La Niña Cause of US Drought?

This article, from NewScientist, discusses two possible causes for the extended heatwave in the US: La Niña or the jet stream being stuck in one place.

More On July's Extreme Heat

Much of the country experienced higher than average temperatures in July.

To follow up last week's post about July's extreme heat, here is another NOAA article about the heatwave that much of the country experienced.

• "41 of the lower 48 states had above-normal, much-above-normal, or a record warmest July."
• "The South climate region -- Arkansas, Kansas, Louisiana, Mississippi, Oklahoma, and Texas -- had its warmest single calendar month for any climate region on record."
• "Exceptional drought, as defined by the U.S. Drought Monitor, covers more than 75 percent of Texas (201,436 sq mi)."

Record high (day and night) temperatures across the US.

July's Extreme Heat

Vegetation anomalies in North America (July 2011)

Throughout July 2011, the United States experienced extraordinarily high temperatures and many states in the Southwest felt the effects of drought conditions. The impact of this drought on vegetation growth can be seen in the photo above. The image, from the NASA Earth Observatory, displays vegetation anomalies across North America in July. To learn about the national weather pattern that caused such extreme conditions, visit this NOAA page. The progression of the heatwave can be seen in these two NOAA Environmental Visualization Laboratory animations that show how conditions changed throughout the second half of the month:

• High Dew Point Makes Heatwave Miserable
• Heat Wave Sweeps Across The U.S.