AgWeatherNet Weekly Weather Outlook for May 29 to June 4, 2020

Thunderstorms Saturday with more seasonable conditions through the week

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

Discussion:

The main weather story this outlook period is the rain showers and severe thunderstorms that are anticipated for eastern Washington Saturday with western Washington expected to see widespread rain without much threat for thunderstorms. Shower and thunderstorm activity look to be thanks to the upper low that had been parked off the coast of southern California the last few days. This upper disturbance is making its way north into the Pacific Northwest creating ample instability aloft. A weak jet streak across British Columbia also looks to aid in creating instability aloft, crucial for thunderstorm development. The thunderstorms likely for Saturday will be enhanced with ample moisture streaming into the Pacific Northwest from the south. This appears to be aided by a weak tropical plume moving into the Pacific Northwest courtesy of a surface circulation centered over the Gulf of Alaska. Dew points look to reach the mid 60s in parts of eastern Washington by Saturday morning, testifying to the moist boundary layer over the region.

Thunderstorm and shower activity look to generally move in from the south with an isolated shower or two beginning as early as Friday night, however, the bulk of the showers aren't expected to begin until Saturday morning. Showers and thunderstorms are expected through the day and most of the night Saturday before beginning to trend dry from south to north late Saturday night with northern Washington likely to not totally trend dry until Sunday afternoon. Western Washington is expected to cling to a few scattered showers through the weekend. Hot temperatures are also anticipated to turn more seasonable, and even slightly cooler than average, statewide after Saturday and into next week.

Some of the top risks associated with severe thunderstorms include instances of damaging wind, hail, and flash flooding. Flooding is particularly true for mountain areas where the impacts of heavy rain will be joined with melting snow, but it is not limited to there. Streambeds that are typically dry may see rushing water if they experience the heavy rain that is possible, and there could be instances of flooding in low lying areas. Blowing dust and possibly damaging winds are also a concern Saturday with gusts associated with thunderstorms capable of reaching 45+ mph. Please be alert to the high probability of hail in conjunction with some of the stronger storms as well. To follow real time and near real time updates on storm warnings, storm reports, and storm outlooks, follow this link to NOAAs storm prediction center webpage: https://www.spc.noaa.gov/. Rain totals Saturday look to range between 0.5" to 1" for western Washington and less than 0.1" to 1"+ in eastern Washington. Rain fall totals through eastern Washington will be highly variable depending on the tracks of thunderstorms and their associated heavy rainfall.

After Saturday's excitement, conditions look to become much more vanilla next week. Mostly seasonable, if not slightly cooler than seasonable weather, is expected after Saturday and through the week, as alluded to earlier. Conditions also look to remain dry Monday and Tuesday state wide. Some showers are anticipated to move into western Washington from the west on Wednesday thanks to a decaying cold front and its associated weak band of rain fall, a product of a robust surface cyclone that looks to move east along the Aleutian islands and into the Gulf of Alaska, essentially replacing the current circulation that has taken residence there. Scattered rain showers are to persist through the end of the week in western Washington. Upland parts of northern Washington and to a lesser extent, the Blue Mountains, will also likely see some light rain showers as well on Wednesday and even Thursday.

As we approach summer, mountain snowpack is melting at varied rates across Washington. As of Thursday, the National Water and Climate Center points toward three main scenarios in mountain regions of the state. For the Blue Mountains as well as mountainous regions north of Spokane, snow water equivalent (SWE) values lie in excess of 110% of climatological norms demonstrating that there continues to be healthy water content still stored in these areas. The Idaho Panhandle, from which many rivers flowing into Eastern Washington are sourced, also exhibits above average SWE values for late-May.

The West Slopes of the Cascades, Okanogan Highlands, and Olympic Mountains all have near-average SWE values for late-May. This is also healthy and is going to be helpful in mitigating drought conditions, particularly in North Central Washington. The East Slopes of the Cascades are struggling to hold snowpack this late in the season with SWE values between 50% and 75% of normal. Some of this stems from the same lack of precipitation that has led to severe drought conditions along the US 97 corridor.


8 to 14 Day Outlook - June 5, 2020 to June 11, 2020
  • Well below average temperatures and above average precipitation are expected during the 8 to 14 day time frame.

Important Points about Next Week's Weather

South Central Washington
Weekend
  • Wind: Light NE winds increasing Saturday with gusts around 25 mph. Winds shifting SW Saturday evening with gusts increasing to around 35 mph. Decreasing through the day Sunday. Gusts 45+ mph likely under any thunderstorm activity.
  • Precipitation: Scattered rain showers and thunderstorms moving in form the S/SW Saturday morning and lingering into the overnight before trending dry. Hail possible with any severe thunderstorms. Remaining dry Sunday.
  • High Temps: Mid 90s Fri, mid 90s Sat, mid 70s Sun.
  • Low Temps: Mid 60s Fri night, low 50s Sat night, upper 40s Sun night.
  • Sky Cover: Sunny Fri, mostly cloudy Fri night, mostly cloudy Sat, mostly cloudy Sat night, mostly sunny Sun, partly cloudy Sun night.
Next Week
  • Wind: Light and generally N Monday. Switching to S/SW Tuesday and becoming breezy at times during the day, especially though the Basin.
  • Precipitation: Dry conditions expected.
  • High Temps: Upper 70s Mon, low 80s Tue, mid 80s Wed, low 80s Thu.
  • Low Temps: Low 50s Mon night, mid 50s Tue night, low 50s Wed night, low 50s Thu night.
  • Sky Cover: Mostly sunny to partly cloudy.

