According to the National Weather Forecasting Centre of the India Meteorological Department:
♦ In view of the enhanced cloud cover and deepening of southwesterly winds upto mid tropospheric levels, Southwest Monsoon has further advanced into some more parts of south Bay of Bengal, most parts of Andaman Sea and Andaman & Nicobar Islands today. The Northern Limit of Monsoon (NLM) passes through Lat.5°N/Long.82°E, Lat.7°N/Long.86°E, Lat.10°N/Long.90°E, Port Blair, Lat.15°N/Long.97°E.
♦ Conditions are becoming favourable for further advance of Southwest Monsoon into some parts of Maldives-Comorin area and adjoining southeast Arabian Sea, remaining parts of Andaman Sea and some more parts of south and central Bay of Bengal during next 48 hours.
♦ The cyclonic circulation over southwest Arabian Sea now lies over westcentral and adjoining southwest Arabian Sea extending upto mid tropospheric levels. Under its influence, a low pressure area is very likely to form over the same region around 29th May. It is very likely to concentrate into a Depression over the same region during the subsequent 48 hours.
♦ The Western Disturbance as a cyclonic circulation over Afghanistan & neighbourhood now lies over northeast Afghanistan & neighbourhood at 5.8 km above mean sea level.
♦ The eastwest trough at mean sea level from East Uttar Pradesh to Nagaland across Bihar, SubHimalayan West Bengal and Assam persists and now extends upto 1.5 km above mean sea level.
♦ The cyclonic circulation over Punjab & neighbourhood extending upto 2.1 km above mean sea level persists.
♦ The trough from south Chhattisgarh to interior Tamilnadu now runs from Rayalaseema to interior Tamil Nadu and now extends upto 1.5 km above mean sea level.
♦ The cyclonic circulation over southwest Bay of Bengal & neighbourhood now lies over southwest Bay of Bengal off Sri Lanka coast between 2.1 and 4.5 km above mean sea level.
♦ The cyclonic circulation over Coastal Karnataka & neighbourhood at 2.1 km above mean sea level has become less marked.
♦ The northeastsouthwest trough in westerlies roughly along Longitude 88°E to the north of Latitude 23°N between 1.5 & 2.1 km above mean sea level has become less marked.
Meanwhile, due to prevailing dry northwesterly winds over plains of northwest India, Central India & adjoining interior parts of eastern India, present heat wave conditions very likely to continue to prevail mainly during next 24 hours.
Meteorological sub-division wise,
Heat Wave is considered if maximum temperature of a station reaches at least 40°C or more for Plains, 37°C or more for coastal stations and at least 30°C or more for Hilly regions. Following criteria are used to declare heat wave:
a) Based on Departure from Normal
b) Based on Actual Maximum Temperature (for plains only)
To declare heat wave, the above criteria should be met at least in 2 stations in a Meteorological subdivision for at least two consecutive days and it will be declared on the second day.
HEAT WAVE WARNING (COLOUR CODES)
Maximum temperatures are near normal
Heat wave conditions at district level likely to persist for 2 days
Severe Heat Alert for the day
(i) Severe heat wave conditions persist for 2 days.
(ii) With varied severity, heat wave is likely to persists for 4 days or more
Extreme Heat Alert for the day
(i) Severe heat wave persists for more than 2 days.