Hurricanes Blanca and Andres Set Records For Early-Season Northeast Pacific Activity

[phantom power]

Hurricane Blanca put on a furious display of rapid intensification this week, going from a tropical storm with 70 mph winds on Tuesday morning to a Category 4 storm with 135 mph winds on Wednesday morning--a remarkable 65 mph increase in winds in 24 hours, an intensification rate that is rarely seen. Blanca topped out at 140 mph winds on Wednesday afternoon, making it the fourth strongest Northeast Pacific hurricane for so early in the year. It has been a remarkable run of early-season activity for the region, since just two days before that Hurricane Andres topped out as a Category 4 storm with 145 mph winds, becoming the second strongest Northeast Pacific hurricane for so early in the year. Only six Northeast Pacific major hurricanes have occurred prior to June 5 since accurate satellite records began in 1971, and two of them were this year:

1) Hurricane Amanda, 2014: 155 mph winds on May 25
2) Hurricane Andres, 2015: 145 mph winds on June 1
2) Hurricane Adolph, 2001: 145 mph winds on May 29
4) Hurricane Blanca, 2015: 140 mph winds on June 3
5) Hurricane Alma, 2002: 115 mph winds on May 30
6) Hurricane Bud, 2012: 115 mph winds on May 25

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Figure 3. The total heat content of the ocean at 2 am EDT June 4, 2015 showed that Hurricane Blanca has been sitting over a "hot spot" for heat energy over the past three days. For hurricanes with intensities less than 90 mph in favorable environmental conditions for intensification (vertical wind shear less than 15 kt, mid-level relative humidity >50 %, and warm SSTs >28.5°C), values of ocean heat content greater than 50 kJ/cm^2 (yellow colors) have been shown to promote greater rates of intensification. Image credit: NOAA/CIRA/RAMMB.