Extratropical Highlights - February 2025

 

1. Northern Hemisphere

The 500-hPa circulation during February featured a wavetrain pattern across North America and Eurasia with a minima in height anomalies located over the North Atlantic Ocean and a maxima extended from Alaska, across the North Pole and Scandinavia, to central Russia (Fig. E9). The main land-surface temperature signals include above average temperatures across Russia and below average temperatures across Canada (Fig. E1). The main land-surface precipitation signals include drier than average conditions in Northern Europe and western Canada and wetter than average conditions in the U.S. Pacific Northwest and adjacent to the Kara Sea in Russia (Fig. E3).

 

a. North America

The February height pattern over North America was distinguished by a meridional wavetrain pattern that featured above average height anomalies over the U.S. southern tier, below average height anomalies over the northern tier and Canada, and above average heights over Alaska and the Canadian Maritime (Fig. E9). Anomalous troughing was also observed over the North Atlantic Ocean. The height pattern likely contributed to the below average temperatures recorded across Canada, the U.S. West Coast, and the Great Plains, where temperatures reached the lowest 10th percentile of occurrences in some areas (Fig. E1). Above average temperatures were recorded across Alaska, the U.S. Southwest, and Mexico, where many areas reached the highest 90th percentile of occurrences (Fig. E1). Drier than average conditions were recorded along the Alaska Panhandle, the U.S. Southeast, and Southwest, where some areas reached the lowest 10th percentile of occurrences, and wetter than average conditions were recorded for the U.S. Pacific Northwest, northern California, and Ohio Valley with many regions reaching the highest 90th percentile of occurrences (Figs. E3, E5, E6).

 

b. Eurasia

An extended area of above average heights were observed across Europe, Scandinavia, and central Russia (Fig. E9). Temperatures were above average across Europe, Scandinavia, and Russia, where many areas reached the highest 70th percentile of occurrences (Fig. E1). Across most of Eurasia, precipitation was near normal with the exception of drier than average conditions across northern Europe and Norway, and wetter than average conditions along the southern coast of the Kara Sea in Russia (Figs. E3, E4).

 

2. Southern Hemisphere

The 500-hPa height pattern in the Southern Hemisphere resembled a wavetrain of anomalous ridging over the extent of the South Pacific Ocean and anomalous troughing over the South Atlantic Ocean (Fig. E15). The southern section of South America recorded temperatures in the highest 90th percentile of occurrences, as the interior of Africa and Australia recorded predominantly near normal temperatures (Fig. E1). Drier than average conditions were recorded across most of South America, continuing a greater than 1-year long drought, and recorded across central Africa and Australia (Figs. E3, E4). The South African monsoon season runs from October to April. During February, rainfall was again above average with much of the region reaching the highest 90th percentile of occurrences (Figs. E3, E4).