December 27, 2009

Sky Islands

I was looking for an inexpensive vacation last week that offered lots of sun and interesting weather features--well I found one --Tucson, Arizona.

Perhaps my most interesting weather experience was ascending one of the "sky islands" - the Santa Catalina Mountains northeast of Tucson. Starting around 2500 ft in the Tucson metro area, one can take the Catalina Highway/Sky Island Scenic Byway to 9,157-foot Mt. Lemmon over about 25 miles (see map). This topographic "island" within the Sonoran desert provides a wide range of climatic and weather conditions, with temperature dropping and precipitation increasing with height.

We started in Tucson under sunny skies and temps about 55F--surrounded by Saguaro and other cacti. The Saguaro are the cacti that are so often used to represent the Southwest (one is shown in the figure below), but they really only found in southern Arizona and Mexico--they can't handle below freezing temperatures for any length of time. By around 4ooo ft the Saguaro were gone--just too cold.

Weaving up the road, the vegetation and climate changed rapidly, and by around 5000 ft we started to see some SNOW in shaded areas. By 6500 ft there was loads of snow and we had entered a pine forest--reminding me of the eastern slopes of the Cascades. Moving higher, the snow got deeper (perhaps 3-6 inches at 7500 ft) and the air temperature was probably around 35F. So in 45 minutes one goes from desert to snow and a northern-type forest...there is even a ski area at the top!

Average rainfall is roughly 12 inches in Tucson (slightly wetter than eastern Washington) to 30 inches at the Mt. Lemmon site (slightly drier than Bellingham).

But the weather excitement didn't end there. On Tuesday, Dec 22, a cold front was approaching central Arizona, with a low center to the north--the result was a large pressure difference over the region with winds accelerating to 40-50 mph. We were out hiking in Saguaro National Park as the wind hit and the most extraordinary thing was the rapid loss of visibility (see pic). The situation got very bad on I10 south of Phoenix where winds blew over agricultural fields. (it has been a very dry year...Tucson only has received about half their normal 12 inches a year). The result was a severe dust storm that resulted in over 20 accidents on I10, a death, and the temporary closure of the road (graphic).

The adaption of the plants and animals to the dry conditions is really extraordinary, including the ability of big cacti to store tons of water and the dual usage of cactus needles for both protection and shading. I was not a little disappointed about human adaption down there...lots of large vehicles and relatively few solar panels.

And my family's adventure in Tucson was really enhanced by the very nice bed and breakfast we stayed at: a place called Azure Gate. Friendly, helpful people and extraordinary food.

Finally, what about our weather? Our sunny period ends today...and tomorrow will bring increased clouds and a few sprinkles. Then a few weak systems in store...but nothing of any note for several days. Unfortunately, for active weather lovers the influence of El Nino will now become more significant...and that means that weakened and split systems will be more frequent than normal...and snowpack should be below normal.


  1. Light freezing rain in west Olympia at 10:29 pm

    I have really enjoyed this sunshine...very sorry to see it go.

  2. Cliff,
    Nearby Benson AZ has an amazing bed and breakfast The Astronomers Inn. It is owned by a Tucson doctor and is just incredible. We stayed there years ago. Got to watch the sun with the Doc's brand new $15K hydrogen lens. Easy to take trips to Tombstone AZ or visit the Rex Allen (1950's singing cowboy) museum in Benson. We had to prepare all of your own meals. Buy everything in Tucson.
    The rooms are decorated with wild themes. We had a life size Han Solo in out room. Astronomy student from the University in Tucson can be hired to provide guests with "sky tours". Worth every penny.

  3. We were around Sedona Arizona for the same reasons you went, right at the same time. Sedona is at 4500 ft. The vegetation community is a low pinion -juniper woodland, with manzanita and jojoba at the shrub layer. On the famous red rock peaks around town and the grade toward Flagstaff (about 7,000 ft), a ponderosa pine community takes over quickly. On the 22nd, we were out for a hike west of town when the storm started with drizzle at about noon. It was a typical Seattle-like day, gray skies, about 38 degrees and steady drizzle. By afternoon, snow was sticking on those famous peaks. After sundown, snow began to fall down in Sedona but wasn't sticking. On the morning of the 23rd, we awoke to clear weather and a fresh coat of snow on the ground and on the shrubs and trees. It was a magnificent sight. Photographers were all over the place recording the event. By noon, the snow had melted in the valley, but remained higher up.

  4. Solar panels - good idea. We've 14 on the roof. Solar hot water too. Amazing to see the system temp rise when the sun hits it. We'll get our solar investment back - about when the kids get out of high school. Thanks for the trip description Dr Mass, Tucson's a great place.

  5. I just left for Tucson about the same time you did, on the 18th of December. I go to school at U of A and did some research up in the Catalinas on exactly what you're discussing in your blog. It's important to note the wide variety of species that the many sky islands have, ranging from the mexican wolf to Jaguars and Coati's (animals one would never expect to see this far north). Its a crossroads for the species of North and South America and many of them can be found no where else than these isolated sky islands. It's a pretty interesting topic.

  6. Yeah, that's the same storm that caused 45mph gusts during the Oregon St./BYU bowl game in Vegas.

    Suprised that Mt. Lemmon only receives 30 inches a year. Seems like during monsoon season there would be a thunderstorm forming over the top of that mountain everyday. You can see on the map included all the ravines that drain that mountain. Flash flooding might be Tucsons biggest weather concern.

  7. That looked like a great visit to Tucson, one of my favorite places. Hope you got a chance to experience the "Living" Museum. The hiking around there is also very good. Thanks for your weather insight.

  8. Hey Cliff,

    What about the potential for wet snow for alot of areas tomorrow evening. I know that the MM5 models do not show a widespread event, but with 925 temps at or below zero with 850 temps of -2 or -3 and offshore flow I have seen many times alot of areas recieving a quick few inches of snow that the models didn't forecast. I know the NWS isn't saying anything, but the chance is obviously there. What are your thoughts?

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