NOAA'S NATIONAL WEATHER SERVICE SEES THE RETURN OF LA NIÑA
NOT LIKELY TO LAST
January 25, 2001 The National Weather Service's Climate Prediction Center recently issued an updated seasonal outlook confirming that during recent months La Niña has strengthened to moderate force, however, she is expected to weaken once again over the next few months.
Of more significance for U.S. weather patterns is the variability and phase shifts in the regional climate pattern known as the Arctic Oscillation (AO). NOAA scientists say the change in the Arctic Oscillation to its positive phase means relatively warmer temperatures for much of the United States. However, the outlook also says there is no guarantee that it will stay in that phase for the rest of winter. "The AO is highly unpredictable and often reverses its phase on time scales on the order of a week or two," said Jim Laver, deputy director of the Climate Prediction Center. "The result is that we would likely see periods of below and above normal temperatures and precipitation during the remainder of the winter."
The Winter Outlook, originally issued in October, stated that this winter would likely be characterized by colder temperatures than those experienced during the last three winters and that the weather pattern would be more variable. To date, this winter has featured extreme cold during December and warmer than normal conditions for many parts of the contiguous United States in January.
The latest outlook indicates above normal precipitation is likely in the Ohio and Tennessee Valleys and in the Pacific Northwest during the month of February.
National Weather Service Director retired Air Force Brig. Gen. Jack Kelly said, "We still expect considerable swings in temperature and precipitation so Americans must continue to watch local forecasts for the latest winter advisories and be prepared for a little bit of everything."
Updating the late winter to early spring (February through April) Seasonal Outlook, forecasters at the NWS Climate Prediction Center are predicting warmer than normal temperatures along the southern tier states, near normal temperatures in the Pacific northwest, and below normal temperatures for Michigan and Southern Alaska. The expected temperature pattern remains markedly cooler than that experienced during the previous three years, which were warmer than normal across much of the U.S. Precipitation predictions call for dry conditions in Florida and the southwest and above normal precipitation for the Alaskan panhandle. Climatologists define normal temperature as the 1961-1990 average temperature for a given area.
Regional Outlooks for February
Precipitation: Equal chances of above, near, and below normal across most of the United States, including the Mid-Atlantic and northeast states; however, below normal precipitation is expected in Florida and extreme southern sections of Louisiana, Mississippi, Alabama, Georgia, Arizona, New Mexico, Nevada, Utah and Southern California.
Alaska can expect sub-normal temperatures in central and southern sections and above normal in the north. Near-normal precipitation amounts are expected everywhere except the southern panhandle where above normal precipitation totals are expected.
Hawaii can expect above normal temperatures for February through April and near normal levels of precipitation.
NOAA forecasters say a period of moderately warmer temperature is expected to begin over the central states this weekend and spread east by Wednesday, January 31. But, forecasters caution that cold snaps and snow storms are still likely as we proceed through the rest of the winter. Kelly added a reminder about the importance of NOAA Weather Radio, "Having a NOAA Weather Radio, which gives the latest weather reports and warnings, will remain vitally important."
Relevant Web Sites
winter storm watches, warnings and temperatures across the United