AgWeatherNet Weekly Weather Outlook for May 22 to May 28, 2020

A cold Friday night followed by a drying and warming trend statewide next week

Craig Oswald, Field Meteorologist, 509-786-9256
Mark Ingalls, AgWeatherNet Intern
Joe Zagrodnik, Postdoctoral Research Associate

Discussion:

First, many AgWeatherNet stations recorded overnight low temperatures in the mid 30s throughout the upper Yakima Valley last night (Thursday night). And the Moxee.SE station even recorded 32 as the overnight low. Growers in the area, and south central Washington in general, please be alert that similar temperatures are likely again for tonight (Friday night). Temperatures aloft still look to be slightly warmer than last night, however, winds are expected to ease, and skies anticipated to clear during the overnight. This will help the overnight low to achieve more widespread mid-30s temperatures. It also would not be surprising if more 32 degree observations (the potential based on upper air temperatures and surface dew points) were made tonight, especially throughout the upper Yakima Valley. Cloud cover appears to have kept the Okanogan and north central Washington in general much warmer last night (Thursday night) than parts of south central Washington. However, growers here should also be on the alert for mid-30s overnight lows tonight (Friday night), again due primarily to clearing skies. The potential for lows to drop as far as 32 degrees very much exists through some of the usual cold spots in north central Washington as well.

Shifting gears to a more general overview of this periods weather, the upper low that has brought cooler temperatures to Washington state will continue to move through the state and to the southeast. In its wake, a brief modest ridge and more zonal flow looks to move into the Pacific Northwest providing some dry weather and warmer temperatures through the state on Saturday and Sunday. A band of decaying frontal type precipitation looks to begin moving into the state from the west Sunday evening. Any rain showers associated with this disturbance are anticipated to be quite scattered and generally light. Showers will mostly be relegated to the northern half of western Washington and the higher terrain of north central Washington. Conditions are expected to trend dry by mid week and remain so state wide through the remainder of the week as a zonal flow pattern aloft looks to return and take hold for a few days. As stated, temperatures will also be on the increase beginning Saturday with no further concern for overnight frost anticipated after tonight (Friday night). Looking farther ahead, a ridge is expected to build over the western US late next week, bringing above-normal temperatures to all of Washington by next Friday. Another upper low could potentially bring another round of thunderstorms to the state by next weekend, but details are still uncertain at this time.

For interest, unseasonably high rainfall values this week broke several daily rainfall records in Southeast Washington. On Wednesday, the Tri-Cities Airport in Pasco recorded 0.50 of rain, beating the old daily record of 0.39 set in 2006. Walla Walla saw quite a bit more rain  1.66, which exceeded the previous record of 0.92 which was set in 1960. Daily records were also set in Seattle (set in 2012) and Pullman (set in 1912). Many of the records set in the eastern half of the state were thanks to a persistent band of heavy showers that sat over the Blue Mountains and southern Palouse for much of Wednesday. This partially resulted from interactions between two upper-level lows centered near Washington at the time.

Over the past week, much of Eastern Washington saw rainfall values above 150% of climatological norms. Much of Western Washington also saw significant rainfall. This gives us an interesting look into the statistics of our region showing the rainfall divide between the west and the east. While percentages compared to normal were much higher east of the Cascades, areas to the west received more rainfall. The difference here is that we have reached the time of year where the east side of the state rarely experiences significant rain events.

In this, we can also see the divide between our wet season and our dry season. For the current water year, which begins October 1, there are many areas (particularly in Central Washington) where rainfall is below 70% of normal. The vast majority of precipitation in Central Washington falls during November through March. For the Tri-Cities, this time period sees 62% of annual precipitation, with Yakima and Wenatchee having 55% and 64% of their precipitation during those months. Many areas of Central Washington experienced about half of their average precipitation between November and March, which will be hard to make up during the dry season.


8 to 14 Day Outlook - May 29, 2020 to June 4, 2020
  • Well above 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
  • Wind: S to SW flow through the weekend. Breezy Friday with gusts to 25 mph, calming Friday night and remaining light Sat & Sun.
  • Precipitation: Isolated rain showers Fri, particularly around the Blue Mountains. Otherwise dry.
  • High Temps: Upper 60s Fri, low 70s Sat, upper 70s Sun.
  • Low Temps: Upper 30s Fri night, mid 40s Sat night, low 50s Sun night.
  • Sky Cover: Mostly sunny Fri, mostly clear Fri night, sunny Sat, partly cloudy Sat night, partly sunny Sun, mostly cloudy Sun night.
Next Week
  • Wind: Light and variable Mon-Thu, breezy conditions possible Fri with NE flow.
  • Precipitation: Dry conditions expected Mon-Thu.
  • High Temps: Low 80s Mon, low 80s Tue, mid 80s Wed, mid 80s Thu.
  • Low Temps: Mid 50s Mon night, low 50s Tue night, mid 50s Wed night, mid 50s Thu night.
  • Sky Cover: Partly to mostly cloudy Mon-Tue, sunny to partly cloudy Wed-Thu.

