S1 - 21 - Pre-Match Intelligence Preparation and Analysis

How do you plan and prepare for the potential challenges of a new shooting location? Steve and Ed discuss and provide an overview for gathering and analyzing intelligence to prepare for an out of town match or hunting trip to a new location. They review techniques for analyzing map data, travel routes, weather, and converting weather atmospheric data to density altitude values to calculate external ballistics and prepare backup DOPE cards.

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Weather Underground is unique in that much of the raw data aggregated and reported comes from its network of 37,000+ Personal Weather Stations that are owned and operated by individuals or private businesses, that share this information. This network of weather information is the world's largest active community of weather data collectors.

Since this data is provided locally at each station reporting it, and the Weather Underground reports this information as "pressure", 6.5 Guys originally understood this data to be Station Pressure (SP), as opposed to Equivalent Barometric Pressure at Sea Level (SLP). A month after making the video we have learned that this data is actually SLP. Note there is a difference, explained below:

Station pressure is the raw, actual pressure. That's the real pressure measured by the instrumentation at the location.

Sea level pressure is the result of a much more complicated formula that takes as inputs, station pressure, elevation, humidity, and the simple average of current temperature and temperature 12 hours previous. In addition, the National Weather Service formulas add in an adjustment that is precomputed per location (the plateau correction). There are a number of different sea level pressure formulas, giving slightly different results.

Scientists long ago realized that atmospheric pressure drops as your altitude increases, as the atmosphere gets thinner the higher up you go. Thus a barometer reading in Seattle would be a lot different than a reading in Denver at the same weather conditions. To "level" the playing field, so to speak, scientists developed a way to calculate what the pressure is at sea-level, no matter what your altitude is.

Since the "Pressure" data is SLP, to use this information to develop a DOPE card as explained in the video you will need to convert the Pressure reported to the equivalent Station Pressure. To do this, you will need to use the reported "Altitude" shown by the station reporting the weather data on Weather Underground, and then run it through a conversion calculator which you can find at this URL:

http://www.csgnetwork.com/barcorrecthcalc.html

6.5 Guys wishes to thank Scott Whitehead for guiding us to make this correction.
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Also Check Out:
8541 Tactical | MCM #24 - How to make dope cards using JBM Ballistics Calculator: http://youtu.be/FHUdPWHnWyA
TiborasaurusRex | Sniper 101 = JBM Ballistics Introduction: http://youtu.be/jMRClBIPgGg

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Hosts: Steve Lawrence, Ed Mobley
Editor: Steve Lawrence
Videographer: Kevin Dittoe
Production Crew: Steve Lawrence, Ed Mobley, Kevin Dittoe