2012 Indian Monsoon Forecast ( IndiMO) Part I ( PUBLIC VERSION)

METD WEATHER
AKSHAY DEORAS
SEVERE WEATHER FORECASTER

16TH MAY 2012
MUSCAT,OMAN

2012 INDIAN MONSOON FORECAST ( PUBLIC VERSION) 

FROM THE DESK-


***METD WEATHER COMPLETES 1,00,000 PAGEVIEWS ON 14TH MAY 2012 SINCE MAY 2010. 


Dear Readers, 
As a part of the annual forecast of the Indian Monsoon (IndiMO) since 2010, METD WEATHER brings you the 2012 Indian Monsoon Forecast ( IndiMO I) PUBLIC VERSION. The Summer Monsoon forecast is prepared using multiple parameters which include the Indian Ocean Dipole ( IOD), Madden Julian Oscillation (MJO),El Nino Southern Oscillation (ENSO) and their inter relation. Its widely observed that the Indian Summer Monsoon is largely affected by the atmospheric patterns such as the Madden Julian Oscillation which is directly linked to the El Nino Southern Oscillation. The Indian Ocean Dipole also plays some role in the strength of the monsoon current and subsequently affects the quantum of the monsoon rainfall. 


 Public version is all about the conclusions explained in simple words for the readers WITH THE HELP FROM THE KEYWORDS (BOTTOM). 


METD WEATHER has all the rights reserved for this forecast and the matter is (C) 2012 METD WEATHER. 


A.Deoras

-------------------------------------------------------------------------------------------------------------------------------------

The June rainfall pattern across India where the monsoon reaches shall be 

MOSTLY NORMAL (85% NORMAL EXPECTED) 

Thus for the monsoon season, NEUTRAL ENSO activity, Weak Positive IOD and lesser interference of MJO is expected. 

The Ekman Drift will play a significant role in deciding the rainfall amount in this region. The Great Whirl also will play a significant role as the MJO is expected to be more towards a DRY PHASE resulting in the amount of rains.

Concluding these factors, it appears that for India, the overall ( quantum) of 2012 Summer Monsoon will 

be "SLIGHT DEFICIENT" WITH THE QUANTUM ANOMALY FOR THE SEASON EXPECTED TO BE - 

~ 85% NORMAL 

~ 15% DEFICIENT 

REGION WISE FORECAST- 

1) SOUTHERN INDIA 

The IOD which is expected to be more towards weakly negative will lead to dry phase development which may reduce the rainfall amount in this area. A Slow Monsoon phase shall be likely in June due to no MJO activity. The rainfall amounts shall increase from July. 

Region will witness " DEFICIENT" Rainfall with around 75% NORMAL RAIN and 25% DEFICIENT

2) Western India

The same conditions shall apply for Western India also as if the MJO activity remains less, monsoon winds shall be weak in this region. The rainfall pattern is expected to be slow in June month with monsoon making a slow entry. The rainfall amounts shall revive at the mid monsoon stage onwards when a Positive IOD consistency will develop

The region will witness "DEFICIENT" rainfall around 65% to 70% NORMAL and 35-40% DEFICIENT 

3) Northern India

The region can expect good rainfall unlike the other areas. The primary reason seems to be the wind patterns expected. The region will receive some rains from the Western Disturbances which may have a southernly dip than normal. This factor was observed in April month also when greater than normal thunderstorm activity was reported across North-East India as the trough dug more southward and brought rains. 

Aperiodic rainfall shall be there with 85% NORMAL and 15% DEFICIENT CONDITIONS

4) North East India

NE India will witness "Slightly Weak" Monsoon with the primary reason expected to be the less effective Bay of Bengal current. Due to lesser MJO events the current may not be that strong to produce much rains in the region

Expected 80% NORMAL RAINS AND 20% DEFICIENT 

5) East India

Region shall witness SLIGHTLY WEAK MONSOON CONDITION. 

