1. 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, April 2010

2. 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

3. Wettest month
Monsoon

7. 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

8. 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

9. 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

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

15. 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

16. Thank You !

17. 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: 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: 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: 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