Archive for the ‘Hurricane Ophelia’ Category

Ophelia, Philippe and proto-Rita

Saturday, September 17th, 2005

So much for a lull in the tropics. Tropical Storm Ophelia is hitting Nova Scotia as we speak… Tropical Depression 17 has become Tropical Storm Philippe… and Tropical Depression 18 has formed, with a rather ominous-looking track.

And there are three named storm in the eastern Pacific, too! Check out the current map:

Wow.

Ophelia skirts MA, aims for NS; T.D. 17 forms

Saturday, September 17th, 2005

Tropical Storm Ophelia is making its closest approach to southeastern Massachusetts as we speak — and it’s not that close:

I’m sure they’re getting some gusty winds, but the rain is almost entirely offshore. The same will not be true in Nova Scotia, which Ophelia will whack with rain and wind tonight and tomorrow. (Track.) In fact, it’s already raining there.

In other news, Tropical Depression 17 has formed east of the Lesser Antilles. If it strengthens into a tropical storm, it will be named Philippe.

This will probably be my last hurricane post for a while. I’ll have football on the brain for the rest of the day. GO IRISH!!! FIGHT ON, TROJANS!!! BEAT SPARTANS!!! BEAT THE HOGS!!! :)

Ophelia finally recurves

Saturday, September 17th, 2005

Tropical Storm Ophelia has finally moved away from North Carolina, and the damage wasn’t that bad. Now she’s got a date with southeastern Massachusetts (though that will be a glancing blow at worst) and then Nova Scotia and Newfoundland. The latest forecast track is here. Computer models here.

Dr. Jeff Masters has more, including an impressive rainfall-totals map and a description of a “scientific first” — a remotely piloted “drone” aircraft successfully flew into Ophelia today! He also notes that the tropics are looking more active (after a lull over the last 10 days or so, usually the peak of hurricane season), and Tropical Depression 17 could form very soon. The next name on the list is Philippe. We’ve got six names left (Philippe, Rita, Stan, Tammy, Vince, Wilma) before the Greek alphabet comes into play.

Weird-lookin’ Ophelia drifts toward NC

Tuesday, September 13th, 2005

Steve Gregory calls Tropical Storm Ophelia “one of the strangest looking storms I’ve ever seen in the Atlantic Basin.” I second that emotion:

“Ophelia’s convection looks more like a rubber tire than tire than a spiraling raging storm,” Gregory adds. And no, that’s not a giant eye in the middle — Ophelia doesn’t have an “eye” at all; her eyewall totally disintigrated yesterday, thanks to dry air and cool water. Her current appearance “is a classic example, I suppose, of what a storm will look like when it starts to run out of fuel (warm ocean surface) while trying to fight off dry air intrusion,” Gregory writes.

The above photo was taken late yesterday evening. Overnight, Ophelia has developed some more convection on her right side:

The NHC writes in its 4:00 AM discussion: “Satellite imagery and radar data indicate that Ophelia is gradually becoming better organized. The convective tops have cooled… especially to the southeast of the center…and the convection is starting to wrap around the west side of the circulation.” But it remains to be seen whether the trend toward strengthening will continue. Ophelia, currently a strong tropical storm, is forecasted to regain minimal hurricane strength before landfall, but the NHC admits that the intensity forecast is “problematic” and it seems, frankly, like they really have very little idea what’s going to happen with this uniquely hard-to-forecast storm.

