Chill blows into the area

A day that begins on the mild side ends with plunging temperatures



Temperatures dropped 20 degrees in three hours yesterday afternoon in the Baltimore area and headed toward freezing as a powerful cold front barreled across the state with rain and gusty winds, ushering in the coldest weather of autumn.

The mercury topped out at 75 at Baltimore-Washington International Thurgood Marshall Airport, just one degree shy of the record for the date set in 1928.

The highest temperature we can hope for today will be in the low 40s, forecasters said.

"That's a big change," said Steven M. Zubrick, science and operations officer for the National Weather Service forecast office in Sterling, Va. "Somebody who walks out and thinks they're ... . not going to wear a coat, they're going to be very surprised."

The forecast called for more cold weather ahead, and a chance of snow showers today in parts of Western Maryland.

Happily, yesterday's abrupt change in the weather came without the tornadoes that marked the cold front's passage through the Midwest on Tuesday.

Nearly three dozen twisters churned across parts of Kentucky, Indiana, Tennessee and Illinois and Missouri, killing at least two people.

Cold meets warm

Meteorologists blamed the violent weather on the collision of the cold front with warm, unstable air that stretched from the Gulf of Mexico to Canada.

Meteorologists regard autumn as their "second season" for tornadoes, a time when cold air masses begin plunging into the United States from Canada and running into still-warm air from the gulf.

The first season is spring, when the first warm air masses collide with the winter's departing cold weather systems.

Snow fell yesterday at the northern end of the boundary between the cold and warm air masses. As much as 8 inches fell in parts of Minnesota, Wisconsin and Michigan. At least four people were killed in snow-related auto crashes.

It was balmy in Baltimore for much of the day. The overnight low at BWI never sank below 63 degrees, and temperatures climbed to 75 by 1 p.m.

Then the atmosphere began shifting gears.

The frontal passage was marked by an abrupt wind shift after 3 p.m., from the south-southwest to the northwest. Wind speeds peaked at 23 mph, with gusts to 30 mph, and the barometer reversed its day-long fall.

Temperatures dropped to 55 degrees by 4:30 p.m. The sky grew dark, and the rain began. By midnight, more than half an inch had fallen at the airport, and the temperature was 44 and dropping.

The arrival of colder weather ended what had been an extraordinarily mild late summer and early autumn in Baltimore.

September averaged 72 degrees, the 17th-warmest September in 134 years of recordkeeping for Baltimore, and the mildest in 25 years.

October was 2.4 degrees warmer than the norm, at 57.8 degrees. That made it the warmest in a decade.

November, until yesterday, was running 6.4 degrees above the 30-year average, at 54.2 degrees.

It has been unusually dry, too, except for the tremendous soaking when the remnants of Hurricane Tammy collided with a frontal system here Oct. 7 and 8:

September saw just 0.67 inches of precipitation at BWI, the 10th-driest September on record in Baltimore. Washington received even less and notched the driest September on record at Dulles International and Reagan National airports.

October was the wettest on record in both cities, with 9.23 inches of rain falling at BWI. That bested the previous record of 8.09 inches, set in 1976. Most of the total - 7.65 inches - came with Tammy. Without that storm, the airport clocked 1.58 inches of rain.

`Freaky' pattern

Zubrick pronounced the pattern "freaky."

"I don't think we've ever had the driest followed by the wettest month ever," he said.

November produced 0.02 inches of precipitation through Tuesday. From here on, Zubrick said, "I think we're going to see a more normal November."

For Baltimore, it is expected to include clearing skies and sunshine through Sunday. Daytime highs should creep back into the 50s by Saturday, with overnight lows remaining below freezing through the weekend.

Looking ahead to Thanksgiving, Zubrick said, "It looks like greater odds [for] below-normal temperatures over much of the Eastern United States, with a big warm spot over Montana. Go to Montana."

It also will be dry in the East, he said.

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