More cool air, rain in the future for northwestern US

By Alex Sosnowski, AccuWeather.com Senior Meteorologist

May 15,2016; 12:22AM,EDT

 

 

Following predominately warm and dry weather since early April, wetter and somewhat cooler conditions are in the offing for the northwestern United States for the third week of May.
While the rainfall may not be welcomed by all, especially those with outdoor plans, moisture is needed following several weeks of mainly dry conditions. The atmosphere will oblige.
A storm already responsible for some rainfall and cooler air will cycle slowly inland into Monday.

The combination of cloud cover and rainfall will result in temperatures averaging near to slightly below normal for the several-day stretch ending later Monday.
"Sunshine will bounce back over the region during Tuesday and Wednesday," according to AccuWeather Meteorologist Eric Leister. "The weather on Tuesday and Wednesday will be the best part of the week for outdoor plans."
Along with the sunshine, temperatures will rebound, but not to the extreme levels experienced during most days during the first half of May.
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Highs in Seattle and Spokane, Washington, and Portland, Oregon, will be in the lower to middle 70s F during Tuesday and Wednesday. Temperatures will approach the upper 70s to near 80 in The Dalles and Pendleton, Oregon.
A large storm system with more rain will settle into the Northwest during the latter part of the week.
While this storm will not be terribly strong, it will be slow-moving and will help to soak the soil and keep temperatures lower during the daytime.

Multiple days of clouds, showers and lower temperatures are likely from Thursday to next weekend. Highs will generally range from the lower to middle 60s along the coast of Washington and Oregon to within a few degrees of 70 east of the Cascades.
Rainfall from the storm this weekend and later during the third week in May will help reduce the risk of wildfires in the short term.
Up until this weekend, very little rain has fallen in recent weeks.

Since late April, many areas of Washington and Oregon have only received 25 to 50 percent of normal rainfall. Some areas have received less than 10 percent of their average.
Temperatures during the first couple of weeks of May have averaged 5-10 degrees Fahrenheit above normal over much of the Northwest.

Daytime temperatures surged into the 70s and 80s, compared to normal highs in the 60s for many locations.
When the soil dries out during the spring and summer, the landscape can behave more like a desert. Strong sunshine can speed the drying process this time of the year. In turn, daytime temperatures can overachieve with the aid of strong sunshine and dry soil.
The cooler and wet conditions prior to the end of May are not likely to set a long-term trend for the Northwest. Heat, dryness and the risk of wildfires will ramp up as the summer progresses.