Watching the Tropics

By: Nate Harrington, Mike McCall Email
By: Nate Harrington, Mike McCall Email

We are entering into the busiest time of the hurricane season.
With some very interesting tropical weather developing in the coming days, this will be a spot for discussion and interpretation of computer models that predict the path of tropical storms and hurricanes.
*****DISCLAIMER*****
THESE ARE COMPUTER MODELS THAT I'LL BE DISCUSSING. A LOT CAN HAPPEN IN A WEEK OR EVEN A FEW DAYS. DO NOT BASE ANY DECISIONS ON THESE MODELS. THIS IS FOR DISCUSSION AND EDUCATIONAL PURPOSES ONLY.

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Monday August 22nd 11:59pm

Irene intensified to a Category 2 hurricane Monday evening just north of the Dominican Republic. Since it is moving away from the mountains of Hispaniola, and into an area of very warm water and favorable upper level winds, further strengthening is likely. The National Hurricane Center (NHC) forecasts Irene to become a major, Category 3 hurricane on Tuesday, and it is possible that it could reach category 4 status in the next few days. There have been no major changes to the forecast computer model tracks. Most of the models are clustered along a track that would take Irene through the Bahamas, and then approx. 100 miles off the east coast of Florida - and moving to the north by that time, in the general direction of the Carolinas. This track would essentially mean very little, if any impact on our part of south Georgia and the Florida Big Bend. However, if it deviates farther to the west in the next day or two, that could change. We're definitely looking better, but we'll still keep a close eye on it.

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Monday August 22nd 12:00 pm
Irene officially became the first Atlantic Hurricane of the 2011 season. It reached 75 mph winds around 5:00 this morning which classifies it as a category one storm. The latest forecast shows Irene picking up strength and becoming a major hurricane as it passes over the Bahamas on Thursday morning. The forecasted wind speeds at this point are 115 mph, putting Irene at a category 3 hurricane.

Irene is moving over very warm waters in the Atlantic. Water temperatures are in the upper 80s which is very conducive for strengthening. Also, the environmental conditions favor development because there is little wind shear.

The forecast models are in better agreement, and have consistently been shifting Irene's track further East. Most models now have Irene scooting up the East coast of Florida. Anyone in Eastern Florida and the Carolinas should start preparing now! That means stock up on water, canned food, batteries, flashlights, waterproof containers for important papers, cash, etc. Storm surge is the deadliest part of a hurricane, and this could be a real issue for the East coast!

The big bend region is on the very edge of the cone of uncertainty. It was completely within the cone before, but the official track forecast has shifted further East. That means it's not out of the question that Irene pays a visit to the Eastern big bend, but it is looking more unlikely at this point. Even if we dont take a direct hit from Irene, our weather on Friday and the weekend may be impacted. Especially because Irene could be a major hurricane at that point. The outter bands of the hurricane could produce heavy rains and lightning. If Irene takes the far East side of the track, we may actually be seeing the sunshine this weekend! So it's still up in the air.

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Sunday August 21st 11:30 pm

Big changes to talk about with IRENE. The National Hurricane Center released its 11pm update, and shifts the track of IRENE about 30 miles east. That's good news for people along the Gulf Coast, but bad news for those along the east coast of Florida and the U.S.

Looking at computer models, most are still in agreement that the track will be more east. There are still a couple of outliers that send IRENE into the Gulf of Mexico, so we aren't totally out of the woods yet.

Intensity wise, IRENE is now a very strong Tropical Storm, almost a hurricane, with winds at 70 mph. Puerto Rico will be the target over the next few hours, with Hurricane Warnings posted there, and for the entire coast of the Dominican Republic.

Expect Hurricane IRENE by early tomorrow morning. I'll have more posts as the week progresses.
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Sunday August 21st 5:30 pm

Just like we talked about this morning, we see more and more agreement with the computer models taking IRENE more on a easterly track, toward south Florida and the east coast of the U.S.

There are however, a couple of outliers, that take IRENE into the Gulf of Mexico and eventually to close for our comfort toward the end of next week.

We are still a little too far out to tell exactly what IRENE will do in the next few days, but we are getting a much clearer picture. It will all depend on the strength of a trough of low pressure moving off Florida and how much of an impact that has on the subtropical high which is steering IRENE to the west right now. A little weakness in that ridge of high pressure, and IRENE will take a northerly turn.

Currently, IRENE is looking better organized on satellite and is starting to develop an eyewall, based on radar from Puerto Rico. It most likely will strengthen once it passes Puerto Rico tomorrow afternoon, and will hit Hispaniola as a category one hurricane.

