In Eastern Pacific: As El Nino Gathers – Strongest May Hurricane on Record
May 26, 2014
Amanda became the strongest May eastern Pacific hurricane on record Sunday morning a peak winds approached that of a Category 5 hurricane.
Amanda’s maximum sustained winds increased to near 155 mph and its central pressure dropped to 932 millibars by 11 a.m. PDT Sunday, meaning Amanda was very powerful Category 4 hurricane.
Although Amanda has weakened some from its peak strength, sustained winds remain at Category 4 strength as the storm moves slowly northward over the eastern Pacific.
Adolph from 2001 originally held the distinction of strongest May hurricane in the basin. At the peak of Adolph’s intensity, the central pressure bottomed out at 940 millibars and winds were nearly 145 mph.
Below, reposting part 1 of my recent interview with Kevin Trenberth – at about 4:30 begins to discuss hurricanes in eastern pacific, but good contextual info on anomalous warmth as El Nino builds.
Amanda is also the earliest Category 4 hurricane in the eastern Pacific, ahead of Hurricane Adolph in 2001, and the second earliest major eastern Pacific hurricane on record, behind Hurricane Bud in 2012.
Adolph reached Category 4 strength on May 28, 2001.
It is unusual, in terms of climatology, to have a minimal hurricane form in the eastern Pacific in May, let alone a strong Category 4 hurricane.
Maximum sustained winds within a Category 4 hurricane range from 130 to 156 mph. On average, it takes until June 26 for the first hurricane to form in the eastern Pacific. The first major hurricane of the season typically does not form in the eastern Pacific until July 19.
There has never been a Category 5 hurricane in the eastern Pacific during May.
As is usually the case when an El Niño event is threatening, NOAA’s pre-season prediction for the Eastern Pacific hurricane season, issued on May 22, is calling for an active season. NOAA expects there to be 14 – 20 named storms, 7 – 11 hurricanes, 3 – 6 major hurricanes, and an ACE index 95% – 160% of the median. The mid-point of these ranges gives us a forecast for 17 named storms, 9 hurricanes, and 4.5 major hurricanes, with an ACE index 127.5% of average. The 1981 – 2010 averages for the Eastern Pacific hurricane season are 15 named storms, 8 hurricanes, and 4 major hurricanes. The outlook calls for a 50% chance of an above-normal season, a 40% chance of a near-normal season, and a 10% chance of a below-normal season. El Niño decreases the vertical wind shear over the tropical Eastern Pacific, favoring the development of more and stronger tropical cyclones. Since 1995 the Eastern Pacific has been in an era of low activity for hurricanes, but this pattern is expected to be offset in 2014 by the impacts of El Niño.