AgWeatherNet Weekly Weather Outlook for Dec 6 to Dec 12, 2019

Unsettled weather with mild temps and on/off precipitation

Craig Oswald, Field Meteorologist, 509-786-9256
Joe Zagrodnik, Postdoctoral Research Associate

Discussion:

A large surface circulation just off the coast of the Pacific Northwest looks to provide a bit of unsettled weather for the state this weekend. This region of low pressure is anticipated to reach the coast of northern California Saturday evening with the greatest impact felt there. Fortunately (or perhaps unfortunately) Washington will see mostly light and somewhat scattered rain, and snow showers throughout the higher terrain, without much concern for strong winds. This first round of activity is expected to move out of the state by Sunday morning. This makes Sunday afternoon the best time for any outdoor related activities this weekend as temperatures look to remain stable before dipping slightly Monday and Tuesday.

Conditions look to become mostly sunny Monday and Tuesday with the passing of the circulation to our south and our brief residence beneath a ridge. Temperatures will be slightly cooler than the weekend as stated earlier but are anticipated to remain pleasant for this time of year.

We look to be impacted by a remnant band of precipitation associated with a decaying cold front beginning Tuesday evening. This banded precipitation currently looks to begin moving into the state from the west before becoming disorganized as it moves east across the Cascades. This should bring rain and high terrain snow throughout much of the state. The weather will remain quite unsettled from this point forward with dreary conditions abound. A stronger frontal system might impact the state sometime in the second half of next week. Models have been inconsistent with this storm so it is too early to pin down details, but there is at least some hope that this will be a decent snow producer for the Cascades.

For the second half of next week and beyond, there are some indications of a pattern change that could lead to more active weather over Washington State. The broad trough of low pressure over the Aleutian Islands (know colloquially as the "Aleutian low") will broaden and shift eastward to a position that is more favorable for sending storm systems toward Washington State.

Of important note, valleys and low areas in general will be impacted by fog and freezing fog throughout most of the period, primarily during the overnights and morning hours until after sunrise/mid-morning.


Key Points:

  • Light rain showers and high terrain snow showers for most of the weekend.
  • A generally unsettled weather pattern for the latter part of the week, bringing periods of light rain and snow.

Temperatures
  • Temps slightly cooler Monday and Tuesday but remain fairly stable through the period.

Precipitation
  • Periods of light rain and high terrain snow move in from the SW this weekend.
  • Light precip to return by Tuesday night with occasional rain and snow showers impacting much of the state for the remainder of a dreary week.

Wind
  • Light wind through the period.

8 to 14 Day Outlook - Dec 14, 2019 to Dec 20, 2019
  • Slightly above average temperatures are expected with near average to slightly above average precipitation likely statewide during the 8 to 14 day time frame. At this time an active weather pattern is expected during the third week of December with additional frontal cyclones impacting the state.

Important Points about Next Week’s Weather

South Central Washington
Weekend
  • Light rain showers to move into the region from the SW beginning Saturday morning and lingering into the overnight. A lingering light rain shower or two possible early Sunday morning before becoming dry.
  • High near 40 on Saturday, and mid 40s on Sunday.
  • Lows in the lower 30s on Saturday morning, and mid 30s on Sunday morning.
Next Week
  • Dry Monday and Tuesday. A slight chance of rain showers Tuesday night with unsettled weather through the remainder of the week bringing the threat for light rain at times, particularly Thursday night into Friday.
  • Highs in the low 40s for the week, mid 40s Thursday and Friday.
  • Low near 30 Monday and Tuesday morning. Lows in the low 30s for the remainder of the week.

North Central Washington
Weekend
  • Light rain showers and some snow showers at approx. 3000ft+ to move into the region from the W beginning Saturday morning and lingering into the overnight. A lingering light shower or two possible early Sunday morning before becoming dry.
  • High near 40 on Saturday and Sunday.
  • Lows in the low 30s on Saturday and Sunday morning.
Next Week
  • Dry Monday and Tuesday. A slight chance of more rain and snow showers Tuesday night with unsettled weather through the remainder of the week bringing the threat for light rain and snow at times, particularly Thursday night into Friday. Snow levels look to remain at approx. 3000ft+
  • Highs in the mid 30s for much of the week, highs in the upper 30s likely by Thursday and Friday.
  • Lows in the upper 20s on Monday morning and for the week. Lows near 30 by for Thursday and Friday mornings.

Eastern Washington
Weekend
  • Light rain showers and some snow showers at approx. 3000ft+ to move into the region from the W beginning Saturday morning and lingering into the overnight. Light showers to remain into Sunday morning before becoming dry.
  • High near 40 on Saturday and Sunday for northern areas, slightly warmer for southern areas.
  • Lows in the mid 30s on Saturday and Sunday morning.
Next Week
  • Dry Monday and Tuesday. A slight chance of more rain and snow showers late Tuesday night with unsettled weather through the remainder of the week bringing the threat for light rain and snow at times, particularly Thursday night into Friday. Snow levels look to be at approx. 2500-3000ft+
  • Highs in the upper 30s for much of the week, highs in the low 40s expected by Thursday and Friday.
  • Lows in the upper 20s on Monday morning and for the first part of the week, climbing to the lower 30s by weeks end.

Western Washington
Weekend
  • Rain showers and mountain snow showers at approx. 5000ft+ to move into the region from the SW beginning Friday night and lasting until Sunday morning before becoming dry.
  • Highs in the upper 40s on Saturday and Sunday, slightly warmer at the coast.
  • Lows near 40 on Saturday and Sunday morning, slightly warmer at the coast.
Next Week
  • Dry Monday and Tuesday. More rain and snow showers return Tuesday evening with unsettled weather through the remainder of the week bringing rain and snow at times, particularly Wednesday night and into Friday. Snow levels look to remain at approx. 5000ft+
  • Highs in the upper 40s for the week. Slightly warmer at the coast.
  • Lows near 40 on Monday morning and for the first part of the week, climbing into the low 40s for the second half of the week. Slightly warmer at the coast.

Washington State University