Five steps from a problem to its solution.

Help me design and build a first working prototype for this problem in Uttarkashi, Uttarakhand, India.

Problem: Trekkers on Uttarakhand's high passes don't get bad-weather warnings in time to turn back.
Who it hurts: Trekking groups, mountaineering expeditions and their local guides and porters on routes such as Kalindi Pass and Auden's Col, including foreign visitors.
The moment it hurts: Days into a trek beyond mobile coverage, when a red alert is issued in the valley and the group has no way to hear it.
What people do today: Warnings go out through district administrations and the news; groups already on the route learn of them late or not at all, and rescue starts once they are missing or stranded.
Why it is still unsolved: High routes have little or no mobile signal, there is no shared register of which groups are on which route, and forecasts aren't pushed to the operators and guides who could reach them.
What solved looks like: A trek registration linked to route and dates, so that when IMD issues an alert for a district, every registered operator, guide and emergency contact for groups on those routes is notified at once, by SMS and satellite messenger where available, with a clear turn-back advisory.
Where: Uttarkashi, Uttarakhand, India

First, list what you would need to learn from the people affected before building, as interview questions.
Then propose the simplest version that would help, the screens or messages it needs, and the data it would use.
Keep it cheap to run, accessible, and respectful of people's privacy. Flag anything you are unsure about instead of guessing.