Shimla, April 15 -- Himachal Pradesh may witness a wet spell from April 17 to 20 as a fresh western disturbance is likely to affect the western Himalayan region from April 15, the local Met office predicted on Tuesday. The meteorological centre in Shimla has also issued a yellow warning for thunderstorms, lightning, and gusty winds with speeds of 30-40 kilometres per hour in isolated places across four to seven of the 12 districts on Friday and Saturday. Meanwhile, the weather remained mainly dry in the last 24 hours since 6 pm on Monday, the meteorological office said. Keylong was the coldest at night with a low of 0.4 degrees Celsius. Meanwhile, Una was the hottest during the day with a high of 34.2 degrees Celsius, it further said....