The India Meteorological Department (IMD) has declared the formation of an anticipated low-pressure around over the South Andaman Sea and adjoining South-East Bay of Bengal in its bulletin issued around Friday noon.
The IMD, however, said that its intensification is expected to be slower than earlier expected and delayed. As per the new schedule, the low may become well-marked over the same region during the next two days, and concentrate into a depression over the Andaman Sea and the adjoining South-East Bay during the subsequent two days (around May 5) 48 hours and intensify only thereafter.
No stress on Myanmar track
It is very likely to move to the North-North-West till May 5, the IMD said, but didn’t indicate anything on the likely track to the North-North-East (towards Myanmar-Bangladesh) that it had initially projected.
International models suggest that the delay in intensification and the longer stay in the waters might also cause the storm to change track slightly.
In the light of the formation of the low and its intensification, the IMD has given out warnings with respect to the likely adverse weather over the South Andaman Sea and adjoining South-East Bay during the next five days.
Adverse weather forecast
Light to moderate rainfall is forecast at many places over the Andaman & Nicobar Islands on Friday and Saturday and at most places during Sunday-Tuesday.
The Nicobar Islands may experience heavy rainfall at isolated places on Saturday and Sunday. Heavy to very heavy rainfall is likely over the Andaman &Nicobar Islands on Monday and Tuesday.
Squally winds with speeds reaching 40-50 km/hr gusting to 60 km/hr are is likely to prevail over the South-East Bay on Friday and over South-East Bay and the South Andaman Sea on Saturday and Sunday; 45-55 km/hr gusting to 65 km/hr over the South Andaman Sea and adjoining South-East Bay on Monday; and 50-60 km/hr gusting to 70 km/hr over the South Andaman Sea and adjoining South-East Bay on Tuesday.
Fishermen warning
The sea condition will be rough to very rough (wave heights of 8 -20 ft) over the South Andaman Sea and South-East Bay of from Friday to Tuesday. Fishermen are advised not to venture into South-East Bay on Friday; the South Andaman Sea and South-East Bay on Saturday and Sunday; and over the Andaman Sea and the adjoining South-East Bay on Monday and Tuesday.
Earlier, BusinessLine had reported that the two timelines set by the IMD for the first pre-monsoon low-pressure area to form in the Bay had passed, forcing it to extend the watch for another 12 hours (into Friday evening).
Competing pulls
The IMD had initially fixed the timeline for April 29, which was later revised to April 30. Normally, this is taken to mean the likely loss of confidence with respect to the forecast time and place of its eventual occurrence. In this case, a preparatory cyclonic circulation is hovering over South Andaman Sea and needs to build just the required mass to convert itself.
One potential reason why it is not able to do just yet is the competing pull on the south-westerly flows it shares with a stronger circulation over the East Indian Ocean off Sumatra (Indonesia) and a couple of less-intense ones over the Malacca Straits (off Malaysia) to the South-East, from where it had reached the South Andaman Sea.
Sumatran circulation
The Sumatran circulation is attracting a bulk of the south-westerly flows across the Equator that would normally have got directed into the South Andaman Sea. Some flows are taking a detour from here to feed into the Malacca Straits. The Sumatran circulation would have to blink first for the South Andaman Sea circulation has to prosper and intensify.
On the other hand, the delay in genesis and a slight change int track into a warmer (sea surface temperatures closer to 30 Degrees Celsius or above) into West-Central Bay of Bengal could, as a few models venture to suggest, intensify the system to near-cyclonic strength.
This is because it allows the system to gather strength in linear progression as it shifts its base from the South-East and adjoining South Bay (sea-surface temperatures of 28-29 Degrees Celsius) to the West-Central Bay (30-31 Degrees Celsius). Warmer seas and longer stay in the waters will just accord it the attributes needed to intensify.
Sea surface temperatures
If this were to happen, the models project that the storm (a deep depression, as indicated by the IMD and supported by the US Navy Global Environmental model) may inch closer to the Andhra Pradesh coast before veering to the opposite (North-North-East) and heading for the Myanmar-Bangladesh coast.
But it would also enter a less warm seas of the North and North-East Bay of Bengal. The European Centre for Medium-Range Weather Forecast suggest that the system may reach even closer to Visakhapatnam by May 10 until when forecasts are available.