The Hindu Business Line : Hailstorm threat to standing wheat crop

Thiruvananthpauram, April 3 The churn in weather in north and northwest India has tossed up the threat of hailstorm to standing rabi crop, especially wheat, which has entered the harvesting stage.

As of now, hailstorm is the only meteorological event that could harm the prospects of the standing wheat crop. The extended winter this year and the cooler climes are otherwise seen as aiding the cause of a bumper rabi harvest this year.

A warning issued by India Meteorological Department (IMD) and valid for the next 48 hours said that isolated thunder squalls accompanied by hail is likely over the Jammu division, Punjab, Haryana, Chandigarh, Delhi, Uttar Pradesh, Uttarakhand, Himachal Pradesh, West Bengal and Sikkim.

THUNDER SQUALLS

Rain or thundershowers are also likely at a few places over north Rajasthan and isolated over south Rajasthan. Isolated thundershowers are likely over Gujarat, Konkan, Goa, Madhya Maharashtra and central India from Friday onwards.

The plains of northwest India and Rajasthan experienced scattered thundershower activity during the 24 hours ending Thursday morning. The causative western disturbance and the cyclonic circulation it has induced will ramp up the rain/thundershowers to become fairly widespread over the next three days. Day temperatures are currently below normal over most parts of the region and may fall further till the weekend.

DESTRUCTIVE FORM

Hail is the most destructive form of precipitation. The damaging impact is not just from falling hailstones, but also from accompanying high winds and torrential rains. Northern India is a soft target for large hail, and has reported more hail-related losses than anywhere else.

Hailstorms usually occur during March but have been delayed this year by an uncharacteristically extended winter. The last major event was in March last year when heavy rains and hailstorm damaged wheat, sugarcane and oilseed crops in thousands of hectares in Punjab and Haryana.

MOST COMMON

Hail is most common in mid-latitudes during early summer where surface temperatures are warm enough to promote the instability associated with strong thunderstorms, but the upper atmosphere is still cool enough to support ice.

The problem with heavy rains is that the soil becomes loose, especially in the case of the late-sown crops. The crop becomes prone to ‘lodging’, more so if there are accompanying high winds. But the crop can very well do with the largely ‘sprinkler’ effect from light rains.

But the falling temperatures are seen as benefiting the late-sown crop. The flowering to grain-filling stages determines the weight (and, therefore, yield) of the grain harvested after mid-April. As long as the maximum temperature does not cross 35 degree Celsius till the end of March, the normal onset of summer would dry up the moisture and makes the grain hard.

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