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North Carolina radar at 11:52 AM:

I’ve been booted off both of my computers by job candidates taking online tests, so I can’t do much in the way of work at the moment… which gives me a golden opportunity to update y’all on Hurricane Isabel! :)

Here in Lower Manhattan, and especially up here on the 13th floor in Lower Manhattan, the winds are quite gusty. But the real action is down in North Carolina, where, as the National Hurricane Center declared at 11:00 AM:

…Eyewall of Isabel coming ashore on the North Carolina Outer Banks…

At 11 am EDT…1500z…the center of Hurricane Isabel was located near latitude 34.4 north… longitude 75.7 west or about 55 miles south of Cape Hatteras North Carolina. This position is also about 50 miles east-southeast of Cape Lookout North Carolina. The eyewall of Isabel…where the strongest winds are located…is currently coming ashore along the southern Outer Banks. Isabel has a very large eye…and winds within the eye will diminish…before increasing rapidly as the back edge of the eye passes by. People are strongly cautioned not to venture out during the eye passage unless absolutely necessary.

As of 5:00 AM, the Tropical Storm Warning that previously had its northern endpoint at Sandy Hook, New Jersey, has been extended eastward to Moriches Inlet on Long Island. You can see it as a blue shaded area in the latest track:

I’m not sure if the warning area technically includes New York Harbor or not, but I am going to officially consider myself warned. :)

Here are a couple of satellite views of Isabel as it approaches the coast:

This is a very unusual-looking hurricane, especially given how relatively strong it still is (a Category Two with 105 mph). Instead of a classic shape with a thick CDO, or central dense overcast, near the center, Isabel looks more like a spiral galaxy… or an octupus… with lots of arms reaching out from the center. This is the result of lots of dry air that has been absorbed into the circulation over the last few days.

Nevertheless, “there is still a slight chance of slight strengthening” before landfall, the Hurricane Center says. As of now, Isabel has a “classic concentric eyewall formation,” with the stronger winds in the outer eyewall, 50 to 60 miles out from the center.

Landfall will occur this afternoon along the North Carolina coast. Tonight and tomorrow morning will be the peak of the bad weather in New York. Here’s a local statement from the National Weather Service here:

(more…)

Sean says I’m obsessing over Isabel. Obsessing? Moi? No way! Certainly I would never devote 16 consecutive posts to one topic…

Well, maybe 16, but not 17. And so, in the interest of breaking the monotony, and in the name of horrible yet funny black humor, I give you this headline from the front page of this week’s Onion:

God Grants John Ritter’s Wish To Meet Johnny Cash

The National Hurricane Center’s 5:00 PM advisory contains this altogether fascinating analysis of Hurricane Isabel’s intensity:

If flight-level observations were all we had…Isabel would be a category three hurricane. The hurricane hunter aircraft this afternoon found a number of spots of winds of [125 to 140 mph]. This would normally correspond to surface winds of [115 to 120 mph]. However…numerous dropsonde profiles in the high wind regions of the circulation show a consistent and unusually steep fall-off of wind in the boundary layer. This is consistent with the meager convection in the hurricane core. Based on these profiles…the initial intensity is set at [105 mph].

Translation: Because much of Isabel’s strong thunderstorm activity — represented by those red and orange colors on the infrared satellites — has been sheared away, the strong winds up in the clouds are not making it down to the surface. As a result, Isabel’s surface winds are considerably weaker than one would normally expect, given the strength of its upper-level winds. Thus:

The official forecast does not anticipate any significant increase in strength prior to landfall…but should there be a substantial increase in deep convection, Isabel could quickly reach category three status.

Yes, quickly indeed, especially if the Gulf Stream has anything to say about it, says I. It will be very interesting to see how this plays out over the next 18 or so hours. Hopefully there won’t be a burst of convection and a return to Cat. 3 status. But if there is, I definitely won’t be shocked. In fact, if Isabel were to make landfall as a strengthening hurricane with 125 mph sustained winds, I wouldn’t be shocked by that, either. And that would be a very bad thing, because strengthening hurricanes are actually worse than weakening hurricanes of identical intensity. I don’t entirely understand why this is true, but I think the wind gusts tend to be stronger.

Well, enough doom and gloom. What can I say–I’m an alarmist by nature when it comes to hurricanes. Hopefully it will not be all that bad. The official forecast calls for Isabel to make landfall with an intensity of 110 mph — one mph short of Category Three status.

As to track, the NHC makes this point:

Isabel has a large circulation…including a large extent of damaging winds. Therefore…it is especially important not to focus on the precise landfall location…since significant impacts will be felt at large distances from the landfall point.

Yeah, the National Weather Service is predicting 35 to 45 mph winds in New York tomorrow night!!! That’s bordering on tropical-storm force, and we’re hundreds of miles away! Ah, but it’s that pesky pressure gradient. As my dad says, “sick of the isobars!”

