Strike like lightning, crash like thunder; students of the Way of the Storm learn to harness their ki to become living forces of nature's raging wrath. Based on the teachings from the Way of the Four Elements, masters have forgone the balance of the prime elements and have embraced the unhesitating nature of lightning and the totality of thunder. Able to swiftly move around the battlefield, these monks channel their momentum to deliver devastating blows to their foes.

All credit to u/dueyfin for the base subclass. I have tinkered with the numbers and details to attempt balancing it a little more evenly (in comparison to the other Monk subclasses).

Fists of Thunder and Lightning

Starting when you choose this tradition ta 3rd level, you can charge your strikes with the elemental forces of thunder and lightning. When you hit a creature with an unarmed strike, you can spend 1 Ki point to impose one of the following effects, or you may utilize one of these effects as part of your Flurry of Blows ability:

Fist of Thunder. Your attack deals additional thunder damage equal to one of your Martial Arts die and pushes the target 10 feet away if it is size large or smaller

Fist of Lightning. Your attack deals additional lightning damage equal to one roll of your Martial Arts die to the target and it can't take reactions until the start of its next turn.

You can use this feature only once per turn.

Thunderous Stride

At 3rd level, you can use the Step of the Wind feature without spending the ki point for Step of the Wind.

Storm Surge

At 6th level, you can channel your ki to give you a stunning burst of speed. As an action, you can spend 4 ki to cast the haste spell targeting yourself, without providing material components. 

In addition, if you were to take either thunder or lightning damage, you may use your reaction to reduce that damage equal to one roll of your Martial Arts die + your Wisdom modifier (minimum of 1) and you gain 1 Ki.

Voltaic Strike

Starting at 11th level, you can use the extra kinetic energy built up by your speed to unleash a devastating strike. If you move at least 10 feet in a straight line immediately before making an unarmed strike, you can empower that attack. You have advantage on the attack roll, and if it hits, it deals additional thunder damage equal to one roll of your Martial Arts die. This damage can be increased by an additional roll of your Martial Arts die for every 10 feet of movement you took in a straight line before making the attack, to a maximum of 30 feet.

You can use this feature a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.

Become The Storm

At 17th level, your Ki mastery allows you to physically embody the destructive elements you wield. As a bonus action, you can spend 5 Ki to become a living bold of lightning for 10 minutes. This form ends early if you are incapacitated, or if you die. In this form, you gain the following benefits. 

Elemental Resistance. You are immune to thunder and lightning damage.

Empowered Fist of Thunder and Lightning. You can use Fists of Thunder and Lighting without spending the ki point for the ability and it deals its maximum damage. You can use Fists of Thunder and Lightning twice per turn if you spend a Ki point on another Monk ability, but you cannot use the same fist ability (Fist of Thunder or Fist of Lightning) twice in one turn.

Improved Movement. While in this form, you can move through creatures and objects as if they were difficult terrain. The first time you move through a creature on your turn, it takes lightning damage equal to one roll of your martial arts die + 5 + your Wisdom modifier (minimum of 1). If you end your turn inside a creature of object, you take 1d10 force damage.