Tag Archives: tropical storm hanna

8am: Increasing divergence ahead of landfall

8am Hanna Computer Models

Here’s the 8am model runs. Note the increasing amount of divergence ahead of Hanna’s landfall. There’s still reasonably strong agreement for the Horry County landfall scenario, but I would not be surprised to see the track jog west a bit more before it’s all said and done.

The 8:00 advisory slows Hanna’s forward motion down ever so slightly (to 18 MPH instead of 20). It’s still headed northwest. Winds are still 65 MPH, but the pressure is down a bit more. Satellite imagery is indicating that the shear has backed off some; note the gigantic plume of convection trying to wrap itself around the center. A hurricane at landfall is reemerging as a possibility.

Stay tuned…

5am: Hurricane watches now up for the area

5am Hanna Watches

As of 5am, hurricane watches are now up from Surf City, NC, to just north of Hilton Head, SC. Tropical storm watches extend from roughly Hilton Head down to almost the Georgia/Florida border.

Hanna’s still a 65 MPH storm, headed to the northwest at 11 MPH. Its satellite presentation has been less than impressive this morning; however, strengthening is still fairly likely and Category 1 strength at landfall is to be expected.

Tropical Storm Hanna 5am 09/04:  Wind Field

The 5am track speeds up the timeline a bit and shifts landfall slightly left. As of now we’re looking at a landfall a bit closer to the NC/SC border (almost right on top of Wilmington) around 2am Saturday. Tropical storm force winds should begin to arrive in Charleston around noon tomorrow, or so. Today is another clear day, so today is the day to finish your preparations. Conditions will turn drastically downhill as Friday comes along. On the current track — still very subject to change — the center of the storm will probably pass to the east of here from around 7 to 9 PM Friday night. Once this occurs, conditions will begin to improve as Hanna’s not expected to have much on its southwest side.

More after 8 or so with the new model runs and the intermediate advisory.

11 PM: Hanna begins northwest turn; watches likely tomorrow

Tropical Storm Hanna 11PM Advisory 09/03:  Satellite Photo

The 11PM advisory is now out on a steadily reorganizing Hanna. Winds remain around 65 MPH, and pressure is sticking around 989 millibars. The Turn has really started to happen, as NHC states forward motion is north-northwest at 13 MPH.

The Track

Tropical Storm Hanna 11PM Advisory 09/03:  Track + Uncertainty Cone

The track seems to have shifted a bit more leftward before landfall; there’s still a fair bit of uncertainty. In the discussion, NHC acknowledges low confidence in the track, citing some spread in the forecast models.

Tropical Storm Hanna 11PM Advisory 09/03:  Forecast Models

There’s good consensus for a turn to the north and then the northeast; the big question is where it will happen. There’s decent consensus heading toward Wilmington, but there’s spread on the western periphery of the consensus — including a HWRF model that generally gets a fair bit of weight from NHC forecasters — hence the uncertainty and the slight leftward jog in the track.

NHC is saying that hurricane watches are likely for a “large portion of the southeast US coast” by tomorrow morning. It’s probably safe to assume that we in Charleston will be included in this watch.

It’s worth noting that the storm will be relatively short-lived; it’ll be increasing in forward speed throughout its approach. In Charleston, it’s likely that Hanna will have largely cleared the area by Saturday night. This is good for reducing the threat of severe flooding. There will still be heavy rains, but at least they will be short-lived.

Effects

Charleston should start feeling effects from Hanna as Friday wears on. As it gets closer, winds will increase. I’ve been able to use an experimental forecast wind field product as a decent guideline for what we might see here.

Tropical Storm Hanna 11PM Advisory 09/03:  Forecast Wind Field

The forecast says that we’ll see some of the worst of the weather Friday night into early Saturday morning, as the center passes within 75 miles or so of Charleston. Sustained winds of 58 miles per hour or greater — as indicated by the purple shading in the map above — are possible for a brief period. As mentioned above, rain totals will probably hit 6″ in some places, but this won’t be a storm that sits and spins and dumps 30″ of rain like a Fay over Florida.

