Over the last few years of this Bulletin, forecasts of Canadian temperature and precipitation using the multivariate statistical technique of canonical correla-tion analysis (CCA) have been presented. For Canada, we have developed the predictive relationships between evolving large scale patterns of quasi-global sea surface temperature, Northern Hemisphere 500 mb circulation, and the subsequent Canadian surface temperature and precipitation. Here, we present forecasts for Dec-Jan-Feb 1997-98 using the predictor fields through August 1997. These forecasts are made with a lead time (the time from the end of the predictor period to the end of the predictand season) of 9 months. Further detail about Canadian CCA-based seasonal climate prediction is found in Shabbar (1996a, 1996b) and Shabbar and Barnston (1996).

Figure 1 shows the CCA-based temperature forecast for the Dec-Jan-Feb 1997-98 period, expressed as a standardized anomaly. Table 1 shows the value of the standard deviation in C at selected stations. The mean skill over all 51 stations, and the associated field significance, are given in the caption beneath the forecast map. The field of cross-validated historical skill (correlation) for the Dec-Jan-Feb forecast time period at this lead time is shown in Figure 2. The forecast has a mean national score of 0.30. The field significance is 0.016, which surpasses the traditional 0.05 rejection cutoff. Field significance reflects the probability of randomly obtaining an overall map skill equal to or higher than that which actually occurred. It is evaluated using a Monte Carlo procedure in which the forecast versus observation correspondences are shuffled randomly 1000 times. The skill of the temperature forecast is highest in winter in Canada.

Local skill is highest from the southern Canadian Prairies extending into central Quebec, and modest skill is found over the northwest arctic islands. Virtually all of Canada is expected to have positive temperature anomalies; negative anomalies are forecast over the extreme northwest high arctic.

Figure 3 shows the CCA-based precipitation forecast for the Dec-Jan-Feb 1997-98 period, expressed as a standardized anomaly. Table 1 shows the value of the standard deviation (mm) at selected stations. The spatial field of cross-validated historical skill (corre-lation) for this lead and time period is shown in Fig. 4. The forecast has moderate expected skill, with a mean national score of 0.20 and a "perfect" field significance of 0.000. Local skills are highest over sections over the southern Prairies extending into the Great Lakes region. Most of southern Canada is expected to have a deficit in Dec-Jan-Feb precipitation. Only the Northwestern Territories show above normal values.

Both oceanic and atmospheric indices are now clearly showing the establishment of a warm ENSO episode. Additionally, most statistical and dynamical models are predicting continuation of the warm episode for the rest of 1997 and into early 1998. The Dec-Jan-Feb 1997-98 forecast recognizes the strong influence of the warm event on the Canadian climate over the winter season.

Table 1. Standard deviation of temperature (Temp) and precipitation (Prcp) for the 3 month period Dec-Jan-Feb at selected Canadian stations.

Station	Temp (oC)	Prcp (mm)
Whitehorse	5.7	8.6
Fort Smith	4.2	9.1
Innujjuak	3.4	7.4
Eureka	3.5	2.0
Vancouver	1.6	51.9
Edmonton	4.5	10.8
Regina	3.9	9.3
Winnipeg	3.4	11.9
Churchill	3.1	10.1
Moosonee	3.1	18.6
Toronto	2.3	20.7
Quebec City	2.6	35.8
Halifax	2.0	56.7
St. John's	2.5	55.0

 
 
 
 
 
 
 

Shabbar, A., 1996a: Seasonal prediction of Canadian surface temperature and precipitation by canonical correlation analysis. Proceedings of the 20th Annual Climate Diagnostics Workshop, October 23-37, Seattle, Washington, 421-424.

Shabbar, A., 1996b: Seasonal forecast of Canadian surface temperature by canonical correlation analysis. 13th Conference on Probability and Statistics in the Atmospheric Sciences. American Meteorological Society, San Francisco, California, February 21-23, 339-342.

Shabbar, A. and A.G. Barnston, 1996: Skill of seasonal climate forecasts in Canada using canonical correlation analysis. Mon. Wea. Rev., 124, 2370-2385.

Fig. 1. CCA-based temperature forecast for the 3 month mean period of Dec-Jan-Feb 1998. Forecasts are represented as standardized anomalies.

Fig. 2. Geographical distribution of cross- validated historical skill for the forecast shown in Fig. 1, calculated as a temporal correlation coefficient between forecasts and observations. Areas having forecast skill of 0.30 or higher are considered to have utility. The mean score over 51 stations is 0.30. Field significance is 0.016.

Fig. 3. As in Fig. 1 (CCA anomaly forecast), except for Dec-Jan-Feb 1998 precipitation.

Fig. 4: As in Fig. 2 (geographic distribution of correlation skill) except for the precipitation forecast shown in Fig. 3. The mean score over 69 stations is 0.20. Field significance is 0.000 (see text).