2011 WINTER FORECAST OF INDIA

 2011 WINTER FORECAST FOR INDIA

* AKSHAY DEORAS

SEVERE WEATHER FORECASTER

METD WEATHER FORECASTS "COOLER THAN NORMAL" WINTER FOR MOST OF STATES IN INDIA EXCEPT NORTH EAST

• CENTRAL AND WESTERN INDIA SHALL FACE COOLER THAN NORMAL WINTER CONSECUTIVELY FOR THE SECOND YEAR
• 2011 WINTER FOR CENTRAL INDIA SHALL BE NEARLY THE SAME AS 2010 WINTER.
• THE RECURRENT LA NINA IS RESPONSIBLE FOR THIS.
• LESS NUMBER OF WESTERN DISTURBANCES THAN NORMAL POSSIBLE.
• CENTRAL AND WESTERN INDIA TO BE COLDER THAN NORMAL. 
• NORTH EAST TO REMAIN WARMER THAN NORMAL.

FORECASTING BASIC-

The South West Monsoon retreat is almost complete as the Sun is apparently shifting Southwards which plays a major role in the decrease in the average surface air temperature over Central and Northern India prominently. 

The Winter Forecast for India isn't restricted to the local weather phenomena which people believe i.e if there has been strong monsoon there will be good winter and vice versa. It has now been realized that the entire weather of India and many parts of the world is governed by the Global Weather Phenomena of El Nino Southern Oscillation happening in the Equatorial Central Pacific Ocean briefly. 

Though not fully understood, the phenomena is of oscillating sea surface temperatures in equatorial pacific regions between above normal,normal and below normal temperatures. The scientific reason is with the variation in the trade winds blowing eastward at the surface level which leads to changes in sea water level in some areas of Pacific Ocean like Indonesian coast, Australian Coast and offshore Peru.

The phases of ENSO are 

El Nino- When Sea Surface Temperature(SST) of Eq Pacific is warmer than normal

Neutral- When SST is normal

La Nina- When SST is cooler than normal in Eq.Pacific 

It has been widely observed that winters in India go comparatively cooler than normal during La Nina.

Though this will create controversy with what the India Meteorological Dept mentioned in their winter forecast but its true that La Nina creates cooler than normal winters across most of the states of India. 

Explanation to Cooling effect of La Nina

 A possible explanation which I think is the application of concept of intensified jet streams during la nina over Indian continent. 

La Nina is marked by the increased convection in west pacific than east pacific due to strong winds towards west and vice versa at the upper air. 

Thus an amplified subtropical jet stream will tend to bring more cold air in the Indian subcontinent particularly in Northern,Central and . In the case of El Nino, due to less amplified subtropical jet streams the blast of cool air is partial and it brings a noted warmer effect on the surface air temperatures. 

Example- A river is like Jet Stream. When the river's speed is greater it will drag the stones in its way. When speed is less, stones will not be carried with it. Stones can be compared with cold air. 

Current Conditions in Equatorial Pacific - 

As on 24th Oct 2011, Sea Surface Temp anomaly is around -1.5C ( La Nina) in the Equatorial Central Pacific Ocean. 

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ENSO FORECAST-

A Moderate La Nina is expected to continue in the pacific ocean at least for the months November,December 2011 and Weak La Nina for Jan 2012. 

Thus the 2011 Winter will be governed by the La Nina

WINTER OUTLOOK: INDIA

Nov,Dec - 2011 & Jan 2012 

Western Disturbances

The total number of western disturbances for this season shall be less than normal. However they will have more intensity. 

In November around 3 brief western disturbances may hit the hilly regions of the north india.

 STATEWISE FORECAST-

Note-

• The forecast is prepared considering datas from weather models.
• The figures estimated are of personal opinion and may vary with the Meteorological Department.
• The variations are predicted considering average temperature. Average temperature for this forecast refers to the average of the temperature ( minimum) recorded in the areas which are used as standard (normal) average temperature.
• The average temperature and record low temperature can have large differences but the value to be considered is average temperature
• Models used are Global Forecasting System ( GFS),JAMSTEC

1] Jammu and Kashmir,Himachal Pradesh,Uttaranchal

  Normal winter conditions will be observed here.The temperature anomaly ( All season Average) shall be around 0.5C less than average temperature.

2] Punjab,Haryana,Chandigarh,New Delhi

The overall temperature anomaly in these regions depend on the western disturbance. However it does appear that these regions will witness ( 0.5C to 0.9C) less than average temperature. 

After the snowfall events, temperature in the plains will drop suddenly but average will be near to the predicted value. 

3] Central,Northern,Eastern Maharashtra,Madhya Pradesh,Rajasthan,Uttar Pradesh

A Significant Winter Effect is likely in these areas as the intensified jet streams coupled with their more south flow than normal shall lead to drop of temperatures! 

The Average temperatures will be ( 1C to 1.5C) less than average normal temperature. 

4] Western and West Central Maharashtra,Gujarat - 

Average Temp will be around 2C less than the normal average temperature. 

5] NORTH-EAST INDIA

The states will witness comparatively warmer winter with average temperature settling 0.5C more than normal average temperature.

Nagpur forecast

The city has already started getting cold conditions. 

• The minimum temperature in November shall settle around 12C as the lowest in the last few weeks of the month
•  Not more than a day of rainfall will take place in the city in Nov and December
•  In December,minimum temperature shall make a low of 7.5C (+ - 1C)  in Nagpur.