I find the F215 to be almost useless, because the forecaster chucks in everything he can think of.
The PROB30 has been degraded by the fact that only PROB30 & PROB40 are permitted under ICAO.
So PROB30 is now a shorthand for "a small chance of it happening but pretty unlikely" and normally you find that anytime there is a trough on the MSLP chart (see the link I posted) that appears as a PROB30 TEMPO TSRA in the TAFs.
PROB40 means that he thinks it will happen, probably.
What makes a massive difference is using GPS and doing things the "modern way". If you cannot navigate in haze then (sorry to say this) you are wasting your time doing a PPL, because you can be grounded for much of the summer.