365 Days of Climate Awareness 151 – 2009 State of the Climate, North America and Europe

2009 US Climate Data

• Global atmospheric CO2 concentration: 386.5ppm, +1.48 ppm from 2008
• Average air temperature: 54.5°F, 36th all-time 1895-2021
• Average precipitation: 29.22”, 27^th wettest (101^st driest) 1895-2021
• Tornadoes: 1156, 114 (9%) below the ten-year average 1270
• 9 named tropical cyclones: 3 became hurricanes, 2 major (winds > 111 mph, 3-5 Saffir-Simpson)
• Atlantic ACE: 57.3 x 10⁴ kts²
• ENSO: Neutral through May; moderate El Niño through year’s end

Larger (low res) Version

North American & European Conditions

• Warmer than average: Southwestern US; Canada; Mexico; continental Europe; Scandinavia
• Cooler than average: Midwestern US
• Drier than average: Southwestern US; Canada; parts of France and Spain; Russia; the Mideast
• Above-average precipitation: Midwestern, southeastern, & northeastern US; eastern & southeastern Europe; Great Britain; Ireland; Scandinavia
• Wildfires: British Columbia

Temperature variations from seasonal means in the United States were quite strong, and therefor lost in annual averages. In February 2009, the polar vortex—the Jetstream-constrained zone of frigid polar air—split into two separate halves, one centered over northern Siberia, the other over central Canada. The Canadian vortex brought waves of very cold temperatures through the United States, which alternated with warmer, subtropical air. Though on the whole 2009 was not a record-setting year for temperature, it was one for wild extremes.

2009 northern hemisphere polar vortex. (Left) January, centered over the North Pole. (Right) February, split into Eurasian and North American halves

Northern hemisphere snow cover was below the 1966-2009 average. The El Niño contributed to lower Atlantic cyclone activity,  but its appearance late in the year and relative mildness kept it from having a broad warming effect on northern hemisphere air temperatures. Toward the end of the year the Arctic Oscillation went very negative, indicating very high air pressure in northern Europe, which was matched by very cold temperatures to end the year.

2009 US Area Percentage Very Warm vs Very Cold

2009 US Area Percentage Very Wet vs Very Dry

Tomorrow: 2009 State of the World Climate.

Be brave, and be well.