Friday, May 15, 2009

IMD: Forecast for the 2009 Monsoon Onset over Kerala


Forecast for the 2009 Monsoon Onset over Kerala

1. Background

Since 2005, India Meteorological Department (IMD) has been issuing operational forecasts for the monsoon onset over Kerala using statistical techniques. During all the four years (2005 to 2008), the operational forecasts were correct. In 2008, IMD predicted 29th May as the date of monsoon onset over Kerala and the actual monsoon onset took place on 31st May just one day prior to the normal date of monsoon onset, i.e., 1st June. IMD has now prepared the forecast for the 2009 monsoon onset over Kerala.

2. Advance of monsoon over Andaman Sea

The normal date of advance of monsoon over Andaman Sea is 20th May. It is expected that within 2-3 days, monsoon flow will start appearing over Andaman Sea and monsoon is likely to cover the Andaman Sea close to its normal date. Past data suggest absence of any one to one association between the date of monsoon advance over Andaman Sea and the date of monsoon onset over Kerala.

3. Forecast for the 2009 Monsoon Onset over Kerala

For predicting the 2009 monsoon onset over Kerala, IMD used an indigenously developed statistical model, based on the following six predictors:

i) Minimum Temperature over North-west India ii) Pre-monsoon rainfall peak over south Peninsula, iii) Outgoing Long wave Radiation (OLR) over south China Sea (iv) Lower tropospheric zonal wind over southeast Indian ocean, (v) upper tropospheric zonal wind over the east equatorial Indian Ocean and (vi) Outgoing Long wave (OLR) over south-west Pacific region.

The statistical forecast model has a model error of ± 4 days. The mean monsoon onset date over Kerala is 1 June.

The onset forecast model suggests that the monsoon onset over Kerala in 2009 is likely to be on 26th May with a model error of ± 4 days.

original from:

Mercury rises; Orissa toll up to 130

Most parts of northern India on Thursday experienced high temperature with Churu and Kota in Rajasthan recording 46.5°C each as death toll in Orissa rose to 130 with two more people succumbing to blistering heat wave.

Casualties due to suspected sun-stroke were reported from Jagatsinghpur and Keonghar in Orissa where Titlagarh sizzled at 44°C though some places in the state were lashed by rains.

Normal life and public transport were badly affected in Rajasthan as scorching heat continued to sweep the State with mercury soaring at almost all places.

Churu and Kota remained the hottest with 46.5°C each followed by Bikaner which recorded a maximum of 46.4°C.

Heat wave conditions intensified in some parts of Punjab and Haryana with Hisar touching 44.4°C, which was hottest place in the region.

Chandigarh recorded a two degrees below normal temperature at 35.8°C while Amritsar in Punjab experienced a hot day at 40.2°C.

Mercury rose marginally in Himachal Pradesh in the absence of rain and snowfall. Occasional cool breeze, however, kept weather in capital Shimla relatively pleasant that registered 17°C.