Weather Calculations - My Process

[krista]

Given the discussions last night and today, I wanted to send out a list of weather sites I use to inform my decision. It isn't the best compilation, but it's relatively easy to use. I really need to learn more about the weather, but the textbook I bought on it just seems overwhelming.

Any way...

I start with the winds aloft.
-- Go here: https://www.aviationweather.gov/adds/winds
-- Select wind streams.
-- View at 6000, then go down to 3000 since the uppers often mix lower down. If you know what going on above you, then you can anticipate what may come next.

Next, I go here to compare and get a bit more data.
-- Link: http://weather.nostepper.com
-- Make sure to put in the data to get the ARL winds aloft reading.
-- This site allows you to compare the other winds aloft to this site, as well as seeing a break down of what it is doing at various levels.
-- You can also see the thermal updraft forecast, which give you a prediction on how bumpy it will be.

Then, I check XC skies.
-- You need a subscription and to pay for it, but most of the time someone is already posting the graph to the list serve.

After that, I start looking at ground winds through a few sites.
-- Underground hourly reporting and historical reporting: https://www.wunderground.com/
-- NOAA: Look at the table and play with it. Example here: http://forecast.weather.gov/MapClick.ph ... =graphical
-- Anything else.
-- There are also some apps (e.g., Windfinder) that provide actuals. These can be super helpful too.

Then, I kick myself for not yet learning how to fully understand pressure systems and skew Ts.

Happy flying!

[XCanytime]

Having flown for 25+ years, well before the age of the internet, I have seen the evolution of weather forecasting. I believe in the KISS principle. There is such a thing as too much information, and there definitely is when it comes to weather forecasting today with the internet. There is no need to overcomplicate things; multiple inputs sometimes serve only to confuse, especially when they don't agree. The new pilot is overwhelmed with sensory inputs from all angles during their initial flights, so initially I recommend keeping it simple in the beginning and recommend just looking at the hourly surface forecast on weather.com for a location very close to or at the flying site. That gives you the general wind flow direction and speeds during the day. The observer of the student pilot should be weather savvy enough to know when to allow the student pilot to fly with a healthy safety margin built in. But that does not mean that the student should completely rely on the observer for that determination. In parallel, Dennis Pagen's "Understanding the Sky" is highly recommended reading for the student pilot. Then actual flight experiences can be correlated with the information presented in the book. Years of observation are necessary to understand particular sites' behaviors and peculiarities, but a general understanding of the sky is provided by Dennis' book. Skew-T plots and other high-powered parameters are really unnecessary for the student pilot. However, once a pilot thinks about going XC, or is thinking about competing, those parameters are useful in determining what may be a good day to go XC, or a good competition day. But remember, those are only forecasts. Sometimes they can be off. You have to get out and fly and observe for many years at many different sites at different times of the year to build up a database of forecasts vs. actual conditions for each site at different times of the year. That database will allow you to see and recognize patterns and be able to efficiently choose where and when to fly. There is no substitute for experience. Flying is all about understanding the behavior of the big "ocean" of air above us, and knowing if it is a good day to go "swimming" in that big ocean, or a day to just stay on the ground. Bacil

[brianvh]

Krista - I like your approach of starting with upper level winds first, as this is what most people neglect and can get them in trouble.

Skew-Ts are confusing because they a skewed in part to get the whole plot on one page: there are other reasons that can be dispensed with. Stuve plots do not have this skewness built in. You can go to this teaching site: http://www.ametsoc.org/amsedu/dstreme/stuve.html which unfortunately doesn't list many cities, but gives an idea and you can search for more cities. Stuves are much easier to read. Green are the dry adiabats, dotted blue the moist adiabats.

[CraginS]

I agree with Bacil's KISS advice. Even some of the most experienced pilots follow that path. Many years ago the Pittsburgh crew advised those of us who spent an hour or more analyzing multiple sources before deciding where or whether to go on a potentially flyable day to look at the hourly forecast, pay attention to wind direction and speed and precipitation, and hit the road. Getting to a site early and being set up when flyable conditions hit is the best way to play the odds and actually fly. A lot of detailed analysis and dithering over multiple weather forecast sources can eat an hour or two out of the day before you even load the glider on the rack.
Even I do not use all of the sites linked on my flying-site oriented WX page. The listed sites are there for each user to choose favorites and get to them quickly.
By the way, if newer pilots have not looked at my page (see my sig file below) and the club's weather sites page, please spend soe time viewing both. FInd the forecast sites that work for you.

[Eric]

This is helpful to me as a new H2 who just had his first mountain flight on 3/25. Since I fly a Falcon, my main concern is getting too high in altitude where the wind wind speed is too high to penetrate then getting blown over the back. I'm also worried about my ground speed getting out to the LZ from the ridge, for example at Woodstock. Additionally, it seems like the challenges associated with the differences in lift and sink and wind speed that I encountered on the training hill, particularly when trying to spot land, are encountered on a macro level when trying to get from the ridge to the LZ.

From reading above, it sounds like the key to keeping it simple is understanding the general wind direction and the wind speeds aloft in relation to the speed my glider can fly and also an understanding of how the wind behaves at the particular site I'm flying on a given day. Is this a correct way to begin thinking about flying mountain sites?

Also, a book that I've found intuitive to grasp has been Burkhard Martens' Thermal Flying recommended to me by Jonathan Dietch. I guess I need to crack open Understanding the Sky as well based on Bacil's advice above...

[lbunner]

My process after flying for 41 years is a bit more complex but still simple. I pay an annual subscription for XCSkies to obtain the models from RAP, NAM and GFS to determine top of lift, climbrates, bouyancy shear (measure of how nice and big the thermals will be), cloud base, wind direction and velocity at various altitudes and how these conditions will change throughout the day. I then use the Skew T diagram which plots the data from the radiosonde balloons that are sent aloft two times each day as another input. This diagram uses several models to interpret the data and will provide wind strength and direction at all altitudes, dew point, temperature and collate them into a readable format for determining top of lift and whether there will be any clouds. This diagram is very reliable and free! It should be in every serious xc pilots tool kit. I also use 'old school' methodology such as; is it post frontal, is the grass dry in the morning or laden with dew, call Bacil (when I lived in Pa.). The key is to use the same references and analyze the results to factor them into the future.

83 hrs 57 minutes and 1400 miles so far this year!!

[krryerson]

I just text Bacil.That works 95% of the time.

[mingram]

Bunner is crushing it! Where are you getting most of your flight time?

[lbunner]

All of it has been at Quest Air in FL. There is a good group of pilots there that are similarly motivated. We pick a task every day we fly and work together as a team to make it happen. As a result, I'm averaging just over 2 1/2 hours and 45 miles per flight! Others have similar results. Got to fly with John SIMM on a couple big ones, man that dude is a good climber! Also flew with Greg S and Dan L in the GSSK this week and had a blast! Greg won one day and was oh so close on the last day. Florida is really good in March and April. You all should really take a break and get some for yourself as its a great way to start the year!

[lbunner]

Oops, John Simon.