That’s What MTOS Looks Like

(The following photo-essay is meant to exemplify what winter weather can look like, and illustrate what kind of trouble one can easily get into when flying in the mountains on a “weather day”. There’s always an easy escape route to clear weather and lower terrain, a must-have in such conditions. Y’all fly safe, OK?)

I thought I had a plan. On 12/30, a cold, wet system had just blown through. On the 31st, the day was supposed to be mostly clear, and I expected it to be a great day to just take a few hours of a day off to go fly and take a few nice photos after a fresh snowfall, starting in the Tonto Basin.

A check of the statewide weather noted an AIRMET for mountain obscuration (MTOS) over the Colorado Plateau (at 7000′). Below and south of that (where I wanted to go) was forecast to have been reasonably clear. So, off I went to go take a peek.

But a forecast is, after all, one possible prognosis, never a guarantee.

Trying to get out of the area to the northeast into the basin, here’s my first problem:

Verde River Valley - 12/31/10

Northbound up the Verde Valley

That’s a river valley in the left of the frame, angling off to the right. Locally, there’s an overcast layer around 6500′ with occasional snow showers down to around 4500′. Since I’m flying this drainage upstream (and thus uphill), it’s just going to get worse than what we see here, and it’d be really easy to get trapped in a snow shower that’s going to close off all escape routes.

There’s absolutely no good reason to go any farther. It’s still quite clear in the desert behind me, so I make a turn to the southeast along a ridge to see what it looks like from another angle.

On a normal day, I could easily climb over this pass to the basin, but not today:

None-Shall Pass

None-Shall Pass

The other side of that ridge isn’t a good place to be at all. If I was trying to travel, I’d just go back where I started and wait it out. But since I’m only after some airtime today, I’ll use the clear space to the southeast to go see what this looks like. A few minutes later, a familiar 7600′ peak disappears in the murk:

Peaks Hiding in the Snow

Peaks Hiding in the Snow

Holding a camera still here is really quite a challenge, the air is anything but smooth, with a healthy post-cold-front westerly flow blowing upslope over some rugged lower hills just west of me. It’s still very clear to the southeast, so I always have an easy and obvious route to clear weather and lower terrain (else I’d simply not be here!), so I continue to proceed southeast.

The last path into the basin is up this canyon, now a chain of man-made lakes. Clearly, this isn’t any better either:

Salt River Canyon Closed for the Day

Salt River Canyon Closed for the Day

Since I just want some time in the air today, I just keep flying to the southeast just to see what I run into. Consequently, I fly 65 miles (!) up the Gila River drainage to an area east of Tucson. On the east side of the Santa Catalina mountains is a nice rural strip with inexpensive fuel, and it’s normally a convenient place to stop (I do still have 2+ hours fuel remaining at this point). But when I get there, I find that there’s a 20-25kt crosswind blowing across the runway, and it’s downwind of a mountains (making some unpredictable up and downdrafts probable), so this isn’t a great place to go either.

Several AWOS-equipped airports on the west (upwind) side of the mountains mention winds 10-15kts and clear, so that’s a better place to go to fuel up. I’m approaching 2 hours of bouncing around under this stuff, and the morning’s coffee is working on me, so I’m really ready to crawl out of the airplane for a bit. I head for AVQ, just north of Tucson, reporting clear and a 12kt quartering crosswind. On the way, Mount Lemmon disappears in the same stuff:

Santa Catalina Mountains, Fully Obscured

Santa Catalina Mountains, Fully Obscured

I top up the airplane, stretch my legs, and head back home across the desert in nice clear weather.

By the time I’m back to my home field, 4 hours later, most of this weather had blown clear, and I could have stuck to my original plan (good photos and all with the fresh snowfall) had I just waited a few hours. But, it’s New Year’s Eve, and I have things to do, so I’ll tie the airplane down for the day, and hope for another opportunity sometime.


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