Monsoon Watch-7 , Part -2 , -Advance, Quantum and Initial Strength.
This Watch will evaluate the progress of the SWM advance, and its estimated initial strength.
Looking at the synoptic situation today, 20th, it seems the SWM winds in the Arabian Sea and Bay sectors are hesitant, and not gaining the momentum required. SW winds over the primary destination, Maldives, are still below 20 knts, not enough to usher in the SWM. Normally, the date is 20th, but it seems the Maldives and Sri Lanka would get the SWM, albeit a weak force, by the 23rd and the 26th resp. And, I would not be too sure of its initial momentum and intensity, as the MJO wave in this region seems to be fading , and going into a weak phase from the 25th to the 4th of June.
The further current into Kerala would be "reluctant" to move ahead in a weak MJO. The MJO wave, for the Arabian Sea region is forecasted to gain inertia from the 4th of June. So, thru this wave, I would estimate the SWM to advance into Kerala around the dates initially estimated by Vagaries : June 3rd/June 4th could be the date for Kerala.
Initially, riding on a strongish MJO wave, the SWM could precipitate good rains in Kerala, and advance into coastal Karnataka 48 hrs from 4th June. Again on this wave, SWM could advance into interior Karnataka, Goa and S.Konkan by the 8th, and Mumbai by the 9th/10th.
Advance further will not be a hindrance, by the 15th, I would include entire Mah and South Gujarat as covered by the SWM.
Vagaries has put up a map for easy reading.
Intensity and strength of SWM in these regions will be good till the 23rd. After 24th June, a "slow down" could be expected, in precipitation in the SWM regions, and further advance.
The Monsoon forecast for June put up by Vagaries on May 7th, as MW-5 Part-2.... holds good.
Mumbai can expect about 650 mms in June this year.
In the Bay sector, SWM will start covering the Bay Islands from the 23rd, and subsequently reach the NE states by the 1st of June.
These are my personal views and for commercial decisions consult local weather bureau.