Widespread fog prompts a change of heart about personal minimums on departure.
I have never been a fan of personal minimums—the idea that you should set limits for yourself short of what's required by the FAA. Particularly for instrument flying, if you aren't prepared to shoot an approach to minimums as specified on the chart, you shouldn't file, because you're going to have to deal with whatever weather develops.
That's one reason for the "1-2-3" rule about specifying an alternate if the weather isn't forecast to have at least a 2,000-foot ceiling and three miles visibility for one hour before and after your planned time of arrival.
But I've had a change of heart, at least in one respect: I've now set personal minimums for visibility and ceiling when departing on an IFR flight. That came about as a result of planning for a flight to Los Angeles with my wife during the fog season.
We were in a relatively wet winter season here in California's Central Valley, which makes fog common. When there's no frontal weather, radiation fog is common most mornings and indeed sometimes builds up to persistent tule fog that can cover fairly large areas.
Most of the time, the fog will burn off as the sun comes up, but deep in the winter you get a condition where the fog never completely burns off—it just rises into a low stratus, then settles back on the ground at night.
Periodically, a weather system moves through and disrupts the stable pattern, but between those systems, morning fog is the rule here until spring. It's just something we learn to live with, and one of the reasons that an instrument rating really helps.
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