Monday, May 27, 2013

Monsoon LIKELY TO BE STALLED after entering Kerala

Akshay Deoras
Severe Weather Forecaster

METD WEATHER's Indian Monsoon Forecast ( IndiMO) is already out! Check the monsoon forecast for your region here  (PUBLIC VERSION)

The monsoon has already arrived in Andaman and Nicobar Is and may be at the doorstep of India but the wait should be more as was expected and mentioned in the forecast.

As per the latest guidance from 00z, 28th May 2013 GFS, a low pressure system is mingling offshore Yemen-Oman as can be seen from this IMD IR imagery

One can clearly see the system just touching Yemen-Oman in the Arabian Sea region which is still having intense convection as being suggested by the two dense reflectivity (compact white regions)... If one believes the track of this system, the system will have a very strange and mingling motion in the Arabian Sea as it will move now south then again intensify head ENE then again WNW as a low pressure system prominently.. Convergence is doubtful with it as the GFS precipitation forecast does show many rain bands around the system and hence not consolidating as a Tropical Depression/Cyclone in the coming days. 

The forecast says that the system will move towards Oman ( Muscat ) as an insignificant system around 3/4th June 2013 and will likely bring rains there. We will update that on our facebook page as it comes in the Short range forecast panel. Some light clouds will continue in Muscat occasionally due to the system apart from rainfall in the shore of Oman-Yemen ( facing Arabian Sea)

However, this system will cause a big problem as feared! Lets have a look at the 850mb map showing the moisture. 

The top-most image is of the the present conditions ( 00z,28th May 2013) where this system can be noticed as anti-clockwise circulation region offshore Yemen-Oman. We can clearly see that the moisture at that level is being spread over Arabian Sea into West of India ( As the Somali Current has intensified allowing this to happen). However when one looks at the bottom image of the forecasted conditions on 2/3rd June 2013, one can clearly see the system gaining size ( hence strength) and pulling moisture in it. As a result, the amount of moisture in the Arabian Sea will decrease and subsequently the monsoon advance will get stalled for India ( Excluding the Bay Bengal branch)

In fact, NE India will see the monsoon advancing on time and hence eastern NE India states like Mizoram etc will witness the onset ON TIME AS MENTIONED BY METD WEATHER i.e around 1-3rd June 2013

The SW monsoon also will hit Kerala, some parts of Tamil Nadu that tenure itself but then as the system dominates, the advance is likely going to be affected.. We will wait for more details to come but the chance of happening this looks high as of now.

The monsoon will revive after a 5-6 day gap and hence advance into Karnataka-Andhra Pradesh by 10th June 2013 ( As per METD WEATHER's forecast).

II Bay System

Rains are being reported in Orissa and subsequent East India as a low pressure system continues to churn in the Bay of Bengal sending pulses towards India. Heavy rainfall ( accumulation over 100mm) is likely in Odisha in the next 48hrs ( prominently between Bhuvaneshwar-Kolkata geographical wise). That system will then move North and bring heavy rains in Western West Bengal,Jharkhand and southern Bihar by 1st June or so. 

People of Odisha and West Bengal coast must be attentive due to this system's movement and the rainfall due to it. 

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