North Central Washington
Weekend
  • Wind: Breezy areas with W/SW flow Fri and gusts to 30 mph through the Basin. Light and variable Sat & Sun.
  • Precipitation: Isolated showers Fri & Sat with the highest chance being E of Republic. Otherwise dry.
  • High Temps: Low 60s Fri, low 70s Sat, mid 70s Sun. Cooler in higher terrain.
  • Low Temps: Low 40s Fri night, upper 40s Sat night, low 50s Sun night. Colder in higher terrain and deep valleys.
  • Sky Cover: Mostly cloudy Fri, mostly cloudy Fri night, sunny Sat, partly cloudy Sat night, partly sunny Sun, mostly cloudy Sun night.
Next Week
  • Wind: Remaining light and variable early in the week. Becoming breezy at times through the Basin mid week and remaining so until weeks end.
  • Precipitation: Isolated showers in the Okanogan Tue, otherwise dry.
  • High Temps: Mid 70s Mon, upper 70s Tue, upper 70s Wed, low 80s Thu. Cooler in higher terrain.
  • Low Temps: Low 50s Mon night, upper 40s Tue night, low 50s Wed night, low 50s Thu night. Cooler in higher terrain and deep valleys.
  • Sky Cover: Partly to mostly cloudy Mon-Tue, sunny to partly cloudy Wed-Thu.

Eastern Washington
Weekend
  • Wind: Breezy and windy SW winds to ease through Friday night. SW and light yet breezy at times Saturday. Becoming light and mostly SW to SE Saturday night and remaining so for Sunday.
  • Precipitation: Any lingering scattered rain showers to trend dry through Friday night. A few light showers likely to remain over the Blue Mtns into Saturday before trending dry. Conditions expected to remain dry for the weekend.
  • High Temps: Low 50s Fri, near 60 Sat, upper 60s Sun.
  • Low Temps: Upper 30s Fri night, near 40 Sat night, mid 40s Sun night.
  • Sky Cover: Mostly cloudy Fri, mostly cloudy Fri night, partly sunny Sat, mostly clear Sat night, mostly sunny Sun, mostly cloudy Sun night.
Next Week
  • Wind: Mostly S/SW yet variable. Mostly light yet becoming breezier at times during the day.
  • Precipitation: Chance for a light rain shower or two through the Blue Mtns Monday, otherwise dry conditions expected for the week.
  • High Temps: Near 70 Mon, low 70s Tue, mid 70s Wed, mid 70s Thur.
  • Low Temps: Low 50s Mon night, upper 40s Tue night, upper 40s Wed night, upper 40s Thu night.
  • Sky Cover: Sunny to partly cloudy.

Western Washington
Weekend
  • Wind: Becoming calm to light and variable through Friday night and remaining so for the weekend.
  • Precipitation: Scattered rain showers to trend dry through the day Saturday. More rain showers expected to begin moving in form the west Sunday evening, primarily through the northern half of the region
  • High Temps: Near 60 Fri, mid 60s Sat, mid 60s Sun. Much cooler through the Cascades and Olympics.
  • Low Temps: Low 40s Fri night, mid 40s Sat night, low 50s Sun night. Much cooler through the Cascades and Olympics.
  • Sky Cover: Mostly cloudy Fri, partly cloudy Fri night, partly sunny Sat, partly cloudy Sat night, mostly cloudy Sun, mostly cloudy Sun night.
Next Week
  • Wind: Mostly W yet variable through the week while remaining light to slightly breezy at times.
  • Precipitation: Scattered rain showers to become more consistent Monday and slowly trend dry through Monday night and Tuesday with the northern half of the region to see most of the shower activity. Dry for the remainder of the week.
  • High Temps: Upper 60s Mon, low 70s Tue, mid 70s Wed, low 80s Thu. Much cooler through the Cascades and Olympics.
  • Low Temps: Upper 40s Mon night, mid 40s Tue night, mid 40s Wed night, upper 40s Thu night. Much cooler through the Cascades and Olympics.
  • Sky Cover: Partly cloudy to overcast.

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