Of forecasts and facts

January 11, 2012 by Bruce Landsberg

On two local flights over the holidays the weather dissemination system didn’t exactly work as one might hope.  Day 1 – Cessna 172 flight to a small airport about 40 miles to the northwest. Forecast was for great weather: ceiling above 10,000 visibility greater than 6 miles – no mention of snow flurries.

Shortly after takeoff, the ridges to the west took on the distinctly gauzy appearance of snow showers and the higher we climbed, the more the visibility declined.  I called Flight Watch to ask what they were showing. “Well the forecast is looking good and although there was some virga reported, no widespread snow. ”

Yes, but looking out my windshield there’s quite a bit of snow and so here’s a pirep of marginal VFR and it could be going IMC over the mountains.  “Yes sir but the forecast ….. ”  We returned to home base about 15 minutes later. For a good part of the afternoon,  there were snow showers that came and went. Not so good for VFR and nice to be inside with a cup of coffee – wishing I were aloft but not in a C172.

Day 2 – Got a full weather briefing for another VFR trip in a DA-40 to another airport – this one about 65 miles north. It was kind of hazy but the sun was up there – shining through . Forecast was for good VMC and even though temperature dewpoint spread was close, the briefer warned of marginal VFR to IMC up north. Aside from the early morning haze that would burn off as the temperature dewpoint separated, what other indications were there? Was there a ceiling that might preclude the sun from heating up the air the way it was forecast? Had there been any pireps? What other information did he have that might invalidate the forecast that good VFR was in the offing in about an hour?

The briefer responded that he had none of those but was still concerned about the conditions. I volunteered to give a pirep once aloft. By the time we got to where the MVFR or IMC had been, it was beautiful day with temperatures in the 50s, no ceiling and visibility 10 miles or better.

Why tell the story? It points out, to me, a weakness in our weather information system. It is not intended to slam the forecasters. In the first case, the weather moved in and reality was much worse than expected. In the second case, VFR not recommended continues to dissuade pilots to fly until they decide to see for themselves and find a perfectly flyable day.  Unfortunately, too many become emboldened by the occasionally inaccurate forecast and the understandably conservative approach taken by the briefers.  Ignore what happen on flight one and then things can get very ugly indeed. Believe what you’re told on what happened in flight two and you may begin to start ignoring forecasts when the wolf really is out there.

As a famous president once said, ” Trust but verify.” Seems we should be doing that with aviation forecasts.

For more information on this topic check out ASI’s SkySpotter interactive course.


Bruce Landsberg
President, AOPA Foundation

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11 Responses to “Of forecasts and facts”

  1. Herb Ludgewait Says:

    Why is it that I could rely on wx reports and forcasts when flying charter and instruction in the 1970′s, and they are almost totally wrong in this age of technology. The answer, I believe is human experience with, especially, micro wx. Today the low level charts are wrong, winds aloft forcasts are never correct. Lockheed Martin has told me IFR not recommended! when VFR existed and forcast 35 miles away. They reported cieling up to 8000 feet when I saw blue through a thin 2k layer, and it goes on and on daily.

  2. Bruce Landsberg Says:

    Herb….

    Thanks much for your note. Others should be weighing in – agree or disagree. Will behaving the discussion with the Aviation Weather Center, the FAA and the NTSB in the next several months.

    I’d like to have the group’s true opinions.

  3. Hank Says:

    Weather forecasts are wrong too often to trust, and right too often to ignore.

    That’s where PIREPs really come in handy! That, and a recent satellite view, clouds and IR for precip. Sometimes, though, you just have to take a chance, like in your two flights.

  4. John White Says:

    Pireps should be automated and leave the human (FSS personell) out of it. We have the technoligy! XM weather in the cockpit and a subscription to Weathertap plus use Fltplan.com will cure your ills with forecasts and WX reports from “Scare you out of the sky” FSS people that are not even Pilots.
    QCIP weather is available and part 91 ops do not require QCIP.
    The FAA could shut down the FSS system buy every licensed Pilot an XM and Weathertap subscription plus a GPS that would display the info or an IPAD and save money and the whole General Aviation world would be much better informed and safer. This is the 21fst century and if you can afford the gas to fly cross country you can really afford the equipment and subscriptions. I fly GA Professionally approximately 600 hours a year and have not called FSS in the last 6 years and have very few doubts about what the weather is doing or going to do.

  5. Alan D. Resnicke Says:

    Unlike Mr. White, I prefer to speak with the experts before I go out. Although I flew USAF helos for 19 years (VFR and IFR, including overseas), I now fly for fun and sighseeing. I don’t want a heads-down intensive cockpit or a bag full of spare batteries for all of the electronic stuff. Give me a paper chart, a few steam guages, and a friendly voice on the other end of the FSS line any day. I generally ask to where I’ve been connected… if an in-state FSS I trust their call more than someone from another area of the country without the local experience. Keep the FSS for me – technology tends to fail, lockup, or fritz just when you need it most!

