Climate Outlook
ASIA July - December 2006
Issued: June 2006
The IRI has prepared this experimental Climate Outlook for Asia for July - December 2006.
Of relevance in the preparation of this outlook is a moderately strong likelihood that the present neutral to slightly above average tropical Pacific SSTs will continue, and perhaps rise to slightly farther above average over the coming months. Such neutral to slightly warm and tropical Pacific conditions are indicated in the SST predictions on which these climate forecasts are based. See the IRI's ENSO update for a discussion on the ENSO outlook (see IRI Probabilistic ENSO forecast). Somewhat warmer than average SSTs are now observed in the western and central tropical Pacific, with near average SSTs in the and eastern tropical Pacific, and slightly below normal SSTs near the South American coastline. The central equatorial Indian Ocean, and the north tropical Atlantic Ocean, continue to show above-average SSTs (SSTs). The Indian Ocean SSTs are predicted to weaken over the course of the forecast periods, and the north tropical Atlantic SSTs are predicted to slowly change their pattern favoring positive departures from normal near the Gulf of Guinea by northern mid-summer. (July-September 2006, August-October 2006, September-November 2006, October-December 2006).
METHODS -
This Outlook was prepared using the following procedures and
information:
A) Coupled ocean-atmosphere model predictions of tropical Pacific SST
covering the forecast period. Particularly heavy weighting has been
given to predictions from the coupled model operated by the NOAA
National Centers for Environmental Prediction, Climate Modeling Branch.
This model suggests a continuation of near-average conditions during the
first forecast season. The forecast for near-neutral conditions is
consistent with some, but not all, numerical and statistical forecasts
of central and eastern Pacific SSTs.
B) Forecasts of the tropical Indian ocean using a statistical model
developed by the IRI.
C) Global atmospheric general circulation model (GCM) predictions of the
atmospheric response to the present and predicted sea-surface
temperature patterns.
D) Other sources of information include
NASA's
Seasonal to Interannual Prediction Project (GSFC-NASA)
and also seasonal prediction research at COLA.
The procedures, models, and data used to derive this Climate Outlook may
be somewhat different from those used by the national meteorological
services in the region. Thus, this product may differ from the official
forecasts issued in those areas. The Climate Outlook for
July - December 2006
is dependent on the accuracy of the SST predictions. For the
tropical Pacific, these predictions can be expected to provide useful
information, but there is some uncertainty concerning the evolution of
SSTs. Spread in global SST predictions is a source of uncertainty in the
Outlook provided here. Note that even if perfectly accurate SST
forecasts were possible, there would still be uncertainty in the climate
forecast due to chaotic internal variability of the atmosphere. These
uncertainties are reflected in the probabilities given in the forecast.
It is stressed that the current status of seasonal-to-interannual
climate forecasting allows prediction of spatial and temporal averages,
and does not fully account for all factors that influence regional and
national climate variability. This Outlook is relevant only to seasonal
time scales and relatively large areas; local variations should be
expected, and variations within the 3-month season should also be
expected. For further information concerning this and other guidance
products, users are strongly advised to contact their National
Meteorological Services.
OUTLOOK -
This Outlook covers four seasons: July-September 2006,
August-October 2006, September-November 2006 and October-December 2006.
Maps are given showing tercile probabilities of
precipitation and temperature. The maps for precipitation indicate the
probabilities that the seasonal precipitation will fall into the wettest
third of the years (top number), the middle third of the years (middle
number), or the driest third of the years (bottom number). The color
shading indicates the probability of the most dominant tercile -- that
is, the tercile having the highest forecast probability. The color bar
alongside the map defines these dominant tercile probability levels. The
upper side of the color bar shows the colors used for increasingly
strong probabilities when the dominant tercile is the above-normal
tercile, while the lower side shows likewise for the below-normal
tercile. The gray color indicates an enhanced probability for the
near-normal tercile (nearly always limited to 40%). As before, numbers
and their associated histograms show the probabilities of the three
terciles. In areas with lots of spatial detail, there may not be
sufficient room on the map, to allow histograms for each region. In
those cases, some idea of the probabilities may be gained from the color
alone. A qualitative outlook of climatology ("C") indicates that there
is no basis for favoring any particular category.
Areas that are marked by "D" represent regions for which less than 3cm of
precipitation typically occurs over the season.
Otherwise, for example, in the case of
southern Myanmar in July-September 2006
(Map A),
there is a 25% probability
that the precipitation will be in the wettest third of the years, a 35%
chance it will be in the near-normal third of the years, and a 40%
chance that the precipitation will be in the driest third of the years.
Maps of temperature show expected probabilities that the seasonal
temperatures will fall into the warmest third of the years, the middle
third of the years, or the coldest third of the years
(Map A).
The numbers for each region on the temperature maps
indicate the probabilities of temperatures to fall in each of the three
categories, above-, near-, and below-normal.
