Numbers at the top are the W* or the expected Thermal updraft velocity in feet/min without cloudsuck or ridgelift at that time.
Small clouds represent the expected LCL (lowest cloudbase), but do not mean that there will be clouds..
Areas of white cross-hatching are times and levels where relative humidity > 95% so actual clouds are very likely there. Marine stratus seems to show up nicely.
Snowflakes mark the lowest freezing level at that particular time.
Backround colors represent the "local" lapse rate at each time and altitude in C°/1000ft (See color key below windgram).
The altitude scale is at best approximate at 32ft /1 Hpa. or every 10mb is about 320ft. So 850 is usually around 5000feet and
Sea Level is 1014 ish, on average. The correspondence can easily change by 300feet over the course of a day,
so think of these as relative altitudes, not absolute. [precise calculation]
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The colors in the background represent the "local" lapse rate at each time and altitude. Red is unstable and if it continues up off the chart it will likely mean big showers and or thunderstorms. When the unstable region only goes a bit above launch, that means strong thermals in that region.
Where the background color shows, any lift will be either lucky or induced by winds hitting the terrain.
See this link for a summary of the different ways we try to measure instability.