  6. Jeff Veers Says:

    I fly professionally and rarely use FSS briefers for weather briefings, usually only to file, open and close flight plans in remote ares. When I do get a FSS weather briefing, is far less comprehensive than the picture of the weather I can generate from a couple great online resources. That being said however, I also instruct; and I come across may pilots who do not have the time and/or desire to become independent weather product consumers. I always recommend they talk to a briefer to be the mediator between the mass of weather information and their flight. A great feature for these pilots would be web-based briefings like a voice chat where the briefer can share his or her screen with the pilot and point out the features they are talking about. Not sure if Lockheed offers this or not, but they should.

    As far as pireps, I would like to see the NextGen ATC system integrate reporting into the ADS-B system. Wind/Temp aloft data could be sent from aircraft directly to forecasters to maintain a much more accurate and up to date winds/temps aloft matrix. En-route aircraft could be queried for estimated cloud tops, layers, icing, and precipitation conditions in their area. Many times I have been on the ground wondering if I can be on top or between layers at a certain altitude when an aircraft in the area could probably give me the answer with a courtesy prompt to the pilot. The technology will be there, lets make it useful for us pilots who will be shelling out for it! In the time being, please leave pireps whenever you can, especially you two pilot crews out there!

  7. Dan Vigesaa Says:

    I agree with Herb. The current weather reporting and forecasting system is pathetic. I have been teaching for 45 years. I used to send students out to do solo practice when the reported ceiling was 3,000 feet. Now I often find clouds at TPA when an AWOS or ASOS reports 3,000 feet. I used to check weather along the route of flight for a cross country. Now I find that I better check within hundreds of miles or I might be surprised. The current environment is treacherous for students and other low time pilots.

  8. Alan D. Resnicke Says:

    What I find frustrating is the lack of low altitude radio repeaters out West (NM, AZ, UT). There have been times I’ve wanted to file a PIIREP only to find I can’t raise Flight Watch or FSS because I’m not high enough to get radio reception. Although I generally flight follow with Center, often the traffic with the commercial liners and bus-jets isn’t worth tying up their freq for them to relay.

  9. Mark C Says:

    I am one of those low-time/student pilots. I like getting weather from the briefers for a x-c. Most of them are very good and will offer some interpretation and point out things I may have missed on the computer – like one day there was 40 kts. of wind shear at TPA at my destination airport, which I had overlooked. But the briefers are only as good as the information they have to work with, and I have my doubts about the AWOS out there. I went out a couple weeks ago to do pattern work. On the ground the AWOS was reporting 2000′ scattered. On my first circuit I turned crosswind and found myself in the clouds below TPA. I hurried back to the ground, parked, and called the AWOS and got 1400 overcast, when I had just left 700 overcast five minutes earlier and it sure didn’t look like it had gotten better.

  10. Robert Buerkle Says:

    My two cents:

    On AWOS reports:
    As an airport manager and private pilot, I can say that I have a viewpoint on AWOS data from both sides of the fence. Remember, AWOS ceilometers only measure distance to cloud bases very near the AWOS site, not within the entire traffic pattern. Clouds form as they will so differences in actual vs. reported values may differ. Also, you need to realize that AWOS sensors, while FAA certified as extremely accurate and reliable devices, do occasionally malfunction or can be out of calibration between the mandated quarterly AWOS equipment inspections.

    On weather forecasting:
    Wx forecasting is most accurate over a broad area and less accurate over smaller or micro climate areas (i.e. it is nearly impossible to accurately forecast lake effect snow and rain events near and close to large lakes). This is due to the NWS forecast models being designed for meso-scale or synoptic event forecasting. The amount of sensor data required for accurate micro forecasting would require a huge expenditure so i do not see it happening soon. As for using automatically produced and transmitted data form aircraft for use in forecasting models, that sounds intriguing. But the conservative engineer voice in my head would always question sensor accuracy and calibration – therefore the question would be – “Yeah, OK, I have all this data from different aircraft, but is it accurate enough to use for forecasting?”

    Seems the best way to be is to “Trust but verify”. Verify with your eyes and your common sense.

    Happy and safe flying to all.
    Happy and safe flying to all

  11. Joe Subits Says:

    Bottom line on forecasts. Now matter how sophisticated technology and other forecasting tools become, for every flight, it is still WYSIWIG (What you see is what you get). It still amazes me how many pilots practice see and ignore vs. see and avoid when it comes to weather.

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