31st May 2010 6.00 pm.
India Meteorological Department has declared the Onset of Monsoon over Kerala by citing various favourable conditions such as Rainfall at various stations; winds in the area from equator to Lat. 10ºN and Long. 55 ºE to 80ºE. should be of the order of 15 – 20 Kts. at 925 hPa.; & OUTGOING LONG WAVE RADIATION (OLR) value should be below 200 wm-2 in the area confined by Lat. 5 -10ºN and Long. 70- 75ºE.
IMD says that the Southwest Monsoon has further advanced into most parts of South Arabian Sea, entire Kerala, South Tamilnadu and some more parts of Southwest Bay of Bengal today, the 31st May 2010.
The Northern limit of Monsoon (NLM) passes through Lat.12.0°N/
Long.60.0°E, Lat.12.0°N/ Long.70.0°E, Kannur, Salem, Nagapattinam, Lat.
12.0°N/Long. 84.0°E, Lat. 15.0° N/ Long. 87.0°E, Lat. 18.0° N/ Long. 90.0°E and Lat. 21.0° N/ Long.93.0°E. The map showing NLM as on 31st May 2010 is given below:
My Observations:
Although the South West Monsoon has been declared over Kerala, the rainfall quantity will not be spectacular due to the presence of a Depression over Central Arabian Sea at 15N. 64E. Convective clouds from the South Arabian Sea will be sucked into this System and Kerala will be deprived of much rainfall.