Our heating-up desert is in final dress rehearsal for summer - but a vertical mile above Tucson this is a time when seasons can't quite make up their minds.

Fall lingers high in the Catalina Mountains in the form of leftover autumn leaves and ferns in brown decay on the forest floor.

Winter makes a last stand with a dusting of snow that cloaked the landscape on Saturday.

Spring shows itself in fresh green growth poking out of the snow.

"You're bound to see this overlap when you go up there at this time of year," said Joshua Taiz, district biologist with the U.S. Forest Service.

"There's no telling what you'll run into" in terms of signs of the seasons, Taiz said. "It's always going to be neat though."

Early this week, the "synergy of the seasons" show played out along mountain routes such as the Sunset Trail, which begins at a trailhead between mileposts 22 and 23 on the Catalina Highway. Elevations along the trail range from 7,400 feet to 7,750 feet.

Warming weather is likely to melt snow along that trail quickly this week - but leftover signs of autumn and new sprouts of spring will remain.

Trails higher in the range - such as the Red Ridge Trail at an altitude of about 8,000 feet in its upper section - probably will hold the snow a bit longer.

To reach the trail, follow the Catalina Highway past Milepost 24 to a turnoff for Mount Lemmon Ski Valley. The trailhead is on the right, 0.7 of a mile up the road toward Ski Valley.

Contact reporter Doug Kreutz at dkreutz@azstarnet.com or at 573-4192.