The IRI has prepared this experimental Climate Outlook for North America for October 2001 - March 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, October-December 2001, November-January 2002, December-February 2002, while during the second season, January-March 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 CPC ; 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 July - December 2001 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 two seasons: July - September 2001 and October - December 2001. 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 October-December 2001 (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 over the Hawaiian Islands.

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.

October-November-December 2001:

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for most of western and much of southern Alaska, U.S.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for southern Greenland.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for part of eastern and south-central Canada, and the north-central United States.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for part of the western United States and northwestern Mexico.

Slightly enhanced probabilities for near normal precipitation (30%-40%-30%) are forecast for parts of Nicaragua, Costa Rica and Panama.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%) are forecast for part of southwestern Canada and northwestern United States.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for part of central Mexico and the southern United States along the Gulf of Mexico.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for Hawaii, United States.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for the Yucatan Penninsula of Mexico, and parts of Belize and Guatemala.

An enhanced probability for above normal temperature (20%-35%-45%) is forecast for western and south-central Alaska, U.S., surrounded by more weakly enhanced probabilities for above normal temperature in additional portions of Alaska, U.S.

Slightly enhanced probabilities for above normal temperature (30%-30%-40%) are forecast for part of northwestern Canada.

A very greatly enhanced probability for above normal temperature (10%-30%-60%) is forecast for most of Cuba, Jamaica and Haiti, surrounded by more weakly enhanced probabilities for above normal temperature in central and southern Latin America and the southeastern United States.

A greatly enhanced probability for above normal temperature (20%-30%-50%) is forecast for the east-central United States, surrounded by more weakly enhanced probabilities for above normal temperature in additional portions of the eastern and central United States and southern Ontario of Candad.

A greatly enhanced probability for above normal temperature (20%-30%-50%) is forecast for west-central Mexico, surrounded by more weakly enhanced probabilities for above normal temperature in significant additional portions of Mexico as well as the southern and southwestern United States.

An enhanced probability for above normal temperature (20%-35%-45%) is forecast for the Canadian Maritime Provinces, surrounded by more weakly enhanced probabilities for above normal temperature in additional area in southeastern Canada.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for extreme northeastern Alaska, U.S.

Slightly enhanced probabilities for near normal temperature (30%-40%-30%) are forecast for the western portion of north-central Canada.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the Alaska Panhandle, extreme western Canada and part of the northwestern United States.

Slightly enhanced probabilities for near normal temperature (35%-40%-25%) are forecast for eastern Canada, and the extreme northeastern United States.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the extrme southwestern United States and northern Baja California, Mexico.

A greatly enhanced probability for below normal temperature (50%-30%-20%) is forecast for Baffin Bay in northeastern Canada as well as along the southern shore of Hudson Bay of Canada, surrounded by more weakly enhanced probabilities for below normal temperature in much of the remainder of central and eastern Canada, the extreme north-central United States, and western Greenland.

Slightly enhanced probabilities for below normal temperature (40%-30%-30%) are forecast for the western Queen Elizabeth Islands of Canada.

Slightly enhanced probabilities for below normal temperature (40%-35%-25%) are forecast for a small part of the northwestern United States.

November-December-January 2001-2002:

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for southern Baffin Island in northeastern Canada.

A greatly enhanced probability for above normal precipitation (25%-25%-50%) is forecast for central Canada, on the south shore of James Bay of Hudson Bay, Canada, surrounded by more weakly enhanced probabilities for above normal precipitation in significant portions of southern Canada and northern United States.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for part of the Aleutian Islands of Alaska, United States.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for the a portion of the Maritime Provinces of eastern Canada.

An enhanced probability for above normal precipitation (25%-30%-45%) is forecast for a small part of the southwestern United States (state of Arizona), and extreme northern Mexico, surrounded by more weakly enhanced probabilities for above normal precipitation in more of the western United States and northwestern Mexico.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for the windward Lesser Antilles in the Caribbean region.

Slightly enhanced probabilities for near normal precipitation (35%-40%-25%) are forecast for a small part of the southern United States.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%) are forecast for Baffin Island of northeastern Canada.

An enhanced probability for below normal precipitation (45%-30%-25%) is forecast for part of the southeastern United States, surrounded by more weakly enhanced probabilities for below normal precipitation in additional portions of the southeastern United states as well as northern Cuba and a part of the Bahamas.