The entire coastline of New Jersey, all the way up to Sandy Hook at the mouth of New York Harbor, is now under a Tropical Storm Warning as of 11:00 AM, even though Isabel’s center is still expected to track well to the south and west.

Definitionally, that means tropical storm conditions, including sustained winds of 40 mph or greater, are expected along the Jersey Shore within the next 24 hours or so. In reality, the NHC tends to stretch the definitions of storm warnings a bit, so it might be more like 36 hours. But the bottom line is, they are apparently expecting some pretty rough conditions in Jersey, thanks to the large size of this storm — particularly its stronger eastern side.

There’s already a breeze up here on the 13th floor in Lower Manhattan, where I’m at work. (I’m on lunch break right now; hence the blogging.) Indeed, the “fierce winds” of Isabel — or rather, of the tight pressure gradient between Isabel to the south and the high-pressure system to the north — already claimed their first victim earlier today: my morning cup of coffee. It was brutally blown off the desk and onto the floor by a sudden gust from the window. :)

Anyway, back to the actual hurricane. As of 11:00 AM, there is a Hurricane Warning from Cape Fear, North Carolina to Chincoteague, Virginia — the exact geographical parameters of my original Hurricane Watch prediction two days ago.

The Tropical Storm Warnings extend southward to South Santee River, South Carolina, and northward to, as I mentioned, Sandy Hook, NJ. There are no more watches — only warnings, which makes sense, since wherever Isabel hits, she’s going to hit soon.

Landfall is expected in the early- to mid-afternoon tomorrow, along the southern Outer Banks of North Carolina. The track would put the always-strongest “right front quadrant” over Pamlico Sound, so expect some serious flooding there.

The worst for the New York area should be overnight tomorrow night and the first half of Friday. By Friday afternoon, Isabel will be speeding past Buffalo and heading into Canada; by Saturday, she’ll be an extratropical memory.

As for intensity, Isabel is still at 110 mph for now, but the Hurricane Center suspects she’s really closer to 100 mph, according to the latest advisory. “If the convection does not strengthen, the intensity will likely be lowered a bit this afternoon,” the discussion states. “Either way, Isabel is a category two hurricane.” As for what will happen next:

While a more favorable upper pattern is beginning to develop as forecast by the global models…the low-level environmental thermodynamics and current storm structure are expected to limit the ability of Isabel to respond to the upper forcing. Little change in strength is expected prior to landfall. However… intensity forecasts tend to be less certain than track forecasts… and an intensity forecast error of one Saffir-Simpson category…up or down…would be entirely possible.

Remember, if Isabel makes landfall as a Category Three, her name will be retired from the hurricane lists. If she hits as a Category Two or less, the name will stay in the every-six-years rotation.

There is also this, regarding the track:

There has been no significant change in the official forecast track…although the model guidance has shifted its landfall point a few miles to the west. The GFDL adjustment was the largest…about 30 miles…and it is rather amazing that this is about the biggest adjustment we have seen over the past couple of days.

Indeed. The computer models this week have been about as consistent as I’ve ever seen them with any hurricane, and if Isabel indeed makes landfall on the central or southern Outer Banks as expected, the NHC will be able to look at this set of forecasts with pride and say, “We called it.”

Okay, lunch break’s over. Back to work.

“Oh poor Isabel,” Becky wrote in an e-mail to me this afternoon. “I was hoping for a bitchin hurricane to hit the East Coast, and all you’ve got is this puny little cloud passing by. Really. I think a 2 year old could be more threatening.”

Heh. Well, I don’t know, 2-year-olds can be pretty scary…

Below are a few photos of Isabel’s surf on Rockaway Beach (which is in Queens, not Brooklyn as I stated earlier) this evening. These are the waves that the hurricane generated back when she was a monster Category Five. They’ve travelled hundreds of miles over the open ocean, yet now they seem to herald the storm’s ever-closer approach to shore:

And here’s a photo of our emergency-supply cabinet at the apartment, which my mom replenished on Sunday and Monday in order to stock up for the hurricane’s possible approach:

The “BAM” — my dad’s favorite computer model, and quite possibly Emeril Lagasse’s favorite as well — is once again predicting something a bit different from the other computer models:

The BAM does not have a terribly good record with this particular hurricane, but nevertheless, I figured this was worth pointing out, because it seems to add one interesting, if unlikely, scenario to the mix: an unexpected right-hand turn just as the hurricane reaches the Carolina coast. I assumed that once Isabel’s acceleration toward the Outer Banks began, we would be able to consider the track nearly set in stone. But this seems to suggest there is at least some possibility of a late change. Let’s see how it looks after the next computer-model run.

