If you believe that a format called Soft Adult Contemporary can boom, it’s booming now. On Monday, Nov. 12, when iHeart’s WISX Philadelphia and KBEB Sacramento and Entercom’s WDZH Detroit dropped Throwback Hip-Hop and Top 40 respectively, each to become “The Breeze,” the Soft AC building boom took on the same sort of momentum that defined the growth of Bob- and Jack-FM-type Adult Hits in 2004-05. At this moment, it’s occupying the headspace of a lot of radio people in a similar fashion, and for similar reasons. Jockeying is suddenly taking place for a format that has been hiding in plain sight for years.

So why now? I was asked that Monday, shortly after the Philly news broke, and the list of reasons isn’t short.

The Millennial AC Miracle Is Endangered. The steady stream of mother/daughter-friendly music making its way from Top 40 allowed Mainstream AC to eliminate the ‘70s, reduce the number of ‘80s songs, and force tempo. Then, around the time of Katy Perry’s “Dark Horse,” EDM and Hip-Hop-influenced ballads started to make their way into the format, each one a record that adult women really seemed to like. Now, that discussion is about “Never Be the Same” by Camila Cabello. Or is it “In My Blood” by Shawn Mendes? Because that’s almost all CHR is sending now.

Meanwhile, AC has essentially disabled its ability to start songs without Top 40. “Tequila” by Dan + Shay and “You Say” by Lauren Daigle are the 2018 equivalent of “Live Like You Were Dying” by Tim McGraw and “I Can Only Imagine” by Mercy Me — the sober but quite legitimate Country and Christian AC crossovers that gave AC something to play in the early-to-mid-‘00s, before the CHR product began flowing again. (And, yes, this particular take on “Tequila” is quite sober.) But Mainstream AC isn’t even playing those songs yet. In most cases, they’re expected to go through a six-month apprenticeship at CHR, or at least Hot AC, first.

The Success Stories Have Accumulated. WDUV Tampa was always successful with the format but seemed to be regarded as an anomaly by the industry — if it even noticed. WFEZ (Easy 93) Miami, then KISQ (The Breeze) San Francisco, each battled back and forth with the incumbent ACs. But the current success of those stations, plus the growth of KSWD (the Sound) Seattle, has created the critical mass a format boom needs.

The Growth of Me-TV-FM. It’s not on a frequency that every car can receive. It cheerfully plays records-that-don’t-test, a lot of them. WRME-LP (Me-TV-FM) Chicago has been an undeniable success story that has clearly informed the growth of Soft AC. It hasn’t led to a lot of affiliations for the syndicated format, but it has definitely inspired programmers to try their less-stylized version of the format.

The Growth of the Format Around the World. Okay, I don’t know if Australia’s Smooth FMs and Dublin’s Sunshine 106.8 really came up in American programmers’ discussions or not. But Entercom Houston APD and ratings guru Chris Huff has been flagging them for the last few years.

Adult Formats Are Booming. Mainstream AC and Classic Hits are thriving, probably because usage by younger listeners is declining at a faster rate. Suddenly, a format that fits beyond Mainstream AC and Classic Hits is more attractive.

No Format Gets to Be Alone for Long. Over the last 20 years, the hot format has often been the one that is least fragmented in the most markets. Eventually, those success stories led to an influx of traffic in Country, Top 40, and Urban, and is now bringing fragmentation to Mainstream AC.

Christmas Time Is Here. It’s the time of the year when stations turn their attention to format changes, anyway. A new Soft AC can either counter-program an incumbent that has disrupted its format for holiday music or use holiday music to stunt.

Smooth Jazz Is Gone. It’s been nearly a decade since broadcasters used PPM as the public rationale to turn the lights out on the “Lights Out” format. In Los Angeles, KTWV (The Wave) successfully evolved to what can best be described as soft crossover R&B. But the vocals that powered Smooth Jazz, from Ambrosia to Earth, Wind & Fire, are part of even a pop Soft AC station, too — and that’s particularly the case in markets like Miami and San Francisco. KISQ (The Breeze) San Francisco isn’t The Wave, but it has a clear soulful component that allowed it to take advantage of the audience from Jammin’ Oldies, much of which did not immediately make its way to Urban AC KBLX, but helped swell KISQ’s listening instead.

It’s Not Really So Old and Soft. As long as there has been Supersoft AC, the game plan for many stations has been to make a statement long enough to make inroads, then become newer and (relatively) hotter, especially if the incumbent can be driven out of the format. Some stations start out with those songs that aren’t soft, but are safe and universal — WISX is playing “Don’t You (Forget About Me)” already. A programmer friend messaged me about the boom to say that he always expected it. But the Soft AC he helped launch a few years ago has already evolved.

What Is “Old and Soft” Anyway? Classic Hits and Mainstream AC stations have few problems with Michael Jackson, “Human Nature” (soft ballad by a core artist), or “(I’ve Had) The Time of My Life” by Medley & Warnes (where the artist is really the Dirty Dancing soundtrack). From Neil Diamond/Barbra Streisand/Barry Manilow to Celine Dion/Michael Bolton now, the issue hasn’t always been texture as much as artist image. And now the “yacht rock” phenomenon has neutralized that issue for almost any act that was not at the Manilow/Bolton level by allowing, say, Pablo Cruise to bask in Steely Dan’s cool.