General Weather/Earth Sciences Topics > Weather Conditions Discussion

Short term 10ºF temp rise

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CW7491:
shimon,

I used to live out in WA for a few years and it's a very interesting place to live with a weather station because you often see some huge variations due to extreme microclimates. Proximity to the sound and to the Cascades will do interesting things with just slight wind shifts. This looks like what happened in your case. If you notice, winds were very light out of the SW to WSW when your temps were down near freezing, but then the wind picked up and shifted to the north. Looking at your location, this north wind comes down a narrow valley from the Cascade foothills whereas the SW to WSW wind comes out of the Skagit Valley and the Puget Sound.

In the winter months, there is a phenomenon you're probably familiar with called the Frasier Outflow. This develops when there is a large pressure gradient due to high pressure over the Frasier plateau in BC and east of the Cascades. The air pushes down the Frasier River valley and results in very strong winds in the Puget Sound area, particularly in Bellingham. Usually this wind is a very cold wind, but in this case, it looks like it was a relatively warm wind. Take a look what happened at the Bellingham Airport around 11p on 16Nov ... https://www.weather.gov/wrh/timeseries?site=KBLI&hours=72

It looks like you were sheltered from this wind due to the terrain to your north and east, but you started seeing some of it make it down that narrow valley around the time you saw the temp spike and then it dropped off again and shifted back to the SW and your temp dropped back down. This is ultra-localized, so pretty interesting to have a weather station on your property to measure it.

If you're interested in reading more about local phenomena in the Puget Sound area, I highly recommend following Cliff Mass' blog (Professor at UW) and after just checking, he sure enough wrote about this very event in his latest post ... https://cliffmass.blogspot.com

CW2274:
A few months ago a member here, Randall, who only lives a couple miles from me as the crow flies, had a sudden increase of 12F higher than me, and this was at night as well. I was somewhat stupefied, then noticed he had a brisk east flow of wind, which comes off the Rincon Mts. My wind was dead calm. That caused down sloping winds, which compresses the air, making it much warmer. Happens here quite often. Think Santa Anna winds that Socal gets. Same thing. No idea if that applies here, though.

CW7491:
Definitely can get downslope warming and upslope cooling in the PNW, but usually these events are high pressure air masses to the east, blocked by the Cascades, that force themselves through valleys and the airmass pours into the Puget Sound region like filling a bowl. Strong ones will effect the whole region, while weaker ones will result in localized winds near those cuts in the Cascades. Typically it is a winter phenomenon and results in the moderate maritime airmass being replaced by a bitter cold continental airmass.

shimon:

--- Quote from: CW7491 on November 18, 2022, 11:49:52 AM ---shimon,

I used to live out in WA for a few years and it's a very interesting place to live with a weather station because you often see some huge variations due to extreme microclimates. Proximity to the sound and to the Cascades will do interesting things with just slight wind shifts. This looks like what happened in your case. If you notice, winds were very light out of the SW to WSW when your temps were down near freezing, but then the wind picked up and shifted to the north. Looking at your location, this north wind comes down a narrow valley from the Cascade foothills whereas the SW to WSW wind comes out of the Skagit Valley and the Puget Sound.

In the winter months, there is a phenomenon you're probably familiar with called the Frasier Outflow. This develops when there is a large pressure gradient due to high pressure over the Frasier plateau in BC and east of the Cascades. The air pushes down the Frasier River valley and results in very strong winds in the Puget Sound area, particularly in Bellingham. Usually this wind is a very cold wind, but in this case, it looks like it was a relatively warm wind. Take a look what happened at the Bellingham Airport around 11p on 16Nov ... https://www.weather.gov/wrh/timeseries?site=KBLI&hours=72

It looks like you were sheltered from this wind due to the terrain to your north and east, but you started seeing some of it make it down that narrow valley around the time you saw the temp spike and then it dropped off again and shifted back to the SW and your temp dropped back down. This is ultra-localized, so pretty interesting to have a weather station on your property to measure it.

If you're interested in reading more about local phenomena in the Puget Sound area, I highly recommend following Cliff Mass' blog (Professor at UW) and after just checking, he sure enough wrote about this very event in his latest post ... https://cliffmass.blogspot.com

--- End quote ---

Thank you for the informative, clear and excellent explanation.  Your analysis seems spot on.  I have perused the Cliff Mass Weather Blog previously but will take a closer look as I haven't visited it in a while.

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