Hurricane Irene Model and Forecast Discussion

[LakeEffectKing]

GFDL would interest some folks in the MA.....Drives it straight north from coastal N. Carolina:

[HKY_WX]

GFDL would interest some folks in the MA:

That would wipe out all the little towns and establishments in the NC sounds, outer banks, and outlying islands.

[lsukev]

Is that a west shift from earlier in the gfdl?

[tombo82685]

i believe this is the correct time stamp for the hwrf, but it has shifted towards the gfs track. I believe 12z run was inland

[HurricaneJosh]

That would wipe out all the little towns and establishments in the NC sounds, outer banks, and outlying islands.

The area has withstood many hurricanes-- I don't think it will be wiped out, even if Irene took that exact path. (The 925 mb should be ignored, of course-- it's not accurate.)

[Big Jims Videos]

Uh yeah gfdl would destroy hstteras to li. The surge running uP the coast makes me shudder. Show me that on Thursday before panic mode

[Thunderdude]

Uh yeah gfdl would destroy hstteras to li. The surge running uP the coast makes me shudder. Show me that on Thursday before panic mode

I think the chances for that type of solution to happen is slim to none but NC could get a hit though then my thoughts that it would then be the question whether how much will keep taking the turn to the N or will it make the shift NE spare LI and SNE.

[HurricaneJosh]

Uh yeah gfdl would destroy hstteras to li. The surge running uP the coast makes me shudder. Show me that on Thursday before panic mode

But it wouldn't be the first time in history that a hurricane took that track. I'm not trying to underplay it-- and since I might chase it to NY of course I want it to be big-- but I think it's important not to overreact to these models. History tells us such a track would be damaging and disruptive-- but not Armageddon.

[LakeEffectKing]

I think the chances for that type of solution to happen is slim to none but NC could get a hit though then my thoughts that it would then be the question whether how much will keep taking the turn to the N or will it make the shift NE spare LI and SNE.

It does have the last 2 Euro's tagging with it (within 50 or so miles up near the Bay) so there is a bit more value in this run...and most of the globals to have a halt to recurvature. But, I think if Irene's speed is modeled off just a bit , we could end up with a few decent model shifts (either further east or west)....the timing with the interaction with the several troughs (as well as the orientation and strength of those troughs) still is yet to be determined...and the nuiances of the track post 35N lat. are very sensitive to the aforementioned factors. Keep an eye on Irene's forward speed vs. what is generally progged.

[packbacker]

Is that a west shift from earlier in the gfdl?

Yep, sure is, first shift west in a while.

18z at 108

http://raleighwx.americanwx.com/models/gfdl/18zgfdl2500mbHGHTPMSL108.gif

12z at 114

http://raleighwx.americanwx.com/models/gfdl/12zgfdl2500mbHGHTPMSL114.gif

[Big Jims Videos]

No Josh I am not riding the gfdl by any means. But in a few generations people in Nj never experienced a true hurricane. You've been in these things before and know what 80 mph gusts can do. Snookie doesn't. Gloria scraped us. That's about it. And if the tanning salons are closed for a few days with no power trust me it is Armageddon. I think Thursday's runs will tell the story. And if it can hit high cat 3. And if one NYC tv station broadcasts that gfdl on the 11pm news oh boy...where you gonna chase?

[HurricaneJosh]

No Josh I am not riding the gfdl by any means. But in a few generations people in Nj never experienced a true hurricane. You've been in these things before and know what 80 mph gusts can do. Snookie doesn't. Gloria scraped us. That's about it. And if the tanning salons are closed for a few days with no power trust me it is Armageddon. I think Thursday's runs will tell the story. And if it can hit high cat 3. And if one NYC tv station broadcasts that gfdl on the 11pm news oh boy...where you gonna chase?

With that track, it would reach NJ as a Cat 1-- definitely not a 3. It would be over land for too long to be any stronger.

It it stays more over water, then it could be a much bigger event for NJ-- say, if it scraped the NJ coast. If I happened to be in the NY area and the center rode right up and along the Jersey coast, I'd station on W Long Island-- even Queens-- to try and get the max winds.

[jm1220]

With that track, it would reach NJ as a Cat 1-- definitely not a 3. You're right, it would be the biggest for NJ in over a century, so I'm not trying to downplay it.

If I happened to be in the NY area and the center rode right up and along the Jersey coast, I'd station on W Long Island-- even Queens-- to try and get the max winds.

With a track and strength like the Euro's over the past few runs, I would almost definitely be mandatory-evacuated. Much of this area would almost certainly be under water.

[HurricaneJosh]

With a track and strength like the Euro's over the past few runs, I would almost definitely be mandatory-evacuated. Much of this area would almost certainly be under water.