The track forecast seems to be getting a little less “problematic,” though. A computer-model consensus has formed around landfall in roughly 48 hours in extreme southeastern North Carolina, followed by rapid recurvature out to sea — though only time will tell if this “consensus” is actually correct. FWIW, the discussion states:

Water vapor imagery shows the mid/upper-level ridge axis north of Ophelia is now along 81w…moving steadily eastward. Once the ridge moves east of 78w…which should take 12-18 hr…opehlia should begin a slow northward motion through about 36 hr. After that…increasing deep-layer southwesterly flow should turn Ophelia northeastward with some acceleration. Model guidance has come into much better agreement on this scenario…with the GFDL and the global models forecasting Ophelia to be near Cape Fear in 30-36 hr…followed by passage across extreme eastern North Carolina into the Atlantic. The new forecast track is an update of the previous package through 48 hr…along the left side of the main envelope of guidance. It is also faster than the previous forecast…although not as fast as most of the global models. It should be noted that some westerly component of motion is still possible in the next 12-18 hr before the northward turn occurs.

Whether the new data is enough to overcome Dr. Jeff Masters’s warning yesterday morning — “Don’t believe any of the computer forecast models or the official NHC forecast–no one knows where Ophelia is going” — I’m not certain.

Dr. Masters also writes: “The exact landfall point for Ophelia is much less important than for most hurricanes; the dry air that has plauged the storm the past two days destroyed her eyewall [Monday], and Ophelia doesn’t have the narrow concentrated area of winds that usually make the precise landfall point such a big deal. There will be a large area of the coast that will receive tropical storm force winds and a storm surge of 4 -6 feet characteristic of a Category 1 hurricane. Tropical storm force winds extend out about 160 miles from the center, an exceptionally large area for a tropical storm.”

Ophelia weakens; may remain stalled all week!

Monday, September 12th, 2005

Ophelia has weakened to a tropical storm, having essentially disrupted her own energy source: the ceaseless barrage of winds over the same patch of ocean has caused “upwelling,” bring cold water from the ocean depths up to the surface. As a result, sea-surface temperatures underneath the storm are too cool to support a hurricane.

Officially, Ophelia’s maximum sustained winds are at 70 mph, and that is “probably generous,” according to the discussion. There is still a decent chance Ophelia will re-strengthen, however, because once she gets a move on, she’ll pass over the Gulf Stream, where the surface water is warmer — and the warm waters go deeper.

Potentially more significant than the weakening trend is some bad news on the track-forecast front:

Some global models…namely NOGAPS and the Canadian…indicate that the broad 500 mb trough approaching the eastern United States in a couple of days will lack sufficient amplitude to pick up Ophelia and accelerate it northeastward. Therefore we have the unpleasant possibility that the cyclone could linger near the southeast U.S. through 5 days. The GFS and GFDL still move Ophelia northeastward over the Atlantic beyond 3 days…but they are somewhat slower than their previous runs. In deference to this numerical guidance…the official forecast is a bit slower than the previous one in the 3-5 day time frame.

Here’s the official track, which now has the storm remaining offshore until Wednesday afternoon. Here’s the NOGAPS model loop, which shows Ophelia still being stalled south of Cape Hatteras six days from now.

Ophelia is reminding me a bit of 1995’s Felix, which lingered offshore for what seemed like ages, menacing North Carolina but ultimately never striking. But Ophelia is closer to the coast that Felix was, and seems poised to sit and spin longer than Felix did.

Ophelia’s leftward drift

Sunday, September 11th, 2005

Hurricane Ophelia is doing her best impression of the other Democratic candidates after the emergence of Howard Dean — moving slowly but surely to the left. :) She’s actually drifting WSW at the moment, but although that movement is considered “temporary,” it may have significant consequences down the line (see: Katrina’s left turn over Florida). More importantly, a computer model consensus is forming around a North Carolina landfall. So, just when it seemed Ophelia might drift harmlessly out to sea, that now seems less likely. Here’s the official track, and the 10:00 PM discussion indicates a further leftward shift is likely at 4:00 AM. Luckily, we have plenty of time yet to talk about this — landfall is at least three days away, maybe four. But if you live in the Carolinas, especially North Carolina, you ought to be getting ready now for a Category 1 hurricane which may have a larger-than-usual storm surge.

Will Ophelia stay offshore?

