When storms change their mind - Bay of Bengal 26-29July2026

A low pressure area (see above) formed in the Bay of Bengal around the 25/26July2026 which quickly intensified into a depression and thereafter into a deep depression, more or less in the same area. 
The forecast track of the depression was initially in a NWly path:

 

The subsequent path followed by the storm and forecast by the IMD are shown (all images from  https://mausam.imd.gov.in/responsive/cycloneinformation.php):

The latest position of the storm is shown below: it is located South West of where it formed. 

Updated track of the storm as it traversed the breadth of the country (01Aug2026)

Praful Rao
SaveTheHIlls
savethehills@gmail.com
9475033744

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

Onset of SouthWest Monsoon 2016.

 Forecast of the Onset Date of Southwest Monsoon - 2016 over Kerala (Excerpts)

1. Background
The onset of southwest monsoon over Kerala signals the arrival of monsoon over the Indian subcontinent and represents beginning of rainy season over the region. The normal monsoon onset over Kerala is 01 June. Since 2005, India Meteorological Department (IMD) has been issuing operational forecasts for the date of monsoon onset over Kerala using an indigenously developed statistical model with a model error of ± 4 days.

The forecasts of the monsoon onset issued during the past 11 years (2005-2015) except 2015 were proved to be correct. 

2. Advance of monsoon over the Andaman Sea
The southwest monsoon advances over the Andaman Sea normally around 20th May with a standard deviation of about one week. Strong convective activity has been observed over the equatorial Indian Ocean for the last several days. A well marked low pressure area has formed over the Indian Ocean which will concentrate into a depression and move north-westwards. As a result, conditions are becoming favorable for the onset of southwest monsoon over Nicobar Islands, south Andaman Sea and parts of south Bay of Bengal around 17th May and advancement over the entire Andaman Sea close to its normal date. Past data suggest that there is no association of the date of monsoon advance over the Andaman Sea either with the date of monsoon onset over Kerala or with the seasonal monsoon rainfall over the country.

3. Forecast for the 2016 Monsoon Onset over Kerala
The statistical model forecast suggests that the monsoon onset over Kerala in this year is likely to be slightly delayed. The southwest monsoon is likely to set over Kerala on 7th June with a model error of ± 4 days.

Read full article here

Praful Rao,
Kalimpong,
Darjeeling district

South Westerly Monsoons 2014 - advance and withdrawal

Praful Rao,
Kalimpong,
Dist Darjeeling