The Weather Geek: hello low

Let’s get the geek business out of the way first. If a person who has an abiding interest in weather, especially as it relates to flight operations, is a geek, then I am a weather geek.

Highs and lows are what make the weather engine go. Highs aren’t exciting, lows can be full of thrills. I was reminded of this when we had that October snowstorm in the northeast.

I read the NWS forecast discussion for the area any time there is anything other than clear weather around. Three days before the storm, I could tell the forecaster was getting excited. He said if the H8 (850 millibar level which is a few thousand feet above the ground) temperatures did such-and-such he would be forced to inject the “S” word into the forecast.

Snowstorm damage in New York
A residential street in suburban New York one day after the storm.

H8 did as he thought it might and history was made with that record October snowstorm.

Things like that are what make me think about weather vertically as well as horizontally. I spent all my life flying around mostly below 20,000 feet and I like to think about everything that is going on between the surface and that level as well as within hundreds of miles.

I’m going to tell you about a couple of flights that relate to this. The first was over 50 years ago, the second about 35 years ago, but weather lessons are timeless.

As young marrieds were prone to do, we wanted to spend Christmas where we used to live. That meant venturing to both Little Rock, Arkansas, and Dothan, Alabama, from our New York City area location. That would be thousands of miles of flying in our Piper Pacer which seemed to have a headwind even when in the hangar.

The low pressure area lesson came on the last part of the trip, from Dothan back to Linden, New Jersey, near NYC.

I had a faint hope that the headwinds we had encountered on other legs would have come around to tailwinds by this time. Woe, though, there was a low pressure area off the coast that was pumping cold and damp air over the route in a northeasterly flow, right on the nose. I figured it would take a couple of days flying to cover the 850 or so statute miles. (No nautical then.)

It actually took two overnights and two days plus a relatively brief hop after the second overnight. If you don’t think I flew along looking at cars passing us beneath and wondering how fast a car I could get in exchange for our Pacer, you would be wrong.

My weather lesson came a couple of days later. I was visiting with a friend who had an Aero Commander. He had flown virtually the same route, doing so on the second day of our trip.

I asked him how long his trip had taken. Not long, he said, an easy nonstop from the Florida panhandle to Reading, Pennsylvania. How could that be on the same day I was clocking a groundspeed of 60 mph, going in the same direction?

Well, I wasn’t thinking vertically. The low was offshore and there was a strong southwesterly flow aloft, running up over the relatively shallow northeasterly surface flow. My friend flew in the mid-teens, on top, sucking a little oxygen, going like the wind. I spent a while wondering if I could have coaxed the Pacer up into that tailwind but decided it probably couldn’t have happened.

It was virtually the same setup that caused the October, 2011, storm except for the fact that the low to the east did not get the same upper level support that it got in 2011 when the ingredients came together to mix the warm moist air coming from the south with colder air.

As an aside, the wind can be the same all the way up when the strong wind is within an air mass, as after a cold front passes. On the Linden-Little Rock trip that Christmas it took us 16:45 (in one day) to cover the distance. That was awful. The next day, though, I learned that it took my friend Claud Holbert almost 11 hours to get Winthrop Rockefeller from New York to Little Rock in his Beech 18, which was probably the fastest business airplane of that day.

The other trip was one where there was no clear-cut low when I checked the weather. I was living in Little Rock and was headed to Wichita, for the day, in my Skyhawk. I flew that trip about once a week for seven years, so you might say it was a familiar route.

850mb chart
The 850 millibar chart reveals a lot.

It was obvious something was going on because there were clouds and rain all along the way with the chance of embedded thunderstorms in the forecast. That is pretty standard fare on that route in early March.

The trip to Wichita was smooth, I got there on time, and I finished up and was ready to get back to Little Rock before dark. The only thing I had in mind related to the wind aloft on the morning trip. It had been stronger and more southerly than forecast. That meant something could be brewing off to the south or southwest.

I had to do the delicate dance around icing as the trip started but a lower than usual altitude, 4,000 feet, took care of that.

There was no convective weather along the route and life was good until I checked the weather with about an hour left to fly. Little Rock was reporting 200 obscured, two miles visibility, moderate rain and fog, surface wind 070 at 20 with gusts to 35. There was nothing like that on the forecast I had read a couple of hours earlier.

I had plenty of fuel so I thought I would carry on. An ILS to runway 4 was available at Little Rock and a Skyhawk is a fine airplane for low approaches. Everything unfolds slowly, giving plenty of time for thought.

By the time I got there the ceiling was up a bit and the wind had abated to 20 knots without the gusts.

The widespread inclemency was likely related to a stationary front. The brief disturbance at Little Rock was from a low pressure wave that formed on that front and moved to the northeast.

Low pressure waves are pretty common and while the flying can be wet and bumpy as you pass through a wave, there are no real depth charges in there. Waves can develop, move along a stationary front, and then dissipate, for days. Sooner or later the atmosphere rearranges itself and enough instability shows up to support the development of a full-service low pressure storm system.

So, some lows are big and brash, other not so much so. But all do indeed teach lessons.

Geeky?

2 Comments

  • I’m glad to see you mention the forecast discussions. When I discovered these, I couldn’t believe no one had told me about them. They made a huge change in my understanding of the weather, and the variability of the forecasts. There’s still so much I don’t understand, I guess I should be re-reading Buck’s “Weather Flying” continuously.

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