Thiruvananthapuram, Oct. 25
The northeast monsoon has still not been able to fire on all cylinders due mainly to the positioning of the inter tropical convergence zone (ITCZ) with a pronounced southerly bias.
The global band of low-pressure has to move farther north to around the 10N Latitude for weather-creating systems such as `lows'/depressions to take shape, said Dr Akhilesh Gupta of the Department of Science and Technology.
RAINS TO SUSTAIN
But passing easterly waves, backed up by cloudiness associated with the ITCZ lying currently along lower latitudes, are enough to sustain the ongoing wet session for another four to five days. This will also indirectly help throw up the anticipated `low' over southeast Arabian Sea by the weekend.
Dr Gupta said the ITCZ has to lie at a specific distance away from the Equator to trigger energetic weather systems over the warm waters of the Arabian Sea or the Bay of Bengal.
At this distance, clusters of cloudiness get detached from the parent ITCZ to spin up as `lows' or depressions.
MORE TIME NEEDED
"The seas are warm enough and it is up to the atmosphere to respond in kind to complete the cycle," he said.
It will be `some more time' until the ITCZ manages to break itself away and move sufficiently north to set up the first few weather systems of the season. Dr Gupta did not see this happening during the next four to five days at the least.
But there is no cause for worry since the ITCZ has been known in the past to take a while to get accentuated along the right latitudinal position. The current location around the 5N benefits southern Kerala and south Tamil Nadu, apart from Sri Lanka to the immediate south.
Forecasts by the India Meteorological Department said that under the influence of an easterly wave, fairly widespread rainfall is likely over the southern peninsula during the next three to four days.
Numerical weather models continue to suggest the formation of a `low' over southeast Arabian Sea by the weekend. This may cause increase in rainfall activity over Tamil Nadu, Kerala and Lakshadweep where isolated heavy rainfall is also likely.