If you have selected a "Saved Location", the map view does not update automatically after it has been selected - and does not re-size itself.

If, however, you have selected to view your "Current Location" and you have "Background Tracking" Enabled*, Storm Shield automatically updates your location once every minute. 

When this happens, the map refreshes, re-centers the locating pin, and returns to the default zoom setting.

If preferred, this can be prevented by disabling "Background Tracking" and simply setting one of your "Saved Locations" to your current location.

You can also control Storm Shield’s ability to access your location for any purpose through your device’s 

iOS Settings app (Settings > Privacy > Location Services > verify “Location Services” is enabled, then scroll through the list of apps to locate Storm Shield and verify it is enabled).