Well, it's confirmed: It was a hot one

The temperature at BWI-Marshall Airport reached 91 degrees Tuesday, setting a record for the most 90-degree days in a calendar year and topping off more than eight months of weather extremes in Maryland.

Since last winter's blizzards and record accumulations, 2010 has brought drought, crop losses, rising numbers of heat-related deaths and the hottest summer on record for Baltimore.

Many of these events can be traced to natural climate variability, enhanced by the influence of global warming, according to Kevin Trenberth, head of the climate analysis section at the National Center for Atmospheric Research in Boulder, Colo.

"Global warming is not the major factor, but it is a nontrivial factor," Trenberth said. "We can say that these [extreme] events very likely would not have happened without global warming."

The heat has been especially costly for Maryland.

The Maryland Department of Health and Mental Hygiene on Tuesday reported two more heat-related deaths, bringing the total this year to 28. It is the highest count since 2006, but well below the record of 48 deaths in 2005.

Health officials said both individuals had underlying health conditions, and both were found in un-air-conditioned homes where temperatures had climbed to more than 90 degrees. One was an adult in Dorchester County, the other a senior in Baltimore.

Meanwhile, drought conditions in Central Maryland earlier this summer, and drought that persists in Western Maryland, Southern Maryland and the Lower Eastern Shore, have resulted in significant crop losses. Gov. Martin O'Malley asked the U.S. Department of Agriculture last month to consider the entire state for designation as an agricultural disaster area.

State Agriculture Secretary Earl "Buddy" Hance said, "I've farmed all my life, and this looks to be the worst year we've ever had."

Corn losses in Southern Maryland, where he farms, are estimated at 70 percent, he said. "If we can get the rain very quickly, we could salvage the soybean crop, but these hot, windy days aren't helping us."

Vegetable crops, accelerated by the heat, have come in so much earlier than usual that supplies are growing short, Hance said. And withered pastures are forcing livestock producers to buy more hay to feed their animals now and get them through the winter. That has added costs and shortened supplies.

And fields in many areas are "hard as a rock," threatening to frustrate farmers trying to plant winter wheat and barley if rain remains scarce.

As if heat and drought weren't enough, the National Weather Service forecast office in Sterling, Va., posted a Fire Weather Watch for Wednesday in most of Maryland west of the Chesapeake, as dry weather and a windy cold front raise the dangers of spreading wildfires.

Not everyone has hated the weather this year. Inside a Harborplace pavilion, Shan Howard, 27, of Baltimore, said the heat hasn't really affected him. He liked the snow, too.

"I enjoyed it because it was a long time since we got snow," he said. "But it was a lot," saying that one night he had to walk six miles home from work because buses weren't running. "Warmer days are fine," he added. "I went to Ocean City." He also has a friend with a pool.

But Tyreese Smith, 24, also of Baltimore, is looking forward to fall for the fashion — long boots, leggings and sweaters. In this kind of heat, and in last winter's snow, she said, "it's best just to stay inside." Luckily, her utilities are included in the heat. "I live in the house."

Not far away, Blake Wideman, 21, was cooling himself in the shade of an awning on Calvert Street. He's had enough of the heat. He likes to jog, but all summer the heat has been overwhelming. "Even at night it's hot."

The bad weather got a running start from the Dec. 18-19 blizzard that dropped 18 inches of snow at the airport, and more in other locations. An El Nino pattern contributed by sending repeated storms across the southern United States and up the East Coast, Trenberth said. Cold air injected by atmospheric patterns over the North Atlantic did the rest.

Back-to-back snowstorms piled up 25 inches on Feb. 5-6, and another 19.5 inches just three days later. The final February total, 50 inches, was a record for any month in Baltimore, besting the previous snowiest February, only seven years ago, which saw 40.5 inches.

And the season's total, 77 inches, was the most snow for Baltimore in any winter since the first official snow records were kept in 1883. The runner-up winter was 1995-1996, when 62.5 inches was recorded.