Saturday, September 10th, 2005

Looking at the latest computer model runs, Dr. Jeff Masters writes: “It is becoming increasingly likely that Ophelia will deliver at worst a glancing blow to the Outer Banks of North Carolina, and spare the U.S. a direct hit.”

Steve Gregory elaborates: “the trend for the last 2 days, or 8 model runs, has been to continually shift the track further north and east.” I vividly remember another hurricane, also offshore of the East Coast, that exhibited a similar trend: Hurricane Edouard in 1996. At first, landfall was expected to occur in North Carolina; then in the Mid-Atlantic states; then on Long Island (and later Connecticut); then on Cape Cod. But the track kept inching to the right with each successive forecast was issued, and ultimately, Edouard missed the coast entirely.

Will the same thing happen with Ophelia? Dr. Masters says we’ll have a better idea soon:

Before we get too enthusiastic about this development, we need to look at one more cycle of model runs. The 00Z (8pm EDT) runs of all the models will finish up sometime after midnight tonight. These model runs should have a much higher than average reliability. They will use data from the NOAA high-altitude jet, which is flying a high-density data mission tonight. If the models all show a continued track for Ophelia past the Outer Banks and out to sea, we can have some modest confidence that Ophelia will pull her punch.

Meanwhile, Ophelia is also weakening. So, good news all around. But stay tuned; it’s too early to say we’re out of the woods just yet.

Ophelia’s target: North Carolina?

Saturday, September 10th, 2005

Hurricane Watches have been issued for the entire South Carolina coast and the southern half of the North Carolina coast, as Hurricane Ophelia sits and spins 240 miles south of Cape Hatteras. But, oddly given the state of the watches, the storm’s most likely target is not South Carolina, but North Carolina. The NHC discussion explains:

No significant motion is anticipated during the next 24 hours until the high to the north of the cyclone becomes established. Thereafter…I must emphasize that the track forecast is highly uncertain since the spread in the models have increased a lot since the last run. But in general… latest models have shown a gradual shift to right with most of the tracks now over eastern North Carolina. The exception is the GFDL which is bringing the hurricane near the North Carolina/South Carolina border. This is a small shift to the right from its previous run. Due to the change in the guidance…the area of Hurricane Watch may be required to be shifted northward later tonight. At this time…I would rather wait for tonight’s model run which will include the data from the NOAA jet. I want to make sure that they do not shift back to the left like they did last night.

Steve Gregory thinks the NHC should have adjusted the watches already: “From my point of view — there is enough evidence to support letting folks know, the whole state [of North Carolina] is at greatest risk.”

Gregory adds, “It is NOT likely to be stronger than a borderline CAT 1 / CAT 2 [at landfall]. But the storm surge from this very slow-moving storm could be 1 full Category above the reported wind speeds!”

Here’s the official track, for what it’s worth. Here’s a look at the computer models.

Ophelia a hurricane again; could hit Southeast next week

Friday, September 9th, 2005

As of 4:00 PM EST Tropical Storm Ophelia has re-strengthened into a hurricane, and her future track is becoming at least a little more clear. She’s currently moving slowly northeast, but she’s expected to make a “left turn” sometime in the next couple of days, and start meandering back toward the coast. Alas, that’s about all I can say with any confidence right now. Whether Ophelia goes north, northwest, west, or southwest, and at exactly what speed and angle, will determine which portion of the U.S. coast she hits — if any. (She’ll eventually recurve out to sea, as all of these storms ultimately do, so if she moves slowly enough and stays on a sufficiently northerly course, it’s still possible that she might not make landfall anywhere.)

The official track has Ophelia hitting South Carolina on Monday night or Tuesday morning, but the computer model predictions for her landfall location range from Cape Canaveral to Cape Hatteras. Bottom line, the entire southeastern U.S. needs to be watching this thing over the weekend.

