18th May Post
Highlight: Pre Monsoon Low in Arabian Sea precipitates heavy rains in Kerala and Coastal Karnatak upto Goa.
Kozhikode 101 mm
Kannur 88 mm
Cochin 54 mm
Gadag 84 mm ( Kar)
Mangalore 14 mm(Kar)
Goa Margao 47 mm
Goa panjim 11 mm
This Low will, later in the week, mildly activate the Off shore West Coast Trough.
Hence some pre monsoon thundershowers can be expected Along entire West Coast from 24th May - 28th May.
Konkan ( Mumbai) can expect showers from 24th - 28th May.
Monsoon Watch - 4... Summery 👉
16th May
1. ENSO Status
Current ENSO conditions remain Neutral.
Latest model guidance indicates that El Niño conditions may begin evolving after July, with a more noticeable strengthening likely after September.
The present indications suggest that ENSO is not expected to significantly interfere with the initial onset phase of the South-West Monsoon.
A noticeable South-Westerly turn is visible off the Somalia coast, with Sea Surface Temperatures (SSTs) there around 24°C, supporting gradual strengthening of the low-level jet.
The Seasonal Low over the core Thar region is currently around 998 mb, which is considered satisfactory for this stage of May.
Formation is progressing well despite temperatures remaining broadly within the normal range.
However, the pressure gradient still needs further strengthening during the coming 10–12 days.
The South-West Monsoon has entered the Andaman Sea, marking the formal beginning of monsoon advancement across the eastern sector.
Arabian Sea branch parameters are also progressing steadily and favorably.
Increasing heat across Central and Northwest India, with temperatures expected to cross 45°C more frequently, should help strengthen the required monsoon pressure gradient further.
At present trends, the Kerala Monsoon onset is expected around 30th May to 1st June.
The overall monsoon progression presently appears largely on schedule, with both Arabian Sea and Bay branch indicators gradually aligning positively.
While ENSO evolution towards El Niño later in the season remains a factor to monitor carefully, the immediate onset phase currently does not show any major adverse signals.
Rainfall as on 16th Morning in Andamans (Weak Monsoon Advance)
Carnicobar 44mms
Mayabandar 14 mms
Nancowrie 12 mms
Port Blair 5 mms
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15th Night Post
South West Monsoon Announcement # 3
South West Monsoon Advances into South Andaman Islands as a weak current..15th May.
Bulletin of Thai Met Dept.
"The southwest monsoon prevails over the Andaman Sea and the South with more rain and isolated heavy rain in the upper country, while isolated very heavy rain is likely in the North, the Central, and the East."
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13 May observed wind speed during squall and observed lightning strikes
Meerut saw a whopping strike of 519 in 1hr
Unnao massive 952 strikes in 1hr
Raebareilly 655 lightning strikes in 1hr
Observed windspeed in UP on 13may
Monsoon Watch - 4 on blog tomorrow 16th
Southwest Monsoon Announcement # 2
The South-West Monsoon will advance in the Andamans Region by 16th May.
Subject: Heavy to very heavy rains in Thailand,
Strong Wind-Waves in the upper Andaman Sea
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The active low-pressure cell in lower Bay of Bengal will move to the upper Bay of Bengal while the southwest monsoon prevailing over the Andaman Sea, Thailand and the Gulf will strengthen."
Meanwhile ,
12th May Night Post:
A weak low (BB 1) forms in BoB, displacing the anticyclone.
This is likely to intensify a little and open the doors for the cross equatorial flow to enter southern BoB.
SWM 2026 onset over Andaman & Nicobar islands likely by 15th/16th May as a weak current.
Estimated winds on 15th: 👇
As BB 1 moves NE, rainfall will reduce over the Islands, hence weak current.
Arabian Sea anticyclone also weakens, but ridging persists.
As the Somali current intensifies, and the SST drops along the Somali Coast in the last week of May, pre monsoon thundershowers can commence along Keralam and Coastal Karnatak by May end
Note and images compiled by Vagarian Shreyas.
18th May Post Highlight: Pre Monsoon Low in Arabian Sea precipitates heavy rains in Kerala and Coastal Karnatak upto Goa. Kozhikode 101 mm...
