Saraju K. Baidya Department of Hydrology and Meteorology Nepal Monsoon of Nepal Saraju K. Baidya Department of Hydrology and Meteorology Nepal First session of South Asian Climate Outlook Forum (SASCOF-1), Pune, India, 13-15 April 2010

Westerly systems Summer Monsoon South West Monsoon Turkmenistan 26º 22' N - 30º 27' N Lat. 80º 4'E - 88º 12'E Long. 200 400 100 Kilometers India China Iran Pakistan Myanmar Thailand Afghanistan Laos Nepal Cambodia Bangladesh Oman Bhutan Sri Lanka Turkmenistan Malaysia 130 260 65 Westerly systems Summer Monsoon South West Monsoon

Wettest month Monsoon

Monthly, correlation of ANMR with Nino 3.4 SST Bold values represent correlation at 95% significant level Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec -0.21 -0.31 -0.41 -0.55 -0.64 -0.56 -0.54 -0.58 -0.63 -0.65 -0.70 During the monsoon season (June-September) the largest correlation with Nino 3.4 is seen in June suggesting that the beginning month of the season is more perturbed by changes in slowly varying boundary conditions (e.g. SST). The lower correlations during July and August imply that the established phase is less susceptible to forcing from the central Pacific SST

Correlation of ANMR with individual months Bold values represent above 95% confidence level June & Monsoon July & Monsoon August & Monsoon September & Monsoon All years 0.52 0.62 0.34 0.39 El Nino/La Nina years 0.47 0.49 0.41 Extreme monsoon years 0.88 0.80 0.31 0.63 The correlation with July rainfall is highest suggesting its major role in the seasonal total. During extreme monsoon years, the correlation with June and July increases substantially. This implies that the early parts of the season (onset phase and the subsequent month July) are most important in determining the seasonal rainfall anomaly in extreme years

Rainfall during the first three weeks of July was very weak Onset on 23rd June, delayed by 13 day Rainfall below normal in large parts of the country Rainfall during the first and the third week of August was particularly intense and widespread

Change of CV between 1991-2008 and 1971-1990 Spatial distribution of Coefficient of variation Monsoon rainfall Change of CV between 1991-2008 and 1971-1990

The long winter drought devastated winter wheat and maize 30 % - 70% of main summer crops failed (paddy, maize) in many places during 2009 Urgent need to develop local Seasonal Forecast for better management in the agriculture sector and in turn strengthening the food security in Nepal

Thank You !

Record break extreme rainfall in August 2009 EXTREME RAINFALL IN AUGUST AT DADELDHURA 20 40 60 80 100 120 140 160 180 200 220 240 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 Year Rainfall (mm) Extreme rainfall ever recorded: 226.2 mm on 18th August 2009 226.2 187.4 EXTREME RAINFALL IN AUGUST AT DIPAYAL 20 40 60 80 100 120 140 160 180 200 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 Year Rainfall (mm) Extreme rainfall ever recorded: 183.9 mm on 18th August 2009 183.9 EXTREME RAINFALL IN AUGUST AT DHANGADHI 30 60 90 120 150 180 210 240 270 300 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 Year Rainfall (mm) Extreme rainfall ever recorded: 269.4 mm on 18th August 2009 269.4 265 EXTREME RAINFALL IN JULYAT DANG 116.0 155.6 20 40 60 80 100 120 140 160 180 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 YEAR Rainfall (mm) Extreme rainfall ever recorded: 195 mm on 13th June 1999