Recently I described on the BBO forums the outline for ETM Storm:

Forum Post 1

I was asked to explain the rationale for the structure, which I did here:

Forum Post 2

I'll repeat my reply here:

In general with the frequent 11-14 range, the system describes a key nature of the hand so that responder is in good position to take the right steps forward. The primary focus is on possible major fits, both finding ours and trying to be an obstacle to the opponents finding theirs.

The mini-spades 1D opening is to:
1) Get 10-12 with 4Ss into the bidding
2) With 5Ss and 2/3Hs allow for our H fit to be found
3) Have a limited opening so responder can move to the best spot quickly.

The 2H/2S openings try to get to the right spot ASAP, and block out an overcall in the other major as much as possible.

The 2C and 2D deny 4+Ss, so we open at the two level to block out a possible S overcall as much as possible, while limiting the hand and showing opener's longest suit.

The 1S opening is a full-bodied opening, though limited - responder is well placed to judge prospects while the opponents are at risk if they enter the bidding. For example 1S-2H-Pass-Pass;-Double shows 13/14-17. so responder can make a penalty pass with less than in standard. Since 1S is not a flat minimum, responder can bounce to 4S on 10-13 counts and 3+Ss, forcing a tough decision on the opponents if they have a hand that might need to compete, while also not revealing much so that the lead and defense to 4S will not be easy (compare to the 1S-1NT;-2x-3S;-4S auction of 1NT forcing).

The 1H opening can have 4Hs if 11-14 with 4+Ds - this means that the opponents cannot count on a true fit after 1H-Pass-2H and must be careful coming in, while if opener is active in later bidding then it promises 5+Hs.

Weak notrump is used since it fits the overall structure. 13-14 balanced with 4Ss needs to open 1NT since 1D cannot handle as wide a range as 10-14 balanced and still have okay rebids.