Tropical Topics: 2009 Eastern Pacific Hurricane Season Opens

May 15 is the opening day of the Eastern Pacific hurricane season. Since many storms in this region do not threaten land, the extent of activity was not fully realized until the satellite observation era. On average, there are 15 tropical storms and 9 hurricanes per year in the North Pacific east of 140 west longitude. The list of storm names for this season is:

NAME           PRONUNCIATION    NAME            PRONUNCIATION
-------------------------------------------------------------
ANDRES         AHN DRASE-       MARTY
BLANCA         BLAHN- KAH       NORA
CARLOS                          OLAF            OH- LAHF
DOLORES                         PATRICIA        
ENRIQUE        ANH REE- KAY     RICK
FELICIA        FA LEE- SHA      SANDRA
GUILLERMO      GEE YER- MO      TERRY
HILDA                           VIVIAN
IGNACIO        EEG NAH- CIO     WALDO
JIMENA         HE MAY- NA       XINA            ZEE- NAH
KEVIN                           YORK
LINDA                           ZELDA           ZEL- DAH 

The National Hurricane Center will be making several changes this season in tropical storm reporting:

• The Tropical Weather Outlook, issued 4 times a day, will include categorical probabilities of storm development: Low (less than 30%), Medium (30-50%), High (over 50%).
• The Saffir-Simpson scale traditionally used to classify hurricane strength will be modified on an experimental basis to exclude storm surge and flooding indications. The reason for doing this is that the Saffir-Simpson scale is primarily a measure of maximum wind speed, but storm surge is affected by several other factors, such as storm size and forward speed, shape of coastline, and water depth. For example, Hurricane Ike last year made landfall as a Category 2 storm, but the storm surge was comparable to what is currently defined as a Category 4-5 storm. Emergency management officials reported that many residents refused to evacuate since the storm was "only" a Category 2 or 3 as it approached land. Likewise, Katrina (2005) had Category 3 winds at landfall, but the storm surge was equivalent to Category 5. On the other hand, Hurricane Charley (2004) had Category 4 winds but only Category 2 storm surge.

The Atlantic season will begin in 2 weeks, on June 1.

CapitalClimate provides a number of links to national, local, and international tropical storm information in the list to the left titled "Tropical Topics". Discussions of significant storms will be provided in blog posts as appropriate during the hurricane season.

Image: Eastern Pacific Tropical Outlook from National Hurricane Center.