How to best predict thunderstorms, kinda confused?

Question

I live in virginia and the weather the past week has been mid 90's with a dew point in the mid 70's it is so humid it feels like 100. I've been studying weather off and on since I was 12 (i'm 20). And from what I understand you need heat, moisture, and instability to produce thunderstorms.

Yesterday it was the same conditions as today and thunderstorms popped up after 6pm everywhere with awesome lighting. Today there was the same % chance but there was maybe 1 or 2 clouds in the sky. Was the atmosphere too stable? the CAPE values were around 1200 J/kg which seemed right but there were barely any clouds, I did notice it was less hazy though. Why didn't thunderstorms form I'm kind of confused on how they can form under set conditions on one day but not under the same the day after. Any insight? Is it the cold front or high pressure?

Answer 1

All the elements must be present for development,  including enough available moisture.  When I was forecasting in Germany,  we had a conference call with the EFU and the weather liaison office.    They were talking about rain and RH's at 850, 700 and 500mb were less than 10%.  So,  I asked them how they could have rain without clouds?

My point is,  that these conditions may be have been highly unstable,  but you do need moisture.   TTs,  CTs,  and VTs are good instruments,  but they must be weighed against the whole.

Rawinsonde data and current conditions may have not been conducive to development today, whereas they were yesterday.  

I remember also times in New Jersey during the winter when storms were moving across the mountains,  but everyone knows that you need moisture,  usually onshore flow to get a major winter storm.   Always make sure that the major elements are there.   Start from the bottom up.  Start simple and make sure those parameters are met,  before buying into the storms.

Observation is a good place to start and then making sure the models agree with what is currently happening.