Expected 85% NORMAL and 15% DEFICIENT

6) Central India

Lesser Bay systems shall reach this area resulting in lesser precipitation as compared to 2010,2011. The southward dip of Jet stream shall assist is some rainfall. 

For South Central India ( Maharashtra parts) rainfall shall be 85% NORMAL and 15% DEFICIENT and for North Central India, rainfall will be 90% NORMAL and 10% DEFICIENT. 

7) Andaman and Nicobar Is. 

Normal rainfall is expected in this region around 95% i.e 5% deficient 

8) Lakshadweep and surrounding

Considering the expected strength of Monsoon current and Ekman Drift this region will witness deficient rainfall 

70% NORMAL i.e 30% DEFICIENT 

-------------------------------------------------------------------------------------------------------------------------------------

SINDH REGION 

CONSIDERING THE CONDITIONS ACROSS ARABIAN SEA AND LESSER LOW PRESSURE SYSTEMS, SLIGHTLY DEFICIENT MONSOON RAINS ARE BEING EXPECTED IN THIS REGION

AROUND 85-90% NORMAL RAINFALL EXPECTED THIS YEAR

-------------------------------------------------------------------------------------------------------------------------------------

7) Inference 

* METD WEATHER ESTIMATES THAT THE SUMMER MONSOON FOR INDIA WILL BE AROUND 85% NORMAL AND 15% DEFICIENT. 

* THE SUMMER MONSOON WILL BE DEFICIENT AS COMPARED TO 2010,2011

* NEUTRAL EL NINO SOUTHERN OSCILLATION (ENSO), WEAK POSITIVE INDIAN OCEAN DIPOLE (IOD) AND LACK OF MADDEN JULIAN OSCILLATION (MJO) SHALL REDUCE THE RAINFALL 

* SOUTHERN AND WESTERN INDIA SHALL GET MORE DEFICIENT RAIN AS COMPARED TO OTHER PARTS

* NORTHERN,CENTRAL INDIA AND ANDAMAN NICOBAR IS. SHALL GET NEARLY NORMAL RAINFALL 

*MONSOON WILL BE WEAK IN JUNE AND EXPECTED TO INTENSIFY ACROSS JULY

* VERY LESS LOW PRESSURE SYSTEMS SHALL AFFECT THIS YEAR

* INDIAN OCEAN DIPOLE (IOD) SHALL TURN TO A WEAK POSITIVE AROUND MID MONSOON PERIOD

* ENSO IS EXPECTED TO REMAIN NEUTRAL THROUGHOUT THE PERIOD

* MJO INTERFERENCE SHALL BE WEAK IN BOTH THE PHASES 


* MONSOON SHALL BE WEAKER IN JUNE MONTH


-------------------------------------------------------------------------------------------------------------------------------------


KEYWORDS-


1) ENSO ( El Nino Southern Oscillation) - 


What is ENSO (El Niño/ Southern Oscillation)?

ENSO stands for El Niño/ Southern Oscillation. The ENSO cycle refers to the coherent and sometimes very strong year-to-year variations in sea- surface temperatures, convective rainfall, surface air pressure, and atmospheric circulation that occur across the equatorial Pacific Ocean. El Niño and La Niña represent opposite extremes in the ENSO cycle.

El Niño refers to the above-average sea-surface temperatures that periodically develop across the east-central equatorial Pacific. It represents the warm phase of the ENSO cycle, and is sometimes referred to as a Pacific warm episode.

La Niña refers to the periodic cooling of sea-surface temperatures across the east-central equatorial Pacific. It represents the cold phase of the ENSO cycle, and is sometimes referred to as a Pacific cold episode. 

