UAL T38 Phlyer

Exactly.

Two cases where I was burned by the forecast come to mind.

One was 20 years ago in the F-4, and the destination was forecast 25,000 cirrus; 10+ miles. No alternate required.

When we got there, a funny thing called "off-shore flow at 4 knots" had decided to go ON-shore at 4 knots. The entire Gulf Coast was 0/0...and we didn't have a lot of gas for options.

About 20-30 other airplanes were in the same predicament. Fortunately, we squeezed in on an ILS to "minimums..."

The second was April this year. About 10 widebody airliners (International arrivals) diverted to New Orleans because a forecast didn't work out.

Yes, I have talked with the weather guy in the Air Force....different example; I didn't like how the radar picture was looking; he assured me all would be well. Turns out, I was right. I too taught my students to "read the sky;" particularly thunderstorms (how to tell if building or decaying), haze layers (usually a wind shift as you go through it), lenticulars, cumulus, different ways fog can form..

Airline: on the New Orleans divert, the Capt talked with all of us AND the dispatcher. He had his doubts, but it looked reasonable. He still added a little gas.

Turned out, HE was right. He knew the weather patterns at Houston better than I or the other F/O.

The alternate was also socked-in. Ooops.

Grillemeyer

So you don't automatically plan for alternates?
I am not familiar with these things, hence my question.


The TS bit is very interesting, because I start my lessons on TS with a short movie, asking my students which of these clouds is likely to become a TS.

May I ask what you base your assessment on?
How does the cloud show you it is still growing / likely to become a mature Cb / decaying? And what about hail... can you see whether there's hail in the cloud?

One thing I use is the "hat". A strong thermal pushes the air above it upwards, like a ship does with the water. At times that produeces a "veil" cloud. If you see that, you are most likely having a thunderstorm 10 minutes later.

Re hail I read about "hail streaks", but I feel there must be some more / other signs in the cloud.


Thanks a lot!
Grille

UAL T38 Phlyer

In military as well as civilian flying, alternates are generally required when the forecast ceiling and visibility go below specified values.

Air Force rules were similar to FAA for general aviation. I did an exchange with the Navy, and was surprised their rules were very different from the Air Force....I had assumed all miltary branches were the same. Actually, I thought FAA rules were the same for everyone.

My first airline was Part 135...their rules were different than Part 121 (Major carriers).

Bottom line: there are many instances where you are not required to designate an alternate.

Thunderstorms: besides the obvious, such as widespread cumulus, I said look for big clouds with sharp, defined edges....like a piece of popcorn. That usually meant it was building, and new growth kept the edges sharp.

On the other hand, if it looked like a cotton ball...soft and fuzzy: it was probably decaying.

Solid, bright white tops, and dark grey bases are obvious signs of abundant moisture and lift.

Use the anvil to predict direction of movement, and stay upwind, if possible. (Hail hazard).

Distance: especially in late afternoon, if the storm has an orange hue with blue shadows, it's about 80 miles away. The color is due to particulates in the atmosphere, just like with a harvest moon. Closer than about 60 miles, you don't see that color.

Air Force wanted 20 miles from storms. If you could see individual bulges and bigger shadows, that would be roughly 20 miles.

The "hat" or veil: if you are talking about a "lenticularish" wave over a ridge or bulge in the storm: very bad sign. Lots of instabilty that means rapid cell growth and turbulence.

This was important stuff in a jet with no radar.

Grillemeyer

Thanks, about that I was not informed. This should help highlighting the importance of critical forecast reading. As luck would have it, we have a Tranining Needs Analysis coming up at my academy in the next months, and the Met syllabus received some criticism for being too demanding (I quote: "...appears to be written for forecasters, not pilots&quot. What I have learned here will certainly help me in the discusssion! Also thanks for sharing your TS criteria. The anvil, sharp edges and dark bases I already mention in my textbook (dark base means loads of precipitable water, and the blurry / cotton wool look indicates ice). In addition, a tree-cake like structure also indicates strong updraught. The distance hints (orange hue / individual bulges and shadows) were new to me, and I will try to incorporate them in any way into my lessons. As to the "hat", I do indeed mean that lenticularish cloud (a Cb with that accompanying cloud is incidentally called "pileus&quot, and I say exactly the same thing: pileus means quite violent updraught. So thanks again for your help, it is good to know that I am doing the right-ish thing in the classroom. Best regards // Grille