Nepal and Bangladesh, is influenced by local and remote forces. In terms of geographical size, NE-India constitutes of about 8% of India's total size. Its population is approximately 40 million, which represents around 3.1% of the total Indian population. This region has a predominantly humid sub-tropical climate with hot, humid summers, severe monsoons and mild winters. Along with the west coast of India, this region has some of the Indian sub-continent's last remaining rain forests, which supports diverse flora and fauna and several crop species. Geographically, two-thirds of the area is a hilly terrain interspersed with valleys and plains. The mean summer monsoon rainfall over the NE-Indian region is around 1400 mm making for huge water and hydropower potential. However, this region has been exhibiting a declining trend in the summer monsoon rainfall since the last 4-5 decades (see Fig. 3, Fig. 4a in Preethi et al. 2016). Hence, it becomes imperative to examine the possible drivers of this variability.Significance for long-term prediction of summer monsoon, considering its massive socio-economic impacts, have been widely attributed to the slowly varying boundary conditions such as sea surface temperature (SST) and snow cover (Shukla 1998). In general, rainfall distribution pattern over different regions of India is inhomogeneous due to influence of several local and remote factors. For instance, over the central Indian plain region, monsoon trough and the Himalayas along with local and external factors play a dominant role in its interannual rainfall variability. Likewise, the northwest region is influenced by the dry climates of the Thar Desert and the Western Himalayas. Apparently from the geographical features as described above, the rain producing mechanism of NE rainfall is a complex phenomenon and is largely dominated by an elevated orography of the Eastern Himalayas and large forests. The NE sector may be considered as a separate macro-region within the Indian Abstract This observational study during the 29-year period from 1979 to 2007 evaluates the potential role of Eurasian snow in modulating the North East-Indian Summer Monsoon Rainfall with a lead time of almost 6 months. This link is manifested by the changes in high-latitude atmospheric winter snow variability over Eurasia associated with Arctic Oscillation (AO). Excessive wintertime Eurasian snow leads to an anomalous cooling of the overlying atmosphere and is associated with the negative mode of AO, inducing a meridional wave-train descending over the tropical north Atlantic and is associated with cooling of this region. Once the cold anomalies are established over the tropical Atlantic, it persists up to the following summer leading to an anomalous zonal wave-train further inducing a descending branch over NE-India resulting in weak summer monsoon rainfall.

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