Hurricane Potential Intensity Maps
Interpretation
Two maps are available at each analysis or forecast time: A map showing the minimum attainable central pressure of tropical cyclones (mb), and a map showing the maximum sustainable surface wind speed. The latter is the maximum gradient wind at low levels reduced by 20% to account for the reduction of surface winds by friction. The method used in calculating these quantities is decribed in a separate document. Experience using potential intensity estimates based on climatology indicate that few, if any, storms will ever exceed the potential intensity value; most storms will not achieve their potential intensity (see figure).
On the other hand, there has been almost no experience to date using potential intensity calculations from real-time data. Hurricanes cannot be expected to develop where the potential intensity estimate is small or zero; but storms moving rapidly from regions of high potential intensity to regions of low intensity can be expected to maintain strength well in excess of the local potential intensity estimate.
Where a storm already exists and its presence is reflected in the NCEP data, the potential intensity estimate may be in error at the location of the storm, because the calculation of the potential intensity assumes that the vertical sounding is an environmental sounding.
Atmospheric data used in these calculations reflects the latest data set available from NCEP; generally the 1 X 1 degree gridded data. Sea surface temperatures are updated weekly. The date on the maps is that of the atmospheric gridded data used.
Location of maps
The maps may be obtained by
clicking here. I am most grateful to Jim Kinter, Paul Dirmeyer, Brian Doty and Jennifer
Adams of the Center for Ocean-Land-Atmosphere Studies for preparing and maintaining these maps. Information about the graphics
package used to make these charts as well as other weather information can be obtained directly from the COLA Home Page.
Comments
Please direct any comments about the format of the maps or the algorithm used to calculate potential intensity to me at (mylastname) at mit.edu
Kerry Emanuel 1 July 1996