Small town USA guy. Politics nerd. Soccer fan. Interested in eyewalls, deformation zones, and hook echos.
By: TropicalAnalystwx13 , 1:32 AM GMT on November 27, 2012
Note: The Tropical Cyclone Report (TCR) below contains comprehensive, yet easily understandable, information on each tropical cyclone, including synoptic history, casualities and damages, provided by a multitude of different, official resources, and the post-season analysis best track (six-hourly position fixes and intensities). A tropical cyclone is defined as a warm-core, non-frontal synoptic-scale cyclone, originating over tropical or subtropical waters with organized deep convection and a closed surface wind circulation about a well-defined center. These include depressions—cyclones that did not attain 34-knot sustained winds—storms, and hurricanes. It should be noted that, while I strive to produce the most accurate information for the particular cyclone listed below, these reports...including the storms' position and intensity...are not official and are no way associated with the National Hurricane Center or any other branch of the National Oceanic and Atmospheric Administration. Please visit the Atlantic TCR page and the East Pacific TCR page for official reports on any desired cyclone within a particular season.
Tropical Cyclone Report
Hurricane Bud (EP022012)
Duration: 21 May – 26 May 2012
Produced on: 26 November 2012
Hurricane Bud was the earliest-forming major hurricane in May in recorded history for the East Pacific basin, and also one of only three May major hurricanes in the basin. The system brought tropical storm conditions to the coastline of Mexico before rapidly dissipating offshore.
a. Synoptic history
The formation of Hurricane Bud can be attributed to a low-latitude tropical wave that emerged off the west coast of Africa and entered the eastern Pacific by mid-May. As indicated by a series of Hovmöller diagrams, the wave departed from the coast of Africa on 5 May and spent over a week crossing the Central Atlantic and Central and eastern Caribbean before entering the West Caribbean on 12 May. As the disturbance entered the eastern Pacific basin and encountered a region of sea surface temperatures greater than 27 °C, convection gradually formed around a developing surface low several hundred miles south of the coastline of Mexico, but was ultimately hindered by intense southeasterly wind shear. A subsequent slight decrease in wind shear on 20 May allowed further consolidation of the shower and thunderstorm activity with the area of low pressure, but the level of organization during did not quite meet the criterion of a tropical cyclone. However, as spiral banding become more prominent during the pre-dawn hours of 21 May, a small yet organized central dense overcast pattern developed atop the disturbance’s low-level circulation, leading to the formation of a tropical depression at 0600z. The best track positions and intensities are listed in Table 1 at the bottom of this entry (to be added).
Despite the slight decrease in southeasterly wind shear, conditions remained quite unfavorable for significant development of the tropical depression. A combination of satellite intensity estimates from several agencies revealed the formation of Tropical Storm Bud around 0000z 22 May. By the following day, with an anticyclone flow aloft, steady to quick intensification of the cyclone began. Bud strengthened into a Category 1 hurricane at 2100z on 23 May as it began a turn to the north-northeast in response to a mid-level trough across the United States Midwest, and a Category 2 hurricane by 1500z the following morning. Data from a NOAA Air Force Reserve mission during the afternoon hours of 24 May revealed 100 knot winds at maximum, which would typically indicate a peak at that intensity. However, given that satellite intensity estimates were higher a few hours previous, Bud’s peak intensity of 105 knots is estimated at 2100z that same day; this is supported by geostationary imagery, which showed the storm with the coolest cloud tops at that time.
As Bud approached the southwestern coastline of Mexico, intense vertical wind shear from the mid-level trough to its north caused dramatic weakening. In a 24 hour timespan, Bud weakened from its peak of 105 knots to 60 knots and further to a tropical depression by 0600z on 26 May. As the circulation drew drier air off the mountainous terrain of Mexico it gradually became unraveled, and it is estimated that Bud degenerated into a remnant area of low pressure at 1200z 26 May, having been void of organized, deep convection for 18 hours or longer. The circulation dissipated six hours later.
b. Meteorological statistics
Observations used to determine the peak intensity of Hurricane Bud include data from a NOAA Air Force Reserve aircraft, satellite intensity estimates from the University of Wisconsin's-Cooperative Institute for Meteorological Satellite Studies Advanced Dvorak Technique (UW-CIMSS), Tropical Analysis and Forecasting Branch (TAFB), and the Satellite Analysis Branch (SAB). Data from the Advanced Microwave Sounding Unit (AMSU) was also useful in constructing the best track of Hurricane Bud.
Data from the NOAA Air Force Reserve Hurricane Hunter aircraft during the afternoon hours of 24 May indicated peak winds of 100 knots in the cyclone at the time. Giving merit to the possibility that Bud may have been a little stronger a few hours previous, as indicated by T-numbers of T5.5/102 knots and T6.0/115 knots from SAB and UW-CIMSS, respectively, the peak intensity of the cyclone was set at 105 knots for 2100z on 24 May.
The development of Bud at 0000Z on 22 May marks the earliest formation of the second tropical storm on record for the East Pacific; the previous record was 29 May. Bud’s upgrade to major hurricane intensity at 2100z on 24 May marks the formation of the earliest-known Category 3 hurricane or higher for the eastern Pacific basin during that month. In addition, Hurricane Bud is one of only three rare May major hurricanes in the East Pacific basin, with the other two being Hurricane Adolph of the 2001 Pacific hurricane season and Hurricane Alma of the 2002 Pacific hurricane season.
The airport located in Manzanilo, Mexico briefly recorded tropical storm-force wind gusts on 25 May, gusting to a peak of 55 mph around 1800z. Heavy rainfall and waves washed out roads and brought down trees along the coastline, but no major damage was reported.
c. Casualty and Damage statistics
Only minor tree and road damage was recorded along the coastline of Mexico as the circulation of Bud remained mainly offshore. No fatalities were reported as a result of the storm.
d. Forecast and Warning critique
Personal Tropical Weather Outlooks (TWOs) were not produced for any tropical cyclone until 1 August.
Figure 1. Satellite imagery of Hurricane Bud at peak intensity.
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