By all measures, the 1997 season was an inactive one but not so inactive as 10 other of the past 30 hurricane seasons. An early start. There has never been a year since 1929 when only one named storm formed in August and September. Unusually warm water developed rapidly with the highest SST anomaly conditions ever recorded for the June to October period. During the height of the 1997 hurricane season, QBO winds were from a relatively westerly direction.
Values are in .
Note that, except for August, the western Atlantic did not have high values of SLPA as is typical during suppressed hurricane years and we did not anticipate positive pressure anomaly to develop this year. These large positive ZWA values were fundamental in explaining why the 1997 season was so inactive. The strong westerly winds sheared off the tops of the easterly waves moving westward from Africa and prevented the organization of all but one of these easterly waves. The Western Sahel region of Africa was quite dry this year, much drier than we had expected.