Monday, August 28, 2023

Kerala monsoon rainfall (1901-2022)

The rainfall in Kerala during the monsoon season is decreasing at the rate of 16.2mm/decade.

During the period 1901-2022, the wettest monsoon season was in the year 1924 when Kerala got 3115.3 mm rain, and the driest monsoon was in the year 1918 when Kerala got 1150.2 mm rain. Data source: IMD


harsha said...

I'm curious how the spread over the entire year has changed over he same duration. General trend appears to be the north coast and ghats are getting wetter and the south coast and ghats are getting drier, but what about the duration throughout the year/ monsoon season?

sset said...

Very interesting and contrasting between konkan and kerala rains...thanks..

Some more anomalies...
1. Gujarat Rajasthan rains increasing
2. Desertification of South east India...anantapur rayalseema cudppah chittor many places if tamilnadu, South east karnatak...places dependent on unreliable failing north east monsoon.

NilaY Wankawala said...

Credit Australian Government Bureau of metereology

Issued Tuesday 29 August 2023

The latest Climate Driver Update and Climate Model Summary are now available on our website.

El Niño Alert continues, positive IOD likely for spring

The Bureau's El Niño Alert continues, with El Niño development likely during spring. When El Niño Alert criteria have been met in the past, an El Niño event has developed around 70% of the time.

Sea surface temperatures (SSTs) in the tropical Pacific are exceeding El Niño thresholds and have continued to warm slightly over the last fortnight. SSTs are likely to remain above El Niño thresholds until at least early 2024.

The 90-day Southern Oscillation Index (SOI) is presently just below El Niño thresholds, However, atmospheric indicators suggest that the Pacific Ocean and atmosphere are not yet consistently reinforcing each other, as occurs during El Niño events.

The latest weekly Indian Ocean Dipole (IOD) index is +1.05 °C, being the second week above the positive IOD threshold of +0.40 °C. However, before an IOD event is declared, several more weeks of the IOD index above the positive IOD threshold are required. A positive IOD typically decreases spring rainfall for central and south-east Australia and can increase the drying influence of El Niño.

The Madden–Julian Oscillation (MJO) is currently weak or indiscernible, and is likely to move over the Maritime Continent or Western Pacific in the coming days. If this pulse moves into the Western Pacific and remains relatively strong it may assist El Niño development by weakening trade winds.

The Southern Annular Mode (SAM) index is currently at neutral values and is expected to become slightly negative then return to neutral during September. A negative SAM is associated with increased rainfall over south-west Western Australia and western Tasmania during spring, while a neutral SAM is associated with typical climate conditions for Australia.

Australia’s climate has warmed by an average of 1.47 ± 0.24 °C since national records began in 1910. There has also been a trend towards a greater proportion of rainfall from high intensity, short duration rainfall events, especially across northern Australia. Southern Australia has seen a reduction, by 10 to 20%, in cool season (April to October) rainfall in recent decades.

More information

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Next update expected by 12 September 2023

  Posted 13th Night: Outlook for Sunday 14th to Wednesday 17th: An off shore trough along the West Coast is expected to bring good rainfall ...