The hottest temperatures of the summer are imminent, with most towns reaching the triple digits. How long will it last? And what weather concerns will we face as we transition away from the heat? Is there any rain in sight? In this blog we will address these questions.
First let's take a brief look at the weather pattern causing the heat.
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| 00z/Aug 14th Grand Ensemble forecast of 500 mb heights and temperatures valid 5 AM PDT Aug 14th |
As you can see from the map, a large area of high pressure encompassing Washington, Oregon, and Idaho. It looks like this ridge will stick around for several days, giving the Inland NW an extended period of hot weather. But if you are not a fan of hot weather relief is in sight. The weather pattern will shift this weekend, as indicated by the forecast weather pattern for Saturday shown below.
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00z/Aug 14th Grand Ensemble forecast of 500 mb heights and temperatures valid 11 AM PDT Aug 19th
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High pressure shifts into the central part of the US with a broad trough along the coast extending into the Inland NW.
The forecast temperatures reflect these trends, going from triple digit heat this week down into the 70s and 80s by early next week.
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| NWS High Temperature Forecast issued 230 PM August 14th valid Aug 15-21th, 2023 |
How do these temperatures compare to the June 2021 record heat wave? Not even close when several locations went above 110F, including 120F in Hanford, WA.
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| Map of high temperatures from June 29th, 2021 |
The nights of mid-August are also longer compared to those of late June. But that doesn't mean this heat wave should be taken lightly, as Excessive Heat Warnings and Heat Advisories are out for the region.
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| NWS Heat Warnings and Advisories as of noon, August 14th |
Some daily record high temperature records will be in jeopardy as well. Be sure to stay safe in the heat including:
- Wear sunscreen
- Drink plenty of water
- Avoid alcohol/caffeine
- Wear a hat and sunglasses
- Wear light clothing
- Find shade and take breaks
- Cool off in air conditioning when possible
Fire Weather Concerns This Week
Looking at satellite imagery Monday afternoon showed several active wildfires producing smoke across Oregon and southern British Columbia, with a few fires also over Washington, Idaho, and NW Montana.
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| Aug 14th (1256-231 PM PDT) Satellite Imagery showing several smoke plumes around the region. |
The hot and dry weather will likely yield increased smoke production from area wildfires over the next couple days.
The second concern is the wind. Typically in weather transitions with falling temperatures, the result is wind and this week is no different. The peak of the fire weather concerns currently looks to fall on Thursday as breezy west to southwest winds develop. Here is the forecast wind gusts for the region for the late afternoon.
While these winds may not seem too noteworthy, when combined with the hot and dry conditions yields a critical fire weather combination. The HDWI (Hot Dry Windy Index) is showing very high chances of reaching or exceeding the 90th percentile (which means top 10% of hot/dry/windy combination). This means that 1 of at least every 10 days doesn't see conditions this extreme.
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Probability of Hot, Dry, Windy Index exceeding 90th percentile
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Thus Thursday has the potential for rapid fire spread with any new or existing fires. Please use extra caution!
Outlook for Next Week
Not only will the trough next week bring cooler temperatures, models are showing a favorable setup for some precipitation as well. The latest 6-10 temperature and precipitation outlooks favor normal temperatures and elevated odds of above normal precipitation
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| Climate Prediction Center 6-10 day temperature and precipitation outlook issued Aug 14th, 2023 valid Aug 20-24th, 2023 |
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