Extratropical Highlights –July 2019

 

1. Northern Hemisphere

The 500-hPa circulation during July featured above-average heights over Alaska, the northeastern U.S., and Greenland, and below-average heights over the central North Atlantic and western Russia (Fig. E9). The main land-surface temperature signals included above-average temperatures in Alaska, the southwestern and eastern U.S., and southern Europe (Fig. E1). The main precipitation signals included above-average totals in southern China, and below-average totals in the northeastern and mid-Atlantic regions of the U.S. (Fig. E3).

 

a. North America

The 500-hPa circulation during July featured above-average heights over Alaska and the northeastern U.S. (Fig. E9). This pattern contributed to above-average surface temperatures in Alaska and in the eastern U.S. (Fig. E1). Much of Alaska recorded temperatures in the upper 90^th percentile of occurrences.

Also during July, below-average precipitation was recorded in the northeastern and mid-Atlantic regions of the U.S. (Fig. E3). Area-averaged totals in both regions were in the lowest 20^th percentile of occurrences (Fig. E5).

 

2. Southern Hemisphere

The 500-hPa height field during July featured above-average heights over southern Australia, the central South Pacific, the high latitudes of the South Atlantic, and the eastern Indian Ocean. It also featured below-average heights over the high latitudes of the eastern South Pacific and in the area south of Africa (Fig. E15). In southern Australia, the above-average heights contributed to anomalously warm (Fig. E1) and dry (Fig. E3) conditions, with many locations recording rainfall totals in the lower 30^th percentile of occurrences.