The Weather Never Sleeps: Exploring the Big Sky Country

Dudley had never seen this much brown on a sectional chart until he'd made his way to Cheyenne, Wyoming (and, in a day or two, depending on weather, Montana). Both the Cheyenne and Billings sectionals were mostly various shades of brown. He'd gotten a good introduction to flying in the high country of Cheyenne (elevation 6,156 feet) from a local flight instructor, then had gone about his business of demonstrating his company's fixed-gear, four-place single to prospective customers.

His next stop was to the northwest in Billings, Montana, where more potential customers were waiting. Getting there would be interesting. If he followed the VOR airways, which lie over less-than-inviting terrain, it would be a 350-nautical-mile flight. But if he jogged just a bit off the middle of the airways, he could always keep a ribbon of concrete - or a river valley - well within gliding distance, and he figured the extra distance, 40 miles maybe, was worth the margin of safety.

Dudley awoke at o-dark thirty. He'd loaded the DUATS software from both DUATS providers, GTE and DTC, into his laptop and was anxious to try them both. To be fair, he flipped a coin. He'd use GTE's Cirrus software on this leg, and DTC on the next.

The Cirrus software let Dudley plan his route before it called for the weather. Rather than put in waypoints to exactly match his planned jog off the airways to stay close to the roads and river valley, Dudley used the navaids and airports in the GTE database to connect the dots on the simplified route. He filled in all the information needed for the standard briefing, flight plan, and graphic weather map scripts, and was surprised to find that he got all his weather data, a flight plan, and all the weather maps (14 of them) - in under three minutes. (With his laptop's 56K modem, the text data arrived in well under one minute!)

The synoptic picture looked great. A high-pressure ridge extended from central California northeastward into the entire area of Dudley's route. A weak cold front was drifting very slowly eastward out of the Pacific Northwest. Dudley happened to look at the surface analysis chart first, and it showed this information nicely - somewhat simplified from its original form (Figure 2). The 12-hour surface forecast looked just the same for Montana and Wyoming. The outlook for central Montana and all of Wyoming was VFR.

After several trips that had required more soul-searching go/no-go decisions, Dudley welcomed the friendlier weather. Even the low-level weather map for 00Z that night gave him little cause for concern (Figure 3). The US radar summary showed no echoes anywhere for 500 miles around (Figure 4). No warnings or SIGMETs were available from DUATS, but there were AIRMETs and they all said "NO SGFNT" for IFR, turbulence, or icing. Right off the bat, the flight seemed a go!

At the present time, the winds were calm, the visibility was observed to be 10 miles, and the skies were clear at all reporting points along his route. All of these were "A02" automated reports, so actually when it said "10 SM" it meant "10 miles or greater," and "CLR" skies covered only up to 12,000 feet AGL (though it was most likely clear above that too, in this case). Also, several of the METARs had "TSNO" appended in the remarks section, which meant that lightning information was not available. (Today, that would be academic.) It was still too early for PIREPs. (Heck, it was too early for daylight!)

Dudley had gotten his weather briefing so early, in fact, that the latest TAFs were still those from just before midnight last night. The surface winds at Cheyenne might reach 11 knots out of the southwest by 11 a.m., but the sky was expected to remain clear with good visibility. Along his route, the only clouds and reduced visibility he might see would be before 9 a.m. around Casper, Wyoming - five miles in mist with a scattered layer of clouds at 500 feet. Because Casper was about halfway up through Wyoming, Dudley probably wouldn't be leaving Cheyenne until about that time, he didn't think it would be an issue.

The Billings TAF was calling for southeast winds at six knots, greater than six miles visibility, and clear skies by the time Dudley expected to arrive at his destination. The winds aloft at Medicine Bow and Crazy Woman, Wyoming, at 9,000 feet were expected to be northwesterly at about eight knots.

The lack of winds aloft reports for 3,000 and 6,000 feet puzzled Dudley for a moment. Then he remembered the brown-shaded sectionals. Because of the terrain elevation in the area, 3,000 feet MSL was underground, and 6,000 feet MSL was just barely above it.

At 12,000 feet the winds aloft report called for northerly winds at 13 knots. Up at Billings, the 6,000 foot winds might be a little stronger and out of the Northwest. (Interestingly, the winds forecast for higher up were not as great.) Considering the good weather, the 10-knot headwind component was a minor penalty.

Dudley found a small surprise when he reviewed the NOTAMs. The Billings VORTAC was going to be out of service from 7:30 a.m. until 8 p.m. the next day. Given the expected "big sky" visibility, the ribbons of highway he would be following, and his GPS, he really didn't think he would be in danger of becoming directionally challenged!

Dudley took off just after 9 a.m. The weather was exactly as forecast, and he had an uneventful trip to Billings - except for some breathtaking scenery. His biggest problem proved to be believing the value for the estimated in-flight visibility when he gave a PIREP just before entering Montana. He'd never reported 80-miles visibility before!