by next Tuesday. By the middle of next week, the warmer and wetter southern branch of the jet will become dominant and will undercut the ridge of high pressure in the central Pacific Ocean. The flow direction over Washington will change from northwesterly to westerly. Lowland snow fall is likely during this transition time around next Tuesday night, with the best chance for at least moderate accumulations in the northern part of the state. The key for any snowfall accumulation will be if significant precipitation enters the area before the cold air is scoured out of Washington. Expect temperature swings at times next week, especially around Wednesday, with much more changeable weather than has been observed since late November. It is also possible that a large temperature gradient could exist between southern and northern Washington at times.

By Wednesday afternoon, a warm front may bring in milder air with windy conditions possible. Stormy conditions will continue for the rest of the week, but temperatures are somewhat uncertain. Snow may change to rain even in the high elevations late next week as an atmospheric river pattern sets up, which could bring a threat of flooding and landslides, although it is not certain at this time.

  • Colder and unsettled weather begins Sunday. Most precipitation will be light initially and confined to the mountains or western Washington.
  • The Pacific Ocean origin of the incoming air mass means that it will NOT be bitter, arctic air such as was observed in late November of 2010. The flow will be mostly onshore (from the west), and the coldest air will remain bottled up in Canada.
  • The most noticeable change will occur in the mountains, where conditions will become colder and snowier than have been observed during the past couple of months.
  • The first system with potentially heavy precipitation is not expected until Tuesday.
  • Travel on mountain passes may be hazardous with heavy snow on Tuesday and Wednesday.
  • Lowland snow is likely around Tuesday night, especially in the northern part of eastern Washington.
  • Milder and potentially windy weather is possible by Wednesday and Thursday of next week.

Important Points about Next Week's Weather

South Central Washington
  • Normal conditions for this time of year would be highs in the upper 30s to low 40s and lows in the 20s.
Weekend
  • Cooler on Sunday with a slight chance of rain or snow.
  • Highs in the 40s on Saturday and upper 30s to around 40 on Sunday.
  • Lows in the mid teens to mid 20s.
Next Week
  • Cold early in the week and then significant moderation by later in the week.
  • A chance of snow early in the week and then a chance of rain at times later in the week.
  • Snow likely on Tuesday night but any accumulation is uncertain. Warmer on Wednesday.
  • Highs trending from the 30s early in the week to 40s later in the week.
  • Lows trending from the mid teens to mid 20s early in the week to the upper 20s to 30s later in the week.

North Central Washington
  • Normal conditions for this time of year would be highs in the low to mid 30s and lows in the upper teens to low 20s.
Weekend
  • Cooler on Sunday with a slight chance of snow.
  • Highs in the upper 30s to low 40s on Saturday and in the low 30s on Sunday.
  • Lows in the mid teens to mid 20s.
Next Week
  • Cold early in the week and then moderation possible by later in the week.
  • A chance of snow early in the week and then a chance of rain or snow at times.
  • Snow likely Tuesday night, with heavy accumulations possible, and then possible melting on Wednesday.
  • Highs trending from around 30 early in the week to the upper 30s to low 40s later in the week.
  • Lows trending from the mid teens to mid 20s early in the week to the mid 20s to low 30s later in the week.

Eastern Washington
  • Normal conditions for this time of year would be highs in the mid to upper 30s and lows in the mid to upper 20s.
Weekend
  • A chance of snow showers by Sunday and cooler.
  • Highs in the 40s on Saturday and low to mid 30s on Sunday.
  • Lows in the 20s.
Next Week
  • Snow showers possible on Monday, and snow likely around Tuesday night with accumulation possible.
  • Rain likely with a slight chance of snow at times and breezy later in the week.
  • Highs trending from the low 30s early in the week to the low to mid 40s later in the week.
  • Lows trending from 20 to 25 early in the week to low to mid 30s later in the week.

Western Washington
  • Normal conditions for this time of year would be highs in the 40s and lows in the 30s.
Weekend
  • A chance of rain on Saturday and a chance of rain or snow showers and cooler on Sunday.
  • Highs in the 40s on Saturday and then into the upper 30s to low 40s on Sunday.
  • Lows in the upper 20s to low 30s.
Next Week
  • Cool early in the week with a chance of rain or snow.
  • Precipitation likely Tuesday night, beginning as snow especially in the Bellingham area, before transitioning to rain from south to north.
  • Warmer later in the week with rain at times.
  • Highs trending from the mid 30s to low 40s early in the week to 45 to 50 later in the week.
  • Lows trending from the mid 20s to low 30s early in the week to low 30s to low 40s later in the week.

Washington State University