What Role Does Wildfire Smoke Play on Radio Signals? - Radio World

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We asked WEWS(TV) Cleveland meteorologist Allan Nosoff

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Normally, the Cleveland, Ohio skyline is clearly visible from the Edgewater Fishing Pier along Lake Erie. Meteorologist Allan Nosoff shared with us this photo of how the thick wildfire smoke blurred the sky on the morning of Thu., July 16. View how the skyline looks on a normal day from the same spot here.<br>Nick’s Signal Spot is a new feature in which Nick Langan explores RF signals, propagation, new equipment and related endeavors.

If you stepped outside late last week in the Great Lakes, northeast or mid-Atlantic, what had originally been forecasted as sunny, hot days were blanketed by rather thick smoke.

In places like Detroit, on July 16, the air quality index reading reached a level of 724 from Canadian wildfire smoke. That’s the worst AQI since 1999, when such records have been kept.

And amidst the rather large area of high pressure — referred to by many as a “heat dome” — radio signals last week across the Midwest were rather all over the place.

Several Midwest long-distance radio enthusiasts, or DXers, took full advantage July 15–18, including Andrew Knafel in Norton, Ohio, west of Akron.

Knafel managed to catch signals stretching down to Raleigh and Roanoke to the southeast, Toronto to the northeast, and Chicago to the west.

It begged the question: What was the smoke’s role in these VHF band conditions?

Greater Cleveland served as the quasi-nerve center for both the DX signals and the thick smoke. WEWS(TV) meteorologist Allan Nosoff — himself an avid radio DXer — has been following the conditions closely.

Cherry on top

Did the smoke strengthen the tropospheric enhancement? Did it even ignite it?

Nosoff told Radio World that the presence of the heat dome was the key. While no two heat domes share the exact same orientation or strength, they help produce regional signal enhancement.

As we’ve explored in previous coverage on how weather patterns bend FM signals, when those temperature inversions are present, they trap radio frequency energy near the ground, carrying distant broadcasts potentially several hundred miles past their normal coverage areas.

“Wildfire smoke is essentially the cherry on top of the heat and humidity inversion cake,” Nosoff told us. “It is a positive feedback loop that only intensifies the inversion and thickens the atmosphere with the particulate matter."

He provided an on-air explainer to his WEWS viewers, that included 106.9 WOOD(FM) from Muskegon, Mich., coming in on his car radio right over a local WTAM(AM) translator.

But the presence of a heat dome explains why this event acted very differently from the wildfire smoke that blanketed the region back in June 2023.

There were no tropospheric anomalies involved with that prolific smoke event three years ago across the Great Lakes and northeast — and the air temperatures were much different.

“There was no heat dome in 2023. In fact, it was a below-average pattern with an upper-level low and northeast wind,” Nosoff explained. “With no heat and humidity to create the initial inversion, there is no layer to ‘trap’ the smoke and amplify the tropospheric ducting.”

The altitude of the smoke itself also plays a role in how effectively signals bend.

"Even if the smoke doesn’t get to the ground, as long as there’s an inversion, it will help intensify signals to a degree," Nosoff said.

"Having it all the way to the ground gets more ducting involved and better DXing results," he told us.

Why all the smoke?

To his northeast Ohio audience, Nosoff described all the wildfire smoke as the “soup in the sky.”

Beside the radio and TV reception byproducts, many have been alarmed by the prevalence of the smoke and its effects on your breathing.

The higher the AQI, the more it affects air quality.

For readers in places like California, Colorado and much of western Canada, there have been many such instances of prominent smoke over the last decade.

Separating weather from climate — did Nosoff find any commonalities between the most recent eastern U.S. smoke events?

"Both the 2023 and 2026 featured a rapid onset of El Niño," he explained, "transitioning quickly out of La Niña conditions toward a potential super El Niño."

When the Pacific Ocean changes as quickly as it has, he said, it drives amplified global weather patterns, creating dry spells and windy conditions across Canadian forests ripe for fires.

Lakeside listening

Nosoff has been able to take advantage of the frequent tropospheric enhancement his location near the lake in Cleveland has offered. It’s inspired some innovative content about radio reception he’s been able to share with his News 5 Cleveland...