Tonight’s briefing started with a recap of Gustav and its impacts in Louisiana. We then moved along to Hanna; the 5PM track continues to take the storm in at the GA/SC border and up the gut of SC, and could potentially bring hurricane force winds to Charleston by Friday. Also, I took a quick look at Ike and yet another area under investigation out in the Atlantic, Invest 99.

I’ll have a full post with the next full advisory at 11PM.

It appears there’s still Internet access down there. Mark Mayhew, in particular, is tweeting up a storm; I suspect we’ll hear more from folks on the ground, they’re just trying to get a little sleep. Here’s hoping those who stayed — not many, according to officials — are able to safely ride out the storm.

Hanna gains some strength, may be reorganizing

Tropical Storm Hanna’s regained a little strength and is up to 50 MPH this morning, and according to the NHC forecast discussion, it could actually be stronger depending on the center position, which has been hard to pinpoint thanks to lots and lots of shear still over the system. It’s drifting westward at 2 MPH toward the Bahamas, which have tropical storm warnings raised.

So where’s this going to go? It’s still touch and go. Here’s the official forecast:

The forecast still takes the storm in at the mouth of the Savannah River; however, the cone of uncertainty is still several hundred miles wide. According to the 5am NHC forecast discussion, Hanna’s size has a lot of bearing on where it goes. Here are the model plots bearing out a number of scenarios:

One area of agreement, finally, is that the storm will indeed take up a northwesterly track toward the southeastern U.S. coast. From there, it all breaks loose; the solutions run the gamut from coming ashore in Florida and riding up the coast to recurving out to sea harmlessly. GFDL, one of the tropically-oriented models, is in favor of a landfall just south of Savannah; HWRF, another tropically-oriented model, takes it into Georgetown.

The variability is just a reminder for all southeast coast residents to keep an eye on things as the week goes on. It’s still too early to tell where this thing is going to hit and who’s going to feel what.

Here’s tonight’s Serious Business/Charleston Weather show concerning Gustav and Hanna. I’ll have a lot more on Hanna as the week goes on as it has a decent chance of causing some inclement weather in Charleston by the end of the week.

Gustav emerged off the coast of Cuba at roughly 11:30 or so and promptly started trying to get its act back together. It looks like it’s in the middle of an eyewall replacement cycle, which basically means it’s reorganizing a bit at the core and should be ready to start strengthening again. Cuba knocked it down to a 140 MPH system, which is still nothing to sneeze at. I suspect we’ll wake up to Gustav as a Category 5 tomorrow morning.

The official track takes the center of the storm roughly 50 miles or so west of New Orleans, which is likely to cause tremendous problems not only for the city itself, but for a fairly wide swath of real estate, as the current scenario could push surge up the Mississippi. It’s a matter of wobbles — again, as I’ve said before, five miles to the east or west could be a world of difference. The computer models continue to show a cone of uncertainty stretching roughly from the LA-MS border to the LA-TX border. The track has continued to go eastward as Gustav wobbled right several times during the day. The landfall point is still very uncertain, and we probably won’t really know where it will end up until the hours immediately leading up to the point of landfall.

The good news is that New Orleans is being evacuated. Here’s hoping they can get everybody out this time — I have a bad feeling that because of the position of the center, this could be worse for NOLA. We’ll see what the next day bears out.

Hanna’s future becoming a smidgen clearer…maybe

Hanna’s still struggling in the face of wind shear and some interference from Gustav. It’s hanging in there at 50 MPH, as it has for much of the day. The wind shear is expected to back off just enough to let it strengthen a bit more, but the NHC discussion forecasts the shear to return Tuesday, which should inhibit development.

Model runs on Hanna run the gamut from a landfall at the Florida/Georgia border (NGP) to a brushing of the Outer Banks and eventual recurvature to sea (GFS). I’m seeing some consensus between the GFDL and HWRF models, specifically designed for forecasting tropical cyclones, in a scenario bringing the center onshore in South Carolina; likely somewhere like Bulls Bay, Georgetown, or Myrtle Beach. However, two models does not a forecast make. Keep in mind it’s still very early — a week away — and that there is still plenty of divergence in the other atmospheric models. The GFDL is being weird about Hanna, too, somehow developing it into a Category 3 despite forecasted moderate wind shear.

As always, it behooves anybody from Florida to North Carolina to keep a close eye to Hanna as it meanders around in the Atlantic. I suspect Hanna is going to become quite a thorn in our side as the week progresses.

Major Hurricane Gustav is closing in on Category 5 status very quickly, raking Cuba and giving Key West quite a blustery time in the process. As of the 5 PM advisory, Gustav’s packing 150 MPH sustained winds, making it an intense Category 4, and is moving to the northwest at 15 MPH. This puts the storm somewhere along the Gulf Coast roughly Monday night. Model guidance agrees well on Gustav’s track at this point; it’s now a matter of wobbles — five miles east or west could change the prognosis for New Orleans, Houston, Biloxi, and other cities along the coast pretty substantially. As it stands, New Orleans may see sustained hurricane force winds on the eastern side of the storm, which is where the worst storm surge will occur. However, a lot can change between now and Monday.

