20th May

Possible chance of Derailing the El Niño effect this summer: 

A Positive I.O.D. can partially offset weak El Niño effects and sometimes supports a near-normal Indian Monsoon.

A Positive I.O.D. occurs when the western Indian Ocean becomes warmer than normal, while the eastern Indian Ocean near Indonesia turns cooler than normal.

This temperature contrast strengthens winds towards Africa and often helps enhance the Indian Monsoon by increasing moisture flow towards India.

Typical Effects:

Better monsoon support for India 🌧️

Increased rainfall over East Africa

Reduced rainfall near Indonesia/Australia

Vagaries Insight:

The Indian Ocean Dipole (IOD) is currently in a neutral phase, hovering around -0.04.

Forecasts project a shift to a positive IOD phase by late June or July 2026, with the index potentially exceeding the +0.5 threshold as a developing El Niño influences the broader climate system.

This may counter the developing El Nino. Indian Ocean may start working a bit in India’s favour even as the Pacific turns hostile.

Still Too early to make a call

 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.

PLEASE VIEW ON LARGE SCREEN AS IMAGE IS SMALLGives us an analysis of Previous ENSO Events

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.

Graph shows El Nino conditions start after July, El Niño gaining after September.. 

2. Cross Equatorial Winds

Cross-equatorial winds are strengthening steadily near the Equator and are now reaching the East African coast efficiently.

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.

Indicator :+ve

 

3. Seasonal Low

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.

Indicator : Normal.

4. LWD and Bay Low BB 2 formation on schedule. 

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.

Expected Progress Ahead

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.

Vagaries Insight

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.

 Monsoon Watch  4 at 11 pm IST here

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. 

Bulletin from Thai Met Office dt 14th:

 "Weather Advisory

Subject: Heavy to very heavy rains in Thailand,

Strong Wind-Waves in the upper Andaman Sea

No. 4 (64/2026)

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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 , 

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