Also, there are some charts that I don't use on a daily basis, because they cover much larger areas than I need on my regular runs between Montreal and Toronto. When doing my practice questions, I was getting questions with regards to issuing and validity times wrong, so I knew it was time to consult the AIM.
Prognosis = Forecast
Analysis = Observation
Reference AIM MET 3.2.1 Aviation Forecasts and Charts
Significant Weather Forecast - PROG Chart
- prepared 4 times daily, based on 00Z and 12Z data
- issued 12 hours prior to validity time (00, 06, 12, 18Z)
- specific flight level range (i.e. 700 - 400 MB = FL100 - FL240; also FL250-630)
- indicate surface positions of lows, highs, and any significant weather (thunderstorms, turbulence, mountain waves, etc)
- a forecast area of turbulence implies a 50% probability of encountering turbulence somewhere within the depicted area
- jet streams are depicted when the core speed is forecast to attain 80 knots or more
Upper Level Forecast - PROG Chart
- issued 4 times daily, 12 hours before the validity times of 00, 06, 12, 18Z
- applicable FL240, FL340, FL390, FL450
- depicts forecast wind and temperatures for the chart level
Reference AIM MET 3.2.3 Weather Charts
Surface Weather Chart
- observed at 00, 06, 12, 18Z
- issued 2-3 hours after observation
- pressure patterns from surface up to 3000 ft
- surface location of fronts, precipitation, obstructions to vision
Upper Level Chart - ANAL
- observed at 00 and 12Z
- issued over 3 hours after observation
- show reported atmospheric conditions at the pressure levels, such as wind speed/direction, temperatures, moisture content
- the contours or altitude gradient can be considered as the slope of the pressure surface