An
additional precipitation map
is provided for the first season indicating probabilities for extreme
precipitation anomalies. Extremes are defined as anomalies that fall
within the top and bottom 15th percentile of the observed records. A
priori, there is a 15% probability of being within the extremely wet
category, and a 15% probability of being within the extremely dry
category, leaving a 70% probability that the precipitation will not be
extreme. The maps indicate areas of increased risk of extreme
precipitation totals. Three levels of increased risk are defined:
slightly enhanced risk, enhanced risk, and greatly enhanced risk. For
slightly enhanced risk, there is a 25-40% probability that precipitation
will be within the indicated extreme, i.e. wet or dry. This represents
an approximate doubling of the climatological risk. For enhanced risk,
there is a 40-50% probability that precipitation will be within the
indicated extreme. This represents an approximate tripling of the
climatological risk. For greatly enhanced risk, the probability that
precipitation will be within the indicated extreme exceeds 50%, i.e. the
indicated extreme is the most likely outcome. A similar map is provided
in the first season indicating probabilities of
extreme temperature
anomalies.
Boundaries between sub-regions should be considered as transition zones,
and their location considered to be only qualitatively correct.
July-September 2006 through October-December 2006
The following table briefly summarizes the probability anomaly forecasts:
Summary of PRECIPITATION forecast for Asia
Leads 1, 2, 3, and 4 refer, respectively, to the upcoming seasons:
Jul-Aug-Sep Aug-Sep-Oct Sep-Oct-Nov Oct-Nov-Dec
A non-enhanced probability for above or below normal is 33%.
(There is a near-normal category whose non-enhanced probability is also 33%.)
The following countries or regions out of the 55 in Asia
have at least half of their area under a PRECIPITATION forecast for:
At least At least
Substantially slightly slightly Substantially
enhanced enhanced enhanced enhanced
probability probability probability probability
(>48%) for (>38%) for (>38%) for (>48%) for
below normal below normal above normal above normal
AFGHANISTAN
lead 4
BRUNEI DARSM
leads 1 and 2
CAMBODIA
lead 2
INDONESIA
leads 1 and 2
KYRGYZSTAN
lead 3
LAOS
lead 2
MALAYSIA
lead 1
PHILIPPINES
leads 3 and 4
TAJIKISTAN
leads 3 and 4
THAILAND
lead 3
UZBEKISTAN
lead 4
CHINA-South-Central
lead 1
Summary of TEMPERATURE forecast for Asia
Leads 1, 2, 3, and 4 refer, respectively, to the upcoming seasons:
Jul-Aug-Sep Aug-Sep-Oct Sep-Oct-Nov Oct-Nov-Dec
A non-enhanced probability for above or below normal is 33%.
(There is a near-normal category whose non-enhanced probability is also 33%.)
The following countries or regions out of the 55 in Asia
have at least half of their area under a TEMPERATURE forecast for:
At least At least
Substantially slightly slightly Substantially
enhanced enhanced enhanced enhanced
probability probability probability probability
(>48%) for (>38%) for (>38%) for (>48%) for
below normal below normal above normal above normal
ARMENIA
lead 1
AZERBAIJAN
lead 1
BRUNEI DARSM
leads 1 and 4
CAMBODIA
leads 1,2,3 and 4
CAMBODIA
leads 1 and 2
INDONESIA
leads 1,3 and 4
IRAN
leads 1,2 and 3
IRAQ
leads 1,2 and 3
ISRAEL
leads 1,2,3 and 4
ISRAEL
lead 1
JAPAN
leads 1 and 2
JORDAN
leads 1,2 and 3
JORDAN
lead 1
KAZAKHSTAN
leads 1 and 2
KUWAIT
leads 1,2 and 3
KYRGYZSTAN
lead 1
LAOS
leads 1,2,3 and 4
LAOS
lead 1
LEBANON
leads 1,2,3 and 4
LEBANON
lead 1
MALAYSIA
leads 1 and 4
MONGOLIA
lead 1
MYANMAR
leads 1 and 3
NEPAL
lead 1
NORTH KOREA
leads 1 and 2
OMAN
lead 3
PAKISTAN
lead 1
PHILIPPINES
lead 4
SAUDI ARABIA
leads 1,2 and 3
SOUTH KOREA
leads 1 and 2
SRI LANKA
leads 1,2 and 3
SYRIA
leads 1,2 and 3
THAILAND
leads 1,2,3 and 4
THAILAND
lead 1
TURKMENISTAN
leads 1 and 2
UNTD ARAB EM
leads 1,2,3 and 4
UZBEKISTAN
leads 1 and 2
VIET NAM
leads 1,2,3 and 4
YEMEN
lead 1
CHINA-Northwest
lead 1
CHINA-North
lead 1
INDIA-North
lead 4
INDIA-Peninsula
leads 1,2 and 3
RUSSIA-WSibPlain-S
lead 1
OBSERVED CLIMATOLOGY DATA for Jul-Aug-Sep,
Aug-Sep-Oct, Sep-Oct-Nov and Oct-Nov-Dec
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CLIMATOLOGICAL AVERAGE:
TERCILE THRESHOLDS (33%-ile & 67%-ile):
EXTREME THRESHOLDS (15%-ile & 85 %-ile):
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