Slightly enhanced probabilities for below normal precipitation (40%-30%-30%) are forecast for the island of Bermuda in the Atlantic Ocean.

An enhanced probability for below normal precipitation (45%-35%-20%) is forecast for a small part of central Mexico, surrounded by more weakly enhanced probabilities for below normal precipitation in the extreme southern United States and in additional parts of Mexico.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for extreme northeastern Canada and northern Greenland.

Slightly enhanced probabilities for above normal temperature (30%-30%-40%) are forecast for northern and part of central Canada.

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

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for the Aleutian Islands of Alaska, United States.

An enhanced probability for above normal temperature (20%-35%-45%) is forecast for the southern United States and adjacent extreme northern Mexico, surrounded by more weakly enhanced probabilities for above normal temperature in significant additional portions of the United States and Mexico.

A very greatly enhanced probability for above normal temperature (10%-30%-60%) is forecast for eastern Jamaica and extreme western Haiti, surrounded by more weakly enhanced probabilities for above normal temperature in much of the remainder of the Caribbean region and the Yucatan Penninsula of Mexico and part of Belize.

Slightly enhanced probabilities for near normal temperature (35%-40%-25%) are forecast for Moresby Island in western Canada, and in the southern panhandle of Aslaska, United States.

Slightly enhanced probabilities for near normal temperature (35%-40%-25%) are forecast for part of the northern United States and extreme south-central Canada.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for extreme southwestern United States and northwestern Mexico, including northern Baja California.

Slightly enhanced probabilities for near normal temperature (35%-40%-25%) are forecast for parts of southern Mexico.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for Hawaii, United States.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for most of central and southern Latin America, extending southward into South America.

A greatly enhanced probability for below normal temperature (50%-30%-20%) is forecast for part of eastern Canada, surrounded by more weakly enhanced probabilities for below normal temperature in significant additional portions of eastern Canada and the northeastern United States.

Slightly enhanced probabilities for below normal temperature (40%-30%-30%) are forecast for part of the western and northwestern United States.

Slightly enhanced probabilities for below normal and near normal temperature (40%-40%-20%) are forecast for a portion of south-central Mexico.

December-January-February 2001-2002:

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for southwestern Canada and northwestern United States.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for the outer Aleutian Islands of Alaska, United States.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for the eastern part of the Canadian Maritime provinces.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for the extreme southwestern United States and northwestern Mexico.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for the southern Bahamas, the eastern half of Cuba, Jamiaca, and Haiti.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for much of the southeastern United States.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for the island of Bermuda in the Atlantic.

An enhanced probability for below normal precipitation (45%-35%-20%) is forecast for northl-central Mexico, surrounded by more weakly enhanced probabilities for below normal precipitation in additional parts of Mexico, the extreme southern United States (state of Texas), most of Guatemala and part of Belize.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for extreme northeastern Canada and western Greenland.

Slightly enhanced probabilities for above normal temperature (30%-30%-40%) are forecast around the shoreline of Hudson Bay in east-central Canada.

Slightly enhanced probabilities for above normal temperature (30%-30%-40%) are forecast for the southern tip of Greenland.

Slightly enhanced probabilities for above normal temperature (30%-30%-40%) are forecast for the Canada-United States border in the west-central portion of North America.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for the Hawaiian Islands, United States.

A greatly enhanced probability for above normal temperature (20%-30%-50%) is forecast for Jamaica and western Haiti, surrounded by more weakly enhanced probabilities for above normal temperature in most of the remainder of the Caribbean and the Yucatan Penninsula of Mexico.

Slightly enhanced probabilities for near normal temperature (35%-40%-25%) are forecast for western Alaska.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the southern coastal area of Alaska, United States, and adjacent extreme western Canada.

Slightly enhanced probabilities for near normal temperature (35%-40%-25%) are forecast for part of the outer Aleutian Islands of Alaska.

Slightly enhanced probabilities for near normal temperature (35%-40%-25%) are forecast for southwestern Canada and the western and northwestern United States.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the southern United States and part of northern Mexico, including Baja California.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the central and southern portions of Latin America, extending southward into South America.

