CLGC Soaring Weather and Data Analysis
Presentation to CLGC by Greg Chisholm, December 2000 (pdf 3.3MB)
Chicago Soaring Forecasts courtesy of CGC and NOAA-FSL
The following SkewT/LogP diagrams provide both actual and forecast soundings. The forecast soundings are derived from the actual soundings via computer simulations:
- TI's and SkewT/LogP diagrams: Locate the dry adiabat line for the daily forcast high (CGC is approximately 1000mb's MSL). The dry adiabat angles from lower right to upper left - colored blue, numbered in degrees F.
- Follow the dry adiabat up to the intersection with the sounding. The sounding is the squiggly line depicting temperature as a function of altitude - colored red. This intersection is the top of the thermal for today, given no complications, like clamp.
- At any altitude, the TI is the difference between the sounding temperature for that altitude and the dry adiabat temperature for that altitude.
- One rule of thumb is that a glider could expect to top out at TI=-3 (though many have experienced greater heights).
Advanced Digital Data Service (ADDS)
The National Weather Service's ADDS site contains a large amount of general aviation weather data. These links provide you with direct access to a number of these pages.
- ADDS main page
- Joliet Radar
- Visible Satellite image
- ADDS Metar Java page
- FAA Notams (main page)
- FAA Notams (radius search page)
- National Weather Service (NWS): forecast for Minooka, IL.
Dr. Jack's Blipmaps
Direct Link to Dr Jack's BLIPMAP images - Blipmap and Blipspot forecasts. This page contains 4 Blipmap images - Thermal Updraft Strength, Critical Height, Wind Speed, and Wind Direction. It also contains links to the Blipspot forecasts for the CGC location. Note: You must be a Blipmap subscriber to view all 4 Blipmap images.
- MAPS Java Plot for IL59 (CGC) This is the unmodified version or the version from which the above were derived.
- MAPS Java Plot for Freeport (Albertus) This unmodified version is centered on Albertus for the 2003 Region 7 contest.
Forecast by NOAA's Forcast Systems Laboratory. This link provides 5 plots from the current time. I usually select the region around the drybulb from ground (~1000mb) to 10,000 feet (e.g., place cursor to right of drybulb/1000mb intersection, depress left mouse button, drag up and to the left to above 10,000 ft line). Expected cloudbases are indicated by the following: pressure (altitude), wetbulb temp, drybulb temp, and wind direction/speed.
- MAPS Java Plot for ILX
- Plymouth State College - skewt/logp for DVN - RAOB - Derived from the 12 hour balloon soundings.
Additional Helpful Stuff on the Web
- DynCorp DUATS on the Web
- DUAT.com by Data Transformation
- Plain English METARs
- Intellicast - Current US Surface Analysis
- Latest GOES Satellite Sounding for Davenport, IA - This provides hourly sounding - though vertical resolution is poor.
- Latest GOES Satellite Sounding for Chicago, IL
- Air Sports Net page for Joliet
- John Cochrane's soaring forecast links page for CGC
General Purpose Sites and Educational Information
The following is a collection of sources for the above graphics as well as some selected information sources on reading these graphics.
- Kevin Ford's Thermal Report Generator
- MAPS/RUC Page Interactive - home of a java applet that's really cool
- MAPS/RUC Page Non-interactive - Pick your favorites(ILX/DVN,???)
- Plymouth State College - depicts parcels -- nice size on a white background
- READY Page from ARL where you can get animations and pick the size of the plot (first enter your preferred station id (e.g., dvn), pick a size (900x900), start time, number of hours, Full Sounding or only up to 400 mb, select a chart, and Request plot
- The READY Page for dvn (ilx not in database)
- Temperature Converter from Intellicast
- Southern Eagles Soaring Forcast Page a compendium of web weather sites prepared by Chris Ruf
- Upper Air Data Details- a description of upper air products available and what they tell you.
- Upper Air Sounding Details - a concise description including parcel trajectory.
- The Thermal Soaring Adiabat Chart an explanation by P.J. Kelly of the Valley Soaring Association
- Forecasting Soaring Weather another article by P.J. Kelly of the Valley Soaring Association
- General Information - GOES Atmospheric Soundings Display
- Soaring Weather - Shenandoah Valley --- How to read a RAOB/SkewT
- Soaring Weather - Shenandoah Valley
Created by Greg Chisholm December 1998
Modified by Rich Carlson July 2004