Needless to say, if Isabel were to take the BAM track, things would be a lot more stormy in New York City and New England — and the Jersey Shore would suffer what might as well be a direct hit.

BAM notwithstanding, here is the official forecast for Isabel’s track, complete with the current watch and warning areas:

If I’m not mistaken, that 8:00 PM Friday position puts Isabel pretty much directly over Becky’s old house in Amherst, New York. :) Seriously, if Isabel follows this track, it will be a major rain- and wind-producer for Buffalo. Who knew that I could potentially end up being jealous of my friends in Buffalo for getting a more direct impact from a hurricane than I do?

Anyway, you’ll note that New York City is almost outside the “track cone” now. Interestingly, though, the website Weather Underground is rather more generous with the right side — only the right, not the left — of its track cone:

I wonder if they know something we don’t know? Maybe they’re big believers in the BAM…

So the forecast takes Isabel’s center onshore along North Carolina’s Outer Banks, then inland over central or western Pennsylvania, and eventually up towards Buffalo. But what does that mean for those of us living in the Northeast, not directly in Isabel’s path, but not too far away from it, either? How much rain and wind can we expect? I was wondering that myself, so I made an extremely crude diagram to try and figure it out:

The above map is based on the current infrared satellite image and the current NHC forecast track. The red line is where Isabel’s center is expected to go; the purple line is where the eastern edge of Isabel’s heavy-duty storm clouds (a.k.a. CDO, or Central Dense Overcast) would go if the center follows the expected track and if the hurricane maintains its current size and shape.

As you can see, this map seems to suggest that New York City would be on the periphery of the heavy rain and wind as the storm’s center moves over Pennsylvania. Of course, it will be greatly weakened by then — a tropical storm or depression, most likely — but if anything, Isabel will probably get bigger geographically as it starts to become extratropical (non-tropical) and gets sucked into a frontal boundary. So although the map is crude, I think the conclusion is correct: Friday will probably be a nasty day in New York, even if Isabel stays as far west as predicted.

And then there are the alternative scenarios. The BAM model is causing trouble again — more on that shortly.

As expected, Hurricane Warnings are now up as Isabel approaches. They are confined exclusively to North Carolina, encompassing almost the entire coast of that state:

At 11 PM EDT…0300z…a Hurricane Warning is in effect from Cape
Fear North Carolina northward to the North Carolina/Virginia state
line including Pamlico and Albemarle sounds.

The forecast track, having very, very slowly edged to the left over the last couple of days, now calls for landfall pretty much smack-dab in the middle of the North Carolina coast. The Weather Channel points out, however, that this is only one reason the Hurricane Warnings don’t go further north; the other is timing. Hurricane Warnings are supposed to mean hurricane conditions in roughly the next 24 hours, and even if hurricane conditions do eventually reach Virginia, the Chesapeake and the Delmarva, they won’t reach those areas for some additional hours.

Anyway, as of 11:00 PM, Isabel has strengthened slightly, from 105 to 110 mph. But now, instead of forecasting further intensification, the NHC says, “Little change in strength is forecast prior to landfall.” The BrendanLoy.com Hurricane Center says, take that prediction with a grain of salt until Isabel has crossed the Gulf Stream without exploding back into a major hurricane. I’m not predicting anything, I’m just saying the impact of the Gulf Stream is notoriously hard to predict, and thus bears watching.

By the way, here’s some hurricane trivia to keep in mind: if Isabel makes landfall as a Category Three or higher (115 mph+), its name will be retired, meaning there will never be another Tropical Storm or Hurricane Isabel in the Atlantic. But if it makes landfall as a Category Two or lower, its name continue to be recycled every six years, just like all the other names are, in which case we could be dealing with another Isabel in 2009. :)

I’m at Rockaway Beach in Brooklyn, where the seas already feel angry. The waves aren’t HUGE, but there are some big ones. You can almost hear the ocean announcing Isabel’s approach.

“Breaking News: Isabel may brush New York City and shuffle off to Buffalo,” declares the New York Daily News website, blatantly ripping off BrendanLoy.com’s genius headline of two days ago (which tends to indicate that it’s not really “breaking news”). Heh. Should I sue?

As of 5:00 PM:

At 5 PM EDT…2100z…a tropical storm watch has been issued north of Chincoteague Virginia to Little Egg Inlet New Jersey…including Delaware Bay. A tropical storm watch means that tropical storm conditions are possible within the watch area…generally within 36 hours.

Hurricane warnings will likely be required tonight for a portion of the watch area.

UPDATE: Recent fixes from NOAA and Air Force reserve hurricane hunter aircraft indicate that the weakening trend has ended…at least for the time being.

It may even have strengthened somewhat, but they’re waiting for more data before they say so. Some re-strengthening is expected at some point:

The explicit intensity guidance…the ships and GFDL models…now show some reintensification [before landfall].

The forecast track remains the same.