No FastCast this morning. An update about the fire weather situation is below.
Saturday morning’s view from the NOAA GOES Weather Satellite shows the fire weather situation around the Pacific Northwest.
Smoke is present in the Puget Sound Lowlands, though not very thick in most areas. Note the two large smoke plumes in the Pacific Northwest. The largest plume, in Oregon and SW WA, is due to the Cedar Creek Fire in the Oregon Cascades, which grew by about 20,000 acres on Friday. The plume in Washington is a new fire near Skykomish (about 20 miles west of Stevens Pass) that has caused evacuations and a closure of US-2. There is a smaller plume between these that is the Goat Rocks Fire, which rapidly expanded yesterday, closing US-12 over White Pass and prompting evacuation orders near Packwood.
Surface smoke will increase through the day on Saturday. The HRRR forecast for surface smoke at 12 PM Saturday is below.
By noon, surface smoke will increase to moderate concentrations over the lowlands, likely more than what was observed on Friday. Conditions will get worse through the evening. The 8 PM forecast is below.
By 8 PM, the offshore flow will be slowly shifting back to onshore (southerly) flow. That will advect smoke from fires in the Cascades and in Oregon toward the lowlands. Air quality will be worst (moderate to unhealthy categories) Saturday evening. All people who are outside should take precautions. When smoke is heavy, it is best to stay inside.
Meanwhile, smoke aloft will also increase throughout the day, as seen at 8 PM.
We can expect moderate to heavy smoke aloft to continue through Sunday, potentially into Monday morning. Surface smoke will hang around through Sunday evening before clearing completely by Monday morning.
Fire weather conditions and the spread of existing fires will be worsened by very dry conditions forecast by Saturday afternoon. The HRRR relative humidity forecast is below.
Expect relative humidity to drop to 15-25%. This is very low for Western Washington and will not help with fire weather. Low humidity will be a driving factor of the fire growth in Skykomish.
Additionally, temperatures will be quite hot for September. The HRRR forecast for Saturday’s highs is below.
Smoke will likely limit highs to the mid to upper 80s. Areas near the water will be even cooler due to a northerly breeze. The hottest conditions will be found in the foothills and from the Tacoma area southward.
Finally, localized gap winds have been gusting most of the night in the Enumclaw and North Bend areas. The gusts at 9:40 AM are below.
Notice gusts of 25-40 mph near Enumclaw and North Bend. The 56 mph gust is at the summit of Crystal Mountain. Stronger winds (40-55 mph) have been recorded near gaps in Northern Oregon and Southern Washington.
Stay tuned to @The_Weatherman2 on Twitter for the latest updates. You can find links to air quality, Twitter, and wildfire information on the right side of the blog.
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