Flight Training - August 2022 - 21

BY THOMAS A. HORNE
WHAT I WOULD DO
LONG STORY SHORT: I THINK OPTIONS 1, 2, AND 3 WILL ALL WORK. ANYTHING BUT
drive. Our pilot did all the right things-checked METARs and TAFs, called flight service,
and even spoke to a human briefer, and got his father-in-law's in-person, albeit
unofficial, observation.
But there's another angle that this pilot missed. It's the big picture. There are some
key facts lurking behind the granular details he obtained in his preflight weather briefing.
Often dismissed as too broad-brush to be of any use, there are clues relating to the synoptic
scale situation that offer some reassurance. " Synoptic scale " means weather systems
lasting up to a week or so and covering anywhere from 600 to 1,000 square miles.
So, what have we got here, synoptically speaking? Morning fog in the mountains
expected to burn off, clear skies along the route, light southwest winds at 6,000 feet,
and a chance of thunderstorms in the afternoon. Oh, and perhaps most important,
soaking rain in the past two days.
All these things are synoptic-scale events, and they indicate that the flight will take
place in the warm sector of a low-pressure system. Ahead of a northeast-southwest
cold front to the west, there is mountain fog along the Appalachians-one of the foggiest
areas in the eastern
United States.
All that rain saturated
and cooled the ground, and
as the sun rises it burns off
the cool air near the surface
produced during the
coldest times of the night
before the flight. That
southerly flow aloft is a
clue that warm air is moving
in ahead of the cold
front to the west. As this
air moves north, it flows
up and over the colder air
farther north, up near the New England states.
Will there be thunderstorms? Maybe. But that 50-percent chance for Martinsburg
sounds like a cop-out. Any low-level moisture from all that rainfall could, yes, condense
into clouds, rise in the heat of the day, and produce rain and/or thunderstorms.
But the big picture points to a decent forecast all along the route-once that fog
burns off, which will be around 11 a.m. or so. The pilot is in a huge area of warming
air, but any real action won't happen until that cold front makes its appearance on the
scene. And that won't be for another day or two.
If you pay attention to surface analysis maps, Storm Prediction Center convective
outlooks, and " general " thunderstorm probability maps you should be able to get a
fairly good grasp on the situation at hand. Of course, TAFs are another must, as is a
look at the dew points at METAR stations. Dew points above 70 degrees or so are
signs of very moist air that could later produce thunderstorms-even severe ones.
There's a good feeling about this day once 11 a.m. rolls around, and before the hottest
part of the day could kick off a storm here and there. So, the two-hour flight time should
be good. When it's thunderstorm season, pilots are always wanting to know exactly
where, when, and how long a thunderstorm will happen. But individual storms are
small-scale events-like most of the worst weather, such as tornados and hail-and
difficult to predict for any one location. Larger scale events, such as storms moving
in lines or clusters along a front, are easier to nail down in terms of time and place.
But there's nothing like that in the picture-yet. Any " scattered " thunderstorms
of the sort mentioned in the forecast should be circumnavigable. Synoptics say that
VFR flight is a " go " for today. But there will be some bumps along the way. Rising air
means turbulence. Shown above is the surface analysis chart for 7 a.m. that day.
FLIGHT TRAINING AUGUST 2022
21

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Flight Training - August 2022

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