Snow-clearing operation in full swing near Gulaba, about 23 km from Manali on the Manali-Leh highway.

Called the Inter-Tropical Convergence Zone (ITCZ) in meteorological parlance, the northern extent of the monsoon system is a broad swath running across the Amritsar-Chandigarh-Delhi-Luchnow-Ranchi axis and it is along this trough line that precipitation occurs. The line moves northwards from the Indian Ocean towards the Himalayas and then moves back the same way as monsoon sets in and then retreats.

“Preliminary investigations into the weather phenomenon this season shows that the trough initially associated with the ITCZ stayed more or less in the same vicinity. This has resulted in more winter precipitation south of the Pir Panjal range,” Ashwaghosha Ganju, Director, Snow and Avalanche Study Establishment (SASE) said. “This is highly unusual and is not known to have occurred for the past many years,” he added.

Many areas in north India received heavy rain and snow this winter. Some areas in Himachal received snow after about 40 years, while areas around Pathankot in Punjab witnessed minor snowfall for the first time. This was due to the existence of multi-layer clouds over the region for that particular period and the extension of cyclonic circulation associated with the WD up to the lower levels in the atmosphere. The months of November 2011 and February 2012 saw lower temperatures than preceding years.

According to data compiled at SASE’s observatories spread across the Himalayas, about 45 per cent of areas in Jammu and Kashmir and Himachal Pradesh have received excess snowfall this winter, while the situation is more or less normal in other areas. Since the snow season in upper Himalayas extends up to the beginning of April, more snowfall is expected and any deficiency in some pockets may be made up. Consequently, the availability of fresh water during the summers may be good.