National Fall Season Temperatures - September-November 2002

larger image

The graph to the left shows seasonal mean temperature averaged across the contiguous United States based on long-term data from the U.S. Historical Climatology Network (USHCN). The value for September-November 2002 (climatological Autumn) is estimated from preliminary Climate Division data using the first difference approach. September-November 2002 ranked as the 51st warmest such period in the 1895 to present record, which translates to near average temperature for the Fall months. The preliminary nationally averaged temperature for the season was 54.3° F (12.4° C) which was 0.1° F (0.06° C) above the long-term mean.

Statewide mean temperature for the September-November period was below average in 9 states and above average in 12 states with the remainder averaging near-normal. None of the contiguous states averaged much above or much below normal for the Fall season.

Over the September-November period, while no state-averaged temperature was much cooler or warmer than the long-term mean, when broken down by climate division, central Texas had the coolest divisional temperature anomalies in the contiguous nation as can be seen in the map to the right. Significantly warm divisional temperature anomalies were confined to several divisions in the southwest and west. The pattern of fall temperature for the contiguous U.S. corresponds quite well with height anomalies in the 500mb level of the atmosphere. Though the negative height anomalies were not large for the September-November period, they were associated with cooler than average Statewide temperature across the mid-section of the contiguous U.S. Averaged over the Fall months, there were no significant positive height anomalies in the continental US except for the extreme northwest. But most notably, height anomalies over Alaska were significantly greater than average and this is reflected by surface temperatures which were warmest on record in that state for the September-November period, as can be seen by the graph to the right.

larger image larger image

November Temperatures

larger image

The graph to the left shows monthly mean temperature averaged across the contiguous United States based on long-term data from the U.S. Historical Climatology Network (USHCN). The value for 2002 is estimated from preliminary Climate Division data using the first difference approach. November 2002 ranked as the 51st warmest November in the 1895 to present record, which translates to near average for the month of November. The preliminary nationally averaged temperature was 42.6° F (5.9° C) which was 0.1° F (0.6° C) above the long-term mean.

Below average warmth generally occurred in the southern and eastern half of the country in November, while the western half of the country averaged slighly above normal. No statewide mean temperature ranked much above or much below average for the month. The east-west temperature difference over the nation is reflected in the mean 500mb height and anomalies chart, which shows general ridging in the west and troughing in the east. This can be translated to cooler than average surface temperatures in parts of South and East. The map of divisional temperature (below right) shows that the cool anomalies were reasonably widespread in the eastern half of the nation. Temperatures in Alaska were record warm relative to the period 1971-2000 indicating again the ridging over western North America. An animated image of daily average temperature anomalies shows the persistent warm anomalies in the state of Alaska and variability across the rest of the nation.

larger image larger image

Regional Temperature Ranks for the
Contiguous U.S., November 2002

Region	Rank
Northeast	41st coldest
East North Central	49th coldest
Central	33rd coldest
Southeast	37th coldest
West North Central	83rd coldest
South	34th coldest
Southwest	62nd coldest
Northwest	61st coldest
West	79th coldest

Temperature Departures

The map to the right, based on over 500 airport stations, shows departures from the 1971-2000 normal temperatures for November 2002. Warmer than average temperatures extended along the west coast and in parts of the High Plains, with the largest positive departures in the contiguous U.S. (greater than 6.0° F [3.3° C]) occurring in Montana. The largest negative temperature anomalies were recorded along the east coast where widespread anomalies of -3.0° F occurred. By far the largest anomalies occurred in Alaska with anomalies greater than 9.0° F being recorded at many stations.

larger image

Questions?

For all climate questions other than questions concerning this report, please contact the National Climatic Data Center's Climate Services Division:

Climate Services Division NOAA/National Climatic Data Center 151 Patton Avenue Asheville, NC 28801-5001 fax: 828-271-4876 phone: 828-271-4800 email: questions@ncdc.noaa.gov

For further information on the historical climate perspective presented in this report, contact:

Catherine Godfrey NOAA/National Climatic Data Center 151 Patton Avenue Asheville, NC 28801-5001 fax: 828-271-4328 email: Catherine.S.Godfrey@noaa.gov

Jay Lawrimore NOAA/National Climatic Data Center 151 Patton Avenue Asheville, NC 28801-5001 fax: 828-271-4328 email: Jay.Lawrimore@noaa.gov

NCDC / Climate Monitoring / Climate of 2002 / November / U.S. Temp. / Search / Help