2) Indian Ocean Dipole (IOD)

The Indian Ocean Dipole (IOD) is a coupled ocean and atmosphere phenomenon in the equatorial Indian Ocean that affects the climate of Australia and other countries that surround the Indian Ocean basin 

The IOD is commonly measured by an index that is the difference between sea surface temperature (SST) in the western (50°E to 70°E and 10°S to 10°N) and eastern (90°E to 110°E and 10°S to 0°S) equatorial Indian Ocean. The index is called the Dipole Mode Index (DMI). The map below shows the east and west poles of the IOD for November 1997; a positive IOD year.

A positive IOD period is characterised by cooler than normal water in the tropical eastern Indian Ocean and warmer than normal water in the tropical western Indian Ocean (see map below for an example of a typical positive IOD SST pattern). A positive IOD SST pattern has been shown to be associated with a decrease in rainfall over parts of central and southern Australia.

Conversely, a negative IOD period is characterised by warmer than normal water in the tropical eastern Indian Ocean and cooler than normal water in the tropical western Indian Ocean. A negative IOD SST pattern has been shown to be associated with an increase in rainfall over parts of southern Australia

3) MADDEN JULIAN OSCILLATION (MJO)

Tropical rainfall also exhibits strong variability on sub-seasonal time scales. These fluctuations in tropical rainfall often go through an entire cycle in 30-60 days, and are referred to as "intraseasonal oscillations". Four other terms that are often used interchangeably to refer to intraseasonal oscillations are "Madden-Julian Oscillation" or "MJO", "30-60 day oscillation", and "30-60 day wave". In this summary we will refer to this phenomenon by "intraseasonal oscillation" or the "MJO".

The MJO is a naturally occurring component of our coupled ocean-atmosphere system. It significantly affects the atmospheric circulation throughout the global Tropics and subtropics, and also strongly affects the wintertime jet stream and atmospheric circulation features over the North Pacific and western North America. As a result, it has an important impact on storminess and temperatures over the U.S. During the summer the MJO has a modulating effect on hurricane activity in both the Pacific and Atlantic basins. Thus, it is very important to monitor and predict MJO activity, since this activity has profound implications for weather and short-term climate variability through the year.

The MJO is characterized by an eastward progression of large regions of both enhanced and suppressed tropical rainfall, observed mainly over the Indian Ocean and Pacific Ocean. The anomalous rainfall is usually first evident over the western Indian Ocean, and remains evident as it propagates over the very warm ocean waters of the western and central tropical Pacific. This pattern of tropical rainfall then generally becomes very nondescript as it moves over the cooler ocean waters of the eastern Pacific but reappears over the tropical Atlantic and Indian Ocean. Each cycle lasts approximately 30-60 days

There are distinct patterns of lower-level and upper-level atmospheric circulation anomalies which accompany the MJO-related pattern of tropical rainfall. These circulation features extend around the globe and are not confined to only the eastern hemisphere. Thus, they provide important information regarding the regions of ascending and descending motion associated with particular phases of the oscillation over those parts of the tropics where rainfall is generally low or absent.

There is strong year-to-year variability in MJO activity, with long periods of strong activity followed by periods in which the oscillation is weak or absent. This interannual variability of the MJO is partly linked to the ENSO cycle. Strong MJO activity is often observed during weak La Niña years or during ENSO-neutral years, while weak or absent MJO activity is typically associated with strong El Niño episodes.

4) Ekman Drift

Ekman drift (or Ekman spiral) is a phenomenon, caused by a combination of the Coriolis effect and friction in the water column, that results in a net drift of ocean water to the right of the wind’s direction in the northern hemisphere, and to the left in the southern hemisphere.  On the US West Coast, Ekman drift is responsible for forcing surface water offshore when pushed by northerly winds, causing upwelling, and conversely forcing surface water to flow onshore and causing downwelling when pushed by southerly winds.

5) The Great Whirl- 

Region of High pressure ( at lower atmosphere) in the Arabian Sea. 

6) Jet Stream 

High velocity winds at the upper part of atmosphere ( troposphere) having motion from West to East. 

SOURCE- Climate Prediction Center,Bureau of Meteorology, Advanced H20 Power,