The 1997 El Niño: Potential effects in New York - 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.
The 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. Three types of products are included.
The first consists of U.S.-wide maps of average precipitation rankings during El Niño episodes for
the November-December and January-March periods. El Niño impacts vary with season. Although
El Niño may have an impact on New York precipitation, historically there has not been a consistent
response. Similar U.S.-wide maps of average temperature rankings during El Niño episodes for the
December-February and February-April periods follow. The second product type gives the change in
temperature probabilities by season. The Climate Prediction Center of NOAA makes seasonal
forecasts for temperature probabilities in three categories: the warmest 1/3; the near normal 1/3; the
coldest 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 warmer or colder than normal can be dramatically changed
by El Niño. The third type of figure converts the average rankings shown earlier to average
temperatures and a departure from average. This estimate gives a temperature that might be expected
based on historical data. However, because of the probabilistic nature of the forecasts, the range of
the average temperature could be significantly warmer or colder.
Historically, moderate to strong El Niño episodes have featured an increased frequency of occurrence
of near or above normal temperatures over the state during December-February. During nine moderate
to strong El Niño episodes temperatures averaged 1-2 degrees Fahrenheit above normal. Interestingly,
during the nine moderate to strong El Niño episodes selected, none of New York's 10 climate divisions
experienced below normal average temperatures for the December-February period.