Pacific Northwest Heatwave Likely
The Pacific Northwest is going to feel the heat for the next week as mother nature opens up the oven door in what has the potential to be the longest stretch of hot weather in several years. Models are coming into agreement today that a strong ridge of high pressure will build across the region Friday and hold through most of next week. Low level winds at the surface will switch from onshore to offshore beginning on Friday. This coupled with a strong ridge of high pressure at the upper levels of the atmosphere will allow the heat to build over the weekend and last into next week. There is also the potential for some moisture over the weekend which could trigger thunderstorms over the Cascades and eastside. Most residents consider three or more days at or above 90 degrees in Portland as the benchmark for a Pacific Northwest heat wave. At the present time, forecast models are indicating the potential for as many as 5-6 consecutive days at or above 90 degrees between Friday and next Wednesday. Although models are still finalizing the exact details of the upcoming heat wave, it will most certainly be the hottest weather of the summer so far. Depending on the exact location of the building ridge of high pressure, we may have the potential for seeing temperatures reaching 100 degrees in Portland.
For historical perspective, Portland averages approximately 12 days at or above 90 degrees each year. So far this year, Portland has reached 90 degrees or higher twice. In 2009 Portland met or exceeded 90 degrees 24 times, setting a new record for number of 90 degree or higher days in a given year. In July and early August of that year Portland reached or exceeded 90 degrees 10 “consecutive” days in a row with three of those days at or above 100 degrees. During that heat wave Portland fell one degree short of its all-time high temperature of 107 degrees set in August of 1981. Vancouver, Washington set its all-time record high of 108 during that heat wave. Records in Vancouver date back approximately 125 years. The upcoming heat wave does not appear to be as hot as the 2009 heat wave, but will most likely be noted for its duration. Overnight low temperatures will also remain quite warm which will make it uncomfortable for those without air conditioning. Utilities will also see power demands increase as the heat sets in.
Columbian Newspaper Weather Blogger
Owner, Northwest Weather Consultants (NWC)
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