By Jim Stefkovich, Meteorologist, Alabama Emergency Management Agency
CLANTON –Thursday, 8:00 am June 2, 2022
Part 1 on Wednesday focused on your developing a hurricane plan. If you missed it, it can be found here: As It’s Hurricane Season and Time to Prepare in Alabama – Part 1 – Alabama Emergency Management Agency shown in the graphic above, we’re already started an active season with tropical storm watches or warnings possible for portions of South Florida later today.
The first thing I want to stress is that you should receive critical weather information from the National Hurricane Center https://nhc.noaa.gov , the National Weather Service https://weather.gov , your local Emergency Management, and/or a trusted media source, ONLY. Beware of social media sites! The graphics below are a few examples, including one that has the NOAA logo and another that had over 77,000 “hits”. Shameful!
I also want to go over some misconceptions people may have about tropical storm and hurricane products.
The graphic below is from Hurricane Sally, which eventually made a direct hit in Baldwin county in September 2020. The forecast cone represents the forecast area where the center of storm may be. However, actual impacts, including storm surge, high winds, flooding rains and tornadoes often occur well outside the cone.
The center of the storm remains within the cone approximately 2/3 of the time. But, this also means that for any five day forecast, the center of the storm will NOT remain in the cone. In addition, just a shift of tens of miles can have dramatic changes in impacts across hundreds of miles. This in fact was the case with Sally. Note the cone doesn’t include coastal Alabama, but it would take a direct hit a few days later.
Why is this important to know? Because of what is called “anchoring”. At times, people don’t keep up to date with changing forecasts and anchor on a particular forecast which may be a few days or even hours old. They are then surprised to see changes right before landfall and are not prepared.
That’s why it’s important to constantly keep up to date with the latest forecasts from the National Hurricane Center (NHC) and your local NWS office.
Some storms are well-defined and the forecast cone of uncertainty is much smaller. Others, like Sally, are much harder to predict both in landfall and intensity. The graphic below shows the large spread in computer model guidance on where Sally would make landfall.
It’s very common for people to say, “I lived through hurricane “X”. We’re fine.” Every storm is different and can’t be compared to one you may have experienced years ago!
Another useful product is the arrival time of “sustained” tropical-storm-force winds (39 mph – 73 mph) as shown below.
This arrival time is when substantial damage can begin with downed trees, power lines, and building damage. All outdoor preparations should have been completed by this time or you should have already evacuated to a safer location.
A tropical system’s rainbands often contain damaging high wind gusts, flooding rain, and tornadoes well away from the sustained tropical-storm-force winds. You should consider having your action plan completed before the earliest time of arrival for these winds.
The bottom line is to focus on the potential impacts of any storm and not the category. A tropical storm or category 1-5 hurricane is based on wind speeds ONLY. And, as shown in the graphic below, most fatalities occur from flooding, many times well away from where the center makes landfall.
There is no way to know if Alabama will be directly or indirectly impacted this season from a tropical storm or hurricane, but we must all be prepared. It’s not a question “if” Alabama will be impacted, it’s a question of “when”.