Saturday, March 25, 2017

How to convert your smartphone into an Early Warning (EW) device

1. I was tracking the storm (Slide 1) over Nepal last evening on this IMD website and had to resist an urge to post it on STH's  'Hazard Alert', What'sApp group because I was not too sure of the movement of the storm.
2. Having tracked storms on broad band internet for over 5 -7yrs now ( see 1, 2), I am cautious about creating panic or apprehension by uploading inaccurate weather forecasts - nevertheless because of the prevailing westerly upper winds, I was more or less certain that the storm would reach us if it did not dissipate elsewhere. Where I was wrong was in the timing - I expected the storm to reach us in 2 hrs.
3. Six hrs later, at 3.30am this morning, I was woken up by the sound of driving rain, followed by loud peals of thunder and lightning. A glance at the IR satellite imagery (Slide 2) on my smartphone told me that the storm had arrived over us.
4. It dumped almost 40mm of rain in as much time which gives an approx intensity of 60mm/hr - an intensity which can trigger off landslides if the precipitation is sustained.
5. But here is the bottom line :-
a. Updated satellite imagery (IMD updates its images every 30mins) together with cloud movement animation and other web - based info (like Lightning Location) can provide us with powerful tools to give us EW info on  storm movements.
b. Major weather events like cyclones and hurricanes give ample warning (5-6 days)
c. Minor weather events like local storms generated by micro-climates are often the only ones which do NOT show up on satellite imagery.
d. I rely a lot on IMD satellite imagery but there are many others which I hop to when IMD website is down (eg. Bangladesh and Nepal meteorological dept websites)
6. While all this is pertinent to hydrological events only, one need not wait for the next BBC weather bulletin to check the forecast
- instead just convert your smart phone into an early warning device!

Praful Rao
Kalimpong district,
Darjeeling-Sikkim Himalaya

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