Team Advice

Knowing “Weather” Or Not To Fly

  • July 16, 2014

Two days ago we had mounted a very large group of pilots to go fly one of our favorite big mountain sites for a late evening “sled ride.”  This is a wonderful site for all pilot levels and gives everyone a chance to launch with some real altitude.  Upon reaching launch and looking over the valley some 5,000 feet below we felt super calm air, with no sustained wind, but could see a large dark band many, many miles away.  Some of the experienced pilots ribbed each other on who was launching first, with a sarcastic smile.  We all knew we were not going to be launching, but joked as we talked back and forth.  One of the newer pilots asked in all sincerity, “so what are we waiting for?”

It seems the trick with any air sports, especially paragliding is knowing when, and more importantly, when NOT to go flying.  There are many factors that we must consider before we step up into the sky, but I would like to talk briefly about just one today…!  Weather is an intense topic and can (and often does) become a lengthy discourse about all the components that make up the behavior of this fluid we call air.  This post too may be lengthy, but I hope to discuss a few things that relate to helping us make our own ultimate decision to fly or stay on the ground.

Daily Routine

The first thing I do when I wake up in the morning is check the weather.  I get asked all the time “what do you look for.”  So, I thought I would share my daily weather routine.  I rely heavily on the NOAA forecasting center, because they are the ones who dictate aviation weather in the US, have the most resources to analyze and create the best forecast models we have.  Likewise, their models run often, so things tend to be more accurate and up to date.  So here is my routine:

  1. What kind of flying am I doing today?  This is a very important question as it will dictate what I look for.  Am I wanting to do some XC, or a hike-n-fly sled run, or some ridge soaring?
  2. Current Regional Surface Winds:  This tells me really quickly if there is a strong wind pattern developing in the valley or mountains around me.  I can quickly see a trend if winds are strong across a region…not just at a single site.  Generally if I see large gusts (red numbers), then I really do not want to go flying.
  3. Front Locations:  I check to see if there are any fronts approaching.  In short, if a cold front (blue triangle line) is approaching it is going to get windy.  If a front recently passed it is likely to be windy now, but the wind should be dying over the next 24 hours.
  4. Forecasted Regional Surface Winds:  This graphic tells me if the surface winds are going to be strong later on today.  If it is mostly gray or light purple, winds are going to be light.  Darker and brighter colors mean it is going to be too windy.
  5. Forecasted Regional Cloud Cover:  This graphic tells me if the sky is going to be covered in clouds.  This is especially important if I am wanting to do some XC that day.  Straight forward, gray means clouds, blue means blue sky.
  6. Forecasted Regional Precipitation:  This graphic, along with cloud cover can tell me real quick if the clouds are going to over develop (OD) into large clouds that will produce rain, snow, or otherwise non-flyable conditions.
  7. This is where I take stock on the day.  Decide if I will be spending the whole day at work, or if I need to have my gear packed and ready.  Right now you should have a pretty good idea on if your are flying today or not.  If things are looking good then I dive a little deeper.
  8. Soaring Forecast: Regardless of whether I am doing XC or not, I want to know how the air is going to “feel.”  This is where the dialogue can get lengthy and could be a post in and of itself.  This is such an important document to understand especially if you are doing any XC flying.  I specifically look at 5000 FT MSL index, -3 INDEX , FIRST USABLE LIFT, MAXIMUM LIFT, UPPER LEVEL WINDS.  Learn what each of these mean.  I would be happy to do a post on this page alone if it would be helpful.
  9. Winds Aloft Forecast:  Here I check to see the forecasted winds for the day at different elevations.  One important trick, make sure you click in the upper right of the page to select the time frame you will be flying.  If it is the afternoon make sure you are clicking somewhere between 2100z and 0600z.  If you do not know how to read this chart, learn (click on the FYI/Help section).  In short you scroll down to your airport of choice (SLC) and look at the numbers at corresponding elevations (at top).  The first 2 numbers are bearing, the second 2 numbers are wind speed in knots.  So if it says 3215+08 at say 9000 it means that at 9,000 feet winds are blowing from 320 (i.e. NW) and are blowing 15 knots (~18 mph), the +08 means the air temperature at 9,000 feet is +08 degrees Celsius (better bring a coat). What if the number says 9900?  This means “light and variable” and is what we would love to see all the way to the top of the -3 INDEX….if not 9900, then as light a wind as possible.
  10. I then check the air pressure to see it is within optimal limits.  The best and most productive air occurs when air pressure is between 29.90 and 30.10.  Any higher than 30.10 thermals are likely to be rockets (both up and down) and can be unsafe to fly in.  Likewise anything less that 29.90 tends to be what I call “sky diarrhea” and is a bubbling mess of unorganized air.
  11. If everything looks good at this point, then you can likely count on a good day of flying.  I will generally dive in a bit deeper and look at the Skew-T plots for the day and make sure I know where cloud base will be, any inversions, and to make sure I am not going to get sucked up to 40,000 feet in an overdeveloped cloud.

As you read this, I am sure you are thinking “holy crap, that is a lot of stuff.”  In reality it takes about 10 seconds (thats right, seconds) to go through the first 7 steps to know if the day is flyable.  It takes maybe another 1-2 minutes to dive in deeper.  I got really frustrated early on in my flying career as I too didn’t know where to find all this stuff and thus created my own weather page that has ALL of this information in one place.  It has evolved over the years and now is found at the Wasatch Free Flight Weather Page.

Look Around

Group looking at "technology" in an effort to reconcile what they were seeing with their eyes.  ALWAYS LOOK AROUND!

Group looking at “technology” in an effort to reconcile what they were seeing with their eyes. ALWAYS LOOK AROUND!

When it comes to weather, there are many things to learn, and I encourage us all to continue to be students of the weather.  In today’s world of having technology, computer models, and everything else I mentioned above right at our fingertips, it is important to never forget to look around.  When assessing the final conditions of whether to fly or not, be sure to check the weather forecast, but more important look at the visual cues around you.  Watch the trees, the flags, ripples on the water, dust, the clouds above, and use those visual clues to verify the sky is behaving as you thought.  If you are with more experienced pilots, let them go first, but know that just because they fly, doesn’t mean you should.

“So what are we waiting for?”  The honest question still hangs in the air.  The forecast was perfect, the numbers looked right, but the small band of virga dropping out 30 miles away from a swirling cloud cell over our head is reason to pause.  It was clear the numbers did not match what our eyes were seeing.  In wisdom we all stood on launch, gliders packed in our bags and watched the virga create a 60 mph gust front that ripped across the valley.  That is what we were waiting for!

We continue to do more and more field trips as a Team these days and encourage everyone to come out and fly with us.  It has been a great time meeting and flying with so many new people this year.

Posted by: Jeff Ambrose