Again, a lot of this is contingent on something resembling the current track holding. There’s more time for stuff to wobble back and forth, and Charleston is still in the cone of uncertainty, so there’s still stuff to watch. However, the direct strike scenario is looking less and less likely.

Closures, etc.

Keep an eye to media outlets and other sources for closure information in the Charleston area tomorrow, as I expect most of those closures (or lack thereof) would be announced during the day. A good resource for this is the @news2 Twitterstream.

Check out Lowcountry Bloggers’ Storm Buzz

The Lowcountry Bloggers roundup site has launched Storm Buzz, an automated feed of hurricane-related posts from the Lowcountry blogosphere. This is a good one-stop resource to see what Charleston bloggers have to say about Hanna and Ike.

Speaking of Ike…

Ike exploded into a dangerous but equally gorgeous Category 4 storm during the day Wednesday. It’s in a perfect environment for strengthening and could be a 5 before it’s all said and done. It’s expected to weaken to a 3; tentatively, it’s headed to the Bahamas, but there’s a lot of spread and uncertainty. It could recurve out into the sea — which would be ideal, of course — or it could threaten the U.S. within the next five or so days. Ike is one to watch because it’s expected to retain major hurricane status as it traverses the Atlantic, with fluctuations in intensity characteristic of huge storms.

For now, though, all eyes will continue to be on Hanna as she makes her move toward the coast. I’ll have more in the morning, probably shortly after the 8am advisory unless there’s a major shift in track that needs immediate attention.

Coverage Continues

Another video briefing will be broadcast at about 9:15 PM, with a roundup of the day’s information and hopefully a better fix on what Hanna’s going to do. She’s still got a history of behaving badly and needs to be watched closely.

Coverage will be more frequent as conditions deteriorate; I’m planning on bringing in additional folks to assist with coverage. Additional streams are planned for as long as power is viable. Now’s the time to follow @chswx and my own personal Twitter account for information and accounts of the storm, too.

11am: Track shifts eastward

The 11am advisory is out and shifts the track of Hanna eastward toward a landfall in Georgetown and Myrtle Beach. This is in line with the tropical models I discussed in the previous post, which had shifted significantly rightward. The NHC doesn’t commit as much to the right turn as the models do but this is fairly huge for Charleston. It remains to be seen whether this will stick, though.

Hanna also appears to be making the turn to the north and northwest; once motion resumes, we’ll have a better idea of what’s happening. It’s still too early to judge exact landfall points.

Winds are still 60 MPH; pressure’s at 997 millibars. The NHC noted in the public advisory Hanna’s size; tropical storm force winds now extend almost 300 miles north of the center. It’s expected to organize a bit more as the day goes on and should strengthen back to a hurricane sometime tomorrow. Keep an eye out, and there will be more at 2…

And ’round and ’round we go…

Tropical Storm Hanna: 5am

Hanna continues to frustrate folks here in Charleston from just northwest of Haiti as it does a little loop-de-loop (it’s already completed one) over the water, waiting for the high pressure system to build in, pick it up and whisk it off to the northwest. The good news is that it’s still on a slow weakening trend; this morning’s satellite image, depicted above, has her looking like a flat-out mess. The thunderstorms are fairly well-separated from the center; it’s amazing it’s maintaining 60 MPH winds as it interacts with Hispaniola.

Because The Turn hasn’t happened yet, we still are stuck in a wait-and-see pattern. This is frustrating because as NHC’s stated before, we won’t have any idea of exactly where landfall will happen until this thing starts to get going.

The 8am model runs showed a wild rightward shift in almost every model, probably as a result of Hanna’s eastern motion. Time will tell if this shift is anomalous or shows more of a permanent rightward trend. The 2am models started to demonstrate more rightward movement, but the 8am ones are the first time that I’ve seen the HWRF and GFDL models tack as significantly northward as they have.

Tropical Storm Hanna: 5am

The official forecast should look pretty familiar to you at this point, if not a smidge more rightward than previous tracks. Will be interesting to see what 11am brings.

