Moving right along, we've reached August in the 2005 Atlantic Season-in-Review. If June and July weren't active enough, with a combined 7 storms and the two most intense storms before August 1st in recorded history, August continued with the season's record pace with an additional 5 named systems and 1 unnamed tropical depression. Included within these 5 named storms is the costliest natural disaster in American history, Hurricane , with an estimated $75-80 billion in US damages.
The month started off quickly with the development of a tropical depression southwest of Bermuda late on August 2nd. By midday on August 3rd, this feature became Tropical Storm Harvey. Like Franklin in July, Harvey formed from the interaction of a tropical wave with a region of diffluence to the northeast of an upper-level low pressure system. Harvey initially moved slowly toward the north around the eastern edge of the upper low in a region of relatively weak steering currents, gradually accelerating toward the northeast on August 3rd and 4th. Harvey passed just south of Bermuda on August 4th near its peak intensity of 55kt/994mb, resulting in only minimal impacts to the island. Harvey continued toward the east-northeast for the next several days, maintaining intensity between 45-50kt throughout, before turning to the northeast on August 6th. Harvey was declared in the north Atlantic midday on August 8th.
While Harvey passed near Bermuda, another tropical system was organizing west-southwest of the Cape Verde Islands. The development of this feature was well-predicted by most of the global computer models for several days and, sure enough, on August 4th a tropical depression formed along 35W, the first Cape Verde system of the season. Despite bullish predictions toward development and a potential impact upon the northern Lesser Antilles down the line, the depression continually reorganized to the north and west, placing it in the midst of strong upper-level winds and subsidence induced by the Saharan dust layer. Nevertheless, by midday on August 7th, the depression had a sustained burst of convection and organization that brought it to tropical storm status, acquiring the name Irene. Over the next several days, however, Irene weakened back to a tropical depression and barely remained classifiable with intermittent bursts of convection just to the northeast of the center of circulation.
During this time, due to the weakened state of the system, Irene turned toward the west along 22N, passing well to the north of the Lesser Antilles on August 10th but not recurving out to sea like it might have were it a stronger system. As Irene made it to the central and western Atlantic, upper-level and surrounding atmospheric conditions improved, allowing the storm to reacquire tropical storm intensity late on August 10th and strengthen over the following few days. As it became stronger, however, the storm turned to the northwest, suggesting a possible threat to Bermuda. This threat never materialized, however, as the storm completed a half-loop around the island from a safe distance between August 13th and 16th. As this turn occured, Irene reached hurricane intensity late on August 14th and peaked in intensity as a minimal category 2 storm on August 16th. Irene later accelerated toward the northeast in advance of an upper-level trough and was declared on August 18th. As an cyclone, Irene rapidly intensified as it passed to the west of Greenland, becoming a rather significant midlatitude cyclone for the summertime months in the Northern Hemisphere.
As Irene looped around Bermuda, yet another tropical wave passed the Cape Verde islands and began to organize in the central Atlantic midway between the Cape Verdes and the Lesser Antilles. On August 13th, this feature became the season's 10th tropical depression. Slow development was forecast as the system moved toward the west, but it met much the same fate as did Irene -- strong upper-level winds and dry air aloft suppressed development. Unlike Irene, however, the system did not remain classified, dissipating as a tropical depression on August 14th. The low-level vortex would continue to be tracked over the following week as it moved slowly toward the west-northwest, being located near the central Bahamas around August 22nd. Here, the vortex merged with another tropical wave that had overtaken it from the east and began to interact with an upper-level low to its southwest. On August 23rd, in the central Bahamas, a tropical depression formed once again, operationally dubbed TD 12 instead of reacquiring the TD 10 moniker. This feature would move slowly toward the northwest over the next day and a half before turning to the west on the eastern periphery of a strong ridge of high pressure across the eastern US; as it did so, it began to strengthen, becoming Tropical Storm on August 24th.
Once the turn to the west occurred, all indications were that the storm would be making at least one impact upon the United States coastline -- and potentially two. First up was southern Florida, with varying ideas on where the storm would head from there on out with the central Florida panhandle deemed the best bet. As the storm approached the southern Florida coastline on August 25th, it became a minimal hurricane, making landfall during the evening hours of the 25th between Miami and Ft. Lauderdale. From there, it unexpectedly moved toward the southwest across the narrowest part of the Florida peninsula through the Everglades, weakening only minimally as it did so. Emerging off the coastline early on the 26th, spent the next day or so reorganizing and gradually strengthening -- but, in the face of all available model guidance, continuing to move toward the southwest and west-southwest. This prolonged movement placed the eventual second landfall of the storm further to the west -- with most model guidance converging near New Orleans during the late afternoon hours of Friday, August 26th -- and allowed the storm to pass directly over the Loop Current in the central Gulf of Mexico.
