[UPDATE, 10:10 PM Pacific Time: The 0Z GFS computer model is out, and it shifts Irene's landfall point to the east, again. More here.]
As of 5pm Eastern Time, Hurricane Irene has weakened back to a Category 1 hurricane, with winds of 90 mph. Or more precisely, reading between the lines of the National Hurricane Center’s discussion, the NHC is now acknowledging a bit of weakening that probably really happened sometime last night.
On balance, however, the 5pm advisory is arguably bad news. Yes, Irene has weakened, and yes, wind shear may keep her intensity down a bit, at least for a while. But there’s still a good chance she’ll get to major hurricane status as she approaches the coast. And meanwhile, the track forecast just got a little scarier.
Remember what I said about this morning’s “one fairly clear piece of good news,” that the nightmare scenario painted last night by Weather Channel hurricane expert Bryan Norcross — that Irene might start to “recurve” off to sea, but then its recurvature would stall, and it would temporarily shift course back to the “left” (i.e., north or north-northwest), possibly toward New Jersey or New York harbor — no longer appeared to be in play? Well, the NHC just dumped a bucket of cold water on that “good news”:
AFTER [2 TO 3 DAYS]… IRENE IS FORECAST TO MOVE NORTHWARD TO NORTHEASTWARD AROUND THE ATLANTIC RIDGE. SEVERAL OF THE MODELS… INCLUDING THE GFS… ECMWF… HWRF… AND GFDL… SHOW A TURN BACK TOWARD THE NORTH NEAR THE END OF THE FORECAST PERIOD. THIS APPEARS TO BE IN RESPONSE TO A WEAK TROUGH THAT MOVES THROUGH THE SOUTHEASTERN UNITED STATES BEHIND THE HURRICANE. THE UPDATED TRACK FORECAST HAS BEEN SHIFTED EASTWARD AT 72 AND 96 HOURS BUT THE NEW 5-DAY POINT IS STILL ALONG THE LEFT SIDE OF THE GUIDANCE ENVELOPE… IN AGREEMENT WITH THE MODELS MENTIONED ABOVE.
Specifically, the current forecast track has Irene hitting South Jersey on Sunday.
The NHC’s discussion of a possible “turn back toward the north” contradicts what I wrote earlier — possibly because conditions have changed, or possibly because my analysis was simply incorrect. I’m frankly not sure which. I’m just a layman, remember! But either way, this is distressing news. The New Jersey landfall prediction isn’t the point; again, 5-day track forecasts are subject to huge errors. (So, don’t panic, Snooki!) The point is that the NHC has now raised the specter of the dreaded incomplete recurvature, which is a necessary — though by no means sufficient — condition to bring about the New York City nightmare scenario, in which a storm surge would catastrophically flood New York harbor.
Don’t get me wrong. That particular scenario is still unlikely, kids, still very unlikely. But that scenario will always be unlikely, until just before it happens. That’s a big part of the reason why it’s such a troubling scenario.
It’s important to note that the “GFS… ECMWF… HWRF… AND GFDL” aren’t just any computer models. There’s a reason the NHC’s forecast track is biased toward the “left side of the guidance envelope,” and it’s not because they’re watching MSNBC. It’s because those particular models are some of the best ones out there. In my previous post, I presented a “spaghetti chart” of the model tracks for Irene and said, “I’m not qualified to try and referee between the computer models, and won’t attempt to do so.” But perhaps I should walk that back a little. The GFS and European (ECMWF) are the some of the more reliable models in existence, and they’re among the ones spitting out some of the scarier scenarios at the moment. The Houston Chronicle‘s Eric Berger elaborates and illustrates:
The latest (12Z) run of the European model, which probably is the best in the world right now, paints a fairly serious scenario showing a very strong hurricane just to the south of New Jersey on Sunday morning.
Rendering of the 12Z ECMWF model. (Ryan Maue)The latest GFS model run depicts a similar scenario:
… Under the best-case scenario the storm would continue to veer toward the northeast after [its] encounter with North Carolina, and remain at sea. Some track models are going for this solution. … But that’s far from certain at this time, as the European and GFS models are telling us a more northerly track is possible.
If these two models verify we’re talking about at least hurricane-force winds over parts of the very heavily populated corridor from Washington, D.C. to New York City, and possibly extending most of the way to Boston. There also could be flooding rains.