North Central Washington
Weekend
  • Wind: Light N/NE winds increasing Saturday with gusts around 25 mph through the Basin. Winds shifting SW Saturday evening with gusts increasing to around 35 mph through the Basin. Decreasing through the day Sunday. Gusts 45+ mph likely under any thunderstorm activity.
  • Precipitation: Scattered rain showers and thunderstorms moving in form the S/SW Saturday and lingering through the overnight. Hail possible with any severe thunderstorms. Trending dry Sunday morning.
  • High Temps: Near 90 Fri, low 90s Sat, upper 60s Sun. Cooler in higher terrain.
  • Low Temps: Low 60s Fri night, mid 50s Sat night, mid 40s Sun night. Cooler in higher terrain and deep valleys.
  • Sky Cover: Sunny Fri, mostly clear Fri night, partly sunny Sat, mostly cloudy Sat night, partly sunny Sun, partly cloudy Sun night.
Next Week
  • Wind: Light and generally SW yet variable. SW winds becoming breezy at times during the day though the Basin.
  • Precipitation: Chance for a few scattered mountain rain showers Wednesday. Otherwise dry conditions expected.
  • High Temps: Mid 70s Mon, upper 70s Tue, upper 70s Wed, upper 70s Thu. Cooler in higher terrain.
  • Low Temps: Near 50 Mon night, low 50s Tue night, near 50 Wed night, low 50s Thu night. Cooler in higher terrain and deep valleys.
  • Sky Cover: Mostly sunny to partly cloudy.

Eastern Washington
Weekend
  • Wind: Light NE winds increasing Saturday with gusts around 25 mph. Winds shifting SW Saturday evening with gusts increasing to around 35 mph. Decreasing through the day Sunday. Gusts 45+ mph likely under any thunderstorm activity.
  • Precipitation: Dry Friday except isolated showers around the Blue Mtns. Showers and thunderstorms likely Saturday afternoon from the S/SW. Hail possible with any severe thunderstorms. Lingering isolated showers Sunday morning before trending dry.
  • High Temps: Mid 80s Fri, Low 90s Sat, mid 60s Sun.
  • Low Temps: Low 60s Fri night, upper 40s Sat night, mid 40s Sun night.
  • Sky Cover: Sunny Fri, mostly clear Fri night, partly sunny Sat, mostly cloudy Sat night, mostly sunny Sun, partly cloudy Sun night.
Next Week
  • Wind: Light and generally N Monday. Switching to S/SW Tuesday and becoming breezy at times during the day, especially though the Basin and Plaouse.
  • Precipitation: Dry conditions expected Monday. Isolated showers possible Wednesday and Thursday, particularly around the Blue Mtns.
  • High Temps: Near 70 Mon, mid 70s Tue, mid 70s Wed, low 70s Thu.
  • Low Temps: Near 50 Mon night, low 50s Tue night, near 50 Wed night, low 50s Thu night.
  • Sky Cover: Mostly sunny to mostly cloudy.

Western Washington
Weekend
  • Wind: Breezy with N flow on the coast Fri with gusts to 30 mph. Widespread breezy conditions with W flow and gusts to 25 mph Sat, light wind with W flow Sun.
  • Precipitation: Isolated mountain showers Fri. Widespread rain Sat, scattered rain Sun.
  • High Temps: Near 80 Fri, low 60s Sat, mid 60s Sun.
  • Low Temps: Low 50s Fri Night, mid 40s Sat Night, mid 40s Sun night.
  • Sky Cover: Sunny Fri, mostly cloudy Fri night, cloudy Sat, cloudy Sat night, partly sunny Sun, partly cloudy Sun night.
Next Week
  • Wind: Light winds with generally W and NW flow Mon-Thu, except on the coast where gusts may reach 30 mph Mon-Tue.
  • Precipitation: Mostly dry Monday and Tuesday with scattered showers moving in from the W Wednesday and lingering through the end of the week.
  • High Temps: Low 70s Mon, low 70s Tue, low 70s Wed, upper 60s Thu.
  • Low Temps: Mid 40s Mon night, mid 40s Tue night, upper 40s Wed night, mid 40s Thu night.
  • Sky Cover: Mostly sunny to mostly cloudy.

Like us on Facebook at https://www.facebook.com/AgWeatherNet
Follow us on Twitter at https://www.twitter.com/AgWeatherNet
Washington State University