As this occured, the storm became a major hurricane early on Saturday, August 27th, spurring mandatory evacuations for the Louisiana, Mississippi, and Alabama coastlines. Through the day, it maintained this minimal major hurricane status with guidance continuing to suggest an impact upon New Orleans. This spurred on mandatory evacuations for the entire city of New Orleans, one of the largest peace time evacuations in US history. Those who did not evacuate on Saturday, hoping for better news when they woke up early Sunday morning, would be left in awe by the events of Saturday night and Sunday morning. During the overnight hours, rapidly intensified, going from a 100kt/939mb category 3 storm at 11p ET Saturday night to a 150kt/907mb category 5 monster at 11a Sunday morning, likely triggered by the aforementioned Loop Current as well as a dual outflow channel pattern aided by two upper-level lows well-removed from the storm. The ultimate peak intensity of 150kt/906mb placed the storm as the 4th most intense in the Atlantic basin at the time, now since surpassed by and . More harrowing was that the track was not changing -- the storm was on a beeline for New Orleans. Evacuations were stepped up with the storm less than a day from landfall and the Superdome was opened as a shelter of last resort for those who could not get out; people began to realize that could be the doomsday storm for the city that had been predicted for years.
As the storm turned toward the north south of the mouth of the Mississippi River late on the 28th of August, it began to move away from the loop current and into a region of slightly less favorable upper-level winds. Despite SSTs near 90F near the coastline, the upper oceanic heat content was not as high near-shore, coupling with an eyewall replacement cycle and inner-core fluctuations to bring about a steady weakening of the storm as it approached land. ultimately made landfall near Buras, LA as the sun rose on Monday, August 29th as a strong category 3 storm (edited from category 4 to match the best track file). It moved toward the north, skirting the border between land and water, over the next few hours, ultimately passing just east of New Orleans as a category 3 hurricane. Final landfall was made near the mouth of the Pearl River near midday on August 29th as a category 3 hurricane. remained a hurricane well into Mississippi, only weakening to a tropical storm near Jackson, and a tropical storm into central Tennessee. brought about massive wave damage to the Mississippi and Alabama coastlines, heavy wind damage along its path into northern Alabama, and a breakdown of the levee system protecting New Orleans in several locations. All in all, the entire coastline from Alabama to west of New Orleans was devestated by the storm, resulting in over 1200 deaths and an estimated $75-80 billion worth of damage. More information on 's aftermath can be found from many sources found on the Internet, including elsewhere on this website, and on the 's webpage in the recently released preliminary report. 's remnants accelerated after declassification across the Ohio River valley in advance of a midlatitude trough and did not result in substantial impacts to the northern tier of states as an system.
Between TD 10 and , however, we had another Bay of Campeche quick-hitting tropical storm, Tropical Storm Jose. Jose formed in the extreme southwestern Bay of Campeche on August 22nd, quickly intensifying into a tropical storm later that day. Less than 24hr after it was classified as a tropical depression, Jose made landfall along the southern Mexican coastline at its peak intensity of 45kt/1001mb, bringing heavy rains to the central and southern parts of the country. Jose quickly dissipated over the highlands of Mexico and was dropped by the on August 23rd, almost exactly 24hr after it was first classified. Jose's development, track, and impacts were much the same as Bret in June and Gert in July. According to the , Jose was responsible for 6 deaths in Mexico.
The month's last storm was yet another Cape Verde system that was negatively impacted by upper-level shear and dry air aloft. On August 28th, as was turning toward New Orleans, the season's 13th tropical depression formed midway between the Cape Verdes and the Lesser Antilles. Much like TD 10, however, the depression dissipated on August 29th as it moved toward the west-northwest. Its remnants began to turn toward the north around the periphery of an upper-level ridge that built in to its east and gradually began to organize once again, becoming classified as a tropical depression on August 31st. At the end of the month, the depression briefly became organized enough on satellite imagery to be classified as Tropical Storm Lee. Operationally, this designation lasted for all of one advisory cycle; in the post-season analysis, this designation lasted for two advisory cycles. Unfavorable upper-level winds and cooler waters brought about a fairly quick demise of the storm as it turned back toward the west-northwest, with final dissipation coming on September 1st.
Unlike July, August did not feature the same favorable upper-level pattern across much of the basin. In fact, the eastern portion of the basin was largely quiet due to strong bursts from the Saharan dust layer and unfavorable upper-level winds, while most systems in the western portion of the basin only reached their peak intensity at higher latitudes or via interaction with upper-level areas of low pressure. This would set the stage for much of the development we would see throughout the rest of the season, which we'll take a look at in the final 3 installments of the 2005 Atlantic Season-in-Review over the next couple of weeks.
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