Thunderstorm accompanied by lightning/gusty winds(40-50 kmph) is likely to occur at isolated places over Almora, Bageshwar, Chamoli, Champawat, Dehradun, Haridwar, Nainital, Pauri Garhwal, Pithoragarh, Rudraprayag, Tehri Garhwal, Udham Singh Nagar, Uttarkashi in next 24 hours.