From my home office, the weather is beautiful: sunny skies and a light breeze blowing through the palm trees. Yesterday was also a picture perfect day in most of Florida, but the Bay area is now under a Tropical Storm Watch as all eyes keep a close look on Isaac. The nice morning weather we are having today should not lull Floridians and others in coastal states from taking precautions. Tropical Storm Debbie was a great reminder that a windstorm, even with a lower classification, can cause evacuations and loss of life.
If you have been following our blog, you may be familiar with guest posts by Rocco Calaci, a noted meteorologist expert witness in the Hurricane Katrina legal wars.
Just this morning, I received an update on Tropical Storm Isaac from Rocco, and the information warrants sharing with our readers.
(*Note from Rocco Calaci: I started issuing a "plain talk" interpretation of National Hurricane Center bulletins at the beginning of the 2008 hurricane season. I remind everyone that this is strictly a courtesy, I have no affiliation with any government agency, this is not a commercial service and the information is not for any type of decision. It is strictly FYI).
August 25, 2012
Good Morning,
There isn’t a lot to talk about this morning concerning Tropical Storm Isaac. Overnight, the storm moved over the western portion of Haiti and will start being dragged over the mountains of Cuba today.
Here is a satellite image of Isaac as it moved onshore in Haiti last night.
All the models are bunched together and Northwest Florida is the target area. For the past 12 hours, the models have been in strong agreement concerning the track of Isaac for the next 4 days. The key to this show of agreement is having a solid fix on the center of the storm.
On Thursday, the NHC could not get a firm idea on the storm’s center; therefore we saw model results from Miami to Houston and the NHC track moved westward at an alarming pace. I noted that the NHC always said they were having difficulty centering the storm and we knew that the model results were extremely mis-leading.
One thing of note…everyone is always screaming that the ECMWF model is superior to all others…it isn’t. The ECMWF has failed all year during tropical situations.
As any tropical system develops, trying to locate where its’ center is, can be exhausting as we saw from Tuesday through Thursday. Everything is based on the center of the storm. As the old saying goes…garbage in, garbage out.
It’s still my belief that the folks at the NHC and NWS are over-tasked, undermanned and definitely under-funded, but that’s not our concern right now.
Now that there isn’t any disagreement on where Isaac is heading, we have to turn our attention to the expected wind speeds at landfall.
At the moment, I’m hearing TV types talking about Isaac being a low Category 1 at landfall next Tuesday. Don’t believe it!
Folks on TV aren’t reading the NHC advisories correctly. Here is the wind forecast from the NHC as of 4:00AM CDT this morning.
48H 27/0600Z 25.0N 81.8W 70 KT 80 MPH
72H 28/0600Z 27.7N 84.9W 80 KT 90 MPH
96H 29/0600Z 30.5N 86.0W 70 KT 80 MPH…INLAND
On Tuesday morning, 1:00 AM CDT, (28/0600Z) Isaac is projected to be 150 miles South of Destin Florida with a sustained wind speed of 90 miles per hour. This would be a high Category 1 hurricane.
The next wind forecast isn’t until 24 hours later, after Isaac has made landfall and the expected winds are sustained at 80 miles per hour. This is how the NHC issues wind speed forecasts at days 3, 4 and 5…24 hours apart.
The NHC doesn’t state the highest winds to only be 90 miles per hour, but I know many other TV sources will make this mistake.
This also means that from early Tuesday morning until Isaac is within a few miles of landfall, the wind speeds can (and will) increase. As I’ve been saying, I’m looking at a hurricane hitting Northwest Florida as a high Category 1 or low Category 2 hurricane.
All day Tuesday, weather conditions are going to deteriorate…increasing clouds, winds getting stronger and spiral bands whirling through with heavy rains. For some strange reason, it seems that the worst conditions caused by hurricanes always occur at night…Hurricanes Opal, Ivan Katrina, Ike, etc.
As for wind gusts…that’s a real crapshoot. Let’s use a sustained wind speed of 95 miles per hour as an example. Sustained wind speeds are defined as the highest 1 minute average for hurricanes.
The gust factor for hurricanes starts as low as 115%, all the way to above 160%. This means you take 95 miles per hour and multiply it by the gust factor to determine the highest wind gust.
There lies another problem…wind measuring equipment is not located everywhere. The highest wind gust could occur at the beaches of Sandestin and it would never be recorded.
So here is my forecast as of now…high Category 1/low Category 2 hurricane upon landfall. Sustained winds between 92 to 100 miles per hour and wind gusts between 105 to 115 miles per hour.
Can any of this change? Certainly…if Isaac does something unexpected, or if the water temperatures are warmer/colder than anticipated, wind speeds can definitely change.
On Monday, I’ll be issuing some things everyone needs to know, such as what to do if you see an incoming waterspout or a tornado on land. Believe it or not, many people have strange beliefs about what really occurs during a hurricane and I want all of you to understand what is really happening.
For family and friends, from Mobile to Panama City…get ready. Make sure you secure outdoor items, have plenty of gas in your car, lots of cash in your pocket.
Since I’m comfortable with what Isaac is doing and the forecast, my next newsletter will be tomorrow morning…unless the entire situation changes.
Rocco
