Tropical Update-01

MONSOON ENTERS SOUTH-WEST BAY OF BENGAL ON ACCOUNT OF LOW IN SOUTH-WEST BAY :

Latest satellite image of Himawari shows a Cloud band over South-west Bay close to Srilanka coast at around 380kms eat-southeast of Trinconamalle. It has good convergence and likely to develop into a well-marked Low in next 48 hours. 

Under the influence of LOW over Bay of Bengal, the Monsoonal flow has entered the South-most parts of Bay of Bengal and adjoining Indian ocean. The cross equatorial currents making an entrance and has given an arm to Sumatra. Depending on the movement of Low, The Inter-Tropical Convergence Zone moves up, giving monsoonal flow in Bay of Bengal arm. Monsoon might touch Andaman and Nicobar island around May 14th if the low moves north-wards. We can also see a ridge formed in Bay of Bengal  close to Burma. 

Cyclone-Tracking-

Chandra Mouli, a member of Weather of South India said that the High pressure area over 200hPa (4-5 kms height from ground) likely to form a ridge and make the system to make land fall from the coast of odisha to Tamilnadu.

Leading Weather Organization ECMWF tells that the system will stay south and cross the South-Tamilnadu coast.

GFS were consistent for Land fall close to Tamilnadu but recently they changed the Place and taking it to Burma.

Ensemble Models like EPS, GEPS, GEFS are consistent over Andhra and Tamilnadu coast.

"If ECMWF forecast over indian ocean Basin comes true then there will be good and much needed rainfall to Tamilnadu and Andhra coasts. At the same time, it helps in the progress of South-West Monsoon particularly in Bay of Bengal Branch.

Vortic Innings-2016

A Possible Cyclone-Genesis over Indian Ocean Possible In Third Week-

Generally we have many systems that arise in hot summer Temperatures. Cyclone Mahasen, Cyclone Gonu, Cyclone Laila, Cyclone Giri, Cyclone of Bengal etc... Generally the High Pressure area over 200hPa levels gives effective steering of the cloud band in lower levels (500,700,1000 hPa)...Which makes the system to go in different directions. May cyclones contain a good cloud band, formed by good heat. It will lead to good rainfall associated with heavy winds with high TCHP(Tropical Cyclone Heat Potential) Values.

Tropical Cyclone Heat Potential(TCHP):

It is defined as the Heat stored in the Atmosphere in the form of Potential Energy. When a cyclone passes through an area of High TCHP, it results in heavy cloud band and causes the intensification of Storm. Cyclones intensify well in the presence of Low-Wind Shear and the presence of Madden Julian Oscillation, Arctic Oscillation etc..

It is also seen that the central Band i.e the Band close to the eye wall is very strong and causes torrential downpour. Hence the places near coast get more heavy rainfall than interiors during an april-may system.

From the above picture, it is evident that the May clones have a very strong outer-core band. See the cloud band of Laila its about 18 km in height, which is essential for Severe Rainfall.

What about May-Third Week System-

Though the Models like GFS, ECMWF, GEFS, GEM, CFS changing their forecast for every run, i can put a point that the system will form over coumorin sea. I can also say that the system might move into arabian sea and follow the west coast and cross the Konkan. But the things might change. Track-3 is 70% probable. Let's see, My Chennai friends need some rain. Still many places around chennai hasn't recorded any rainfall from January 1st, 2016. 

WEATHER OF SOUTH INDIA-FOECAST:

AVAILABLE TCHP VALUES IN INDIAN OCEAN-LATEST:

                                                                           

With Regards

Sai Praneeth

(Weather of South India)