AgWeatherNet Weekly Weather Outlook for February 17 to February 23, 2018

Stormy This Weekend; Much Colder Early Next Week

Nic Loyd, Meteorologist, 509-786-9357

A major pattern change will occur this weekend, and should be accompanied by a potentially hazardous spectrum of weather issues. This meteorologically dynamic interval begins with stormy conditions this weekend, and switches to much colder temperatures early next week.

Saturday is likely to be a relatively mild day, with rain in portions of the lowlands, and even some snow in northeast Washington. The mountains can expect heavy snowfall, but the main issue is likely to be the widespread strong winds, as a robust low pressure system passes along the WA/British Columbia border. Damaging gusts of 55+ mph are possible across much of the region, and mainly in central and southern areas. Changes begin on Saturday night, as cold air slowly begins to infiltrate the state.

Although certain areas such as the mountains are forecast to receive much less precipitation by Sunday (relative to Saturday), previously rain-shadowed regions like central Washington may actually see a slight increase in light precipitation chances as the modified arctic front transits the state. Depending upon how quickly the cold air advances, and how much moisture is remaining, light lowland snowfall is possible on Sunday. As conditions begin to dry out, Sunday night is anticipated to be the first time of notable cold danger due to rapidly falling temperatures.

Despite drier and eventually calmer weather, early next week should be cold day and night, with well below normal temperatures. Highs in the coldest lowland areas such as around Pullman and Spokane may only reach the 20s. Lows in the 20s and even teens are likely in western Washington, while locations east of the Cascades are set to observe teens and even single digit morning values.

The details are unclear later in the period, but it seems that most of the critical conditions are poised to occur during the first part of this outlook time frame. A temperature moderation is likely, and a shift toward an increasingly unsettled regime is possible around mid next week; but how that transition unfolds is still to be determined. A lowland snow event could occur, but the odds are low at this point. In any case, indications are that this wintry pattern shift may linger for a while.

Here are the main weather concerns:

  • Very windy on Saturday, with potentially damaging gusts of 55+ mph expected
  • Heavy mountain snow on Saturday
  • Possible light lowland snowfall on Sunday, and a flash freeze on Sunday night
  • Very cold early next week

For those who are concerned about potential crop damage from the upcoming cold spell, especially given the mild winter and the anticipated rapid rate of temperature decline, here are a few items to consider:

  • Regarding cold mitigation, the first night of major concern is Sunday night/Monday morning. Even if it is not particularly windy at your site, this will be a deep and well mixed (no inversion) cold air mass, and wind machines will not be effective.
  • Tuesday morning may be the coldest of the event, and clear, calm spots could be slightly more stable by mid week than Monday morning. Even so, this is not going to be a strong nighttime inversion cold event, as the entire atmosphere looks to remain rather cold well into next week.
  • Starting on Tuesday morning, colder spots will be the ones with clear skies, light winds, stable conditions, and snow cover.

Temperatures
  • Initially mild this weekend.
  • Much colder by Monday.
  • Milder later next week.

Precipitation
  • Western rain, eastern rain or perhaps snow, and heavy high-mountain snow on Saturday.
  • A chance of rain or snow on Sunday.
  • Drier by Monday.
  • A slight chance of precipitation later next week.

Wind
  • Very windy (southwesterly winds) on Saturday.
  • Breezy to windy (northerly winds) on Sunday into Monday.

8 to 14 Day Outlook - February 24, 2018 to March 2, 2018
  • Overall, near to below average temperatures and near to above average precipitation are expected during the 8 to 14 day time frame.

Important Points about Next Week’s Weather

South Central Washington
  • Normal conditions for this time of the year would be highs in the upper 40s to mid 50s and lows in the upper 20s to mid 30s.
Weekend
  • A slight chance of rain on Saturday, and a slight chance of rain or snow on Sunday.
  • Highs in the 50s on Saturday, and upper 30s to 40s on Sunday.
  • Lows in the 30s to low 40s on Saturday morning, and upper 20s to 30s on Sunday morning.
Next Week
  • Mostly dry. A slight chance of snow or rain later in the week.
  • Highs in the 30s early, and warmer later in the week.
  • Lows in the mid teens to mid 20s on Monday morning, and then colder, and warmer later in the week.

North Central Washington
  • Normal conditions for this time of the year would be highs in the 40s and lows in the mid 20s to around 30.
Weekend
  • A chance of rain or possibly snow on Saturday, and a chance of snow on Sunday.
  • Highs in the 40s on Saturday, and mid 30s to low 40s on Sunday.
  • Lows in the upper 20s to mid 30s on Saturday morning, and mid 20s to mid 30s on Sunday morning.
Next Week
  • Mostly dry. A slight chance of snow or rain later in the week.
  • Highs in the low to mid 30s early, and warmer later in the week.
  • Lows in the mid teens to low 20s on Monday morning, and then colder, and warmer later in the week.

Eastern Washington
  • Normal conditions for this time of the year would be highs in the 40s to low 50s and lows in the upper 20s to low 30s.
Weekend
  • Rain likely or possibly snow on Saturday, and light snow or perhaps rain likely on Sunday.
  • Highs in the mid 40s to low 50s on Saturday, and upper 20s to 30s on Sunday.
  • Lows in the upper 20s to mid 30s on Saturday morning, and mid 20s to low 30s on Sunday morning.
Next Week
  • Mostly dry. A slight chance of snow or rain later in the week.
  • Highs in the mid to upper 20s early, and then warmer.
  • Lows in the teens on Monday morning, and then colder, and warmer later in the week.

Western Washington
  • Normal conditions for this time of the year would be highs in the low to mid 50s and lows in the mid 30s to low 40s.
Weekend
  • Rain on Saturday, and a chance of rain transitioning to snow on Sunday.
  • Highs in the mid 40s to mid 50s on Saturday, and upper 30s to mid 40s on Sunday.
  • Lows in the upper 30s to mid 40s on Saturday morning, and 30s on Sunday morning.
Next Week
  • Mostly dry. A chance of rain or perhaps snow later in the week.
  • Highs in the upper 30s to low 40s on Monday, and then warmer.
  • Lows in the upper teens to 20s on Monday morning, and then colder, and warmer later in the week.

Washington State University