Saturday, April 16, 2011

Weak pre-monsoon ‘low' indicated in Bay of Bengal


There is an emerging consensus among some global forecast models on the possibility of a weak low-pressure area building in the south and adjoining central Bay of Bengal over the next five to seven-day period. A ‘low' in the Bay around this time is a typical pre-monsoon season feature, and will help steer the flows to converge during the rest of the season.

LIKELY ENCORE

Last year the Bay had to wait for the third week of April for the ‘low' to shape up, while the just year before was fortunate witness the same as early as April 12.
It had gone to become a tropical cyclone, but no such forecast was indicated for the impending ‘low' in the Bay.
A favourable phase of the periodical Madden-Julian Oscillation (MJO) wave is seen transiting southwest Indian Ocean below Sri Lankan latitude and towards Indonesia around April 20.

WIDESPREAD RAIN

At least two major MJO trackers suggested that the impact of the upper-level wave, which is known to trigger weather over the region it passes, would last until the month-end.
No consensus outlook was available as to the exact location for the formation of the ‘low,' but the vast seas between Sri Lanka and the Andaman and Nicobar Islands suggested themselves as the most likely area.
Meanwhile, the 24 hours ending Friday morning saw widespread rainfall being reported from Assam, Nagaland, Manipur, Mizoram, Tripura, sub-Himalayan West Bengal, Sikkim, Karnataka and Lakshadweep.
Peaking pre-monsoon activity over land also saw fairly widespread during this period over Bihar, Gangetic West Bengal, Chhattisgarh, Vidarbha and Kerala, an India Meteorological Department (IMD) update said in the evening.
It was isolated over Jharkhand, Orissa, east Madhya Pradesh, Uttar Pradesh, Marathawada and Tamil Nadu.
Isolated rain or snowfall was also reported from Himachal Pradesh and Uttarakhand. 

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