NOAA-NESDIS
Regional And Mesoscale Meteorology Team
Daily Satellite Discussion
Tuesday September 16, 1997
Figure 1
GOES-9 IR average image
Hurricane Linda is shown in a center relative IR average image of 5 images. This is the time (0000-0200 UTC, Sept 12) at which the hurricane attained maximum intensity according to the digital IR technique, which indicated just under 170 kt sustained 1-min average maximum surface wind speed. The National Hurricane Center assigned an intensity of 160 kt with a minimum sea-level pressure of 900 mb, on its advisories at 09 UTC / 12 Sept through 03 UTC/ 13 Sept. This was a record intensity for Eastern Pacific hurricanes. The intensity was not measured by aircraft until Sept 14, after considerable weakening had occurred.

Note that the image which was averaged with respect to the eye location, has a circular ring of cloud top temperatures of -80C or colder. Please refer to RAMM Team Daily Satellite Discussion of Aug 7, 1997, for further discussion of using IR imagery to objectively assign hurricane intensity.

Figure 2
GOES-8 visible, Sept. 5, 1997 at 2115 UTC
On late afternoon of September 5, 1997, Hurricane Erika, was slowly intensifying as a Category 1 hurricane while moving northwest, located just east of the northernmost Leeward Islands of Antigua and Barbuda. The visible GOES-8 image shows Hurricane Erika and its central dense overcast prior to the appearance of an eye, while the plume of the volcano on Montserrat Island streams to the SSW. Please refer to RAMM Team Daily Satellite Discussion of August 12, 1997, for a discussion of volcanic ash detection.

Ray Zehr

We welcome your comments and discussion at ramsdis@comet.ucar.edu

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