For the second time this summer, a major heat wave is ahead for the Pacific Northwest. The forecast below from The Weather Channel shows the expected temperatures across the Northwest.
Notice the incredible 105°+ temperatures in Portland…again. Most areas of the Northwest will come close to or eclipse 100 degrees.
As the heat wave is quickly approaching, NWS Seattle has upgraded the Excessive Heat Watch to an Excessive Heat Warning, in effect from 12 PM Wednesday to 7 PM Saturday. This is our area’s second Excessive Heat Warning of 2021. The alert is below.
The key points for this alert is that it will be very hot (90s to around 100), and nighttime lows will only be in the mid-60s, and even those temperatures will only last for a few hours (temps will be in the 70s most of the night away from the water).
Below is a graphic from NWS Seattle showing Friday’s highs in Western Washington.
Wow! Sweltering temperatures up to 98 degrees in parts of the Puget Sound area! Not as hot as June’s heat wave, but only a few degrees cooler. Areas north of Seattle will be “cooler”, in the upper 80s to low 90s. Areas near the water and on the coast will be the coolest spots.
However, there is one thing that could lower these temperatures…smoke.
Smoke will potentially be moving in aloft and near the surface on Thursday. Smoke aloft will move in from California and Eastern Washington. Below is the forecast for smoke aloft at 4 PM Thursday.
Moderate concentrations of smoke aloft over Western Washington at this time. This would likely lower temperatures by a couple degrees. Thursday is forecast to be in the mid 90s for most of the area, so smoke-impacted temperatures could be in the upper 80s to low 90s depending on how much solar radiation is deflected by the smoke.
Additionally, near-surface smoke may move into Western Washington from fires in Eastern WA & BC due to light offshore flow. Here is the near-surface smoke forecast for 4 PM Thursday.
Near-surface smoke is less certain and likely lighter in concentration, so its impact on temperatures can’t be accurately seen now. Impacts on air quality aren’t certain either, but air quality will likely degrade to the “moderate” category, or possibly “unhealthy for sensitive groups”, but AQI impacts will be a wait-and-see situation.
Bottom line with smoke: Even if smoke is present, it’ll still be hot (upper 80s to mid 90s) in Western Washington. Smoke will reduce temperatures by a few degrees, but the impact of smoke is still uncertain. Stay tuned as more information becomes clear about high temperatures and smoke.
Be sure to prepare for the heat and take adequate precautions. If we learned anything from June’s extreme heat, it’s that taking heat precautions saves lives. Below is the Weather Underground forecast for Federal Way.
The hottest days will be Wednesday through Saturday, with temperatures in the upper 80s to low 100s. Highs from Thursday to Saturday are subject to change due to potential smoke. Also notice lows in the low-mid 60s on the hottest days. A cooldown begins by Sunday!
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