Update: Here’s a map of the official NHC forecast track along with the spaghetti models to demonstrate variability in the landfall locations. Models look roughly at the Texas/Louisiana border all the way to right next to New Orleans, which is a disastrous scenario if that’s the one that comes to pass.

How I’m Following Gustav

Social media has mobilized throughout the day for getting the word out about Gustav. Twitter is figuring heavily into the mix, as one might expect: I’m following Mark Mayhew, who’s on the ground in New Orleans, as well as The Interdictor Project, one of the several aggregators of information about Gustav being made available this afternoon. (Interdictor may sound familiar to those who followed the Interdictor LiveJournal during Katrina; it was one of the best blogs that was actually on the ground through the duration of the storm.) I’ve also begun following Vanessa (aka iThinkMedia), who’s on the ground in Alexandra, LA, and James Wheeler, who lists his location as the Mississippi Gulf Coast. You can get the big picture using this Twitter search. A centralized Gustav Ning site has been set up for disseminating information and also for coordinate efforts to help folks who may be displaced by the storm. Finally, for you FriendFeeders out there, Wayne Sutton is compiling a list of resources for following Gustav.

Gustav is captivating me not just because of the obvious meteorological aspect, but also how folks are mobilizing so quickly using social media tools to disseminate information. This will be quite a study in social media’s maturity, and it’ll be interesting to see how things turn out.

Here in Charleston, we may have a tropical issue of our own to deal with by the end of next week. I’ve been spending a showery morning in West Ashley playing with computer model runs for Tropical Storm Hanna and the end result has been a little heightened concern for our neck of the woods.

Before we dive into Speculationland, let’s first start with the official 5-day forecast track for Hanna as provided by the National Hurricane Center:

Hanna’s currently expected to do something unusual for tropical cyclones and actually take a southward dip toward the Bahamas. I need to reiterate just how weird that is — it doesn’t happen often. (This southward dip is actually much less pronounced than what was being forecast yesterday through 5am.) One thing to note is the gigantic cone of uncertainty, especially as we get into Days 4 and 5. A lot of it has to do with a high pressure system that’s built up over the Southeast. This high pressure is what’s likely to steer Gustav into the Gulf Coast. It’s also expected to move out more into the Atlantic during mid-week, breaking down Gustav’s steering (and stalling it out over Louisiana and Texas, making for a potentially catastrophic flooding event) and also starting Hanna on a northward trajectory. It’s the degree of the high’s movement that makes all the difference.

The long-range models show a variety of northward-turning scenarios. The GFDL has Hanna doing a loop-dee-loop before resuming a northwest motion about a week from now. The HWRF model shows a southward dip and then a resumption of northwest motion. The GFS shows, so far at least, a track that shows a Savannah landfall roughly Thursday night into Friday morning as a fairly deep area of low pressure. Conversely, the CMC shows a dip into Cuba before straddling Florida’s west coast by Friday. Those are just a few of the scenarios out there — it’s really anybody’s guess.

Another area of Hanna’s uncertainty is the intensity forecast. NHC’s official forecast keeps it at tropical storm strength thanks to some persistent upper-level shear; however, the models continue to try to make Hanna at least a Category 1. For a time, in fact, the GFDL shows Hanna touching Category 3 strength before backing off into a Category 2 over the Bahamas. The HWRF is a bit more conservative with intensification, but still makes Hanna a Category 1. The confidence in all intensity forecasts is fairly low and this is definitely a low-confidence forecast.

Needless to say, anywhere from both of Florida’s coasts up the Eastern Seaboard should keep an eye on this one. This has the chance to be even more unpredictable than Fay proved to be, so it’s definitely one to watch especially as the week wears on.

While it’s fairly weak now, Gustav’s going to move back over the water soon — some very steaming hot water to be exact. That, combined with a fairly favorable upper-air setup, will help Gustav get its act back together. The official NHC forecast has it reaching Category 2 and hitting somewhere along the Gulf Coast by Monday night.

These long-range forecasts are tricky. The cone of uncertainty in the five-day in particular is an incredible spread that takes up most of the Gulf. A lot of buzz is being generated because the path currently takes the center extremely close to New Orleans; this, combined with the upcoming three-year anniversary of Katrina, has a lot of folks really worried. Louisiana has already declared a state of emergency well in advance of Gustav’s potential arrival.

If you’ve got interests along the Gulf Coast, it definitely behooves you to watch this thing closely. It really could end up anywhere along the coast at this point.

As for Invest 95, it’s started to flare some convection up, but it’s still awfully hard to identify a circulation and it seems to be a fairly hostile environment at the moment. It’s just drifting around; it’s starting to turn a bit more northwest, but it’s tough to say exactly what it wants to do. Models seem to want to develop it into a Category 1 in a few days and recurve it out dangerously close to Bermuda, but other models also turn it more southward and send it toward Florida. This is, of course, all depending on whether it actually survives. 95′s been in and out of the NHC’s radar, so it’s hanging in there, but it’s still too early to say exactly what it will do beyond bring some rain and wind over the islands.

Oh, and the tornado outbreaks over the last two days in the upstate of SC and into North Carolina? Those were all from the Ghost of Fay. Gotta love systems that overstay their welcome. :)