Back to Tropical Cyclones
Forecasting Page | Back
to Main FAQ Page
Subject: F5) How has the official U.S. Government (NOAA) seasonal
hurricane outlook done in previous years ?
Contributed by Stan Goldenberg
The NOAA Seasonal Outlook for Atlantic basin hurricane activity
does not predict numbers of tropical storms, hurricanes and major
hurricanes directly. Rather, the scheme is set up to forecast a
range of expected values for the
ACE index (Accumulated Cyclone Energy), a measure of overall
activity. The ranges predicted for numbers of systems are obtained
by looking at the years in the historical record which had
observed values for ACE in the predicted range for the current
year. Note that although the range for ACE might verify correctly
for a given year (as it has so far for every year since the
forecast began in 1998 -- see below), it is rare that the ranges
for all three numbers (tropical storms, hurricanes and major
hurricanes) will be correct. However, if ACE is correct, then
usually at least two of the predicted ranges for numbers are
correct as well. (Click here to see a chart
of the observed values for ACE since 1950.)
Verification for the NOAA May Seasonal Outlook for
the North Atlantic basin hurricane activity
from 1999 - 2003
Verification for the NOAA August Seasonal Outlook for
the North Atlantic basin hurricane activity
from 1998 - 2003
Last updated August 13, 2004
Back to Tropical Cyclones
Forecasting Page | Back
to Main FAQ Page
|