Tropical Cyclone Report: Tropical Storm Alberto (AL012012)
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
Tropical Storm Alberto (AL012012)
Duration: 19 May – 22 May 2012
Produced on: 21 December 2012
Tropical Storm Alberto was the first named storm of the 2012 Atlantic hurricane season and one that produced slight wave increases along the Southeast United States coastline, leading to several ocean rescues. Alberto was the first named storm to form in May since Tropical Storm Arthur in 2008 and the earliest-forming tropical cyclone since Tropical Storm Ana in 2003. The combination of Alberto and Tropical Storm Aletta, in the East Pacific, led to the first occurrence where both basins recorded their first named storm before the start of their respective hurricane seasons.
a. Synoptic History
The formation of Tropical Storm Alberto began on 10 May. At this time, water vapor imagery revealed a well-defined, upper-level, cold-core area of low pressure across Arizona and New Mexico. This low organized as it crossed into western Texas, but was subsequently absorbed into a cold front on 12 May. As the front moved eastward, it stalled across the Southeast United States and into the Mid-Atlantic, where thunderstorms produced a few isolated tornadoes. While the aforementioned low dissipated, a new area of low pressure formed across central North Carolina on 17 May, and moved off the coast by the following day. Embedded within an environment characterized by warm sea surface temperatures and marginally favorable wind shear, the low pressure area began to consolidate, and a small area of shower and thunderstorm activity formed atop the center. Banding features became more prominent in association with the disturbance, and it is estimated that the system became a tropical storm by 1200 UTC 19 May, situated roughly 115 miles east-southeast of Wilmington, North Carolina. The best track positions and intensities are listed in Table 1 at the bottom of this entry (to be added).
A large, mid-level area of high pressure over the Northeast United States initially caused Alberto to drift southwesterly. As this drift occurred, the system passed over two ships which recorded maximum sustained winds of 50 knots and 65 knots, separately, around 0000 UTC; the estimated peak of 55 knots is a blend of the two. A subsequent increase in continental dry air, however, prevented any further intensification, and Alberto began a steady weakening trend. A deepening mid- to upper-level trough across the southeastern states caused the system to turn southeastward, eastward, and eventually northeastward out to sea, while remaining minimal tropical storm intensity. Without the thermal energy of the sea surface temperatures within the Gulf Stream, strong wind shear from the aforementioned trough stripped Alberto of all deep convection, and the system weakened to a tropical depression by 0600 UTC 22 May. Within the next six hours, after lacking organized, deep convection for a sufficient amount of time, Alberto degenered into a non-convective remnant area of low pressure, while located over a hundred miles east-southeast of Cape Hatteras, North Carolina. The remnant circulation accelerated rapidly towards the northeast and dissipated the following day several hundred miles south of Newfoundland.
b. Meteorological Statistics
Observations in Tropical Storm Alberto include data from 2 flights of the U.S. Air Force Reserve Hurricane Hunters. Satellite intensity estimates from the University of Wisconsin's-Cooperative Institute for Meteorological Satellite Studies Advanced Dvorak Technique (UW-CIMSS), the Tropical Analysis and Forecasting Branch (TAFB), and the Satellite Analysis Branch (SAB), data from the Advanced Microwave Sounding Unit (AMSU) and Advanced Scatterometer (ASCAT) passes were all also useful in constructing the best track of Alberto.
The estimated peak intensity of 55 knots around 0000 UTC 20 May with Alberto is based on two ship reports on the afternoon of 19 May. 65 knot sustained winds were reported with the ship Sea-Land Champion at 2000 UTC and 50 knot sustained winds were reported with an unnamed ship roughly an hour and a half later. The aforementioned peak intensity value is a blend of the two.
c. Casualty and Damage Statistics
There were no reports of damage or casualties associated with Alberto.
d. Forecasting and Warning Critique
Personal Tropical Weather Outlooks (TWOs) were not produced for any tropical cyclone until 1 August.
Figure 1. Satellite imagery of Tropical Storm Alberto at peak intensity.