Sunday, May 1, 2011

Of Rainfall, Weather Forecasts & Landslides

Most landslides which occur in the Darjeeling - Sikkim Himalaya are rain induced and therefore knowing when, how much, and how heavy (ie intensity) of rainfall is important for us working on landslides in this area.
Fortunately, technology and the internet allows even the lay person to keep a tab on rainfall  and here is an example of the weather forecast in this region, the actual weather/rainfall over Kalimpong and the satellite picture on 01May2011 around the time we had heavy rain:-
  • Kolkata Regional Weather Forecast of 01-05-2011 valid till noon of 02-05-2011
    Fairly Widespread rain or thundershower may occur over Sikkim and Darjeeling, Jalpaiguri and Coochbehar districts of Sub-Himalayan West Bengal.
    Thunder squall with wind speed reaching between 50 and 60 Km per hour may occur at isolated places over Bihar & Sub-Himalayan West Bengal during next 24 Hours.
    (This warning was obtained from the IMD (Kolkata) website but a similar SMS-based warning has been sent by IMD (Gangtok) to thousands in Darjeeling district - see here)
  • Actual weather over Kalimpong
    It was very breezy thru the day with very light drizzle taking place intermittently during the afternoon. However, between 1730h and 1815h, we had experienced sharp heavy rainfall (15mm in about 25mins) accompanied by gusty wind, lightning and thunder.
    By 1830h the cumulonimbus (Cb) cells which caused the downpour had moved away but a light drizzle continued.
  • IR Satellite picture at 1730h on 01May2011

Comment by Praful Rao

The forecast,  severe weather warning and the satellite photo are from here.

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