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HOME > Expert Assessments > Climate Diagnostics Bulletin > Extratropical Highlights
Extratropical Highlights - November 2005

1. Northern Hemisphere


The 500-hPa circulation pattern during November featured persistent positive height anomalies in the western U.S. , in the area south of Greenland , and from northwestern Russia to eastern Siberia , and persistent negative height anomalies over the western and central North Pacific (Figs. E9, E11). The main surface temperature departures reflected above-average temperatures across central North America , in the high latitudes and subtropical latitudes of the North Atlantic , and across northern and eastern Eurasia (Fig. E1). The main precipitation departures included above-average totals in the northeastern U.S. and eastern Canada , and below-average totals in the south-central U.S. and portions of both eastern Europe and central Russia (Figs. E3, E5, E6).


a. North America

During November, a persistent pattern of above-average heights at 500-hPa covered western North America (Figs. E9, E11), and contributed to exceptionally warm temperatures over large portions of Canada and the United States . The largest positive temperature departures were observed in Canada , where monthly temperatures averaged 3-4C warmer than normal. In the north-central U.S. , monthly temperatures averaged 2-3C warmer than normal. For both regions, these anomalies were above the 70th percentile of occurrences.

Precipitation was below average (in the lowest 30th percentile of occurrences) in the Southwest and Gulf Coast regions of the U.S. , and in portions of eastern Europe (Fig. E3). Each of these areas was situated in anomalous descending motion between the mean upper-level ridge and trough axes (Fig. E9).


b. North Atlantic Hurricanes

The extremely active 2005 Atlantic hurricane season produced an additional three named storms during November (TS Beta, TS Delta, H Epsilon), with all occurring during the second half of the month.  By the end of November, the 2005 season had featured a record 26 named storms, a record of 14 hurricanes, and 7 major hurricanes. The previous record of 21 tropical storms was set in 1933, and the previous record of 12 hurricanes was set in 1969.


c. Europe / Eurasia

The 500-hPa circulation pattern during November featured a persistent pattern of positive height anomalies over the central Atlantic , and extending from western Russia to Siberia (Fig. E11). These conditions were associated with a pronounced split-flow pattern over Europe . They were also associated with an enhanced poleward transport of relatively mild, maritime into northern Europe and Scandinavia within the northern branch of the split-flow. This anomalously warm air overspread much of Russia , resulting in the well above-average temperatures from Europe to eastern Siberia .  The most anomalous warmth occurred across Scandinavia and northwestern Russia , where temperatures were 4-7C above average.


2. Southern Hemisphere

The mean 500-hPa circulation pattern during November featured above-average heights southeast of Australia and over the high latitudes of the eastern South Pacific, and below-average heights southwest of Australia, over the central South Pacific, and across southern South America and the western South Atlantic (Fig. E15). Positive surface temperature anomalies were observed over the eastern half of Australia and most of South America , with monthly mean temperatures in both regions exceeding the 70th percentile of occurrences.

In southern Africa the rainy season normally lasts from October to April. Rainfall was slightly above average in this region during November, following well above-average rains during October (Fig. E4). In November, the largest positive rainfall anomalies occurred in southeastern South Africa , and near-normal totals occurred elsewhere.



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Page last modified: November 17, 2005
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