While temperatures remain near-to-above normal across much of the United States, and storms continue producing more rain than snow, signs of the transition to more winter-like patterns are in sight, forecasters at the National Oceanic and Atmospheric Administration's National Weather Service said today.

In an extension of its 2001-02 winter outlook, forecasters predicted late December, and the January-March 2002 period will bring more extreme and frequent shifts in temperature and precipitation for the nation, including cold-air outbreaks, snow, rain and ice storms. Forecasters said the remainder of December will bring much colder temperatures in contrast to the record-breaking warmth some parts of the country experienced in November and early December. The official start of winter is Dec. 21.

Without El Niño, La Niña, Expect Variability

Without the influences of either El Niño and La Niña, forecasters said the winter will bring variable temperatures and precipitation. "We're seeing the likelihood of more variable weather and more winter-like pattern developing during the next week to 10 days, especially compared with the weather of November and early December," said Jim Laver, acting director of NOAA's Climate Prediction Center, a part of NOAA Weather Service.

Laver added, "According to NOAA's National Climatic Data Center, November was the second warmest November in 107 years across the United States, but during the next 2-3 weeks, we expect a change toward a more variable pattern with an increase in the odds of colder and more wintry conditions in the Midwest and East as we close out 2001." (The warmest November on record occurred in 1997.)

Absent any El Niño or La Niña effects, the climate players that will contribute to the variability are the Madden-Julian Oscillation and the Arctic Oscillation, said Wayne Higgins, CPC's principal scientist and expert on linking weather and climate. "We're watching these closely, because the AO can influence the number and intensity of cold-air outbreaks into the South and Nor'easters on the East Coast, and the MJO can impact the number of heavy rain events in the Pacific Northwest," he said.

Drought Picture More Promising

Forecasters said while two-thirds of the East Coast is in some stage of drought, recent rains have improved short-term dry conditions. "The current outlooks, which call for continued regular periods of precipitation heading into late December, offer additional hope for drought alleviation," said Douglas Le Comte, drought specialist at CPC.

And in a meteorological reversal of fortunes, the Pacific Northwest has seen increased amounts of rainfall compared to last year, Le Comte said. Cumulative rain and snow totals since Oct. 1 are 2-3 times as great as they were during last year at this time, with precipitation running above normal across the entire Pacific Northwest region so far this season, he said.

"Most locations west of the Cascades have picked up more than one foot of (liquid equivalent) precipitation since Oct. 1, and more is on tap in the coming weeks," Le Comte said, adding more rain and snow is needed in the coming months to rid the Northwest region of the long-term precipitation deficits, which still range from 1 to 2 feet since the fall of 2000.

Regional Outlooks for January through March 2002

• In the Northeast, colder-than-normal temperatures are expected. Snowfall for the entire region will depend on the fluctuations of the AO;
• The Mid-Atlantic states have about equal chances of above normal, normal, or below-normal temperatures and precipitation. Storm tracks could bring more precipitation than the winters of the late 1990s, but snow amounts will largely depend on the AO;
• In the Southeast, Florida and southeastern Georgia should be drier than normal. Temperatures could average above normal over most of the region.
• In the upper Midwest and Great Lakes, temperatures should be highly variable, with a slight chance of averaging below normal over the Great Lakes. Due to a better supply of Arctic air this year, there will probably be more sub-zero days than the average of recent winters. There are equal chances for above normal, normal or below normal precipitation for most of the area.
• The northern Great Plains and Rockies will also see highly variable temperatures with more sub-zero days than experienced on average during the unusually mild winters of the late 1990s, while wet and mild weather is more likely for the southern Plains. A small area centered over Nebraska and South Dakota may end up slightly drier than normal. The northern Rockies can expect equal chances of above normal, normal, or below-normal precipitation and temperatures;
• In the Northwest, there are equal chances for above normal, normal, or below-normal rain and snow. Heavy coastal rain events are more likely compared to the previous three relatively dry winters. A repeat of the near-record dryness seen last winter is unlikely;
• Expect warmer-than-normal temperatures in most of the Southwest, accompanied by drier-than- normal conditions over California and southwestern Nevada, with equal chances of above normal, normal or below-normal precipitation elsewhere in the region.
• The southern half of Alaska can expect above-normal temperatures. The rest of Alaska and all of Hawaii can expect equal chances of above normal, normal, or below normal temperatures and precipitation, although the long-term drought in much of Hawaii was somewhat alleviated by a wet November.

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