Atlantic hurricane season still lacking hurricanes: any sign of a change?
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30 August 2013
Atlantic hurricane season still lacking hurricanes
Today's update on the conditions and activity across the basin can be found on the Washington Post's Capital Weather Gang blog:
Atlantic hurricane season still lacking hurricanes: any sign of a change?
Atlantic hurricane season still lacking hurricanes: any sign of a change?
28 August 2013
Remembering Katrina
Today, August 28th, is a day many in the hurricane community will never forget. It was a Sunday morning, and we started the day off staring in disbelief at what had become an enormous Category 5 hurricane sitting in the central Gulf of Mexico - and heading north.
It hit Miami, FL three days prior as an intensifying Category 1 hurricane, and strengthened as it crossed over the eastern Gulf. The forecast was, and had been, accurately centered on eastern Louisiana and Mississippi for several days; the big question leading up to that landfall would be the intensity.
For many years, the "New Orleans scenario" was well-known, and had been addressed in practice drills and exercises... it's a very vulnerable city, with many areas situated below sea level. Everyone knew this would be bad; really bad. The NWS forecast office in New Orleans issued the following warning in advance of the landfall:
"MOST OF THE AREA WILL BE UNINHABITABLE FOR WEEKS...PERHAPS LONGER. AT LEAST ONE HALF OF WELL CONSTRUCTED HOMES WILL HAVE ROOF AND WALL FAILURE. ALL GABLED ROOFS WILL FAIL...LEAVING THOSE HOMES SEVERELY DAMAGED OR DESTROYED. POWER OUTAGES WILL LAST FOR WEEKS...AS MOST POWER POLES WILL BE DOWN AND TRANSFORMERS DESTROYED. WATER SHORTAGES WILL MAKE HUMAN SUFFERING INCREDIBLE BY MODERN STANDARDS."
Of course, as dire as that sounds, the end result was even worse. It made landfall on the morning of August 29th... it would become the costliest natural disaster in the history of the U.S. (~$108 billion), and was responsible for nearly 2,000 deaths. The only good news was that it weakened quite a bit prior to landfall, and came ashore as a weakening Category 3 storm (120mph winds) rather than the Category 5 (175mph winds) it was a day earlier. Watch a radar loop of the landfall... and note that the final frame also marks the time the radar there was destroyed.
It generated a devastating 27.8-foot storm surge in Mississippi, and the smaller surge in New Orleans was enough to stress the levees protecting the city beyond their breaking point. Many beachfront communities were erased from the map, particularly in Mississippi.
Later that year, other major hurricanes (Cat3+) made U.S. landfall, wrapping up with Wilma on October 24th when it hit the southwestern Florida peninsula. That remains the last time the U.S. was hit by a major hurricane. I included some details on just how bizarre and unprecedented this span is in my season wrap-up last year (scroll down to the 7th paragraph).
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| Katrina as a Category 5 hurricane on August 28th, 2005. (NOAA) |
For many years, the "New Orleans scenario" was well-known, and had been addressed in practice drills and exercises... it's a very vulnerable city, with many areas situated below sea level. Everyone knew this would be bad; really bad. The NWS forecast office in New Orleans issued the following warning in advance of the landfall:
"MOST OF THE AREA WILL BE UNINHABITABLE FOR WEEKS...PERHAPS LONGER. AT LEAST ONE HALF OF WELL CONSTRUCTED HOMES WILL HAVE ROOF AND WALL FAILURE. ALL GABLED ROOFS WILL FAIL...LEAVING THOSE HOMES SEVERELY DAMAGED OR DESTROYED. POWER OUTAGES WILL LAST FOR WEEKS...AS MOST POWER POLES WILL BE DOWN AND TRANSFORMERS DESTROYED. WATER SHORTAGES WILL MAKE HUMAN SUFFERING INCREDIBLE BY MODERN STANDARDS."
Of course, as dire as that sounds, the end result was even worse. It made landfall on the morning of August 29th... it would become the costliest natural disaster in the history of the U.S. (~$108 billion), and was responsible for nearly 2,000 deaths. The only good news was that it weakened quite a bit prior to landfall, and came ashore as a weakening Category 3 storm (120mph winds) rather than the Category 5 (175mph winds) it was a day earlier. Watch a radar loop of the landfall... and note that the final frame also marks the time the radar there was destroyed.
It generated a devastating 27.8-foot storm surge in Mississippi, and the smaller surge in New Orleans was enough to stress the levees protecting the city beyond their breaking point. Many beachfront communities were erased from the map, particularly in Mississippi.
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| Observed storm surge generated by Katrina. The peak value in the ">16 feet" category was nearly 28 feet in Pass Christian, MS... the largest surge ever recorded in the U.S. (SURGEDAT) |
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25 August 2013
Last week of August comes with increasing activity
As I eluded to in Friday's update, the tropical Atlantic is primed to start cranking out some storms, especially toward the beginning of September. But even now, a couple areas of interest are brewing: one rapidly organizing system in the southern Gulf of Mexico and another near the African coast.
First, the disturbance in the far southern Gulf of Mexico. This is an African easterly wave that was located back over the Lesser Antilles on the 19th, and got more convectively active on the 22nd. Since then it passed over the Yucatan peninsula and just emerged into the Bay of Campeche recently. It has been surprisingly quick to get organized, and an aircraft reconnaissance plane has been tasked to investigate it later this afternoon. The aircraft could possibly find it to be a tropical storm... if so, the next name on the list is Fernand. Fernand is a new name this year, replacing Felix from 2007's list.
Even if it does continue to intensify, its time before landfall is very limited. It's heading generally westward, which brings it over land by this evening. It is already showing up nicely on radar... I have a long radar loop from Alvarado available (Invest 95L). As usual for weaker systems, the largest threat will be heavy rain and flash flooding.
Shifting our attention 5200 miles to the east, a wave has just exited the African coast and though it doesn't look too impressive just yet, several global models do forecast it to get organized over the next several days as it heads W-WNW across the deep tropics. It's coming off at a more typical latitude, centered near 10N 18W, and the environment appears to be favorable for development. I will provide additional details on it as the week goes on.
First, the disturbance in the far southern Gulf of Mexico. This is an African easterly wave that was located back over the Lesser Antilles on the 19th, and got more convectively active on the 22nd. Since then it passed over the Yucatan peninsula and just emerged into the Bay of Campeche recently. It has been surprisingly quick to get organized, and an aircraft reconnaissance plane has been tasked to investigate it later this afternoon. The aircraft could possibly find it to be a tropical storm... if so, the next name on the list is Fernand. Fernand is a new name this year, replacing Felix from 2007's list.
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| Disturbance in the Bay of Campeche, heading west toward Mexico. (NASA) |
Shifting our attention 5200 miles to the east, a wave has just exited the African coast and though it doesn't look too impressive just yet, several global models do forecast it to get organized over the next several days as it heads W-WNW across the deep tropics. It's coming off at a more typical latitude, centered near 10N 18W, and the environment appears to be favorable for development. I will provide additional details on it as the week goes on.
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| Visible satellite image of an easterly wave coming off the African coast. (CIMSS) |
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