A look at weather extremes and the big-picture climate connections.

Weather Extremes Widespread over Memorial Day Holiday

By Andrew Freedman and Michael D. Lemonick

The Memorial Day Weekend brought a rare combination of extreme weather events to much of the U.S., with everything from record heat to wildfires, plus the most intense tropical storm on record to make landfall prior to June 1. Here’s a breakdown of some of the most notable extreme weather events:

Heat

At Chicago's O’Hare International Airport, the temperature hit 97°F on May 27 — the earliest date on record that the mercury has gone this high (it hit 98°F on May 31, 1931). Chicago is on track to have its warmest spring season on record.

Cleveland's Hopkins International Airport set a record high for May 28 of 92°F, surpassing the old record of 89°F, which had stood since 1991, while Toledo hit 96°F.  In Detroit, the temperature soared to 95°F during the weekend, another record.

Record temperatures set or tied on May 28. Credit: Climate Central.

On May 26, at least nine airports in the Midwest had their hottest May day on record, and 58 out of 456 U.S. observing stations set daily high temperature records.

Early season heat waves such as this one are a more significant public health risk compared to heat waves that take place during the middle of the summer, in large part because people have not yet become used to warmer weather. This graphic published in the Washington Post provides useful insight into how the human body adapts to the heat, and why people respond in different ways.

Nationwide, 884 daily record highs were set over the past week, compare with just 97 record lows. For the month to date, the nation has seen 127 all-time highs for any day in May, and just 18 all-time lows. (You can keep tabs on record temperatures using Climate Central's interactive record temperature tracker.)

In recent years, including 2012 so far, record daily highs have been outpacing record daily lows in a pattern that can't be explained by natural variability alone; something else must be involved, and human-caused global warming is an obvious culprit. The picture is even more lopsided when you look at monthly record highs compared with record lows. If the climate weren't warming overall, you'd expect these longer-term ratios to be closer to 1-to-1, on average.

The picture was very different in the northern Rockies, where a late winter storm hit the mountains on May 26. Daytime highs on Monday were 10 degrees below average in Boise, Idaho; and 6°F below average in Laramie, Wyo. Both the record heat and cold weather were tied to the same dip in the jet stream, as a low pressure area drove cold air into Montana and Idaho, while at the same time drawing hot and humid air northward into the Midwest and Ohio Valley.

Tropical Storm Beryl

Tropical Storm Beryl made landfall in Jacksonville Beach, Fla., on May 28. With maximum sustained winds of 70 mph, Beryl was close to hurricane strength when it struck land. Meteorologist Brian McNoldy posted a fascinating radar animation showing Beryl as the storm approached Florida, and the images make clear that the storm was intensifying in the hours prior to landfall. Beryl is the second tropical storm to form in the Atlantic during May, which is extremely rare. As McNoldy noted on his blog, "It is exceptionally rare to have two storms form prior to June 1 . . . this is only the third time in known history (back to 1851). 

Precipitation estimates from May 26-29, showing the heavy rains from Tropical Storm Beryl. Credit: NOAA.

The actual hurricane season doesn’t start until June 1, with the National Oceanic and Atmospheric Administration (NOAA) forecasting a near normal season, with between nine and 15 named storms, of which four to eight will strengthen to a hurricane with top winds of 74 mph or higher. 

Beryl has brought beneficial rainfall to northern Florida, southeast Georgia, and parts of South Carolina. These areas have been suffering from severe drought conditions, and widespread 5-to-8 inches of rain have made a dent, although they have not completely alleviated the drought. During the next two days the remnants of Beryl is forecast to drop several inches of rain in Georgia, South Carolina and North Carolina before heading out to sea.

Smoke from the Whitewater-Baldy Fire Complex makes for a beautiful sunset in Albuquerque. Credit: Flickr/bobthemtbiker.

Southwest Wildfires

Wildfires in New Mexico and Arizona continued to burn out of control during the weekend. Two lightning-sparked fires that had merged last week in Gila National Forest grew dramatically in steep terrain that is difficult for firefighters to access.

The Whitewater-Baldy Complex fire has now burned152,012 acres — just 5,000 acres shy of the total acreage burned in New Mexico’s largest-ever wildfire, which occurred just last year. Firefighters are battling low humidity levels, drought conditions, and erratic and strong winds, making it very difficult to gain the upper hand over the fire.

Smoke from the fire is reducing air quality throughout much of the Southwest and beyond. 

Severe Weather

The weekend also featured several rounds of severe thunderstorms from the U.S.-Canadian border southwestward to Texas. Drenching rains repeatedly doused the Minneapolis-St. Paul area, with flash flooding a key concern. The Twin Cities received so much rain during the past two weeks that they’ve now had the second-wettest May on record, according to meteorologist Paul Douglas' blog

On May 27, a powerful complex of thunderstorms barreled across Pennsylvania toward Maryland and Washington, D.C. Extensive damage in the form of downed trees and power lines occurred in Franklin County, Pa., where a wind gust to 87 mph was recorded by a trained weather spotter.

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