The Euro is really, really overplaying the strength. Usually for a strong hurricane to get to NY, it has to be 1) very intense down in the tropics (like a strong Cat 4) and/or 2) blasting up the coast mega-fast-- like, well over 30 kt. Right now, we have a Cat 1 in the Bahamas with a sketchy upper-air pattern, and while the models have sped up a bit, they're not shooting this thing up to NY super-fast. Given this, I would expect it to get to NY as a Cat 1.

This could all change, but at this point, I'm frankly puzzled by some of these intensity depictions at higher latitudes.

P.S. A Cat 1 hurricane is a big deal-- especially for the Northeast USA-- so I'm not at all downplaying it.

[HurricaneJosh]

To add to the above and give some historic perspective... Gloria 1985 blasted up the coast really fast-- it went from Cape Hatteras to Long Island in ~10 hr-- and when it hit Long Island, it was moving NNE at >35 kt. Even moving that fast, Gloria reached Long Island with winds of only 75 kt.

The current NHC track has Irene moving at about half that speed, as it shows the cyclone still S of OBX at 2 pm Saturday and near DE/NJ 24 hr later. Irene needs to haul azz to reach the Northeast USA as a good hurricane.

[N. OF PIKE]

in regards to intensity forecast, SHIPS maybe picking up on the issue Irene is having with dry air...

the first pic is the 1900UTC screen grab from a pwat animation...the black dashed arrow indicating drier air circulating into Irene..

the 2nd pic is from the Infrared RGB loop from the NWS site: Irene still spewing arc clouds, and i have placed a yellow circle (in the center) where perhaps the untrained eyes on this board may have mistakenly thought Irene was trying to form an eye, in reality it was just the effects of dry air circulating to the center of Irene and choking off convection

couldn't agree more

if i'm not mistaken there was a 968 pressure taken about 2 hours or more ago ...but it had 12knots winds approx...so it was likely a bit lower then ....don't see RI now...tommorrow pm IMO when that southerly inflow channel is wider and not downsloping 8000 foot mtns. tommorrow pm is her time to RI and she will bomb IMO

[PSUBlizzicane2007]

To add to the above and give some historic perspective... Gloria 1985 blasted up the coast really fast-- it went from Cape Hatteras to Long Island in ~10 hr-- and when it hit Long Island, it was moving NNE at >35 kt. Even moving that fast, Gloria reached Long Island with winds of only 75 kt.

The current NHC track has Irene moving at about half that speed, as it shows the cyclone still S of OBX at 2 pm Saturday and near DE/NJ 24 hr later. Irene needs to haul azz to reach the Northeast USA as a good hurricane.

To be fair, Irene will have both better upper level conditions and be better positioned over the Gulf Stream than Gloria

[hazwoper]

Also, Hurricane Gloria hit in late September. SSTs had to be quite a bit lower in the MA and NE then they are in mid to late August.

[HurricaneJosh]

To be fair, Irene will have both better upper level conditions and be better positioned over the Gulf Stream than Gloria

And moving much, much slower.

[NorthNJwx]

The Euro is really, really overplaying the strength. Usually for a strong hurricane to get to NY, it has to be 1) very intense down in the tropics (like a strong Cat 4) and/or 2) blasting up the coast mega-fast-- like, well over 30 kt. Right now, we have a Cat 1 in the Bahamas with a sketchy upper-air pattern, and while the models have sped up a bit, they're not shooting this thing up to NY super-fast. Given this, I would expect it to get to NY as a Cat 1.

This could all change, but at this point, I'm frankly puzzled by some of these intensity depictions at higher latitudes.

P.S. A Cat 1 hurricane is a big deal-- especially for the Northeast USA-- so I'm not at all downplaying it.

I was actually about to post something along these lines, and I'll throw in a little climatology for those unaware: the last hurricane in this part of the country was Bob in 1991. I was born earlier that year, so I've certainly never gotten to observe a hurricane in the northeast. While 20 years is, historically, a longer-than-average return period to get a hurricane in the northeast, it's proof that TCs of hurricane strength are a big deal up here. A Cat 3 like the 1938 storm is such a climatological rarity (and for good reason - if they were more common, the NE would be in trouble) that it's tough to even mention it in discussion, other than to say what is possible as a worst case scenario.

I agree that a Cat 1 is a totally big deal for us. It would be fascinating to see from a meteorological standpoint, and, for those young enough like myself, would be a first as well.

I think seeing the strength on the Euro is a sign that this storm could maintain hurricane intensity this far north. While it's almost certainly way, way stronger than whatever reality will bring, seeing a signal for something that deep might be meaningful. If she doesn't recurve too quickly, Irene may indeed be the first landfalling hurricane in the NE in 20 years, even if the Euro is many millibars too deep.

[LakeEffectKing]

To add to the above and give some historic perspective... Gloria 1985 blasted up the coast really fast-- it went from Cape Hatteras to Long Island in ~10 hr-- and when it hit Long Island, it was moving NNE at >35 kt. Even moving that fast, Gloria reached Long Island with winds of only 75 kt.

