AgWeatherNet Weekly Weather Outlook for Dec 20 to Dec 26, 2019

Another wet weekend followed by a mostly dry week

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

Discussion:

This week's outlook feels like a re-release of last week's outlook: a wet weekend, followed by a drying trend, and a return of wet weather by week's end. The main differences this week are that heavier and more prolonged precip is anticipated for this weekend as well as cooler temps abound.

An atmospheric river, which as a long corridor of high moisture air that usually originates from a more tropical latitude, is the main driver for our wet weather this weekend. This corridor of moisture laden air is following along a cold front associated with a surface cyclone churning off the coast of northern British Columbia. It is and will continue to produce copious amounts of rain for the western part of Washington State and large snowfall totals throughout the Cascades. In fact, several daily rainfall records have already been broken in Puget Sound including 1.32” at Sea-Tac airport on December 19 and 2.25” (as of 10 AM Friday) and counting on December 20. Friday will likely end up as one of the top 10 rainiest days at Sea-Tac airport (records since 1945). Numerous rivers are expected to exceed flood stage by Friday night including the Chehalis and Snoqualmie. The Skagit River is expected to crest slightly below flood stage. Flooding in the lowlands has also been reported, so it is also important to be aware of flooding potential in coastal and low lying areas with a prolonged rain fall event such as this.

East of the Cascades, we will see mostly on and off rain and high terrain snow showers through the weekend. At any rate, a drying trend looks to return state wide early next week with a few scattered and light snow showers clinging to higher terrain. Another round of substantial precip looks to move back into the state from the west by week's end (scattered precip is anticipated to begin building back into regions west of the Cascades by mid week however, ahead of the larger system). Temps look to gradually drop through the weekend before becoming more stable for the remainder of the week. Somewhat breezy conditions may be found at times through the weekend with winds dialing down by early next week.

* There will be no weather outlook released next week during the holidays.


Key Points:

  • Possible record rain fall west of the Cascades and prolonged snowfall throughout the Cascades this weekend.
  • Drying trend early in the week.

Temperatures
  • Becoming cooler this weekend.
  • Temps holding fairly stable for the week.

Precipitation
  • Wet weekend.
  • Drying trend early in the week with return of widespread precip by week's end.

Wind
  • Breezy conditions for the weekend with winds dialing down to light for next week.

8 to 14 Day Outlook - Dec 27, 2019 to Jan 2, 2020
  • Near to slightly below average temperatures and near to slightly below average precipitation are expected during the 8 to 14 day time frame.

Important Points about Next Week’s Weather

South Central Washington
Weekend
  • Mostly dry with light rain at times. Overcast.
  • Highs in the mid 50s Friday, low 50s Saturday, and mid 40s Sunday.
  • Lows in the low 40s Saturday morning, and mid 30s Sunday morning.
Next Week
  • Drying out early. Return of precip by week's end. Partly sunny to mostly cloudy.
  • High near 40 Monday and gradually cooling. Mid 30s by Thursday.
  • Low in the low 30s Monday morning. Dipping to upper 20s for the remainder of the week.

North Central Washington
Weekend
  • Light rain and high terrain snow. Overcast.
  • Highs in the low 40s Friday and Saturday, and upper 30s Sunday. Cooler throughout higher terrain.
  • Lows in the mid 30s Saturday morning, and low 30s Sunday morning. Cooler throughout higher terrain.
Next Week
  • Drying out early with a few scattered snow showers over high terrain at times. Return of widespread precip by weeks end. Partly sunny to mostly cloudy.
  • Highs in the low 30s. Cooler throughout higher terrain.
  • Lows in the upper 20s Monday morning. Dipping to mid 20s for the remainder of the week. Cooler throughout higher terrain.

Eastern Washington
Weekend
  • On/off light rain and snow. Slightly more consistent snow over high terrain. Overcast.
  • Highs in the upper 40s Friday, mid 40s Saturday, and low 40s Sunday. Cooler throughout higher terrain.
  • Lows near 40 Saturday morning, and mid 30s Sunday morning. Cooler throughout higher terrain.
Next Week
  • Drying out early. Return of precip by week's end. Partly sunny to mostly cloudy.
  • Highs in the upper 30s Monday, cooling to mid 30s for the remainder of the week.
  • Lows in the low 30s Monday morning. Dipping to mid 20s for the remainder of the week.

Western Washington
Weekend
  • Moderate rain and high terrain snow. Overcast.
  • Highs in the low 50s Friday, upper 40s Saturday, and mid 40s Sunday. Much cooler throughout the Cascades.
  • Lows in the low 40s Saturday morning, and upper 30s Sunday morning. Much cooler throughout the Cascades.
Next Week
  • Drying out early. Scattered showers to begin building in by mid week with widespread precip by week's end. Partly sunny to overcast.
  • Highs in the mid 40s. Much cooler throughout the Cascades.
  • Lows in the mid 30s Monday morning. Dipping to low 30s for the remainder of the week. Much cooler throughout the Cascades.

Washington State University