Meso/Comp maps and CAP/CIN

[mcallum177]

How do you read the comp map or the meso analysis map for CIN/cap on the SPC website.

http://w1.spc.woc.noaa.gov/exper/compmap/

If I am reading it right light blue means no cap and purple means high cap....but what about areas at the edge of a light blue section and areas with no color does that mean there is no cap there? Also are these the correct cap values? 500-300 = capped 300-150 = mixed 150-0= no cap?

[RL3AO]

Cap/CINH is usually listed as a negative number. The lower the number, the stronger the cap. Zero means there is no cap.

0 to -50 is a weak cap
-50 to -150 is a moderate cap
-150 or below is a strong cap.

[mcallum177]

So it is normal for the most of the country to be uncapped?

[RL3AO]

So it is normal for the most of the country to be uncapped?

Yeah. You need a lot more than that to get severe weather.

[brunota2003]

Plus being uncapped downplays severe weather some.

It allows the weaker updrafts to develop into storms and zap the energy that has built up, keeping it area mostly stable. When you have a moderate cap, it takes a strong updraft to break through it and that updraft stands a better chance of developing.

Too strong of a cap, however, and you kill everything.