I won’t be blogging all that often today; keep an eye to the Charleston Weather Twitter for updates throughout the day. I’m going to do a video briefing at 9:30 tonight; it won’t last too terribly long unless there are significant changes to discuss (and I’m willing to bet there might be). Back to waiting!

Wait and see continues…

The wait and see game continues with Hanna at the 11PM advisory. The storm’s back to being virtually stationary, drifting eastward every now and again, but movement is not very pronounced. NHC continues to list Hanna’s intensity at 65 MPH; however, this could be generous. Check out Hanna’s satellite appearance.

Tropical Storm Hanna at 11PM 09/02:  Satellite

Here’s what the Hurricane Center discussion has to say:

THE CLOUD
PATTERN HAS CONTINUED TO DEGRADE…AND IT IS POSSIBLE THAT HANNA
HAS WEAKENED EVEN MORE. HOWEVER…WE WILL KEEP THE INITIAL
INTENSITY AT 55 KT SINCE ANOTHER AIRCRAFT IS SCHEDULED TO
INVESTIGATE THE STORM AROUND 0600 UTC.

This apparent weakening is undoubtedly good news and appears to have gone on a little longer than previously expected. (We’ll take what we can get here.)

Back on Track?

Tropical Storm Hanna at 11PM 09/02: Forecast Path w/ Cone

The forecast path has not changed much during the day. The angle of approach has been adjusted somewhat, but NHC has been very careful not to alter the path until Hanna finally starts the northwestward turn. Only after the turn begins will landfall points even begin to get a smidgen clearer. One thing to notice is that the updated track is a bit slower (for the moment, at least), pegging landfall now for later on Friday night versus in the afternoon. This is definitely something that could fluctuate depending on when Hanna starts moving and how fast it’s accelerated.

Tropical Storm Hanna at 11PM 09/02: Forecast Models

The computer models want to tell a different tale, though. After a brief jog to the west, they’ve since started trending rightward again, likely as a result of Hanna’s eastward movement during the evening. The models bear out a variety of scenarios; some, like HWRF, favor the southerly track, while GFDL, which has consistently veered more to the north, currently likes Isle of Palms. There’s significant agreement, though, for a landfall near Myrtle Beach. Some consensus is also building for an alternate clipping of the Outer Banks, though I’m not sure if that would come to pass as the HWRF and GFDL models have been exceptionally reliable. It’ll be interesting what will come out of the models when the recon data is taken into account. (NHC lists the next recon plane as going in at roughly 2 AM EDT.)

Impacts

It’s still too early to tell — besides pretty decent amounts of rain and some elevated winds, probably to tropical storm force at times — what impacts Hanna will have on the area as the landfall location is still anybody’s guess. Using the current landfall location, though, I’m able to use an experimental wind field forecast product to give a general idea of what windspeeds to expect.

Tropical Storm Hanna at 11PM 09/02: Estimated Wind Field

The gray field is tropical storm force winds; the purple field are stronger tropical storm force winds up to 73 MPH. No hurricane force winds are depicted yet; if in fact Hanna makes landfall as a Category 1, expect those hurricane force winds (74 MPH or greater) to be concentrated about 20-25 miles to the northeast of the center. Intensity, storm size, etc. are still very touch and go at this point, so don’t read too terribly much into this; however, the estimation does show that a great deal of the state, including points as far west as Columbia and Augusta, could see tropical storm force winds for a time. Again, this should be interpreted as a general idea, and it’s quite possible a lot could change.

Closures, etc.

No word on any closures yet. The Charleston County School District has established a Hanna information page which will update as schedule decisions are made. Dorchester District 2 posted an inclement weather policy, but no closing information as of yet. I’ve not seen anything similar for Berkeley or Dorchester 4. Keep tuned to the local media outlets for up-to-the-minute closures and cancellations information.

More in the morning when the recon data is in; hoping that my getting some sleep will persuade Hanna to make a decision one way or the other so we can start trying to figure her out with some effectiveness. :)

Tonight’s Hanna briefing

Tonight’s briefing covered the latest on a ragged-looking Hanna, which has been erratic most of the day. I focused a lot on the models and a lot of the variation throughout today; things are still quite uncertain. I’m holding out hope that the 11PM advisory will start to shed some light but that might have to wait for a few more hours.