The next advisory from the NHC is at 8pm...I'll update the IRENE particulars on our website and will post here during the 11pm news.
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Sunday August 21st 9:30am

Well wouldn't you know it...those computer models are changing their minds again. Most of them now are shifting back to the east, which places IRENE either right over south Florida or on the east coast of Florida and the U.S. when it makes landfall.

Like I said last night, we don't focus on one particular computer model track, we check to see if most of them are in agreement. Well this morning most of them are, except for a couple of outliers.

Here's a quick look at what the models are seeing. The subtropical ridge or Bermuda High, steers storms in the Atlantic. Think about this as a big circle which moves things that come in contact with it clockwise. So, at the bottom of this circle, where IRENE is right now, this Bermuda High is steering IRENE to the west. Earlier models made this area large, encompassing much of Florida, which meant the gradual turn to the northwest and north, would happen a little bit later. But now the models are picking up on something.

A trough of low pressure is forecast to move off the SE coast of the U.S. by Tuesday...this will weaken the subtropical ridge, or Bermuda High, and allow IRENE to make that northerly turn a little bit sooner. This could spare the Gulf Coast a very strong storm. And actually, wouldn't be terrible for south Florida.

On its present forecast track, it will become a hurricane by Monday afternoon, but will quickly weaken as it moves over the islands of Hispaniola and Cuba. IRENE will only be a minimal strength hurricane when it makes landfall early Friday morning. So this forecast is obviously the best case scenario...if it's going to make landfall, the weaker the better.

However, there are a lot of factors at play and we will continue to monitor IRENE and its progress. I'll have another update for you this afternoon.

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Saturday August 20th 9:45pm

Well, as of 7:15 we can finally call it Tropical Storm IRENE. The National Hurricane Center put out its official track. I will post a link on that below.

Also of note, the computer models this evening have shifted back to the west. Not too many outliers this time...most models have IRENE making landfall next weekend somewhere from south Florida to the western Panhandle, which puts us under the gun.

Like I warned before, these models can change a lot in a 2 days or 12 hours, but right now indications are we will be impacted somehow, someway come next weekend.

And I know we preach this all the time, but there is no time like right now to prepare. Get those hurricane kits and plans in place, just in case evacuation orders are given to the place where you live. Even if IRENE never comes close to us, it's always a good idea to be prepared.

To answer a question posed by Raymond a little earlier...There is no ONE model that works the best in this situation. What we look for is agreement between all the models. We are starting to see a little bit of that now, but will hold off on calling all the models in agreement.
The European model, which handled some of our previous storms this year pretty well is a good one. It has been consistent with a Florida landfall since Thursday. But again, no one model is preferred.

I will update later tonight if things change. If not, I will post tomorrow morning.
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Saturday August 20th 5:00pm

First of all, sorry about the broken link. It worked for me when I tested it, but I guess some people are having trouble. I will post the models from a different site.

OK..Looking at the 18Z (Noon) computer model runs, they are different from this mornings. Actually, they are a lot different. We have a few more that are now forecasting Invest Area 97l to move into the Gulf of Mexico. One takes it into Louisiana, one takes it into Mississippi, another near Pensacola, and another brings it right through the Big Bend. This should tell you a couple of things right off the bat. 1) The strength of the Bermuda High, which is a huge steering influence for tropical storms and hurricanes this time of year, is in question. The stronger the high pressure area, the greater chance a storm has of pushing farther south and west (bad news for us). If it is weaker, the storm makes the classic northerly turn a bit sooner and we are out of the woods. 2) Computer models this far out (most of these models are putting a potential storm in Gulf on Friday) are unreliable from run to run. Meaning there is a lot of variability in their solutions. So, we will continue to watch and wait.

Elsewhere, Harvey made landfall this afternoon near Dangriga Town, Belize with 65 mph winds. It's still a tropical storm but will most likely be downgraded later tonight or early tomorrow as it moves over Guatemala. Right now, heavy rain is the main concern with 10 inches forecast to fall over inland Guatemala.

I'll have another update later tonight, and we will probably have Tropical Depression Nine by then.
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Saturday August 20th 9:00am

Right off the bat this morning, some of the computer models that developed a hurricane in the Caribbean and brought it right into the Big Bend are now singing a different tune.

There is a huge discrepancy with the forecast tracks with some taking the storm up the Eastern Seaboard of the U.S. but one model has the storm making a bee line for the Forgotten Coast. I will post a link to the picture of all the models below.

Even though MOST models have us dodging this bullet.. NOW is the time to prepare for hurricane season. Make a plan and prepare a hurricane kit. All the information can be found on WCTV's Hurricane Headquarters webpage.

I will be posting here as the hurricane season progresses. Please feel free to comment or ask questions.


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