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Rainfall deficiency down to 10%
PUNE: The rainfall deficiency for the country as a whole has gone down to 10% below average for the first time this monsoon season as 73% of the country's total area has now recorded normal rain.
Of the India Meteorological Department's (IMD) 36 sub-divisions across the country, Lakshadweep is the sole area that has recorded excess rain, while 23 sub-divisions have recorded normal rain for the season, so far.
Another 11 sub-divisions continue to reel under the effects of deficient rain, while Saurashtra and Kutch in Gujarat is worst placed with a high deficiency of 60% below average, which is described as scanty rain.
In meteorological terms, an excess rainfall refers to 20% or more than the normal rain recorded by an area for a given period, while normal rain refers to 19% above or below normal. Similarly, deficient rain refers to 20% to 59% below normal while scanty rain is 60% to 99% below normal.
Geographical region wise, the east and northeast India and the northwest India are facing a deficiency of 15% and 14% below normal, while the central India, which includes Maharashtra, and the south peninsula are facing deficiency of 6% below normal each. All these regions had a deficiency of over 25% below normal by the end of July.
Senior IMD officials here have attributed the recovery to the good rainfall recorded in August and the first week of September compared to the highly worrisome scenario in the first two months of the June-to-September monsoon season.
In the last week, between August 30 and September 5, the country recorded 63.8 mm rainfall, which was 31% in excess of the normal of 48.9 mm for the week. A total of 19 sub-divisions, including all four sub-divisions in Maharashtra, recorded excess rain while eight sub-divisions received normal rain. Another nine sub-divisions recorded deficient and scanty rainfall.
The rainfall last week was better than the preceding week, between August 23 and 29, when 13 sub-divisions each had recorded excess and normal rain and the remaining 10 were in the deficient category.
In its first-stage long range forecast (LRF), the IMD had predicted, on April 26, normal rain for the country as a whole at 99% of the long period average (LPA) of 89 cm for 1951 to 2000. The forecast was revised to 96% of the LPA in the second stage LRF released on June 22. The IMD then predicted 98% rain for July and 96% for August with a model error of 9% for both.
On August 2, the forecasting agency released its outlook for the season's second half, predicting below normal rain at 91% of the LPA with a model error of 8% for August and September combine. It did not make a prediction for September.
Speaking to TOI, IMD's lead forecaster D S Pai said, "The actual rainfall for July was 87% of the LPA as against the prediction of 98%. Considering the 9% model error, our forecast for July was off the mark by 2%. This was further set off by the over 100% rain recorded in August as against the prediction of 96% of the LPA for the month."
Pai said, "The IMD did not issue any forecast for September but had said that the rainfall in the second half of the month will not be good owing to the likely emergence of a weak El Nino condition. So far, the rainfall has been good and we have to see how the situation pans out by the end of the season."
Meanwhile, there are no signs of withdrawal of the southwest monsoon yet as good monsoon conditions prevail in the northwest and the central parts of the country. "The withdrawal won't happen quickly and may be delayed by a week," an official from the IMD's weather forecasting section said.
Normally, the monsoon withdrawal commences after September 1 from the extreme northwestern parts of the country. Synoptic features like cessation of rainfall over the area for five continuous days and considerable reduction in moisture are considered for declaration of the first withdrawal from the northwest India.
Further withdrawal is declared considering the spatial continuity of rain and reduction in moisture. The withdrawal from entire country happens only after October 1, when the monsoon exits the southern peninsula and the wind circulation pattern indicates a change from the southwesterly regime.
Rainfall deficiency down to 10% - The Times of India
PUNE: The rainfall deficiency for the country as a whole has gone down to 10% below average for the first time this monsoon season as 73% of the country's total area has now recorded normal rain.
Of the India Meteorological Department's (IMD) 36 sub-divisions across the country, Lakshadweep is the sole area that has recorded excess rain, while 23 sub-divisions have recorded normal rain for the season, so far.
Another 11 sub-divisions continue to reel under the effects of deficient rain, while Saurashtra and Kutch in Gujarat is worst placed with a high deficiency of 60% below average, which is described as scanty rain.
In meteorological terms, an excess rainfall refers to 20% or more than the normal rain recorded by an area for a given period, while normal rain refers to 19% above or below normal. Similarly, deficient rain refers to 20% to 59% below normal while scanty rain is 60% to 99% below normal.
Geographical region wise, the east and northeast India and the northwest India are facing a deficiency of 15% and 14% below normal, while the central India, which includes Maharashtra, and the south peninsula are facing deficiency of 6% below normal each. All these regions had a deficiency of over 25% below normal by the end of July.
Senior IMD officials here have attributed the recovery to the good rainfall recorded in August and the first week of September compared to the highly worrisome scenario in the first two months of the June-to-September monsoon season.
In the last week, between August 30 and September 5, the country recorded 63.8 mm rainfall, which was 31% in excess of the normal of 48.9 mm for the week. A total of 19 sub-divisions, including all four sub-divisions in Maharashtra, recorded excess rain while eight sub-divisions received normal rain. Another nine sub-divisions recorded deficient and scanty rainfall.
The rainfall last week was better than the preceding week, between August 23 and 29, when 13 sub-divisions each had recorded excess and normal rain and the remaining 10 were in the deficient category.
In its first-stage long range forecast (LRF), the IMD had predicted, on April 26, normal rain for the country as a whole at 99% of the long period average (LPA) of 89 cm for 1951 to 2000. The forecast was revised to 96% of the LPA in the second stage LRF released on June 22. The IMD then predicted 98% rain for July and 96% for August with a model error of 9% for both.
On August 2, the forecasting agency released its outlook for the season's second half, predicting below normal rain at 91% of the LPA with a model error of 8% for August and September combine. It did not make a prediction for September.
Speaking to TOI, IMD's lead forecaster D S Pai said, "The actual rainfall for July was 87% of the LPA as against the prediction of 98%. Considering the 9% model error, our forecast for July was off the mark by 2%. This was further set off by the over 100% rain recorded in August as against the prediction of 96% of the LPA for the month."
Pai said, "The IMD did not issue any forecast for September but had said that the rainfall in the second half of the month will not be good owing to the likely emergence of a weak El Nino condition. So far, the rainfall has been good and we have to see how the situation pans out by the end of the season."
Meanwhile, there are no signs of withdrawal of the southwest monsoon yet as good monsoon conditions prevail in the northwest and the central parts of the country. "The withdrawal won't happen quickly and may be delayed by a week," an official from the IMD's weather forecasting section said.
Normally, the monsoon withdrawal commences after September 1 from the extreme northwestern parts of the country. Synoptic features like cessation of rainfall over the area for five continuous days and considerable reduction in moisture are considered for declaration of the first withdrawal from the northwest India.
Further withdrawal is declared considering the spatial continuity of rain and reduction in moisture. The withdrawal from entire country happens only after October 1, when the monsoon exits the southern peninsula and the wind circulation pattern indicates a change from the southwesterly regime.
Rainfall deficiency down to 10% - The Times of India
