|Basic Weather for Balloon Flight Planning|
|Written by Don W. Day Jr|
|Sunday, 26 August 2007 05:06|
By Keith Berry
I love flying my balloon. I also love weather. I guess that is why I was a natural fit for a couple of the local balloon festivals as their Weather Officer/Meteorologist.
After performing those duties for a couple of years, one of the attending pilots and BFA competition committee member asked me to be the 2007 U.S. Nationals Weather Prognosticator in Waco, TX. I was very flattered they had asked and was more than happy to accept their invitation. I promised to do my very best to provide them with a reliable forecast to help in their decision making on flying and what tasks they would assign to the pilots.
Now mind you, I am not a professional meteorologist. I don’t play one on TV or didn’t even sleep at a Holiday Inn Express last night. However, being an LTA pilot and seasoned volunteer severe storm chaser/spotter for the National Weather Service provides me with a mixed knowledge of really nice and really bad weather.
There are those days when anyone can predict you will or won’t fly. For instance, when you are under a high pressure system, the temperature/dew point spread is greater than 5 degrees and the wind is predicted to be 3-4 kts all day up to 3000 ft; let’s go fly! On the other hand, you have the opposite, looking at the local radar and seeing a 100 mile wide swatch of yellow and red bearing down on you at 35 kts, 15 miles from your launch field; bring in the cat and go back to bed. Even an amateur can call those. However, as balloonists, we can’t be amateurs. Our research must be VERY thorough and complete to make the appropriate call as a professional.
The real challenge is when those conditions are marginal and you need to make the go/no-go decision. If you need to call passengers that live 20 – 30+ miles away, you don’t want to have them drive all the way there just to find out you decided it was not going to be flyable. On the other hand, while it may be a safe bet to just call off those marginal days, if you can put together an educated forecast from your research, you can increase your chances of making the right determination prior to leaving home.
With ballooning, we must understand MICRO-meteorology. Most weather forecasters are interested in MESO or large scale weather. A change in wind from 6kts to 12 kts is no biggie to them, and they probably won’t even update a Terminal Forecast just on that change. However, as many of you know, it IS a biggie with us. We need to be cognizant of that potential, as well as various other minute changes that may impact our flight.
One common mistake many people make is only using one or two sources as a reference. With the recent changes in Flight Service you may now get a briefer (after a 20 minute hold) in Timbuktu who doesn’t know a thing about your area or the way the local terrain can impact you. The television and Weather Service forecasters may or may not be in tune with those slight wind condition changes and variations for an area depending on where you live, and they may say it will be 5-10, when it really will be 8-12, gusting to 20.
An advantage we have these days are all of the readily available sources for weather information on the Internet. Many of these are free, so you can gather till your hearts content, or at least until you have so much data you don’t know what to do with it! One note, you still need to call Flight Service, log into DUATS or use a one of the new FAA QICP (Qualified Internet Content Provider) services so it shows you checked weather. However, you can always compile those forecasts with any other information you gather from various sources to make your educated decision.
I use MANY different sources on the Internet to compile my information for flight planning. One of my personal favorites is the RUC (Rapid Update Cycle) wind forecast. It gives an hourly view of winds at various levels from the surface to way above my altitude preference in increments as small as a couple hundred feet. The RUC forecast is made up of various components like the balloon soundings from the NWS, forecast computer models, and even the GPS wind readings from arriving and departing planes in many areas. With all of the data it ingests, it has a fairly high reliability factor. I have found it to be a great reference for many flights.
A user friendly site that provides RUC winds up to 3-4 hours ahead was developed for balloonists by Ryan Carlton at www.ryancarlton.com. He is currently working to enhance the page, so new features will be coming soon!
If you want a farther reaching view, you can go to http://www-frd.fsl.noaa.gov/soundings/java/ and input your nearest larger airport ID, enter 12 in the hours field and choose ASCII-text format. This is a little more cryptic because it doesn’t convert to AGL or MPH for you like Ryan’s page does, but it provides a longer range view. An explanation of the format is at http://www-frd.fsl.noaa.gov/soundings/java/raob_format.html.
Another useful tool is provided by the National Weather Service on their pinpoint forecast page. You can go to their site at http://nws.noaa.gov, click on your location on the map, and then keep drilling down to your local area. The pinpoint forecast is based on a 5 mile radius of your clicked location. Once there, find the link to an Hourly Weather Graph (usually on the bottom right of the page.) This provides a good overall view of the conditions as they have been forecast by the meteorologists at the NWS. One note here, this is not automatically updated from computer models like the RUC, so data may be a little out-dated if a change in the pattern has suddenly developed.
Many balloonists like the VAD or Doppler winds available at http://vortex.plymouth.edu/lnids_conus.html?. These are a good ‘real time’ view of the current winds in 1000ft increments. However, the VAD winds are only reliable out to a 16nm radius of the radar site, and there must be sufficient moisture or other airborne particles in the atmosphere to reflect the radar signal and get a good reading. If you are like me and fly 60+ miles from the radar site, these may not be what’s happening in your neck of the woods. Know how far away you are from the radar site and any pressure gradients or boundaries that may exist between you and the radar location.
Lest we forget, also include the TAF (Terminal Aerodrome Forecast) and AIRMETS. These are invaluable for telling you sky conditions. While at the Nationals, we had a couple of days with great wind conditions to fly, but the ceiling was so low at 5 AM I am not sure you could have seen the top of your balloon standing up. The question was if the low ceilings were going to go away and present a flyable situation. When your reputation as a weather officer is on the line at the Nationals, you don’t want to be the goat for calling off the flight and then have a beautiful morning. With the information from the AIRMET on its expected duration, the NWS meteogram dew point spread, and the input from the briefer at Flight Service, the picture was painted that an early breakfast at Commander-in-Chief Dub-Ya’s favorite coffee shop in Crawford, TX was the answer.
Of course, these are not all of the sources available on the Internet. You probably have your favorites and may choose to use those and collect various other items. The main thing is use them as a tool in your flight planning and use them well.
Another item of importance, besides having a boat load of weather data in hand, is how to apply it to the area you are flying. Make sure you know the area and its behavior. Are you in hills where fog may form in the valleys after sunrise? On flat open areas that will heat up quickly and cause upper level winds to mix down rapidly? If you are unfamiliar with the locale, ask a local pilot (even a fixed wing guy or someone at the local airport.) They can give you a lot of info that will help.
The bottom line is use your balloon pilot instincts as a guide and put as much of the information that is out there into your planning. Question the things that don’t match and rely more on the ones that do. It will become easier to make good calls the more you learn to apply it to your pre-flight decision to help keep you safe.
|Last Updated on Sunday, 12 April 2009 21:20|