A cool & wet spring has turned into a hot summer, and more heat is likely
It’s been almost two weeks since my last post. Summer vacation interfered a bit, plus we keep real busy around here lately...lots of newscasts! Not as much time for blogging during the warm season.
That brief heatwave around the 7th gave us another 100 degree day, then temperatures cooled and SOME of you had quite a thunderstorm on Tuesday evening the 9th. That was mainly down around Salem. The Portland metro area has avoided any sort of overnight lightning event this year. Even though technically we didn’t have 3 days at/above 90 last week, anytime we get well above 95 it’s considered a heatwave.
Our 4th heatwave arrived Monday and today we topped out at 98 degrees. That makes today our 20th day at/above 90 degrees this season
August temperatures are running well above normal now. What a string of warm/hot Augusts...we haven’t seen a cool August since 2010!
The culprit is upper-level heights consistently higher than normal since late June. Right now we’ve got a strong upper-level ridge centered over Idaho.
That ridging keeps the marine layer quite thin and right along the coastline. Strong ridging means nature’s air conditioning (cool ocean air flooding inland) shuts down. It appears this setup may continue through the end of August as well. Take a look at the 500 millibar pattern (lines) and anomaly (colors) the next 7 days. This is around 18,000′ overhead
Then the 8-15 day forecast (ECMWF ensemble average) looks similar
Head down to 5,000′, use the GEM (Canadian) model instead, and the temperature anomaly is there for that last week of the month.
This is going to go down as a very warm August...once again. Let’s just hope we can avoid a setup that could give us strong easterly wind for high fire danger, or lots of thunderstorms. As you probably suspect, this is a very dry pattern. Today was our 42nd day without rain...in 11 days we’ll break into the top 5. Keep watering!
Tonight we are seeing a southerly upper-level flow bringing cloud cover and a few light showers north. The cloud cover overnight following a hot day is the perfect setup for a very warm night. We may only drop to 70 degrees...yuck. Of course the all-time record was set last year during the historic late June heatwave.
These records can be tricky to achieve for two reasons; they are based on the calendar day AND on Standard Time. For example, if we only drop to 70 around sunrise Thursday, it must stay at/above 70 all the way until 1am Friday to have that number stay on the books for August 19th. A strong marine push tomorrow evening could drop us below 70 before that time. We will see!
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