Weather

Aug 8, 2013 5:49 PM by Rob Perillo

2013 Tropical Risk for Louisiana and Acadiana

While NOAA and Drs. Klotzbach & Gray have lowered the total number storms in the Atlantic Basin for the rest of this season, it is still expected to be a busy one.

The venerable Colorado State forecast team lowered their number of expected hurricanes and major storms by one last week, with NOAA following suit today.

Klotzbach & Gray are expecting a total of 18 named storms this season, 8 of which will be hurricanes with 3 becoming major Category 3 storms or stronger.  So far, there have been four named storms in the Atlantic Basin this year.

The reason for the slight decrease in hurricane activity has been due to unexpected anomalous cooling in the eastern subtropical and tropical Atlantic. It's still expected to be busier than normal this year.  

African Dust from the Sahara has been quite dominant across the Atlantic Basin so far this season, with the tropical activity reducing dust reaching Acadiana and portions of the Northwestern Gulf over the last few days. It remains unclear whether this pattern continues, if so, the number of tropical systems this year could be lower than current forecasts.

Weather patterns across the U.S. so far this season has kept a trough along the Eastern U.S. which would tend to turn storms away from the Gulf or send them toward Mexico.  Whether this pattern continues for the latter part of August into September is not known.

As Dr Rick Knabb, director of the National Hurricane Center told KATC earlier this year, "it only takes one storm in your backyard to make it a very busy season".

With that in mind, and as the busiest part of the season is almost here and utilizing the data supplied by the United States Landfalling Hurricane Probability Project, the risk of hurricane conditions for this area can be statistically ascertained.

In any given year, there is a 30% chance of a land-falling hurricane along the Louisiana Coast, this year's statistics yield there will be 40% chance of a hurricane striking Louisiana.  

Keeping in mind that effects upon Acadiana can be quite minimal for a land-falling storm near New Orleans, any system making landfall farther west across the rest of the coast through the upper Texas coast normally means trouble for Acadiana. 

Nearly every other hurricane (40%) that has made landfall in Louisiana over the last 100 years has been a major Category 3 storm or stronger...a sobering statistic.  The normal risk of a major storm striking Louisiana in any given year is 12%, this year it is 16%.

!6% may seem like a low number, but most of us can surely recall when the KATC Weather Team has called for just a 10% chance of rain...and it rains at your location.

Recent Category 3 storms to officially strike Louisiana include Andrew in 1992 with 115mph winds, Katrina in 2005 with 125mph winds and then Rita three weeks later, with 115mph winds.

The annual risk of one or more tropical storms striking the Louisiana Coast is almost a certainty, over 90%. Although in some years, Louisiana has missed out on tropical activity, there are many more years where several storms have struck the coast in a season, keeping the annual risk high.

And while hurricanes usually garner the headlines, tropical storms, especially if they are slow moving, can be quite destructive with copious amounts of rainfall and flooding possible. Tropical Storm Allison in 2001 produced 20-30' of rainfall in portions of Acadiana over an 8 day period.

Further breaking down the numbers by parish can be derived from the aforementioned database..and the numbers are quite surprising and nearly uniform for most parishes in Acadiana along and south of the I-10 corridor.

In the case for Lafayette Parish, the risk of tropical storm force winds in and given year is 31.9%. This year the statistical risk of the same is 41.6%.

The risk of hurricane force gusts in Lafayette Parish is 9.8%, this year it is 13.4%.

Surprisingly, there is a fairly significant risk for major hurricane wind gusts for most Acadiana parishes along and south of the I-10 corridor. In any given year, the risk of gusts 115mph or greater in Lafayette Parish is 3.3%, while this year the risk is 4.6%.

The last storm that produced 115mph wind gusts in Lafayette Parish was Lili in 2002.

Per Dr. Knabb, no matter what the hurricane seasonal forecasts are, residents in hurricane prone areas are urged to "prepare for one or more storms equally, every year...and just because you have been through a storm, it doesn't necessarily mean you are prepared for the next one".

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