Extreme Weather Forecaster,
The South-West Monsoon has totally halted and no new monsoon current has been recorded in India. So far, What I have concluded is that the direction of SW Monsoon winds is more pointing towards western coasts of India and that flow is not very strong to cause heavy rains or rains in Delhi and northern states. Cyclone Phet which was a Severe Cyclonic storm of Cat. 4 which had formed in Arabian sea has caused a very heavy rains in open waters of Arabian sea and along the western coast, With absolutely no Fresh low pressure or cyclone getting created in the bay
of bengal, the monsoon winds are not regulated as they do in every June
Reasons for Monsoon failure!
1. Cyclone Phet
Cyclone phet has affected the monsoon. Phet had formed within the monsoon trough and marched Westwards towards Oman first and then towards Pakistan. This path had consumed the moisture in arabian sea which is pushed by monsoon winds as flow of winds becomes SW. From the Weather models of 850mb and surface winds, its clear that all the moisture in India points towards North and remains at Western Coast and doesn't move inwards due to
Winds surging from South instead of SW.
Cyclone Phet has caused heaviest rains in open waters of Arabian sea more than 600mm.
Phet is still causing more rains in sea than on land
RIGHT- NASA TRMM SATELLITE SEES RAINFALL IN OPEN WATERS OF ARABIAN SEA. THIS IMAGE IS A COLLECTION FROM MAY 31 TILL JUNE 6 WHICH WAS PHET'S LIFE DURATION.
AS A STRONG LOW PRESSURE IS CREATED IN NORTHERN PLAINS, The winds at lower levels flow in a more northerly pattern than westerly pattern. This is preventing Eastern Maharashtra and Eastern states
from receiving the monsoon
3. WEAK MJO AND NEGATIVE IOD
The third main reason for Weak monsoon is Weak MJO and Negative IOD
Madden Jullian Osscilation
is a patch of rainfall anomaly travelling from East to West. The MJO negative phase means more rains than usual and positive means less rains than usual. The MJO current forecast see here is showing a positive cell near India which means relatively less rains then normal
II. Indian Ocean Dipole
is a phenomena similar to El Nino and La Nina but happening in the pool of Indian Ocean. IOD has dipped to -0.8 in June and is expected to be in a negative phase until July end to July mid. When IOD is positive, it means comparitively warm water is present with more rains in Western Indian Ocean than in Eastern Indian ocean.
Historic Forecasts for IOD see here clearly shows a negative DMI
in 2009 and it was a deficient rainfall in 2009. DMI however will rise by August and causing a normal August rainfall for 2010....
4. No Formation of significant low pressure in Bay of Bengal
Once cyclone Laila had formed in BOB which was weaker than Phet. Absence of Low pressure in BOB means no direction of Monsoon winds towards Interior India. If a strong low pressure happens in BOB and if it moves towards Kolkata, then monsoon winds will be steered to Interior India instead of coastal west..
So far, there is no chance of such formation as MJO tends positive and forecasts for MJO not showing any signs.Also broad convection happening in BOB....
Based on all this analysis, Monsoon is delayed by apx. 7 days and in some area by 10 days.
Its a summer condition in Northern India and also in Vidarbha area...
New dates of monsoon onset will be announced in the next post