Positive MEI: Nation's 'Guardian Angel?'

[donsutherland1]

Since 1950 when the major global indices have been available, 24 seasons saw one or more major hurricanes make landfall in the United States. Four of those seasons saw 2 or more major hurricanes make landfall:

1950: 2
1954: 3
1955: 3
1985: 2

In all of those seasons, the Multivariate ENSO Index (MEI) averaged negative for the hurricane season (March through November period).

This season, the MEI has averaged positive so far and a positive outcome is all but certain. Indeed, the July-August MEI has increased to +0.602, which brings the seasonal average to +0.443.

For a time, it appeared that Frances would make landfall as the second major hurricane of the season. However, as Frances moves into the endgame of its trek toward Florida, it has been weakening. It is now a Category 2 storm with 105 mph maximum sustained winds. Even as it emerges in a more favorable environment for intensification, that intensification has not yet begun.

It now appears increasingly likely that Frances could make landfall as a Category 2 storm rather than a major hurricane. This would be good for Florida, which was ravaged by ferocious Charley.

[donsutherland1]

Just to add some statistics concerning the MEI and major landfalling hurricanes:

Since 1950 when the MEI was regularly recorded, there have been 24 years in which one or more major hurricanes had a U.S. landfall.

Breakdown of Seasons by MEI:

Negative MEI: 15 (62.5%)
Positive MEI: 9 (37.5%)

Seasons with more than one major landfalling hurricane:

Negative MEI: 4/15 (26.7%)
Positive MEI: 0/9 (0.0%)

2004 is in line to become the 10th season with a positive MEI. So far, it has had one major landfalling hurricane. Frances might take a crack at trying to be the 2nd, but it will need to strengthen (which is possible) prior to landfall. Ivan might be another possibility, but its long-term track and outlook is far from certain.