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Radio Magic on a Cold Winter’s Night

A January FM E-Skip opening after midnight that was so unusual

In the wee hours of Jan. 14, I experienced a radio propagation event I can only describe as magical. 

If you’re familiar with E-Skip propagation on the FM radio band, you likely associate it with happening in the summertime—and the data backs that up. Now into what will be my 20th year seriously DX’ing on FM, I’ve kept track of when E-Skip openings of more than 30 minutes in duration occur. The lion’s share takes place in May, June and July, with activity often stretching into early August.

Frequency of E-Skip Openings (April to August)
Frequency of E-Skip events since 2005 that I’ve tracked in New Jersey over the April to August period.

But as the late Pat Dyer (WA5IYX), a lifelong student of Sporadic-E, observed, there is also a secondary winter peak period.

Just after midnight on the 14th, I was finishing a walk with my dog, Judy. I noticed on my RabbitEars.Info FM autologger the reception of 92.9 KKXL(FM) from Grand Forks, N.D., approximately 1,230 miles from my location in southern New Jersey. Theoretically, it’s possible to hear that station via meteor scatter propagation, which I’ve written about before. However, that distance would be unusually far for that mode and I’ve never observed KKXL via meteor scatter in the past.

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Lo and behold, I checked DXmaps’ real-time QSO spots for six-meter ham contacts and they were active. It was an after midnight E-Skip opening! I figured it probably would exit the FM band pretty quickly, as a previous one earlier this month that I observed did. But once I got to my SDR at home, the band was alive with activity.

Jan. 14, 2025 E-Skip Receptions
The unusual late night Jan. 14, 2025 E-Skip receptions from my location in southern New Jersey.

It was everything I love about a summertime opening to the upper Midwest, only on a 26-degree night in January. The maximum usable frequency was reaching the top of the FM band. I was hearing signals from Winnipeg, Duluth, Fargo, Bismarck, Minot, Minneapolis and Wausau. It kept going into the 1 a.m. hour and the event didn’t wrap up until after 2 a.m.

FM DX’er and TV meteorologist Allan Nosoff listened to the event from Brooklyn, N.Y. He shared an audio clip of 90.9 WHRM(FM) from Wausau, Wis., at the 1 a.m. top of the hour, which contains Wisconsin Public Radio‘s identifier.

Allan also heard 101.5 KSSS(FM) Bismarck, N.D., from his location, at a distance of approximately 1,390 miles. He shared the opening on social media:

I can’t emphasize enough how unusual this was. As a DX’er, I’d never experienced an opening that good, that late at night. And for it to be occurring in mid-January, it was even more special. Winter openings are typically what I would describe as “novelty” openings for serious FM DXers. 

The research of Pat Dyer (WA5IYX)

What causes this mystical propagation? Unfortunately, not much more is known than when Dyer began studying the phenomenon in the 1960s.  “Since it occurs more often during the hours of daylight, it seems that ultra-violet radiation might play some role in its formation,” he wrote.  However, because it also occurs at night, especially in winter, Dyer suggested auroras and meteor trails as possible sources of ionization.

Dyer performed a seven-year study from 1964—1970 of E-Skip propagation on 50 MHz. For those unfamiliar, the maximum usable frequency (MUF) with E-Skip activity during an opening rises up the VHF band. Many openings are detectable in the six-meter amateur radio band but do not reach the 88–108 MHz FM radio band.

He also noted the diurnal variation of E-Skip activity. During summer, he noted two peaks: one from 10 a.m. to noon and another from 6 p.m. to 8 p.m. “Es propagation is primarily a daytime phenomenon during the summer months, decreasing rapidly after local sundown,” Dyer wrote. 

Pat Dyer's data is a treasure trove for those interested in E-Skip propagation.
Pat Dyer’s data is a treasure trove for those interested in E-Skip propagation.

From his winter data, however, he observed that while peaks occur at similar times, the evening activity extends beyond sundown and into the nighttime hours. 

The winter E-Skip season of 1977 appeared to be exceptional. On Feb. 7 of that year, Dyer observed an event where the MUF reached up to analog channel 13 in the TV band. He saw KSFY(TV) 13 from Sioux Falls, S.D., at a distance of approximately 975 miles.

Dyer also noted the typical “one-hop” distance of sporadic-E signals to be 1,400 miles on 50 MHz. This generally associates with FM radio distances, as well. During the Jan. 14 event, I had signals from as far as Minot, N.D., which exceeded 1,430 miles.

If you’re more interested on all things Sporadic-E, I encourage you to check out Dyer’s data. FM DX’ers will tell you there was no one more devoted to chronicling this phenomenon. He contributed frequently to the ARRL’s QST magazine, in its “The World Above 50 MHz” column. I used to read his real-time logs on the now defunct TV/FM Skip Log in earnest and was very saddened to hear of his passing in 2016.

While things appear to be quieting down, January 2025 was overall active for skip. The opening I observed has not been the only one noted by FM DXers. Activity was reported from northern New England to the Midwest on Jan. 4 and from Massachusetts to FM stations in the southeastern U.S. on Jan. 6.

It sure has made for some entertainment on cold winter nights, even after walking the dog!

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