Smoky & Warm on Wednesday, Cooling Ahead

FastCast—Wednesday, Sep. 21 to Sunday, Sep. 25:

Smoke has caused air quality issues around Puget Sound due to the Bolt Creek Fire as offshore flow brings easterly winds. It was also quite dry on Tuesday, with relative humidity dropping to the 20-35% range. On Wednesday, surface smoke will continue around Puget Sound. Although there will not be much smoke, it will be enough to degrade air quality, especially from Wednesday morning to mid afternoon. Highs will be on the warm side for late September, in the mid to upper 70s. A weather shift will occur late Wednesday through Thursday, with increasing clouds and decreasing temperatures. From Thursday to Saturday, expect partly to mostly cloudy conditions with highs in the mid 60s to low 70s. Temperatures increase with sunnier weather by Sunday, and highs will reach the mid to upper 70s. Lows through the week and the weekend will be in the low to mid 50s.

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Continue reading the full blog below!

Offshore flow has brought surface smoke into the lowlands at times on Monday and Tuesday, especially to the west of the Bolt Creek Fire. Air quality has been degraded around the region, sometimes into the “unhealthy” category.

Offshore flow will bring more surface smoke into the lowlands on Wednesday. The surface smoke forecast for 10 AM Wednesday from the HRRR model is below.

While this isn’t much smoke in the forecast (it has been underplaying it at times), it will be enough smoke to degrade air quality and bring a smell of smoke to the region.

In addition to surface smoke, Wednesday will bring above average temperatures to the region. The NAM forecast is below.

Expect highs in the mid to upper 70s in the lowlands. Eastern Washington and the Willamette Valley will reach the upper 70s to low 80s. 

Flow will switch to onshore by Thursday, pushing smoke out of Western Washington and bringing cooler temperatures. 

Temperatures will be 5-10 degrees cooler around the lowlands and Willamette Valley. Thursday’s highs from the NAM model are below.

Highs in Western Washington will only reach the upper 60s to low 70s. It will feel more like September.

However, that won’t last long, as the NOAA Climate Prediction Center is forecasting above average temperatures for the entirety of the Pacific Northwest for September 26th-30th.

There is a 50-70% chance of above average temperatures to close out September in Western Washington. Southeastern Washington has a 70-80% chance of above average temperatures. It appears likely that crisp fall weather won’t make it to the Pacific Northwest until at least early October.

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Puerto Rico Update:

Hurricane Fiona, now a strengthening Category 3 hurricane (125 mph winds) north of the Turks & Caicos, has left devastating flooding in Puerto Rico. The graphic below shows rain totals in the past 72 hours.

Many areas on the southward facing slopes of the island received an astounding 15-30 inches of rain in just three days. Even areas on the less-exposed northern side of the island have received 4-8 inches. Flooding has been catastrophic.

Additionally, most of the island remains in the dark, as the PowerOutage.us map from Tuesday night shows.

There is good news though…as officials estimate that power will be restored to most of the island within the next few weeks (much sooner than in Hurricane Maria).