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Bud the strongest Eastern Pacific hurricane so early in the year; 94L may develop

By: Dr. Jeff Masters, 2:14 PM GMT on May 25, 2012

Category 2 Hurricane Bud is weakening, but still presents a formidable rainfall threat as it continues north-northeast towards an expected landfall between Manzanillo and Puerto Vallarta, Mexico late Friday night. Thursday night at 11 pm EDT, Bud peaked at Category 3 status, with 115 mph winds, becoming the earliest Category 3 hurricane on record in the Eastern Pacific. Recent Satellite loops show that Bud has weakened, though. The eye has disappeared, and the cloud pattern has shrunk and appears squashed, due to an increase in dry air, wind shear, and cooler sea surface temperatures affecting the storm. These hostile conditions should continue to weaken Bud to a Category 1 hurricane or strong tropical storm by the time of landfall. Bud is projected to cross the coast in a rugged, relatively unpopulated area, so wind and storm surge damage will probably be light to moderate. Heavy rain will cover a much wider area, and will be the main threat from Bud. The coast where Bud is headed towards is very mountainous, and numerous flash floods and dangerous mudslides will affect the region, probably including the cities of Manzanillo and Puerto Vallarta. I don't think Puerto Vallarta will see much in the way of wind or storm surge damage, since it is in a well-protected location and will probably be on the weak (left-front) side of the hurricane. Manzanillo is at higher risk, since it will probably be on the stronger right-front side of the hurricane.

Figure 1. True-color satellite image of Hurricane Bud taken at 12:25 pm EDT May 24, 2012. At the time, Bud was a Category 2 hurricane with 110 mph winds. Image credit: NASA.

A record May for the Eastern Pacific hurricane season
Bud is the strongest Eastern Pacific hurricane on record for so early in the year, and is tied with Hurricane Alma of 2002 (115 mph winds) as the second strongest May hurricane on record in the Eastern Pacific. Only Hurricane Adolph of 2001 (145 mph winds) was stronger. Also, Bud's appearance on May 21 marked the earliest date since record keeping began in 1949 for formation of the season's second named storm. The previous record was set in 1984, when the second named storm formed on May 29. Hurricanes are uncommon in the Eastern Pacific in May; there have been just twelve since record keeping began in 1949--an average of one May hurricane every five years. If Bud ends up making landfall in Mexico as a hurricane, it would be only the second Eastern Pacific May hurricane on record to hit Mexico. The other was Hurricane Agatha of May 24, 1971, which hit the same stretch of coast that Bud is threatening. Agatha made landfall as a Category 2 hurricane about 45 mi (75 km) from Zihuatanejo, Mexico. Ocean temperatures this year in the region where Aletta and Bud formed are only slightly above average, so the large-scale atmospheric patterns are probably more to blame for this year's exceptionally early start to hurricane season in the Eastern Pacific.

Figure 2. Morning satellite image of Invest 94L.

Invest 94L off the Georgia coast could develop this weekend
An area of disturbed weather (Invest 94L) a few hundred miles east of the Georgia coast is headed northeast at about 15 mph. The disturbance has not become more organized over the past day, due to very high wind shear of 40 - 55 knots. However, the latest SHIPS model forecast predicts that wind shear will drop to the moderate range, 10 - 20 knots, on Saturday and Sunday. Most of our reliable models predict that 94L could organize into a subtropical or tropical depression or storm on Saturday or Sunday off the coast of Georgia/South Carolina. NHC is giving 94L a 70% chance of developing into a tropical or subtropical depression by Sunday morning. A ridge of high pressure is expected to build in over the weekend off the East Coast, which will force 94L to the west back towards the coast, and heavy rains from 94L are likely to begin affecting coastal South Carolina, Georgia, and Northern Florida on Saturday and Sunday. There is a lot of dry, continental air on the west side of 94L, so the rainfall amounts from the storm will be limited unless until the center makes landfall. If these rains do materialize, they would be welcome, considering the moderate to severe drought conditions in the area.

I'll have an update Saturday.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.