LONG RANGE FORECAST UPDATE FOR - 2014 SOUTHWEST MONSOON RAINFALL EARTH SYSTEM SCIENCE ORGANIZATION (ESSO) MINISTRY OF EARTH SCIENCES (MOES) INDIA ...
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Earth System Science Organization (ESSO)
Ministry of Earth Sciences (MoES)
India Meteorological Department
Presents
LONG RANGE FORECAST UPDATE
FOR
2014 SOUTHWEST MONSOON RAINFALL
9th June, 2014
Currently used 2-Stage Forecast System for
All India (Nation-wide) Season Rainfall
1st Stage
Forecast based
All India on 5 predictors
June – September April requiring data
Rainfall up to March
Update for All India 2nd Stage
June June – September Forecast based
Rainfall
June on 6 predictors
requiring data
up to May
13-Jun-14
ESSO-IMD’s Operational long range Forecast for the 2014
Southwest monsoon rainfall over country as a whole
(a) Quantitatively, the monsoon seasonal rainfall is likely to be
95% of the Long Period Average (LPA) with a model error of ± 5%.
The LPA of the season rainfall over the country as a whole for the
period 1951-2000 is 89 cm.
(b) The 5 category probability forecasts for the Seasonal (June to
September) rainfall over the country as a whole is given below:
Forecast Climatological
Rainfall Range
Category Probability Probability
(% of LPA)
(%) (%)
Deficient < 90 23 16
Below Normal 90 - 96 33 17
Normal 96 -104 35 33
Above Normal 104 -110 8 16
Excess > 110 1 17
13-Jun-14
Monsoon So Far ….
IMD had forecasted that the
Advancement of Monsoon 2014 monsoon will set over Kerala on 5th
June with a model error of ±4 days.
Southwest monsoon set over
Andaman Sea on 18th may 2 days
earlier than normal date.
Set over Kerala on 6th June 2014,
which is 5 days later than its normal
date
As on 9th June 2013, The northern
limit of monsoon continue to pass
through 12.0°N/60.0°E,
12.0°N/70.0°E, 12.0°N/74.0°E,
Kozhikode, Coimbatore, Cuddalore,
13.0°N/83.0°E, 16.0°N/87.0°E,
18.0°N/90.0°E and 21.0°N/92.0°E.
4
29th June, 2010
Second Stage Forecasts to be issued….
Quantitative and probabilistic
All India forecasts have been prepared
Update for All India
June – September Rainfall
All India Monthly
(July & August) Rainfall
4 Geographical Regions
June – September Rainfall for
Four Geographical Regions
5
13-Jun-14
Second Stage Forecasts: Method
a) Forecast update for the southwest monsoon
season (June-September) rainfall over the country
as a whole using a 6-parameter ensemble
statistical model with a model error of ± 4%.
b) Forecast for the monthly rainfall over the country
as a whole for the months of July & August using
separate principle component regression models
with a model error of ± 9%.
c) Forecasts for the southwest monsoon season
(June-September) rainfall for the following four
broad geographical regions of India using separate
principle component regression models with a
model error of ± 8%.
6
29th June, 2010
Predictors used for Update Forecast for the
Seasonal Rainfall over the Country as a Whole: 2014
Geographical Location
of the 6 Predictors
SN PARAMETER Period
1 NE Pacific to NW Atlantic SST Anomaly Gradient DEC+JAN
2 Equatorial SE India Ocean SST FEB
3 East Asia MSLP FEB + MAR
4 NINO 3.4 SST Anom. Tendency MAM(O)-DJF(-1)
5 North Atlantic MSLP (MAY)
6 North Central Pacific Zonal Wind Gradient 850 hPa (MAY)
13-Jun-14Statistical Ensemble Forecasting System for
Seasonal Rainfall over Country as a whole: June
The average of the ensemble forecasts from best out of all
possible MR (multiple regression) and PPR (projection pursuit
regression) models gives the final forecast.
8Performance of the
June Ensemble Forecasting System: 1981-2013
RMSE = 6 % of LPA
13-Jun-14Probabilistic Forecast Based on
6- Parameter Ensemble Forecasting system:
Predefined Rainfall Categories for Country as a whole
Rainfall Range
Category (% of LPA)
Deficient < 90
Below Normal 90-96
Normal 96-104
Above Normal 104-110
Excess > 110
13-Jun-14Tercile categories for Probability Forecasts of
Monthly Rainfall over the Country as a Whole
Tercile Break Points
µ ± 0.43 σ
July August
Model Model
Category Rainfall Rainfall
Range Range
(% of LPA) (% of LPA)
Below
106
All the 3 categories have Normal
equal climatological
probability (33.33% each)
11Tercile categories for Probability Forecasts of
Season Rainfall over the 4 Geographical Regions
Central South Northeast
NW India
India Peninsula India
Rainfall
Category Range Range Range Range
(% of LPA) (% of LPA) (% of LPA) (% of LPA)
Below
105
Normal
12Experimental Dynamical LRF System:
IMD’s Seasonal Forecast Model (SFM)
Since 2004, IMD has been generating
experimental dynamical seasonal forecast for
monsoon rainfall using seasonal forecasting
model (SFM) originally developed by ECPC.
Now the system generates global monthly and
seasonal forecasts (for next 5 months) in
every calendar month of the year. First such
LRF system in India.
Model run for 5 months. For monsoon season
- ‘0’ lag to ‘5 months’ lag
10 Ensembles - Initial conditions of first 10
days of each month (NCEP reanalysis)
Forecasted SST from NCEP CFSV2 as
boundary conditions (40 ensemble member
from first 10 days).
