Mike McCall's "State of the Tropics" Address - Friday 8/19/11

Fear mongering? Igniting the hype machine? Or just trying to keep everyone aware of the possibilities? I guess that's for you to decide. But, I can tell you that OUR intent is to keep you informed on what is actually happening, and then give you the reasonable forecast possibilities without screaming for you to "RUN TO THE HILLS!" (with apologies to Iron Maiden fans). Believe me, if we ever actually do say "run to the hills", you better pay attention.

The problem with many tropical systems is that we can observe them for days and days - sometimes weeks and weeks before they make landfall somewhere. This may make it seem like we're hyping them, when in fact we're just telling you the facts, and showing you the most likely forecast for the next three to five days. The National Hurricane Center (NHC) issues a forecast out to 120 hours - five days. The average margin of error at day five in the 2010 season was a bit less than 200 miles. So, a storm predicted to hit Apalachicola at 120 hours could just as easily hit Tampa, or hit Mobile Bay. A storm predicted to hit Jacksonville at 120 hours could - ON AVERAGE - end up at Charleston, SC, or Vero Beach. You get the idea. NHC typically does a great job on its forecasts - all things considered. In the 1970's, NHC's forecast only went out to 72 hours - three days. Guess what the average margin of error was back then for day THREE? Approximately 380 miles! By 2010, the average margin of error at 72 hours was approximately 130 miles. They're getting much better, but there will always be a significant margin of error in a long range outlook, both in track AND intensity forecasts. There are just way too
many weather variables in the 4000 miles between the coast of Africa and the U.S. coast, especially considering that almost all of those miles are over water.

Okay, enough on that topic. Now let's talk about the current state of the tropics (as of Friday evening 8/19/11 as I write this). Tropical Storm Harvey is in the extreme western Caribbean along the coast of Honduras and may make landfall near the extreme southern coast of Belize on Saturday as a weak hurricane. If so, it would be the first hurricane of the 2011 season. That in itself is pretty amazing, since it is the season's EIGHTH named storm. Even if it happens, it will have NO weather impact on the U.S. It will certainly bring some very heavy rain along with tropical storm force winds to Honduras, Belize, and perhaps Guatemala and parts of southern Mexico.

The BIG tropical weather story isn't even a depression yet (as of Friday night). I am talking about the tropical wave (or disturbance) that is well out in the Atlantic, and will pass through the Lesser Antilles in the eastern Caribbean this weekend. (By the way - for reference sake - the northernmost islands of that chain are still more than 1600 miles from our area of south Georgia and the Florida Big Bend.) If it becomes a tropical storm this weekend, the next name on the storm list is "Irene". (I'll go ahead and call it "Irene" from now on just to keep things simple.) The computers have been latching on to the development of "Irene" for several days now. These particular computer models are what are known as "global models" meaning that they are run every day and forecast weather conditions on a global level, not for just one part of a country or ocean. There are several global model outputs that you can find online. The most common ones are the GFS, NAM, NOGAPS (Navy Model), CMC (Canadian Model), and my personal favorite - the ECMWF (European Model). Each of these models is pretty good overall. Some work better in certain situations. The ECMWF did a great job in forecasting the demise of Tropical Storm Emily earlier this summer. But, like all models, sometimes they are "not so good", especially when forecasting further out in time. ANYWAY, all these models show some kind of significant tropical development in the Atlantic/Caribbean. Overall conditions the next few days should favor strengthening. However, just about all of the models also take "Irene" very near the mountainous Hispaniola (Haiti and the Dominican Republic) early next week. A direct hit there would certainly disrupt the circulation and weaken it. However, a 100 mile jog to the north or south could allow further strengthening.

Still don't care? I can understand that. Haiti is more than 1000 miles from Apalachicola. However, the global models, including the ECMWF, continue to be fairly consistent in forecasting "Irene" to head in the *general* direction of south Florida by the end of next week. That's where the models begin to diverge. Some take it more toward southeast Florida and then up toward the Carolinas. Others take it more into the Gulf of Mexico and in the *general* direction of Louisiana. Then there's the ECMWF, which takes it across the Keys, but then up into the northeast Gulf of Mexico. Obviously, that's a worst case scenario for our area. BUT, that is also EIGHT days away from the time that computer model ran. An error of several hundred miles for that long of a forecast is common. If it's off by a mere 100 miles in seven days, that could change the Gulf coast to the Atlantic coast. SO, we're not going to panic - AT ALL. There's a reason that we haven't had a significant hurricane hit our area for decades. (In my opinion, Kate in 1985 wasn't even a significant hurricane as far as intensity goes, but that's a story for another time.) It is rare for a strong hurricane to make it into the Gulf of Mexico and THEN make a "right turn" and come up our way. Generally speaking, the steering currents just don't favor that kind of track very often. A more likely target IF it makes it into the gulf would be the western panhandle, Mississippi or Louisiana. But, if it's a strong hurricane at that time, we could still be impacted. No, I can't be specific about possible impacts from a hurricane that doesn't even exist yet, and might hit near us, or might hit 500 miles away, seven, eight or nine days from now. We'll leave that kind of speculation for next week when we're within a 3-5 day forecast window of landfall - wherever that may be.

So, for this weekend, don't worry too much about it. Just watch Nate's weathercasts, and follow us on twitter and facebook (shameless plug - sorry). You can link to them on our weather page at wctv.tv. BUT, it would certainly not be a bad idea to create a plan (if you don't already have one) for what you should do IF a tropical system threatens us in a week (or a month, or two months - whatever). Talk to your family about what to do. Put together a basic hurricane preparedness kit. Our Hurricane Headquarters page on the website has a multitude of great links to help prepare you and your family (and perhaps your business too). Thanks for reading my longwinded weather essay! Have a great weekend.

See you on the tube on Monday! . . . . . . . Mike


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