When Hurricane Laura made landfall at Cameron, Louisiana, just before 1 a.m. on August 27, it was the culmination of a night with only a handful of parallels in tropical climatology.
As with any storm of Laura’s ferocity, it will take many months for scientists to carefully piece together exactly what played out from a meteorological perspective. However, a provisional picture is emerging of a storm that stands toe-to-toe with the biggest names in hurricane history, yet due to its precise track, narrowly avoided the absolute worst-case scenario in terms of surge impacts.
Unfortunately, with around 75% of hurricane season activity still ahead, Laura is unlikely to be the final major hurricane threat of 2020. Two tropical waves in the central Atlantic will need to be watched carefully over the next seven to 10 days, particularly in light of a risky steering current regime.
A blow-by-blow account: Hurricane Laura first Category 4 hurricane to make landfall in Western Louisiana | WeatherTiger liveblog
A storm for the record books
But first, let’s put Hurricane Laura into a broader historical context. While much remains to be figured out, here are some preliminary facts:
Laura was the strongest hurricane to strike between Grand Isle, Louisiana, and western Galveston Bay, Texas, reaching back to the beginning of historical records in 1851. Over these 170 years, Laura is the fourth Category 4 hurricane anywhere in Louisiana, and is tied with the 1856 Last Island hurricane for strongest landfall in the state.
Laura’s maximum sustained winds of 150 mph at landfall are just over 5 mph shy of Category 5 intensity and are tied for the fifth-strongest on the continental U.S. coastline. This is also the second-highest maximum U.S. landfall wind of the 21st century, after 2018’s Hurricane Michael and tied with 2004’s Hurricane Charley.
Between the evenings of August 25 and 26, Laura strengthened from a 75-knot Category 1 hurricane to a 130-knot Category 4 hurricane. This one-day rapid intensification of 55 knots is also among the steepest in the Atlantic historical record.
These numbers are early estimates.
Over the upcoming weeks, National Weather Service personnel will be performing an exhaustive survey of the damage along the Louisiana and Texas coastlines, as well as hard-hit inland communities.
This investigation will review all reconnaissance aircraft data, like the Hurricane Hunter plane reports of winds in the eastern eyewall exceeding 160 mph just above the surface in the hour prior to landfall.
It will also consider ocean and ground-based observations, including the wind gust of 133 mph in Lake Charles that destroyed the airport’s weather radar and instruments. (There is a private weather station report from Lake Charles of sustained winds to 102 mph with a top gust of 137 mph, pending validation).
Such data will inform an official National Hurricane Center report that will be the final word on Laura’s track and intensity, likely to be released next spring. While I wouldn’t be surprised if peak intensity was nudged a little higher in this report, I doubt that an upgrade to Category 5 strength is forthcoming, given what I have personally seen.
A suppressed surge
While Laura was a destructive inland wind event without precedent across Southwest Louisiana, likely producing winds equivalent to an EF-2 or low-end EF-3 tornado across most of Cameron, Calcasieu and Beauregard Parishes, one aspect of the storm that was marginally less apocalyptic than feared in heavily populated areas was surge.
It is important to remember that NHC surge forecasts are for a “reasonable worst case” scenario, or a level of inundation which will be exceeded about 10% of the time. So while NHC forecasts highlighted the widespread potential for 15 to 20 feet of peak surge, in reality such values were only going to be observed near where the strongest southerly winds of the eastern eyewall crossed the coast.
With a landfall near Cameron and Laura tracking north, the devastating winds in Lake Charles blew from due east. For the most part, this wind direction did not drive water north from the Gulf and into the city. An Army Corps of Engineers gauge at Grand Chenier in east-central Cameron Parish recorded over 15 feet of surge in the eastern eyewall, pending validation.
Data points are few at this early stage, but it appears the expected surge values did occur, just south and east of the more populous Lake Charles area.
And so, Laura goes into the history books as one of the most brutal hurricanes of all time, and the 2020 hurricane season rolls into its second quarter following a record-breaking seven U.S. tropical storm and three hurricane landfalls.
For the immediate future, that record is unlikely to be padded. However, upper-level winds and warm sea-surface temperatures remain supportive for tropical storm formation, and the next four weeks are the most historically active in the Atlantic’s climatological record.
Four weeks of tropical turbulence ahead
Currently, two easterly waves are in the central tropical Atlantic, moving slowly westward. While models are only modestly bullish on the development prospects of these waves, computer guidance charitably has been awful in predicting tropical storm formation this year. The “King” Euro model has especially abdicated its throne in this respect, whiffing entirely on the development of Hanna, Laura and Marco.
I think both waves are good candidates for slow organization by early next week. While there is no specific threat at this time, this prospect is concerning as a strong ridge of high pressure over the western Atlantic and coastal Southeast is likely to prevent disturbances from turning harmlessly north into the open Atlantic for the next eight to 10 days or so.
In short, Laura was devastating and exhausting, but the peak weeks of hurricane season are just beginning. Keep your guard up and keep watching the skies.
Dr. Ryan Truchelut is chief meteorologist at WeatherTiger, a Tallahassee start-up providing advanced weather and climate analytics, forensic meteorology and expert witness consulting, and agricultural and hurricane forecasting subscription services. For more information, visit us at weathertiger.com or get in touch at [email protected]
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