FastCast—Wednesday, Nov. 23 to Sunday, Nov. 27:
After an impactful storm that brought significant rain and impactful mountain snow to Washington state, weather will calm down through Thanksgiving, providing a good window of calm weather for cross-state travel. Expect a mostly cloudy Wednesday and partly to mostly sunny Thanksgiving Day. Wednesday and Thanksgiving will have highs in the low to mid 50s, with morning lows on Wednesday in the upper 30s to low 40s, and in the low to mid 30s on Thanksgiving. Showers return on Friday, continuing through the day. There will them be a break until late Saturday, and another system will impact the region into Sunday. Expect mostly cloudy conditions from Friday to Sunday, with highs in the mid to upper 40s and lows in the mid to upper 30s. Rain, mountain snow, and gusty winds are all potentially in the cards after Thanksgiving, so stay tuned, as impacts to travel are possible.
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Continue reading the full blog below!
Thanksgiving is usually wet and cloudy in Western Washington, but 2022 will be an exception. Partly to mostly sunny skies are expected, with warmer conditions than usual for parts of Western Washington. The NAM forecast for high temperatures on Thanksgiving is below.
Expect highs in Western Washington to generally be in the low to mid 50s, with some areas staying in the upper 40s. Eastern Washington will be much colder, with highs likely not making it out of the 30s.
An important note is that conditions will be good for cross-state travel prior to Thanksgiving, though upcoming systems after Thanksgiving do bear watching.
Let’s take a look at the extended forecast for after Thanksgiving from the GFS model.
Rain will likely return to the lowlands, as seen in the rain forecast through 11 PM Sunday.
Expect 0.4-1.5 inches of rain in the lowlands, most in potential Convergence Zone areas between Seattle and Mount Vernon. The coast will receive 0.8-1.25 inches, and Eastern Washington will get 0.1-0.5 inches.
The more impactful weather for post-Thanksgiving travel will be potential mountain snow. The GFS snow forecast through 11 PM Sunday is below. (Ignore the lowland snow near Everett, that is not in consensus forecasts).
The GFS shows significant snow of 12-24 inches at the passes and up to 24-36 inches at higher elevations. Areas north of I-90 in Eastern Washington have a potential to see a dusting to 8 inches of snow, with the most by far in the mountainous areas and closer to Idaho.
There is a lot of uncertainty with weather beyond Thanksgiving, so stay tuned for more information as details become more refined.
A note on Tuesday’s storm:
This storm significantly overperformed from forecast model projections. Total rain around the Puget Sound area ended up reaching 0.75-1.5 inches, much more than the 0.4-0.8 inches in the highest predictions.
This rain did cause some localized flooding and standing water, but was mainly beneficial after a record November dry streak.
Another interesting aspect of this storm was the stubborn cold air that remained in the valleys around Snoqualmie and Stevens Passes, producing a mix of heavy snow and freezing rain that clogged up the highways, as seen in the WSDOT image on Snoqualmie Pass on Tuesday afternoon.
This was originally going to be rain, but cold air near the surface worked its magic and kept snow going all day, eventually forcing a closure of I-90 eastbound around 5 PM Tuesday due to heavy snow and collisions.
This storm was an important reminder that despite the skill of our forecast models, they still have errors and can’t always account for the microclimate features of the Pacific Northwest.
Have a Happy Thanksgiving and stay tuned for more information about the post-Thanksgiving storm outlook!
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