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Texas Emergency Management ONLINE 2016 Vol. 63 No. 12

The 2016 Hurricane Season

In 2016, we saw seven hurricanes in the Atlantic, eight tropical storms, and (as of November 21), two tropical depressions.  This was pretty close to a “near-normal” season, where the averages from 1981-2010 includes 12 tropical storms, 6 hurricanes, and 2 major hurricanes.  The image below shows the tracks and intensities of all of the systems this year (except for Hurricane Otto, which formed on November 21 and is not included on this map).

The Atlantic hurricane season runs from June 1 through November 30.  The first named storm of 2016, however, came outside of the typical season – in January!  Hurricane Alex was a very unusual January hurricane in the northeastern Atlantic Ocean, making landfall on the island of Terceira in the Azores as a 55-kt tropical storm.  More information on Alex can be found in the Tropical Cyclone Report issued by the National Hurricane Center (NHC) at http://www.nhc.noaa.gov/data/tcr/AL012016_Alex.pdf.

The closest system to Texas in 2016 was Danielle (#4 on the map above), which developed over the southwestern Gulf of Mexico on June 19.  Danielle quickly made landfall just north of Tuxpan, Mexico on the evening of June 20, and dissipated inland over east-central Mexico.

    

One lesson learned during this hurricane season was that we can have a system that isn’t classified as “tropical” that still brings tremendous rainfall and impacts to a region.  We saw this in south/southeast Louisiana in August when a low pressure system developed and remained near the coast, producing torrential downpours that led to widespread flash flooding and historic river flooding.  This low was never classified as a tropical system, but had the same, if not worse, impacts to the area than a tropical storm or hurricane.

    

It was an active season for the Southeast and Mid-Atlantic region, however, with Hurricane Hermine and Major Hurricane Matthew being two of the most notable as far as impacts are concerned.

    

Taking a closer look at Hurricane Matthew, this was a unique storm all-around, and one that has many “lessons learned” for hurricane operations and preparations in Texas.  Tropical Storm Matthew formed in the Windward Islands on September 28.  From the beginning, it was forecast to remain on a westward track for several days before taking a sharp right turn and heading towards Jamaica.  Exactly when (and where) it took this turn had a large impact on the eventual forecast, so preparations began well in advance of this storm in Florida due to the uncertainties surrounding the forecast.

    

By Friday, September 30, the state of Florida was included in the National Hurricane Center (NHC) track forecast “cone.”  An understanding of the actual meaning of the cone was important for decision makers in Florida and further up the coast…as it does not account for the uncertainties in the actual track/forecast of each storm…but is rather based on historical official forecast errors over a past 5-year sample (as NHC’s forecasts get better, the cone shrinks). The size of the cone is set so that two-thirds of these historical errors fall within it.   As the forecast progressed the weekend of October 1-2, the cone actually shifted off the Florida coast and when models were a bit more consistent Monday with a more westward track, the cone shifted back west and well inland over Florida with the evening forecast.  This points to a good lesson in preparedness – even when the cone moves just out of your “area,” it doesn’t mean you are in the clear…remember it only accounts for some of the possibilities with the track of the storm (not all) and the cone does not represent where all of the hazards may occur.  Storm surge, heavy rainfall, strong winds…they all can and do occur outside of the cone.

    

Another unique aspect to Matthew was how it paralleled the coast of Florida for over a day.  If the track would have been even 20-30 miles further west, the entire coast could have seen far worse impacts than what was realized.  This type of scenario is not out of the question with the coast of Texas either, and we have actually seen two similar cases in the past – one if you go all the way back to 1837 (the Racer Storm, see below graphic), and another one in 1945 (an unnamed Category 3 that paralleled the coast before making landfall near Matagorda as a Category 2).

This type of track could have serious impacts on evacuations, where a well-inland evacuation plan is so much more important rather than just moving to another portion of the coast.  Speaking of evacuations, when you have a storm that has the potential to produce torrential rainfall amounts well inland, inland flooding can and should have a huge role to play in how far inland and where evacuations might take place…as was the case in North Carolina with Matthew.

If there was another lesson learned from Matthew, it would have to be how much the level of complexity increases for events that span numerous states, contain multiple hazards (river flooding, storm surge, wind, flash flooding) and also higher uncertainties in the forecast.  The NWS is taking great steps to ensure the information presented to all levels (city, county, state, regional and national response entities) is consistent and coordinated, but with so much weather information out there, it’s hard to decipher what actually is important and what the biggest hazard for your jurisdiction might be.  Add in the fact that there are so many ways to present the forecast, and it’s bound to be overwhelming.  This is why pre-season coordination and training is so important.  If the NWS forecasters understand the needs of partners, are involved in exercises, and can present examples of scenarios and products prior to a storm, it makes the material much easier to digest and make decisions with during a storm.  This is especially true with some of the new storm surge products being issued by the National Hurricane Center such as the storm surge watch/warning and the potential inundation graphic. So even the 2016 hurricane season is wrapped up, the time to preparing for next season is…NOW!


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