An enhanced probability for below normal temperature (45%-30%-25%) is forecast for eastern Canada, surrounded by more weakly enhanced probabilities for below normal temperature in an additional portion of the same general region of Canada.

Slightly enhanced probabilities for below normal temperature (40%-30%-30%) are forecast for a small portion of north-central Canada.

Slightly enhanced probabilities for below normal temperature (40%-35%-25%) are forecast for southern Alaska and the adjacent Aleutian Islands.

An enhanced probability for below normal temperature (45%-35%-20%) is forecast for part of central Mexico, surrounded by more weakly enhanced probabilities for below normal temperature in additional portions of Mexico as well as extreme southern United States (state of Texas).

January-February-March 2002:

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for western Canada and southeastern Alaska of the United States, including the upper part of Alaska's panhandle.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for a small portion of east-central Canada, near James Bay.

Slightly enhanced probabilities for above normal precipitation (30%-30%-40%) are forecast for eastern Canada adjacent to the Atlantic coast.

Slightly enhanced probabilities for above normal precipitation (25%-35%-40%) are forecast for part of extreme southeastern Canada and the northeastern United States.

Slightly enhanced probabilities for near normal precipitation (35%-40%-25%) are forecast for part of the western United States.

Slightly enhanced probabilities for near normal precipitation (25%-40%-35%) are forecast for the Hawaiian Islands of the United States.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for a large portion of northern Canada.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for a large portion of the eastern United States.

Slightly enhanced probabilities for below normal precipitation (40%-35%-25%) are forecast for a small part of the southern United States, and a significant portion of Mexico.

Slightly enhanced probabilities for below normal and near normal precipitation (40%-40%-20%) are forecast for parts of Panama, extending into South America.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for part of northern Greenland.

An enhanced probability for above normal temperature (25%-30%-45%) is forecast for part of western Canada, surrounded by more weakly enhanced probabilities for above normal temperature in additional portions of western and central Canada.

Slightly enhanced probabilities for near normal and above normal temperature (20%-40%-40%) are forecast for the extreme eastern Canadian Maritime provinces.

Slightly enhanced probabilities for above normal temperature (25%-35%-40%) are forecast for the south-central United States and adjacent extreme northern Mexico.

An enhanced probability for above normal temperature (20%-35%-45%) is forecast for southern Florida in the southeastern United States, the Bahamas, Cuba, Jamaica and Haiti, surrounded by more weakly enhanced probabilities for above normal temperature in most of the remainder of Florida, the Yucatan Penninsula of Mexico, and part of Belize and Guatemala.

An enhanced probability for above normal temperature (25%-30%-45%) is forecast for most of Hawaii, United States.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the southern "Big Island" of Hawaii, United States.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for southern Alaska.

Slightly enhanced probabilities for near normal temperature (35%-40%-25%) are forecast for the region of Moresby Island, Canada.

Slightly enhanced probabilities for near normal temperature (35%-40%-25% and 30%-40%-30%) are forecast for south-central Canada and north-central United States.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the southwestern United States and northwestern Mexico.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for the a small pocket in the southeastern United States.

Slightly enhanced probabilities for near normal temperature (25%-40%-35%) are forecast for Puerto Rico and the Dominican Republic.

Slightly enhanced probabilities for near normal temperature (35%-40%-25%) are forecast for southern Mexico and most of the Latin American countries to its south.

A greatly enhanced probability for below normal temperature (50%-25%-25%) is forecast for the southern part of Baffin Island in northeastern Canada, surrounded by more weakly enhanced probabilities for below normal temperature in an additional portion of northern and eastern Canada.

An enhanced probability for below normal temperature (45%-35%-20%) is forecast for the Aleutian Islands of Alaska, United States, surrounded by more weakly enhanced probabilities for below normal temperature in an additional part of western Alaska.

Slightly enhanced probabilities for below normal temperature (40%-30%-30%) are forecast for part of Ontario province of Canada, and adjacent portion of the northeastern United States (state of New York).

Slightly enhanced probabilities for below normal temperature (40%-35%-25%) are forecast for part of central Mexico.

OBSERVED CLIMATOLOGY DATA for Oct-Nov-Dec, Nov-Dec-Jan, Dec-Jan-Feb and Jan-Feb-Mar

To top   Back