Wednesday, June 27, 2012

WILL JULY 2012 RAINFALL BE SUFFICIENT FOR THE CITIZENS OF INDIA??

METD WEATHER
AKSHAY DEORAS
SEVERE WEATHER FORECASTER

WILL THE MONSOON RAINFALL REACH IN TIME TO AVOID THE WATER DEFICIENCY???


* AROUND 53.5% OF THE AVERAGE RAINFALL TILL NOW IN MAHARASHTRA THIS MONTH


* SIXTEEN DISTRICTS HAVE RECEIVED LESS THAN 50% RAINFALL IN MAHARASHTRA


* 10% WATER CUT IN MUMBAI FROM JULY 1 2012


* WATER STORAGE IN THE 366 IRRIGATION PROJECTS OF NAGPUR IS 13% ONLY (AS CONSIDERED ON 26TH JUNE 2012)


* WATER SUPPLY TO PUNE CITY LIKELY TO BE IN A GOOD SHAPE TILL 15TH JULY 2012 ONLY. 


* AGRICULTURE GETTING AFFECTED DUE TO LACK OF RAINFALL




Be it agriculture or water level situation, the SW Monsoon is continuing to horrify the citizens of many areas like interior southern India, Central India and the worst for Northern India as well including places like Gujarat etc.

The question arises that will the rainfall be sufficient atleast in the first 15 days of July 2012?

Lets discuss the expected conditions!

The Indian Ocean Dipole which is directly affecting the Indian Monsoon has reached in a very low state ( Negative neutral stage). The DMI ( Dipole Mode Index) in the week 18th June-24th June was -0.09. The DMI has been falling towards neutral and negative since the monsoon commenced in India.

        PERIOD                 DMI

20120528,20120603, 0.78
20120604,20120610, 0.17
20120611,20120617, 0.05
20120618,20120624, -0.09

The above DMI plot clearly shows how good the IOD was till 03rd June 2012 with a value of 0.78. 
A more negative DMI will mean more cooler water in the Western Arabian Sea which means a less favorable conditions for the convection and subsequent the monsoon current ( Somali Current). For a very good monsoon phase ( intensity and progress), the IOD has to be positive. 

The forecasts are indicating that the IOD will have a neutral tendency in July 2012 with the POAMA Model determining a 66.7% of likelyhood. 

Such a neutral IOD is also unfavorable for the monsoon rainfall ( ALL MONSOON RAINFALL MENTIONED IN THIS ARTICLE ARE OF THE ARABIAN SEA BRANCH). The IOD swings between the negative neutral to positive neutral many times in this phase. 

This also affects the Madden Julian Oscillation as a neutral condition will result in a very less interference of the Wet phase of the MJO and also the frequency leading to less rain conditions. 

If the POAMA model is to be believed then the rainfall scenario in India ( Excluding NE India) for July 2012 ( Atleast till Mid July) will likely continue to be the same or slightly improved .In short, this trend of IOD will not assist in much rainfall and hence July 2012 ( Atleast till Mid) may also continue to see a more or less June 2012 situation with slight improvement. The net rainfall is also expected to BE LESS THAN AVERAGE FOR MOST OF THE NATION BUT IMPROVED THAN JUNE 2012

The IOD also has some interim positive values like the one in early June 2012 but the value will be less leading to less than normal rainfall in July as well. 

The POAMA models indicate that the IOD will be at the Positive stage in Aug and Sept 2012. This can bring late monsoon month's rainfall. 

CENTRAL INDIA RAINFALL OUTLOOK FOR AGRICULTURE:


The anticipated low pressure at lower levels in the Bay of Bengal doesn't seem to be in a good shape now. The forecast models also have downgraded the likelyhood of generation of a significant low pressure region. Though a weak low pressure or the so called upper air circulation is still expected to pass through Central India. 

However, the rainfall which has earlier expected to be very heavy and highly favorable for the sowing of the Kharif Crop in the region seems to be reduced. The forecast models do indicate that there will be increased in the moisture levels from around 30th June across the region with good rainfall chance during the period and expected to be a bit significant around 2nd July. As of today, it seems that a marginal sowing can be possible around 1st July or so but the risk factor hasn't vanished. The effect shall go away after 4th July or around with aperiodic rainfall again which can make the survival of the seeds difficult. 

Thus, its a challenging situation as the July 2012 rainfall ( atleast till Mid July) doesn't look impressive for the early July 2012 sowing. If one decides to wait till July end then it will be too late!

NORTH INDIA MONSOON ONSET

North India continues to wait for the monsoon. It appears that the first few rainfall can happen around 7-10th July 2012 in the region. Till that period, the weather will be dry itself. 


2 comments:

  1. Hi Akshay!

    Came across a research - here are the extracts:

    "Severe drought in July over the Homogeneous Indian Monsoon region is more linked to the SST based Indian Ocean dipole mode index prior to July than to the strength of El Ninos of the summer monsoon season.

    When, during El Nino years the Homogeneous India experiences an extremely dry July, the development of the positive dipole mode that usually begins around May-June does not start until the second half of the summer monsoon season.

    The occurrences of positive and negative Indian Ocean dipole events are irregular during the late 19th century throughout the 20 th century.

    The negative events that tend to co-occur with La Nina events dominates over the positive events during the period from the late 19th century to the early 20th century, which was followed by the period of weak dipole events.

    After 1960, the strong positive events with significant anomalous warming over the western pole and cooling over the eastern pole that are not observed in the earlier periods show, tending to co-occur with El Nino events."

    Maybe you can decipher what this means in common parlance.

    Rgds

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  2. Hi,
    Sorry for the late reply. This tends to match with the present thinking that the IOD has a more direct influence on the Indian Monsoon as compared to the ENSO. IMD has recently agreed to take into consideration the IOD phenomena as they use a forecasting technique in which ENSO has a major role. I had also adopted the same method till last year until now when I realized that IOD is more linked.

    We know that the Indian Monsoon rainfall and the (overall temperatures) is more (less) than the normal during a La Nina event and vice versa during the El Nino event.
    What I have observed in the recent is that the MJO waves have greater amplitude and frequency during an active ENSO as compared to the Neutral ENSO. During an El Nino event, the MJO activity observed over Indian regions is dry type and vice versa during the La Nina. Sometimes, the La Nina and Wet MJO ( As the IOD is positive) co-incides which increases the rainfall. MJO is very much linked to the IOD for the Indian regions.

    I am still finding a relation between the IOD and ENSO which I believe will be a breakthrough in the monsoon forecastings.

    Hope its clear and simple!

    Akshay

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