Berger — who worries that today’s earthquake might distract northeasterners from this looming, potentially far more serious threat — adds, correctly, that there’s “a lot of uncertainty as it pertains to the northeastern threat. Irene could weaken significantly if its center spends a lot of time over North Carolina. It could remain offshore. But simply shrugging this off as another Hurricane Earl would be a mistake.” Agreed. It might turn out to be another Earl, but it might not. We just don’t know yet. For now, the threat is real.
Berger concludes: “Stay tuned.” As they say.
Could be an Earl. Could be an Agnes (1972). Stand by. And be like the Boy Scouts. (“Be Prepared”)
Wish we had Alan Sullivan’s input right about now. Sure do miss that man.
Noticed on earlier Visible Sat Imagery that it was just starting to form an eye wall and an eye but then it filled back in. That must have been the weakening eluded to in the latest assessment. However, note also that the strongest I/R and radar returns are starting to move to the center of the storm and the storm is starting to become more perfectly symetrical as it gets more organized. It’s still out over warm water and will intensify yet. Rapid deepening could cause it to slow down and adjust track. Keep an eye on this baby…
Agnes was a serious storm, did damage way inland – western Maryland and on up through PA, in my experience. Heck, Wilkes Barre got hammered by that storm, as did Harrisburg PA, Harpers Ferry WVA and so on. Bad storm.
Just so it isn’t a Fran I am good.
She’s about to move over very warm waters, a degree above normal (which is quite a bit.) These are the same waters that turned Andrew into a Cat 5 almost exactly 19 years ago.
The question is whether dry air coming off land and an eyewall replacement cycle could weaken her as she’s just off shore.
Notice the similarity of Irene’s path compared to the Long Island Express of 1938, one of only 5 major hurricanes to strike New England since 1635, all of which were devastating. Worst case scenario, Irene could be a $40B loss, compared to $16B for Andrew.
http://en.wikipedia.org/wiki/1938_New_England_hurricane
This could be really scary.
Why do I keep seeing so many prophesies that resemble end of the world scenarios right now? The earthqauke? Calm the eff down. Irene’s been trending right (east) for the last 36 hours. The cold front coming in Thursday will push her towards the Canadian Maritimes and they’ll have to deal with her. Seriously, I have to ask…are there a whole bunch of people who just want a Doomsday? Kill yerselves then — I’ve still got a life to live. Get outta my way. Jeez…
Well, as an old codger who spent the day boarding up a house in West Palm Beach, I didn’t experience the shift east at 5pm today as bad news at all!
On the other hand I was planning to fly into DC at the weekend. Not any more!
Very well written article. Both of them. Hurricanes have always interested me here in the panhandle of Florida (Kate Country). Thank you for an immensely enjoyable write-up.
Great discussion. I’m a lifelong Jerseyan and remember Hurricane Belle hitting us when I was four. Most of the storms peter out before they hit us, but maybe this one won’t. Cute joke about Snooki!
Is there some reason hurricanes are not problems until they reach NJ or NY? The way this article is written, it seems to be implied that no humans live south of the Delaware. The NHC’s current prediction (as of 0800 ET Wednesday) seems to show Irene at about Cat 3 when it passes over eastern NC. Believe it or not, there are actual real people who live in flyover country. I know, I’ve seen them.
@quake survivor, I do not mean to downplay the potential impact on eastern NC. However, 1) eastern NC will get the lion’s share of attention from the media in the coming days, as it’s target #1 for the storm, whereas the longer-range threat to NYC/NJ may be comparatively ignored until it’s pretty late in the game to start preparing; 2) the Carolinas get threatened and/or hit by hurricanes frequently enough that folks there presumably “know the drill,” whereas this level of threat is very unusual for NYC/NJ, and people there may need to be figuratively shaken into awareness of the seriousness of the threat; 3) there are a helluva lot more people potentially impacted along the Mid-Atlantic and Northeast than in the Outer Banks, especially given the inevitable evacuations of the Outer Banks; and most importantly 4) the worst-case scenario for NYC is incredibly dire, universally recognized as one of the most serious threats to any American city from a hurricane (along with New Orleans, Galveston, Mobile, Miami and a handful of other cities very vulnerable to a direct hit), so I focus on the NYC scenario for the same reason that I focused on the New Orleans scenario in the run-up to Katrina: not because a landfall by Katrina in, say, the Florida panhandle, wouldn’t have been destructive, but because a landfall in or near New Orleans was always going to be a much bigger deal in the grand scheme of things.