The IRI has prepared this experimental Climate Outlook for Europe for August 2001 - January 2002. Of relevance in the preparation of this outlook is the prediction of near-average to slightly warmer than average conditions in the eastern equatorial Pacific for the next 6 to 9 months. Currently the sea surface temperatures (SSTs) across much of the eastern and central equatorial are near their long-term average (SSTs), although slightly lower than average SSTs have developed along the immediate western coast of South America and warmer than average SSTs persist in the extreme western part of the basin. Near neutral equatorial Pacific SST conditions are in effect for the first season of the forecast, August-September-October 2001, September-October-November 2001, October-November-December 2001, while during the second season, November-December 2001-January 2002, they are expected to be slightly above average. The warmer than average SSTs that continue to dominate much of the Indian Ocean are expected to decrease slowly through the forecast period. The area of above-average temperature in the tropical south Atlantic Ocean is expected to persist through at least the first half of the forecast period.

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).

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 August 2001 - January 2002 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: August-September-October 2001, September-October-November 2001, October-November-December 2001 and November-December 2001-January 2002. 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 experiencing their dry season (less than 15% of annual precipitation) and for which less than 5cm of precipitation typically occurs over the season. Otherwise, for example, in the case of August-September-October 2001 (Map A), there is a 30% probability that the precipitation will be in the wettest third of the years, a 30% 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 in southern Italy, among other countries.

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.

Boundaries between sub-regions should be considered as transition zones, and their location considered to be only qualitatively correct.

August-September-October 2001:

The following regions of enhanced probabilities of precipitation anomalies are indicated:

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for certain portions of Afghanistan and Pakistan

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for west-central Russia, to the west of the Ural Mountains.

The following regions of enhanced probabilities of temperature anomalies are indicated:

A greatly enhanced probability for above normal temperature (20%-30%-50%) is forecast for most of Ireland, part of Northern Ireland, and the southern portions Wales and England. A separate but associated region includes southeastern Spain and extends southward into Africa (20 30 50). Weaker probabilities for above normal temperature (20%-35%-45%, 25%-35%-40%, 30%-30%-40% and 20%-40%-40%) surround and connect these two regions, including most of the remainder of Europe with the exception of Turkey, Scandinavia, northern Denmark, the Middle East, and mainly eastern portions of European Russia.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for part of Iran, Kuwait and northern SW Russia Saudi Arabia.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for Iceland and vicinity.

September-October-November 2001:

The following regions of enhanced probabilities of precipitation anomalies are indicated:

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for extreme northern Norway.

An enhanced probability for above normal precipitation (25%-30%-45%) is forecast for northeastern Affghanistan. Weaker probabilities for above normal precipitation (30%-30%-40%) surround this region, including a significant remainder of Afghanistan and portions of Pakistan and extreme southern Russia.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40% and 25%-30%-40%) are forecast for northwestern Iran, Iraq, and parts of Syria and Turkey.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for central and southern Spain.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%) are forecast for west-central Russia, to the west of the Ural Mountains.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for extreme western Russia and the northeastern tip of Poland.

The following regions of enhanced probabilities of temperature anomalies are indicated:

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for part of central Italy, Corsica and Sardinia.

Slightly enhanced probabilities for above normal temperature (30%-30%-40% and 25%-35%-40%) are forecast for southern Norway, southern Sweden, Denmark, the Netherlands, northern and central Germany, northwest Poland, Shetland Island, all of the United Kingdom, Belgium, and extreme western France and extreme northern France.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for Portugal, Spain and southwest France.

Slightly enhanced probabilities for below normal temperature (40%-30%-30%) are forecast for northeastern Greenland.

October-November-December 2001:

The following regions of enhanced probabilities of precipitation anomalies are indicated:

Slightly enhanced probabilities for near normal precipitation (25%-40%-35%) are forecast for north-central Pakistan.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast along much of the region following the Afghanistan-Pakistan border.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for southeastern Spain, extending southward into Africa.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for Ireland and Northern Ireland.

The following regions of enhanced probabilities of temperature anomalies are indicated:

Slightly enhanced probabilities for above normal temperature (30%-30%-40%) are forecast for southern Norway, southwestern Sweden, and all except the southern tip of Denmark.

An enhanced probability for above normal temperature (20%-35%-45%) is forecast for part of northwestern Iran, much of Iraq, and parts of Saudi Arabia. Weaker probabilities for above normal temperature (25%-35%-40%) surround this region, including central and eastern Turkey, a small part of southwestern Russia, an additional portion of Iran, the remainder of Iraq, and most of Syria, Jordan and the rest of the Middle East.

Slightly enhanced probabilities for near normal and above normal temperature (20%-40%-40%) are forecast for the southern portion of Ireland.

Slightly enhanced probabilities for near normal and above normal temperature (20%-40%-40%) are forecast for southern Portugal, most of the northern and western portions of Spain, and southwestern France.

November-December 2001-January 2002:

The following regions of enhanced probabilities of precipitation anomalies are indicated:

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for parts of Romania, Hungary Slovakia, and southwestern Russia.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40% and 30%-30%-40%) are forecast for southern Russia, northern and western Iran, and much of Iraq.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%) are forecast for the southern parts of Ireland, Wales and England of the United Kingdom.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%) are forecast for Iceland and vicinity.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%) are forecast for the Franz Josef Land islands of Russia, to the north of Novaya Zemlya.

The following regions of enhanced probabilities of temperature anomalies are indicated:

An enhanced probability for above normal temperature (20%-35%-45%) is forecast for southwestern Iraq, and part of Saudi Arabia. Weaker probabilities for above normal temperature (25%-35%-40%) surround this region, including central and southeastern Turkey, Syria and the smaller countries of the Middle East.

Slightly enhanced probabilities for below normal temperature (40%-35%-25%) are forecast for Sicily and southern Italy.

Slightly enhanced probabilities for below normal and near normal temperature (40%-40%-20%) are forecast for much of Spain and southern Portugal.

OBSERVED CLIMATOLOGY DATA Aug-Sep-Oct, Sep-Oct-Nov, Oct-Nov-Dec and Nov-Dec-Jan

CLIMATOLOGICAL AVERAGE: Temperature Precipitation

TERCILE THRESHOLDS (33%-ile & 67%-ile): Temperature Precipitation

EXTREME THRESHOLDS (15%-ile & 85 %-ile): Temperature Precipitation

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