Forecast models are hinting at the formation of an Arabian Sea low pressure area/depression in the coming days. The American GFS model expects it to form off the Mumbai-Konkan coast on September 19, 2016.
This system may intensify into a deep depression as it nudges the Saurashtra coast and head straight west towards northern Oman, reaching it on around September 24, 2016.
The GFS only says it will be a depression. But there are still 10-15 days to go and a tropical cyclone cannot be ruled out.
Other forecast models confirm a low pressure area on Maharashtra on September 19. But they do not attest to the GFS prediction of an Arabian Sea storm. We have to wait a few days for the confirmation. This system will come over from the Bay of Bengal. This is the same cyclonic circulation which is dancing around the eastern coast of India. This is expected to intensify into a low pressure area and move to Maharashtra on September 19-20 via Andhra Pradesh and Telangana.
Meanwhile a depression will move through Vietnam, Laos, northern Thailand and reach southern Myanmar on September 16. But it may fizzle out after that.
The reasons for the disappointing South Asia monsoon this year are 3-fold.
>The Indian Ocean Dipole, IOD, is negative.
>La Niña still continues with her nakhras and refuses to come. Conditions are ENSO neutral.
>The storm maker Madden Julian Oscillation, MJO, had gone for a walk in the Pacific Ocean, so central Pacific Ocean is throwing numerous hurricanes. Though chances are a weak MJO may arrive in the Indian Ocean soon. But this is not confirmed. (See MJO diagram below).
UPDATE, SEPTEMBER 11, 2016
The GFS in its later forecasts now rules out an Arabian Sea depression. But there is a good chance of very heavy precipitation in Konkan, Goa and Mumbai around September 25, 2016. We are talking of 10-20 inches of rain in 2-3 days.
Something is going to happen in the Arabian Sea in the coming days. When forecast models give highly erratic predictions for an area, it rings an alarm bell somewhere.
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