Fires and hurricanes in the West

Despite the lowest number of total burned acres in the U.S. to date in more than 10 years, three major wildfires broke out that sent air pollution levels into the “hazardous” category in the Spokane vicinity. In the Coeur d’Alene region, “very unhealthy” readings were reported Saturday afternoon that got worse Saturday night and early Sunday.

Last Saturday afternoon, according to AirNow, Spokane recorded an Air Quality Index of 429, but a reading of 489 was reported in the northern portion of Spokane, the worst in the entire country. In Coeur d’Alene, air quality levels went to 238. Other stations in North Idaho reported readings in the “unhealthy” to “very unhealthy” category Saturday. The air quality becomes “hazardous” when the readings top 300.

Here in the Inland Northwest, according to the “State of the Air” report from the American Lung Association, we have averaged over 250 days a year with very good air quality. However, we do get long stretches with dry and stagnant conditions that increase the levels of bad air. The smoke from large wildfires, such as the current ones in eastern Washington, has been the primary reason for our region's recent poor air quality.

As of this writing, it looks promising for some much-needed rainfall and better air quality across the Inland Northwest. As I mentioned last week, it’s been a very dry summer in Coeur d’Alene and the rest of the Inland Northwest. For the summer of 2023, only 0.68 inches of rain has fallen in Coeur d’Alene. This is well below the average summer precipitation to date, beginning June 21, of 1.97 inches. At the Spokane International Airport, only 0.37 inches of rain has fallen this summer.

The moisture expected in the region this week would be coming from the remnants of Hurricane Hilary. The big storm was as strong as a Category 4 hurricane and has been moving northward from the eastern Pacific Ocean near Baja California. Hilary weakened as it moved over colder water and land, but a tropical storm warning was issued for Southern California late last week. This was the first time in recorded history that a tropical storm warning was issued for any portion of the Southwestern U.S.

Sea-surface temperatures off the California coast are not very warm as the ocean currents move colder water southward from the north. As of the weekend, readings near the Southern California coast were in the upper 60s. Tropical systems require ocean temperatures to be at least 80 degrees to maintain a strong intensity. However, Hilary was a strong Category 3 hurricane and was moving quickly when it was near Baja California. As a result, the storm reached California as a tropical storm, a very rare event.

There have been many systems that were the remnants of tropical systems that brought inclement weather to California, but the last time a tropical storm made landfall in Golden State was back in September of 1939. It was called the Long Beach Tropical Storm and resulted in about $2 million in damage. In today’s economy, that would be close to $45 million. It was the only system to make landfall in California as an official tropical storm during the 20th century.

In the 1800s, there were some major tropical systems that hit California. According to data from Wikipedia, a potential tropical cyclone made landfall near San Francisco in October 1854. On Oct. 2, the 1858 San Diego hurricane came very close to California and brought very high winds to Los Angeles and San Diego. It’s unclear how strong this storm was as the information was based upon newspaper accounts. In 1859, another possible tropical cyclone hit close to San Francisco.

By the time the storm moves through Southern California and Nevada early this week, it’s very possible that many areas will receive a “year’s worth of rainfall,” especially in the higher elevations of those two states. Massive and life-threatening flooding along with damaging winds were being felt across Southern California and Nevada on Sunday.

Although the huge tropical systems in the eastern Pacific will weaken dramatically as they move northward, the remnants of a tropical storm or hurricane can bring heavy rainfall and strong winds to parts of the western U.S. What’s left of Hilary may deliver some heavy rainfall to southern Idaho early this week along with the possibility of showers and thunderstorms to parts of the Inland Northwest.

The next full moon is Aug. 30, also known as a blue moon and will also be one of the best supermoons of the year. There’s also the chance of more showers and thunderstorms around this date before high pressure is expected to rebuild and bring dry and warmer weather in early September. Stay tuned.

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Contact Randy Mann at randy@longrangeweather.com.