Hanna’s definitely not moving much, and its satellite presentation is very poor. It looks like it’ll be weakened even further with the next advisory…only time will tell. I’ll have more after 11…

2PM: Hanna The Meanderer…for now

Apologies for the later post; the day job has been hectic with storm stuff as well.

Tropical Storm Hanna’s been caught in something of a steering purgatory this afternoon; it continues to rain very heavily on the Turks and Caicos. As of the 2PM advisory, it’s moving SE at 2 MPH. We’re all awaiting the ridge of high pressure to build in and take it away — but it’s all a wait and see, still.

Intensity Rollercoaster

Hanna’s also been in a weakening trend; Gustav’s outflow has been negatively affecting it most of the day, having a great deal of its northwestern quadrant sheared off, helping to weaken the storm to tropical storm status earlier in the day. It’s held on as a 70 MPH tropical storm, so when the shear lets up, there won’t be much inhibiting it to becoming at least a minimal hurricane again.

This weakening has thrown a wrench in a lot of the forecast, though. The 11AM forecast discussion demonstrates significant uncertainty in the intensity forecast — it could barely hang on as a Category 1, or break free from the shear and blossom into a Category 3:

HOWEVER…GIVEN THE PRESENT LACK OF
ORGANIZATION…IT IS DIFFICULT TO KNOW HOW MUCH STRENGTHENING IS
POSSIBLE. THE NEW OFFICIAL FORECAST IS LOWER THAN THE PREVIOUS
ADVISORY BUT SHOWS HANNA BECOMING A CATEGORY ONE HURRICANE IN ABOUT
36 HOURS. IT SHOULD BE NOTED THAT THIS IS A LOW CONFIDENCE
FORECAST. IN FACT…IF ONE CONSULTS THE WIND SPEED PROBABILITY
PRODUCT INCLUDED IN THIS PACKAGE…IT CAN BE SEEN THAT THERE IS
NEARLY AN EQUAL PROBABILITY OF HANNA BEING A TROPICAL STORM OR
HURRICANE AT DAY 3.

A recon flight should shed much more light on Hanna’s structure; a flight’s scheduled for this afternoon and it probably is on the way in as I type. Here’s hoping that information is reflected in the 5PM.

Track Thoughts

The 11am advisory shifted the track back westward a little bit. Here’s the NHC’s map:

The NHC forecast track splits two groupings of model guidance down the middle. Here’s the high-carb meteorological pasta as of 3:15:

Computer Models at 3:00 Tuesday

One camp — with tighter agreement, I may add — takes an even more westward tack, bringing the center of Hanna onshore to central Georgia. Notably, the GFDL and HWRF models favor this scenario, with the GFDL taking a Category 3 just north of Jacksonville Friday. HWRF is a bit weaker, expecting a Category 2 storm. The other camp favors a Charleston-to-Myrtle Beach swath primarily. It’s a bit more divergent than the other two camps in terms of exact points, but remember, it’s still too early to get caught up in little jogs here and there. NHC has not adjusted the track much in part because Hanna’s size and intensity, as well as where it begins its movement from — remember, the storm has been meandering aimlessly southeast — has some bearing on how much and how quickly the expected high pressure will influence it.

Emergency Preparation

I caught Raymond from News 2’s tweets from the Charleston County EOC meeting. EOC has switched to OPCON 3, which activates the emergency operations center and indicates that an emergency situation is imminent. Mayor Riley is giving a press conference at 3:30 this afternoon; I recommend keeping an eye on News2’s Twitter. I’ll be watching that and will retweet big nuggets of information accordingly on both @chswx and @jaredwsmith.

Don’t forget about the video briefing tonight, tentatively scheduled for 9:15 PM. Sorry it’s so late in the night; I have obligations (read: class) to attend to from 7:00 to 8:15. This will give me an opportunity to review the 8PM advisory and break things down a bit better.

A special hello to those of you who came from The State — thanks for stopping in, and thanks to The State for syndicating this blog on their Web site! I hope folks are finding this useful; I know I’m enjoying doing it. :)