At present, Ophelia is expected to remain a Category 1 hurricane, according to the discussion. “However…to err by one or two categories is not impossible…due to our lack of skill in forecasting rapid intensity change.”

UPDATE: Dr. Jeff Masters: “Given the recent model trends, Florida is looking less likely as a landfall location, and North Carolina needs to be increasingly concerned. There is a 10% chance that Ophelia will miss the U.S. entirely, and merely brush the Outer Banks of North Carolina and perhaps Cape Cod.”

Matt Newman, Weather Channel Senior Meteorologist: “Intensity forecasting is problematic, as is usual, but I would guess that given the synoptic pattern it will have a chance to intensify. The question is how strong does it get.”

Ophelia weakens; landfall more likely

Friday, September 9th, 2005

Ophelia was downgraded to a tropical storm at 4:00 AM, possibly because “upwelling” (churning up of cooler waters beneath the surface) has caused her to weaken, but she’s expected to regain hurricane strength within 24 hours.

Perhaps more importantly, more computer models now favor an eventual landfall somewhere on the Southeast U.S. coast, according to the NHC discussion:

Data from the NOAA gulfstream jet have been ingested into the 00z models…and whether by coincidence or consequence…much of the guidance models have shifted to the west…taking Ophelia westward underneath the building high pressure into the southeastern U.S. in 4-5 days. Given the lack of consistency in model guidance thus far with this storm…I have only made a modest westward adjustment with the official forecast at this time. It is too early to be specific about which areas might ultimately be affected by Ophelia…but the proximity of this cyclone to the coast and the weak steering currents dictates that interests from Florida through the Carolinas will need to monitor Ophelia for the next several days.

Here’s at look at some computer models. More views here and here.

Ophelia links

Friday, September 9th, 2005

A few sites to look at for information on Hurricane Ophelia:
The National Hurricane Center
Dr. Jeff Masters
Steve Gregory
Storm Digest

Will Ophelia strengthen?

Thursday, September 8th, 2005

The 10:00 PM NHC discussion on Hurricane Ophelia doesn’t add much new information about the track; that portion of the forecast is virtually identical to what the NHC was saying this morning, that Ophelia is expected to move east, then loop back west, with a great deal of uncertainty over how fast she’ll go and how far she’ll get in either direction. What’s more interesting in the new advisory is the discussion of how strong she’ll get:

The intensity forecast is problematic. On the side favoring strengthening…Ophelia has a good low-level structure…is over the warm Gulf Stream…and is generating convective tops near -80c. On the side inhibiting strengthening…water vapor imagery indicates dry air surrounding Ophelia…and data from the NOAA G4 jet shows 20-30 kt of southerly flow at 250 mb blowing right through the hurricane. Additionally…the slow motion introduces the possibility that Ophelia will upwell colder water underneath it if it moves out of the Gulf Stream. SHIPS and the GFDL both call for strengthening…although SHIPS may be underestimating the westerly shear near the storm after 48 hr. Indeed…most large-scale models show an upper-level trough near the southeast U.S. Coast at 72 hr…which is an another complication. Given the uncertainty…the intensity forecast will be unchanged from the previous package…and a somewhat lower intensity than forecast by SHIPS and the GFDL.

The forecast has Ophelia at 90 mph winds in three days, and not strengthening beyond that. It will be interesting to see how accurate that proves to be.

Hurricane Ophelia

Thursday, September 8th, 2005

Ophelia is now a hurricane, the seventh of the season. She’s still “trapped between two mid-level high pressure areas…and remains nearly stationary,” according to the discussion. The official forecast track calls for Ophelia to move east for three days, then make a clockwise loop and head back west. Computer models here and here.

In other news, Hurricane Maria is heading up to the North Atlantic, Hurricane Nate thankfully missed Bermuda, and… well… don’t look now, but do I hear a Philippe?

Disturbed weather over the southwestern Gulf of Mexico is associated with a broad and weak surface low pressure area. There has been little change in the organization of this system over the past several hours. However some slow development is possible over the next couple of days…as long as the system remains over water.

