All heat waves are not the same.
Some are warmer than others, some are short (a day), others last up to 5 days, some have rapid temperature rise and fall, while others rise slowly and fall rapidly – or vice versa . This won’t be a record, but will last more than 4 days.
We’re in the warmest part of the year right now (see below), so a heatwave to visit is not out of the question (see SeaTac temperatures below, arrows are today, evening). Multi-middles are in red, record highs are in yellow).
The upcoming warm period will be fairly exhausted west of the Cascades, but more noticeable east of the Cascades.
Here are the latest predictions from the NOAA/NWS National Blend of Models (NBM), which combine models, observations, and statistics. NBM did a great job with the last heatwaves!
In Seattle (below), highs will rise to 80s highs Monday and 90s lows Tuesday and Wednesday, slowly dropping to over 80s on Thursday and Friday. And temperatures above 80 continued for several more days.
The keep-warm time is long, so make lots of ice cubes and clean your window fan blades.
But the lows will drop as low as mid-60s per night, so cooling will be possible.
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But east Washington will be a different story….and a hot one. Highs should rise to 110 or 111F Wednesday through Friday, with lows only dropping to around 70F.
That would be annoying.
Warm weather will be associated with the formation of high pressure peaks over the eastern Pacific Ocean. The amplitude of this high pressure (or peak) will peak on Monday night
Altitude 500 hPa on Monday night. Red is much higher than usual
The mountain range weakened slightly and moved eastward on Thursday. This slowly changing peak is why the heat continues for so long.
Thursday afternoon
Color is anomalous to normal within standard deviation.
There are some people who are concerned about wildfires. The heat itself will not cause a fire, although it will contribute to the drying of the fuel surface. But the grass in eastern Washington was dry enough to burn.
What is needed is ignition and wind. Ignition we can control (except lightning). But what about the wind?
The big threat is towards the end of the heatwave over the weekend, when cooler air moves into western Washington resulting in higher pressure there and larger pressure differentials over the Cascades.
The Hot Dry Wind Index combines a measure of dry and windy conditions showing high values (yellow and red) east of the Cascades on Friday afternoon (see below).
We better be careful!
