Jet Stream

Thanks to a ducking-and-weaving jet stream and a colossal low-pressure system nearby, Baltimore was hit this week with the season's first cold punch, dropping temperatures to about five to 10 degrees below normal. The East Coast has plunged into lower-than-normal temperatures and area residents are bundling up - dragging out winter clothing that remained tucked away after an unseasonably warm fall. "Could you close that door?" asked Kiyetta N. Shird, slinging coffee at XandO in Charles Village, after a group of five entered.

WASHINGTON - Frigid weather with potentially dangerous wind chills is about to settle on the eastern United States for at least a couple of weeks, the National Weather Service predicted yesterday. A soon-to-be plunging jet stream will push temperatures 10 to 20 degrees below normal winter readings for a triangle of America ranging from central Texas to Maine and as far south as central Florida. The temperature plunge and the accompanying high winds will feel especially cold because the United States is coming off the second warmest November ever.

Dr. George S. Benton, a retired Johns Hopkins University environmental scholar who championed modern weather forecasting, died Saturday of cancer at his home in the Tuscany-Canterbury section of North Baltimore. He was 82.A former president of the American Meteorological Society, Dr. Benton taught the study of weather and other disciplines at the Homewood campus from 1948 to 1988. He was dean, and vice president of the arts and sciences faculty in the 1970s.Considered one of the nation's leading authorities in atmospheric and oceanographic sciences, he was appointed by the secretary of commerce in 1966 to direct a coordinated federal effort to bolster environmental research.

Somebody left the back door to Canada open this month, and the wind is pouring in.Just ask Will Price, a pilot and flight instructor at Brett Aviation, at Martin State Airport in Middle River."

For people who have suffered through the gales, heavy rains, floods, deep snows, property destruction and lost power of the nasty northeasters of the 1990s, there is little comfort in the fact that recent decades have seen fewer of these classic storms. That is because northeasters generally are more severe than they used to be.The main reason, experts say, is a long-term shift in the predominant winter path of the North American jet stream - the high-altitude, west-to-east river of air in which counterclockwise spinning northeasters are born, from which they draw their energy and by which they are transported.

LOS ANGELES -- As yet another fierce storm walloped Southern California, the National Weather Service's top experts met yesterday in Maryland to discuss whether the abnormal deluge heralds an unusually wet winter for California.Their conclusion: No one knows."We had the best minds in the Weather Service sitting there -- and we couldn't come to a consensus," said Ants Leetmaa, head of a supercomputing project for the Weather Service in Camp Springs, Md."The science is still inexact, and we hope to improve on that.

Somebody called The Sun this week and blamed this month's frigid weather on "that Hubble repair flight in December. It disrupted the jet stream and made us all freeze down here," the caller complained.He may have been half right.Meteorologist Russell L. Martin of the National Weather Service's Climate Analysis Center in Camp Springs says something has indeed disrupted the jet stream, which steers weather systems across North America.But Mr. Martin points at "El Nino," the periodic warming and cooling of Pacific Ocean waters, which can send the jet stream unusually deep into the Arctic and bring it roaring back down across the central and eastern United States with deadly cold, snow and ice.Happily, the latest blast of arctic air -- which has sent temperatures to the single digits as far south as Mississippi -- should be the last for a while, he said.

Unusually cool temperatures in the Pacific Northwest, floods in the Midwest, drought in the East.What separates this year from others, meteorologists say, is unusual activity from the jet stream -- strong winds that sweep like a broad river across the country, mixing hot and cold air in the atmosphere.This year, though, the jet stream has swung farther south than usual and its winds are wringing moisture normally suspended over the Gulf of Mexico down onto the heads of Midwesterners.The jet stream normally shifts northward during the summer as the sun heats the northern hemisphere.

Ah, the winter of 1992-1993. Dry and mild most days, theseason served up an occasional spring-like afternoon to tantalize us.Then winter's evil twin barged in: lashing us with what seemed like unending rain, biting us with cold and, finally, burying the Baltimore area in shin-deep snow.It was a perverse season that delivered a bouquet with one hand and a sucker punch with the other. But it will be recorded as nearly normal, because the mild opening balanced out the wild finale.Fred Davis of the National Weather Service at Baltimore-Washington International Airport remembers getting calls in mid-February from anxious citizens wondering if global warming had push Baltimore into an expanding sun belt.

The Blizzard of '83 was just a gleam in a weatherman's eye the second Tuesday of that year's February, when a low-pressure system entered the country from the cold Pacific Ocean and resolutely headed for the Rocky Mountains.It was over northeastern Nevada by the next day, and the weather forecasters, poring over their charts and checking their computers, began to utter a U.S. Weather Service equivalent of "Uh-Oh." At noon Wednesday, the service issued a winter-storm watch for the East Coast.