Monsoon Watch - 4... 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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South West Monsoon Announcement # 1

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.

South West Monsoon Announcement #1

Here by 11.30 pm IST today
 

Mumbai.. Month of May facts and observations:

(Please see on mobile in horizontal view) 

Hearing a lot of whispers, shouts and complains about Mumbai being " too hot", specially this year. 

Well, it's a lot about the " over enthusiastic" social sites by several forecasters. 

Vagaries simply clarifies with facts about Mumbai's May temperatures over the last 130 years ! ( Santacruz observations started in 1953).

May (Max) Days average over the years. (mobile on horizontal view) 

                         Colaba.      Scruz

1892-1901        32.6c.       No Observations 

1953-1962        33.6c        33.1c

1963 - 1968                       33.3c

2016-2025        34.4c.       34.1c

2026.                 34.4c        34.3c   (May 1-11th)

Conclusion:: Average of May this year (2026) is equal to average of May since 2016.

This year May as yet is definitely 0.8°c warmer than what we see 50/60 years ago.. 

And warmer by 1.8°c from 125 years back. 

All Details of recorded observations compiled by Vag. Shitij Jain (Surat)

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