The latest on Ophelia

Wednesday, September 7th, 2005

Tropical Storm Ophelia, with 50 mph maximum sustained winds as of 7:00 PM, is still sitting and spinning and slowly strengthening off the coast of Florida, writes Dr. Jeff Masters. She “should…approach hurricane strength by tomorrow night or Friday morning,” he predicts.

Meanwhile, the NHC discussion vividly describes the uncertainty of the track forecast:

Models continue in great disagreement with regards to the track. The GFS which looped the cyclone back to the west in the previous run…is now showing a track to the northeast. The NOGAPS which earlier turn Ophelia to the northeast away from Florida is bringing the cyclone back to the U.S. Coast. The GFDL stubbornly insists on a track to the west-northwest toward Florida…and the story GOES on and on. Since the official forecast does not have the luxury of making such large changes in track every six hour…the best option for weak steering current scenarios is to maintain the cyclone nearly stationary.

Two of the things you look for, in assessing how much confidence to place in a hurricane forecast, are in agreement among computer models and consistency across subsequent “runs” of each model. Neither factor is present here at all, which is why the current official forecast track — which “keeps the tropical cyclone meandering within an area of about 100 nautical miles for the next five days” — is very much a “low-confidence forecast.”

But perhaps we shouldn’t be surprised by this. As one commenter wrote, “They name a storm Ophelia.. and then wonder why it’s insane and indecisive? Really now.” Heh.

Whither Ophelia?

Wednesday, September 7th, 2005

Tropical Storm Ophelia is giving forecasters fits. Unlike Katrina, whose track was relatively easy to predict by hurricane-forecasting standards, Ophelia has the computer models all in a tizzy. (See also here.) The predicted tracks are all over the place! Thus, as I pointed out earlier, the current official NHC forecast track is a “low-confidence forecast” (quite unlike the “high-confidence forecast” 48-60 hours prior to Katrina’s landfall, which should have led to a mandatory evacuation of New Orleans on Saturday morning, the use of school buses to evacuate the poor, etc.).

A couple of the computer models have Ophelia trekking across the Florida peninsula and eventually threatening Louisiana, but those models are being “discounted at this time,” according to Dr. Jeff Masters, because they predict immediate westward movement that clearly is not happening. However, while the Gulf Coast probably has nothing to fear from Ophelia at the moment, the East Coast definitely needs to be on its guard. Dr. Masters writes:

The Canadian model takes Ophelia out to sea behind Nate, but is the only model calling for this track. What I believe is the most likely scenario is one that is not promising for the U.S. This solution is the one favored by the GFS, UKMET, and NOGAPS models. These models forecast that steering currents over Ophelia will remain weak the next five days, which will allow her to remain over the warm ocean waters and gather strength. A weak trough of low pressure is forecast to move off the east coast Friday, which should act to push Ophelia away from the coast slightly. This trough could also create some shear and dump cold, dry air into the cyclone, weakening it temporarily. However, the GFS, UKMET, and NOGAPS models forecast that this trough will bypass Ophelia, and a ridge of high pressure will build back in forcing Ophelia westward or south-westward back toward the U.S. coast early next week. With so much time over warm water, and the shear likely to decrease once the trough bypasses her, Ophelia will have a good chance of attaining at least Category 2 hurricane status and making landfall somewhere on the Southeast U.S. coast. All interests along the Southeast coast from Miami to Cape Hatteras need to watch this storm.

Ophelia is already strengthening, according to both Dr. Masters and Steve Gregory, and will probably be a Category 1 hurricane within 24 hours.

As for Hurricane Nate, it is slowly strengthening, and has prompted a Tropical Storm Warning and a Hurricane Watch for Bermuda. At this time, the eye is expected to pass southeast of the island.

Last and least, Hurricane Maria remains a non-threat over open waters.