The model showed some useful skill for the
monsoon season during hindcast mode (1982-
2011).Monsoon Mission Experimental Dynamical Model Forecasting
System: CFS V2 (T382)
Under Monsoon Mission was recently
launched by the ESSO with an objective to
improve the monsoon forecasts over the
country in short range to long range time
scales.
The latest high resolution research version
of the coupled model (Climate Forecast
System (CFS) of NCEP, USA Version-2)
was implemented at the ESSO-IITM, Pune.
To generate the experimental update
forecast for the 2014 SW Monsoon season
rainfall, the April initial conditions were used.
The model shows a moderate skill.
14
29th June, 2010Other National Climate Research Centers
That Provide Experimental LRF
Indian Institute of Science (IISc), Bangalore,
Space Applications Centre (SAC), Ahmedabad,
Centre for Mathematical Modelling and Computer
Simulation (CMMACS), Bangalore,
National Centre for Medium Range Weather
Forecasting (NCMRWF), Noida and
Center for Development of Advanced Computing
(C-DAC), Pune.
Centre for Disaster Mitigation, Jain University,
Bangalore.
13-Jun-14International Climate Research Centers
That Provide Experimental LRF
World Meteorological Organization (WMO)’s Lead Centre
for Long Range Forecasting - Multi-Model Ensemble
(LRFMME), Korea – Forecast from 12 Global Producing
Centers of LRF
National Centers for Environmental Prediction (NCEP),
USA
International Research Institute for Climate and Society
(IRI), USA
Meteorological Office, UK,
European Center for Medium Range Weather Forecasts
(ECMWF), UK
Meteo France
Asian-Pacific Economic Cooperation (APEC) Climate
Centre, Korea
Japan Meteorological Agency (JMA)
13-Jun-14Status of Some Important Factors that
Having Influence on Monsoon
13-Jun-14Global SST Departures (oC) and
ENSO Conditions over Pacific
During the last four weeks, above-average
equatorial SSTs were observed across the
Pacific, near Indonesia, in the western
Indian Ocean and in the eastern Atlantic
Ocean. During April through mid-May the observed
El Niño/ La Niña events tend to develop during the period Apr-Jun and
ENSO conditions moved from warm-neutral to
.
•Tend to reach their maximum strength during Dec-Feb the borderline of a weak El Niño condition.
•Typically persist for 9-12 months, though occasionally persisting for up
to 2 years
•Typically recur every 2 to 7 yearsESSO-IITM CFS2 Forecast of SST Anomaly: Based
on April IC (51 ensembles)
The ESSO-IITM model indicate a continued warming trend, leading to a
moderate El Niño conditions during the monsoon season with a probability of
around 70%.
19Latest Model Forecast for
ENSO Conditions over Pacific
Most of the international ENSO prediction models also indicate about
70% chance of El Niño conditions to develop during the 2014 summer
monsoon season.
13-Jun-14El Nino Vs Monsoon
In general, Indian SW monsoon
El Nino
Jun Jul Aug Sep JJAS
strength
is weaker than normal during
Year the El Nino years. During the
1951 86.4 81.1 87.9 67.1 81.3 ME period 1951-2014, there were 14
1953 101 112 119 100 110 WE
1957 89.2 101 113 77.9 97.6
El Nino years and during 8 of
SE
1963 88.4 84.7 122 94.2 97.9 ME
these years ISMR was below
1965 66.7 95.2 77.3 79.2 81.8 SE normal indicating that there is
1969 76.5 107 106 103 100 WE no one to one association
1972 73.3 68.8 85.9 76.4 76.1 SE between EL Nino and ISMR.
1982 83.2 76.9 109 67.8 85.5 ME
However there is stronger
1987 78.4 71.2 96.3 74.9 80.6 SE
1991 109 91.3 95.5 66.2 90.7
inverse relationship between
ME
1997 106 98.4 109 93.9 102 SE
El Nino and rainfall during later
2002 109 45.8 98.3 87.1 80.8 ME half of the monsoon season
2004 99.2 80.1 95.7 70 86.2 WE (particularly with September
2009 52.8 95.7 73.5 79.8 78.2 WE rainfall)
13-Jun-14Composite Rainfall Anomaly: El NINO Years
During El Nino years, in general, most parts of the
country except northeast India receive below normal
rainfall anomalies. The impact is more over northwest
India and central India.
13-Jun-14Indian Ocean Dipole IOD forecast: A neutral state in the tropical Indian Ocean in 2014. 13-Jun-14
Monthly Snow Cover Area - 2014
Departure from normal
December 2013 January 2014 February 2014 March 2014
Data source:
RUTGERS UNIVERSITY
During all the month from September 2013 to March 2013 except January and March 2014, the snow-covered area
averaged over the NH was normal to slightly above normal with highest anomalies observed during October 2013. The
snow-covered area averaged over the NH during January and March 2014 was less than normal with the March NH snow-
covered area being 6th lowest among the March months of the last 48 years. The NH snow cover during winter and
spring has a general negative relationship with the subsequent Asian summer monsoon.
13-Jun-14SW Monsoon 2014 ?
31-YEAR MOVING AVERAGE OF SEASONAL
MONSOON RAINFALL
4
3
RAINFALL ANOMALY (%
2
DEP. FROM LPA)
1
0
-1
-2
-3 y = 2E-08x5 - 4E-06x4 + 0.0003x3 - 0.0059x2 - 0.0218x
R² = 0.7714
-4
1905
1910
1915
1920
1925
1930
1935
1940
1945
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
2015
YEAR ENDING 31-YEAR SLIDING WINDOW
Negative side of the normal
13-Jun-14Thank you
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