AgWeatherNet Weekly Weather Outlook for December 15 to December 21, 2012

Stormy Weather Through the Middle of Next Week

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

An active weather pattern will commence in Washington this weekend, as several storms take aim on the region. The strongest storm will affect Washington on Sunday night and Monday. Rain, wind, and snow will affect the state through early next week, before slightly less active weather returns later next week. Significant rain will fall in western Washington during the Sunday and Monday time period. Heavy snow will fall in the mountains at times, causing potentially dangerous travel from Sunday to Tuesday across the Cascade passes.

Meanwhile, a mixed bag of weather is likely for areas east of the Cascades, with the potential for rain, snow, and mixed precipitation. The initial wave of precipitation associated with the first storm will occur on Saturday night in central Washington, bringing light rain or snow amounts. A wetter, warmer, and more potent weather system will then arrive on Sunday night, bringing greater precipitation amounts and milder air. The most likely scenario is that mostly rain will fall in south central Washington, while a mix of precipitation may occur in eastern Washington around Pullman and Spokane. Snow is likely in north central Washington, with the potential for moderate accumulations before changing to rain or ending on Monday morning. It is important to note that there will likely be a sharp north to south gradient in the weather during the Sunday night storm system, with a large variety of weather between the Oregon and Canadian Borders. Southern areas around the Tri-Cities and Walla Walla will see rain Sunday evening, ending overnight with mild and breezy conditions on Monday morning. Areas in the north around Omak may see accumulating snowfall into Monday morning and much less warming on Monday.

Despite a brief dry period on Sunday in central Washington, western areas and the mountains will experience minimal if any break in precipitation between the two storms. While southwesterly, downslope winds will generally end the precipitation in south central Washington on Monday, rain or snow will continue in other parts of the state into Tuesday. Cooler and somewhat drier weather is expected for the middle part of next week, although storms may continue to brush the region. By late next week, milder air from the south may move back into the region.

Temperatures
  • Generally near to slightly above seasonal levels.
  • Milder on Monday, especially in central Washington.
  • Cooler around the middle of next week.

Rainfall
  • Rain, heavy at times, in western Washington from late Saturday through early next week.
  • Rain in the south and snow in the north for areas east of the Cascades, especially on Sunday night.
  • Snow, heavy at times, in the mountains from late Saturday through early next week.

Wind
  • Generally breezy from Saturday night through early next week.
  • Possibly windy in south central and eastern Washington on Monday.

Frost Risk Summary
  • This weekend through next week: Generally moderate to high risk east of the Cascades.

8 to 14 Day Outlook - December 22 to 28
  • Seasonal conditions are expected.

Important Points about Next Week's Weather

South Central Washington
  • Normal conditions for this time of the year would be highs in the upper 30s to low 40s and lows in the mid to upper 20s.
Weekend
  • A chance of rain on Saturday night, except a chance of rain or snow around Yakima.
  • Rain, or possibly rain and snow north and west of Yakima, developing on Sunday evening.
  • Becoming all rain and ending overnight, with increasing winds.
  • Highs in the mid 30s to mid 40s on Saturday, and mid 30s to 40s on Sunday.
  • Lows in the mid 20s to low 30s on Saturday morning, and upper 20s to mid 30s on Sunday morning.
Next Week
  • A chance of rain early in the week.
  • Highs in the 40s to low 50s, and then cooler by mid week.
  • Lows in the 30s to around 40 on Monday morning, and then cooler by mid week.

North Central Washington
  • Normal conditions for this time of the year would be highs in the mid 30s and lows in the low to mid 20s.
Weekend
  • Snow or rain likely around Wenatchee, and snow likely around Omak on Saturday night, with light accumulations possible.
  • Snow or rain developing around Wenatchee, and snow developing around Omak on Sunday evening, and then possibly changing to rain before ending by Monday morning. Moderate accumulations possible, especially from Omak and northward.
  • Highs in the 30s.
  • Lows in the 20s on Saturday morning, and mid to upper 20s on Sunday morning.
Next Week
  • A chance of rain or snow early in the week.
  • Highs in the mid 30s to low 40s, and then cooler by mid week.
  • Lows in the upper 20s to mid 30s, and then cooler by mid week.

Eastern Washington
  • Normal conditions for this time of the year would be highs in the mid to upper 30s and lows in the mid to upper 20s.
Weekend
  • Rain or snow likely on Saturday night.
  • Rain or snow developing on Sunday evening, and changing to all rain overnight.
  • Highs in the mid 30s to low 40s.
  • Lows in the mid to upper 20s on Saturday morning, and upper 20s to low 30s on Sunday morning.
Next Week
  • Rain or possibly snow early in the week.
  • Highs in the mid 30s to mid 40s on Monday, and then cooler by mid week.
  • Lows in the upper 20s to mid 30s, and then cooler by mid week.

Western Washington
  • Normal conditions for this time of the year would be highs in the upper 40s and lows in the mid to upper 30s.
Weekend
  • Rain developing on Saturday, with rain on Sunday.
  • Heavy mountain snow possible.
  • Highs in the 40s to around 50.
  • Lows in the mid 30s to low 40s.
Next Week
  • Rain or showers, with heavy mountain snow possible early in the week.
  • Highs in the 40s to around 50, and then cooler by mid week.
  • Lows in the upper 30s to low 40s, and then cooler by mid week.

Washington State University