likely-formation-of-a-low-pressure-area-over-south-andaman-sea-summary

Context: As per the forecast guidance from various numerical weather prediction models, a Low Pressure Area is very likely to form over south Andaman Sea and neighbourhood around the end of this month.

More about the news:

  • It is very likely to intensify further during subsequent 48 hours and very likely to move north-northwestwards initially and then north-northeastwards along & off Andaman & Nicobar Islands.
  • The Cyclone Warning Division of the India Meteorological Department says that the system is under continuous surveillance and the concerned state governments are being informed regularly.

Associated weather phenomena

Under its influence, the following adverse weather is likely over & around Andaman & Nicobar Islands and surrounding Sea areas:

  1. Rainfall:  Light to moderate rainfall at many places with heavy falls at isolated places is very likely over Nicobar Islands. The intensity and spatial extent is likely to increase further during the subsequent days. 
  2. Wind warning: Squally winds, speed gusting to 60 kmph are likely to prevail over north Sumatra coast, south Andaman Sea, Nicobar Islands and adjoining southeast Bay of Bengal.
  3. Sea condition: Sea conditions will be rough to very rough over north Sumatra coast, south Andaman Sea and adjoining southeast Bay of Bengal.
  4. Fishermen Warning: The fishermen are advised not to venture into the Sea along & off north Sumatra coast, Andaman Sea and adjoining areas of southeast & east central Bay of Bengal.   

Low pressure condition on Indian subcontinent and associated phenomena

Source: Financial Express

South West Monsoon Season 

  • Also known as hot-wet season occurs from June to mid-September.
  • Sudden onset is the vital feature of South West Monsoons.

Pressure conditions

  1. Low pressure conditions prevail over northwest India as a result of high temperature.
  2. InterTropical Convergence Zone(ITCZ) also known as monsoon trough lies over the Ganga plain. 
  3. Depending upon the weather conditions,There are frequent changes in the ITCZ location.

Pattern of wind flow

  1. The atmospheric pressure will increase steadily southwards.
  2. As a result  of gradient between north and south, winds blow in a southwest to northeast direction from Arabian sea and Bay of Bengal, over the peninsular India.
  3. Their direction changes in the Indo-Gangetic plain where they move from east to west.

Factors that influence the intensity of South-West Monsoons

  • Low pressure strength over Tibetan Plateau
  • High pressure over the southern Indian Ocean.
  • Somali Jet 
  • Indian Ocean branch of Walker Cell.
  • Indian Ocean Dipole.

Rainfall

Precipitation that comes down to the earth in liquid form is called rain. Other forms of precipitation are snow, sleet, hail.

On the basis of mechanism, there are three types of rainfall:

  1. The Convectional rainfall,
  2. The orographic rainfall and
  3. The cyclonic rainfall

Source: NCERT

Source: accuweather

Source: https://pib.gov.in/PressReleasePage.aspx?PRID=1618439