Climate Assessment for 1995

Michael S. Halpert, Gerald D. Bell, Vernon E. Kousky and Chester F. Ropelewski

Climate Prediction Center, NCEP/NWS/NOAA, Washington, D.C.

Table of Contents


1. Introduction

2. Climate and global change issues

a. Surface temperatures

b. Tropospheric/stratospheric temperatures

1) Troposphere

2) Lower stratosphere

c. Trace gases

1) Ozone

2) Carbon Dioxide

3) Methane

d. Northern Hemisphere snow cover

3. The evolution of recent oceanic and atmospheric anomalies in the global tropics

a. Large-scale conditions in the tropics: 1990-94

b. The 1994-95 warm (ENSO) episode

c. The 1995 Pacific cold episode

4. Regional climate highlights

a. North America

1) December 1994-January 1995: Wet in Western U. S., warm in East

2) April-May 1995: Midwest U. S. floods

3) The 1995 Atlantic hurricane season

4) Mid-July 1995: Midwest U. S. heat wave

5) August 1995: Northeast U. S. drought

6) November-December 1995: Wet in Northwest U. S., cold in East

b. Eurasia

1) January-May 1995: Asian warmth

2) June-August 1995: European/Western Asian hot spell

3) June-September 1995: Southeast Asian/Indian summer monsoon

c. South America

d. Australia

e. Africa

1) June-September 1995: Western Africa rainy season

2) October 1994-April 1995: Southern Africa rainy season

5. Seasonal summaries

Appendix - Contributors




The El Niño-Southern Oscillation (ENSO) phenomenon is a major contributor to the observed year-to-year variability in the Pacific Ocean and in the global atmospheric circulation. The short-term climate system witnessed the return to the mature phase of warm ENSO conditions (commonly referred to as the El Niño) during early 1995 for the third time in four years. This frequency of occurrence is unprecedented in the last 50 years and is comparable to that observed during the prolonged 1911-15 ENSO episode.

These warm ENSO conditions contributed to a large-scale disruption of the normal patterns of wind, rainfall, and temperature over much of the tropics and middle latitudes, particularly during the December 1994-February 1995 period. This period was followed by a dramatic decrease in sea surface temperatures in the tropical Pacific, resulting in a complete disappearance of all warm episode conditions during June-August and in the development of weak cold-episode conditions during September-November.

Changes in the tropical Pacific were accompanied by pronounced, large-scale changes in the atmospheric circulation patterns from those that had prevailed during much of the early 1990s. Particular examples of these changes include 1) a dramatic return to a very active hurricane season over the North Atlantic, following four consecutive years of significantly below-normal hurricane activity; 2) the return to above-normal rainfall throughout Indonesia, northern Australia, and southern Africa, following a prolonged period of below-normal rainfall and periodic drought; and 3) a northward shift of the jet stream and storm track position over the eastern half of the North Pacific during the latter part of the year, following several winter seasons (three in the last four) characterized by a significant strengthening, southward shift, and eastward extension of these features toward the southwestern United States.

Other regional climate anomalies during 1995 included extreme warmth throughout western and central Asia during January-May and colder than normal conditions in this region during November-December, severe flooding in the midwestern United States (April-May), abnormally wet conditions in California and the southwestern United States (December-February) combined with near-record warmth over eastern North America, deadly heat waves in the central United States (mid-July) and India (first three weeks of June), drought in the northeastern United States (August), a drier-than-normal rainy season in central Brazil (September-December), and an intensification of drier-than-normal conditions over southern Brazil, Uruguay, and northeastern Argentina at the end of the year.

The global annual mean surface temperature for land and marine areas during 1995 averaged 0.40°C above the 1961-90 mean. This value exceeds the previous warmest year in the record (1990) by 0.04°C. The Northern Hemisphere also recorded its warmest year on record during 1995, with a mean departure from normal of 0.55°C. The global annual mean surface temperature for land areas only during 1995 was the second warmest since 1951.

The year also witnessed near-record low ozone amounts in the Southern Hemisphere stratosphere, with minimum values only slightly higher than the record low values observed in 1993. The areal extent of very low ozone values during 1995 was as widespread over Antarctica as in the record low year of 1993.