The 1997 El Niño: Potential effects in Alaska - November 1997 to April 1998

Climate Prediction Center (CPC), NWS/NOAA

Updated 17 November 1997

We are currently in the midst of a strong El Niño (warm) episode, which is forecast to continue through February-April 1998. During this period the tropical ocean surface temperatures are forecast to remain comparable in magnitude and areal extent to that of 1982-83, which is considered to be the strongest warm episode of this century. In contrast to the 1982-83 El Niño, which caught the country by surprise, the present El Niño was predicted several months in advance. This improvement in climate prediction is the direct result of intensive research efforts by NOAA and its partners during the last 15 years. Part of this research effort, which is still ongoing, has been devoted to determining the effects of El Niño on temperature and precipitation patterns in the U. S. and globally. Some results of this research for your state are discussed below.

Information on state impacts is derived by looking at what has happened in those years during the past century that featured moderate to strong El Niño episodes. While the special 102 year climate division data base used for products over the conterminous U.S. is not available for Alaska and Hawaii, there is evidence that strong El Niño episodes have consistent impacts on these states. The first product attached indicates that the southern half of Alaska tends to be warmer than normal during the December-March period of a moderate to strong El Niño. The southern fringe of Alaska tends to be wetter than normal during the January-March period of such an episode.

For information purposes the second type product attached consists of conterminous U.S.-wide maps of average precipitation rankings during El Niño episodes for the November-December and January-March periods. Similar maps of average temperature rankings during El Niño episodes for the December-February and February-April periods follow. El Niño impacts vary with season. The Climate Prediction Center of NOAA makes seasonal forecasts for precipitation and temperature probabilities, including those for Alaska and Hawaii, in three categories: the wettest (or warmest) 1/3; the near normal 1/3; the driest (or coolest) 1/3. The probability of getting any one of these three categories would be equally likely in the absence of El Niño. Probabilities of being wetter or drier than normal can be dramatically changed by El Niño.