Here is a lesson plan for using present simple tense to discuss one's daily routine.
There is a short warm up based on the lesson theme which is about superheroes. This might help you get some ideas for other warm up ideas. They don't have to be too complicated or take a lot of time to plan.
Your warm-up for the vocabulary could include something as simple as showing video footage or photos of an avalanche, or using the objects and asking students to guess their names.
You could also have a "grab bag" of items for your noun vocabulary. Have students pull one item out of the bag and ask, "What does it do?"
Lesson Plan: Verbs Daily Routine - Present Simple http://www.associatedcontent.com/article/897483/lesson_plan_verbs_daily_routine.html?cat=4
As far as the pronunciation of the word "thunderstorm," you could have an audio aid to show the sound of thunder or show a video of a thunderstorm for a warm up.
Then, depending on your students' native language, focus on the parts of the word that would be difficult for them to understand. For example, in Pakistan most students can not produce the "th" sound.
I would create a presentation on how the "th" sound is created (by pushing noisy air through the mouth and putting the tongue in between the teeth). Make students bite their tongues and try to say the "th" sounds.
If you have a list of "th" sound words, with both voiced (the, these, that, bathe) and voiceless sounds (like in thunderstorm, bath, path, think) you can have students practice saying the target sounds.
It depends what difficulties your students might have with the word "thunderstorm" how you would choose to teach it.