AgWeatherNet Weekly Weather Outlook Monday Update for Mar 9 to Mar 15, 2020

Impactful weather system Friday and implications for cold hardiness

Craig Oswald, Field Meteorologist, 509-786-9256

Discussion:

Monday night temperatures look to dip dangerously low for some perennial tree fruit crops in southern Washington. Roughly, a line west to east from near Vantage to Garfield and south has the probability to see damaging temperatures tonight (Monday). Temperatures are expected to dip to around the mid 20s in some places. With the early awakening of some tree fruits, such as cherries for example (the Gibeaut cherry cold hardiness model can be found here: https://weather.wsu.edu/?p=109450), due to an unusually warm winter, lethal threat for 10% of buds has raised to around 30°F in some locales. A temperature drop to the mid 20s may approach the 50% bud kill threshold and precautions should be taken. Grapes look to be just coming out of dormancy as well in locations in the southern half of the state, but their cold hardiness ratings remain in the single digits http://wine.wsu.edu/extension/weather/cold-hardiness/.

Temperatures look to slightly recover through mid week with overnight lows expected to approach but not exceed the 10% kill threshold. However, PLEASE CLOSELY TRACK LOCAL NEWS WEATHER REPORTS AND FORECASTS FOR THE MOST UP TO DATE TEMPERATURE INFORMATION THIS WEEK.

A cold air surge is expected after the passage of Fridays weather disturbance as well. Temperatures may reach as low as the low 20s in southern Washington during the overnights through the weekend and subsequently the 50% bud kill level for certain tree fruits may be attained. Northern Washington may see low temperatures reach the upper teens this weekend. However, since tree fruits remain dormant or just beginning to come out of dormancy this weekend in this region, their cold hardiness remains robust enough that the colder temperatures are not expected to make an impact at this time. This cold air surge will continue to be monitored with an update released on Thursday.

Light winds and a chance for precipitation can be anticipated beginning Tuesday afternoon. The expected precipitation is in association with a low pressure system that looks to move into northern British Columbia. Western Washington will likely see light rain and mountain snow move in from the northwest Tuesday afternoon. Northern Washington is expected to see mostly light upland snow showers and eastern and southern Washington a stray scattered shower or two at best.

Conditions look to trend dry through Wednesday and remain so Thursday with only a few lingering scattered showers anticipated through the Cascades and western Washington.

Friday morning looks to see the return of widespread rain and snow showers statewide. Snow levels may lower as far down as 800 feet in eastern Washington as colder air moves in with the precipitation. Lows currently look to reach near the upper teens for eastern and northern Washington and low 20s for southern Washington during the weekend. Temperatures in western Washington are expected to cool to near the mid 20s during the overnights for the weekend. Snow accumulations will likely be between trace at lower elevations to a foot+ through the high Cascades. Conditions look to trend dry through Saturday night with a dry but chilly day on Sunday expected.


Key Points:

Temperatures
  • Cool Monday night with temps rebounding to near normal for much of the week
  • Colder air expected to move in Friday and linger into next week

Precipitation
  • Rain showers in western Washington and mountain snow Tuesday afternoon before trending drier Wednesday with a few scattered showers remaining.
  • Snow down to pass levels.
  • Mostly a low threat for a passing scattered rain/snow and upland snow shower for Washington east of the Cascades beginning Tuesday night and moving NW to SE.
  • Widespread lowland rain and upland rain/snow starting Friday morning, transitioning to upland snow Friday night.

Wind
  • Generally light winds continue through the week yet look to become slightly breezy at times. Wind broadly from a W/SW direction.

South Central Washington
Remainder of the Week
  • Dry much of the week. Low threat for a scattered rain shower or two Wednesday. Lowland rain and upland mixed precip Friday afternoon/evening, transitioning to snow in upland areas Friday night. No significant accumulation expected. Sunny to overcast.
  • Highs in the low 60s Tuesday and Wednesday, upper 50s Thursday, mid 50s Friday.
  • Lows in the mid 20s Tuesday morning, upper 30s Wednesday morning, and mid 30s Thursday and Friday mornings.

North Central Washington
Remainder of the Week
  • Mostly dry with a slight chance for a few rain/snow showers and upland snow showers Tuesday night and lingering primarily through Wednesday. Widespread snow showers move in from the NW Friday morning. Light accumulations in lowland areas and a few inches of accumulation in upland areas can be expected. Mostly sunny to overcast.
  • Highs in the mid 40s Tuesday, low 50s Wednesday, upper 40s Thursday, and mid 40s Friday. Cooler throughout higher terrain.
  • Lows near 20 Tuesday morning, low 30s Wednesday morning, upper 20s Thursday morning, and low 30s Friday morning. Cooler throughout higher terrain.

Eastern Washington
Remainder of the Week
  • Dry much of the week. Low threat for a scattered rain shower or two Wednesday. Lowland rain and upland mixed precip Friday afternoon/evening, transitioning to snow Friday night. No significant accumulation expected toward the south, with a couple of inches possible toward the north. Sunny to overcast.
  • Highs near 50 Tuesday, low 50s Wednesday, and upper 40s Thursday and Friday.
  • Lows in the mid 20s Tuesday morning, mid 30s Wednesday morning, and low 30s Thursday and Friday mornings.

Western Washington
Remainder of the Week
  • Light rain showers and mountain snow showers begin to move in from the NW Tuesday afternoon. Trending dry through the day Wednesday with only a few scattered showers lingering through Thursday. Light to moderate rain and mountain snow returns Friday morning with several inches of accumulation at pass levels expected. Mostly sunny to overcast.
  • Highs in the low 50s Tuesday, Wednesday, and Thursday. Mid 40s Friday. Much cooler throughout the Cascades/Olympics.
  • Lows near 30 Tuesday morning, upper 30s Wednesday morning, and mid 30s Thursday and Friday mornings. Much cooler throughout the Cascades/Olympics.

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