a. North America
During August the far-western United States and Canada were again situated downstream
of an upper-level trough, while most of central North America remained under the influence
of an amplified upper-level ridge (Fig. E9). This
circulation contributed to above-normal precipitation in the Pacific Northwest (Figs. E3, E5) and to below-normal rainfall
across the eastern one-third of the United States (Fig. E3)
in the region downstream of the mean ridge axis. This dryness contributed to a
continuation of drought conditions over large portions of the Southeast and Northeast.
Large portions of the mid-Atlantic states also experienced a continuation of drought
conditions during the month, with some relief occurring at the very end of the month in
association with hurricane Dennis.
Anomalously warm temperatures were confined to the Gulf Coast states during August (Fig. E1), with near-normal temperatures observed across most of
eastern North America. These conditions are in marked contrast to the extreme heat that
dominated most of eastern North America during July.
b. Europe/ Asia
An anomalous anticyclonic circulation again prevailed across southern Europe,
southwestern Russia and northern Africa during August (Fig. T22b).
This circulation has persisted for several months, and has resulted in a continuation of
extremely warm temperatures (exceeding the 90th percentile) throughout the
region during the period (Fig. E1). In contrast, western
Europe and England were situated downstream of a mean mid-latitude trough during the
month, which contributed to above-normal rainfall in these areas. Farther north, a
large-scale pattern of below-normal heights covered all of Siberia and the high latitudes
of the North Pacific (Fig. E9), which contributed to
below-normal temperatures in these regions (Fig. E1).