(The long-range forecast from the National Weather Service shows no clear trend either way for this winter's precipitation or temperatures. AccuWeather.com is predicting an average winter for Maryland.)

As snowy as it was, the winter was not extraordinarily cold. January 2010 was a bit warmer than average, but February was persistently cold, ending 4.6 degrees colder than the norm.

Since then, however, Baltimore has been persistently warm. Every month from March through August averaged several degrees warmer than normal. The hottest was June, which ended 7 degrees above average, followed by July, which averaged 5 degrees warmer than the norm.

The National Weather Service said last week that the meteorological summer of 2010 — June through August — was the warmest on record for Baltimore, breaking the record set in 1943.

The daily high temperatures recorded at BWI-Marshall through the same three-month period were also the warmest on record here. The previous record had stood for just 15 years.

The 90-degree temperatures began adding up in April, with two. There were three more in May, 16 in June, 20 in July and 11 in August.

Now, after three more days in the 90s in early September, the total for 2010 — so far— comes to 55. That beats the all-time record for Baltimore of 54 days. That one had stood alone since 1988, barely surviving threats in 1991 and 1995. Both of those years counted 50 or more days in the 90s.

The summer of 2010 saw one other hot-weather record matched. There were seven days of 100-plus readings at BWI — two in June and five in July. That's only happened once before, in 1988.

The heat came with a scarcity of rain.

After plenty of precipitation through the winter, April, May and especially June, turned out dry.

It was the beginning of the growing season, and many Maryland farmers suffered accordingly. Especially serious were losses to the corn crop during what by July had become an agricultural drought for 64 percent of the state.

And while significant rains in July and August helped lift most of Central Maryland out of the drought conditions, moderate to severe drought continues in portions of Western Maryland and the Lower Eastern Shore — nearly a third of the state.

The hoped-for rescue from a tropical storm never materialized. Hurricane Earl cruised up the coast and roiled the surf, but it stayed offshore and failed to deliver significant rainfall on land. Rain gauges at Salisbury airport and Wallops Island, Va., had barely two-tenths of an inch to show for Earl's visit.

Western Maryland is in even worse shape. Hagerstown hasn't seen more than a quarter inch of rain fall since Aug. 12, and only 3 inches — less than a month's worth of normal rainfall — since June 1.

Washington County and the eastern half of Allegany County are experiencing "severe" drought conditions that extend southward into northern and eastern Virginia, encompassing 30 percent of that state. It's currently one of the largest regions in drought in the country.

Does any of this weather havoc have any significance beyond a statistical oddity?

The Environment Maryland Research and Policy Center, part of a national environmental policy organization, planned to release a report Wednesday citing a "worldwide scientific consensus" to argue that such weather extremes are part of a developing pattern linked to global climate change.

The anticipated extremes include more heavy rain and snow events, more destructive flooding, more frequent and costly droughts and periods of extreme heat, more frequent large wildfires and more-intense hurricanes.

"To protect the nation from the damage to property and ecosystems that results from changes in extreme weather patterns — as well as other consequences of global warming — the United States must move quickly to reduce emissions of global warming pollutants," the report said.

At NCAR, Trenberth said global warming's role is felt most when natural climate variability is already pushing weather events toward extremes. He cited disastrous flooding in China, India and Pakistan this summer, and extraordinary drought and heat in Russia as natural events made worse by global warming.

"In North America there is always a drought somewhere in the summertime. Part of that pattern does indeed get influenced by El Nino and La Nina [natural cycles of warming and cooling of the tropical Pacific]," he said.

"What the global warming component is, is if the drought starts to form, the onset is quicker, it's a little more intense and the heat waves are a little hotter," he said. "So sometimes it's the straw that breaks the camel's back, the thing that causes you to break records."

Batimore Sun reporter Jessica Anderson contributed to this report.

frank.roylance@baltsun.com

http://twitter.com/froylance

Maryland weather blog: Frank Roylance on meteorology

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