NHC's comments on surge
Posted by
cypresstx on 11/13/2011, 8:42 am
wish the "experimental Tropical Cyclone Impacts Graphics" were archived
in PDF document
Storm Surge Scales and Storm Surge Forecasting
During the open public comment period for the draft of the Saffir-Simpson Hurricane
Wind Scale, many people suggested that the National Weather Service develop a storm surge
specific scale as well as improve its forecasting of storm surge. It is acknowledged that there are
some researchers who advocate developing another scale for hurricanes specifically geared
toward storm surge impact by incorporating aspects of the system's size. However, the
National Hurricane Center does not believe that such scales would be helpful or effective at
conveying the storm surge threat. For example, if 2008's Hurricane Ike had made landfall in
Palm Beach, Florida, the resulting storm surge would have been only 8', rather than the 20' that
occurred where Ike actually made landfall on the upper Texas coast. These greatly differing
surge impacts arise from differences in the local bathymetry (the shallow Gulf waters off of
Texas enhance storm surge while the deep ocean depths off of southeastern Florida inhibit
surge). The proposed storm surge scales that consider storm size do not consider these local
factors that play a crucial role in determining actual surge impacts.
The National Weather Service believes that a better approach is to focus directly on
conveying the depth of inundation expected at the coast and inland. Because storm surge
induced flooding has killed more people in the United States in hurricanes than all other
hurricane-related threats (freshwater flooding, winds, and tornadoes) combined since 1900 the
National Oceanic and Atmospheric Administration is working to enhance the analysis and
prediction of storm surge. Direct estimates of inundation are being communicated in the NHC's
Public Advisories and in the Weather Forecast Office's Hurricane Local Statements. New ways
of communicating the threat have also been developed. NHC's probabilistic storm surge
product, which provides the likelihood of storm surge values from 2 through 25 feet, became
operational in 2009, and the NWS's Meteorological Development Laboratory is providing
experimental, probabilistic storm surge exceedance products for 2010. In addition, coastal
WFOs will provide experimental Tropical Cyclone Impacts Graphics in 2010; these include a
qualitative graphic on the expected storm surge impacts. Finally, the NWS is exploring the
possibility of issuing explicit Storm Surge Warnings, and such warnings could be implemented
in the next couple of years. In all of these efforts, the NWS is working to provide specific and
quantitative information to support decision-making at the local level. |
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Nov Q & A with NHC - Michael Lowry -
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