1. Northern Hemisphere

The 500-hPa circulation during March 2003 featured positive height anomalies over the high latitudes of the North Pacific, the western and southeastern United States, and Europe, and negative height anomalies across the central North Pacific, Canada, and western Russia (Figs. E10, E12). These conditions partly reflect the positive phase of the North Pacific teleconnection pattern, and the continued positive phases of both the Scandinavia and East Atlantic/ West Russia teleconnection patterns (Table E1, Figs. E7, E8).

The prominent temperature anomalies during March included cooler-than-average conditions across Canada and portions of the Middle East, and warmer-than-average temperatures over large portions of the U.S., Scandinavia, Europe, and eastern Siberia (Fig. E1). Prominent precipitation anomalies during the month (Fig. E3) included above-average precipitation in the Pacific Northwest, Inter-Mountain, and Southeast regions of the United States (Fig. E5), and considerably below-average precipitation across most of Europe (Fig. E4).

a. Pacific/North America

The upper-level circulation over the North Pacific featured an amplified trough in the middle latitudes and a blocking pattern at high latitudes. These conditions were associated with an extension of the East Asian Jet from the date line to the Pacific Northwestern United States (Fig. T21). Increased storm activity (Fig. E14) within the poleward flank of the anomalous jet exit region contributed to the above-average precipitation in the Pacific Northwest and Inter-Mountain regions of the U.S. (Figs. E3, E5).

In Canada the below-average temperatures occurred during the first half of the month in association with a high-latitude block over the eastern North Pacific and an amplified trough across eastern Canada (Fig. A2.3). This circulation was replaced by a strong flow of marine air into Canada during the second half of the month, which helped to moderate temperatures in the western and central parts of the country.

b. Europe

The upper-level circulation during March featured a ridge across Europe and Scandinavia, and a full-latitude trough extending from northwestern Russia southward to the eastern Mediterranean Sea (Fig. E10). This circulation reflected the combined positive phases of the Scandinavia and East Atlantic/ West Russia teleconnection patterns (Table E1, Figs. E7, E8). These conditions were associated with anomalously warm and dry conditions over much of Europe and southern Scandinavia, with area-averaged monthly rainfall totals in Europe falling below the 10^th percentile (Fig. E4). They were also associated with anomalous northerly flow across western Russia and the central Mediterranean Sea (Fig. E11), which brought below-average temperatures to southwestern Russia, northeastern Africa, and portions of the Middle East (Fig. E1).

2. Southern Hemisphere

In the Southern Hemisphere the 500-hPa circulation during March featured above-average heights across the high latitudes of the South Pacific and southern South America, and below-average heights over eastern Australia, the central South Pacific, and the higher latitudes of the South Atlantic (Fig. E16). Over Australia an upper-level ridge-trough system was evident across the southern part of the continent., which contributed to anomalously cool and dry conditions over most of eastern Australia in the area between the ridge and downstream trough axes (Figs. E1, E3). Elsewhere anomalously warm temperatures were observed across central Argentina extending eastward to southern Africa.

In southern Africa area-average rainfall totals were above average during March (Fig. E4). Most of this increased rainfall occurred in Mozambique, due to the effects of a tropical storm. The southern Africa rainy season normally peaks during November-March. During the 2002-2003 rainy season monthly totals were above average during January and March, and below average during November, December, and February.