Pesky pattern to keep West cool, dreary in the coming days
Mother Nature flipped the seasons switch shortly after May began, plunging much of the western United States into a cool and dreary pattern more akin to March. AccuWeather forecasters say more of the same is on the way for the next day or two, but a weather curveball late this week is set to usher in good news for fans of warm weather.
Places like Seattle and Portland, Oregon, had a single chilly day to welcome May, but quickly rebounded and experienced two days with high temperatures above the historical average. The warmup was short-lived as temperatures came crashing down at midweek to levels 10-15 degrees Fahrenheit below what is typical.
Farther south, Las Vegas has only had one day so far this month where the mercury soared above the historical average temperature of 84 degrees. The city hit 89 back on May 1 and hasn't been able to reach the 80s since.
Forecasters say the cool weather culprit is a persistent, pronounced southward dip in the jet stream in place over the West.
High temperatures into the middle of this week will remain below the historical average for places like Reno, Nevada, and San Francisco.
In addition to the persistent chill, the dip in the jet stream also left the region open to a train of smaller storms. These storms began to track through the area late in the week. Reports of between 1-2 inches of rain south of Portland on Monday evening led to flooding in some spots.
Last week on Friday alone, Seattle recorded 0.70 of an inch of rainfall. This dreary day accounted for about 37 percent of the rainfall the Emerald City typically records for the entire month of May.
Major pattern flip to bring dramatic change late this week
As the pesky pattern in the upper levels of the atmosphere begins to break down this week, warm-weather lovers should prepare to rejoice.
"An expansive area of high pressure is expected to build along the West coast late this week and continue into Mother’s Day weekend, promoting drier and much warmer weather," AccuWeather Meteorologist Reneé Duff said.
High temperatures will jump as much as 20-30 degrees in a week's time for many locations.
"This will translate to high temperatures climbing into the 80s F or even higher along the Interstate-5 corridor of the Pacific Northwest, which is about 10-15 degrees Fahrenheit above the historical average," Duff explained.
Over the weekend, conditions are set to become downright hot for many up and down the coast. While cities such as San Francisco may see some cooler ocean air that keep temperatures near 80 F on Saturday and Sunday, inland cities may not be so lucky. Portland is set to surge into the mid 90s by Sunday, which would easily break the current record for the date of 91 degrees. Even Seattle may reach the 90 degree mark, which could also threaten temperature records.
Farther south, the heat may be even worse. Sacramento and Fresno, California, are forecast to reach the mid to upper 90s on Sunday, while Bakersfield may reach the triple digit mark.
"Not only will conditions quickly turn hot along the West Coast, many buildings in these areas, especially in Oregon and Washington, are without reliable air conditioning. This could make seemingly manageable heat much more problematic," AccuWeather Meteorologist Andrew Johnson-Levine explained.
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