The current NHC track has Irene moving at about half that speed, as it shows the cyclone still S of OBX at 2 pm Saturday and near DE/NJ 24 hr later. Irene needs to haul azz to reach the Northeast USA as a good hurricane.

WRT this system near the northeast coast, this may be a case where we have a deep slp, but (as progged by most models) we will have a pretty darn good ongoing expansion of the wind field, which probably skew the normal correlations of SLP to max core winds. I could see a 950 slp with max sustained winds at 60kts....

[Typhoon Tip]

HurricaneJosh,

all salient points - can't say I disagree. There are just 2 caveats here ...with probably less than even concern but on the table nonetheless.

1) We are at the apex SST of the year. The shelf waters N of the Gulf Stream are in the mid to upper 70s. Obviously the standard model says that's not going to cut it, but, under certain circumstances, such as having very good deep layer mechanics, it would be interesting to see if this assists some robustness.

2) This situation appears to be modeled somewhat unusually in that upper level divergence over the TC and lower overall shear exists pretty far up the coast.

Definitely will be interesting... In the end, it would definitely be better if one is in the business of experiencing a big even to have Irene moving faster.

[HurricaneJosh]

Also, Hurricane Gloria hit in late September. SSTs had to be quite a bit lower in the MA and NE then they are in mid to late August.

Belle 1976 hit in mid-August. It went from a Cat 3 to barely a hurricane (65 kt) at landfall on Long Island because it never sped up like most Northeast USA hurricanes.

[jm1220]

The Euro is really, really overplaying the strength. Usually for a strong hurricane to get to NY, it has to be 1) very intense down in the tropics (like a strong Cat 4) and/or 2) blasting up the coast mega-fast-- like, well over 30 kt. Right now, we have a Cat 1 in the Bahamas with a sketchy upper-air pattern, and while the models have sped up a bit, they're not shooting this thing up to NY super-fast. Given this, I would expect it to get to NY as a Cat 1.

This could all change, but at this point, I'm frankly puzzled by some of these intensity depictions at higher latitudes.

P.S. A Cat 1 hurricane is a big deal-- especially for the Northeast USA-- so I'm not at all downplaying it.

I agree-a cat 1 here would be really bad, perhaps even devastating for some. Just 2 Sundays ago much of this area was ground to a halt because of the massive rains we had from stalled out T-storms, and many of us are barely recovered from the resulting basement/house/garage flooding. The ground is still wet here, and downed trees could be a huge problem. Also, the new moon would make tides even higher, plus whatever wave setup before a storm surge. Where I am would probably be under a few feet or more of water if Irene hit at high tide as even a 80-90 mph or so hurricane. And there's a lot of people potentially at risk who live in low enough lying areas to be inundated around this area. The damage would likely go up almost exponentially if by some chance we do get a cat 2 or more.

I remember the roaring nor'easter we had on 3/13/2010 and the amount of tree damage we suffered with de-foliated trees. This time of year it would be substantially worse. Not to mention, we're setting up for a pro-surfing contest that's starting up here on 9/1. This is a hugely inconvenient time for this to be arriving.

[Riptide]

Belle 1976 hit in mid-August. It went from a Cat 3 to barely a hurricane (65 kt) at landfall on Long Island because it never sped up like most Northeast USA hurricanes.

I guess we should factor in oceanic upwelling even though SST's are reasonable warm (25-27C) south of Long Island, they don't extend far below the surface.

[HurricaneJosh]

I was actually about to post something along these lines, and I'll throw in a little climatology for those unaware: the last hurricane in this part of the country was Bob in 1991. I was born earlier that year, so I've certainly never gotten to observe a hurricane in the northeast. While 20 years is, historically, a longer-than-average return period to get a hurricane in the northeast, it's proof that TCs of hurricane strength are a big deal up here. A Cat 3 like the 1938 storm is such a climatological rarity (and for good reason - if they were more common, the NE would be in trouble) that it's tough to even mention it in discussion, other than to say what is possible as a worst case scenario.

I agree that a Cat 1 is a totally big deal for us. It would be fascinating to see from a meteorological standpoint, and, for those young enough like myself, would be a first as well.

I think seeing the strength on the Euro is a sign that this storm could maintain hurricane intensity this far north. While it's almost certainly way, way stronger than whatever reality will bring, seeing a signal for something that deep might be meaningful. If she doesn't recurve too quickly, Irene may indeed be the first landfalling hurricane in the NE in 20 years, even if the Euro is many millibars too deep.

Agreed. I think it's significant that the Euro is showing an intense system up N-- it says that the Euro senses a favorable upper-air pattern and that it might get N pretty strong. I just think it's important not to get too caught up with those exact mb values.

WRT this system near the northeast coast, this may be a case where we have a deep slp, but (as progged by most models) we will have a pretty darn good ongoing expansion of the wind field, which probably skew the normal correlations of SLP to max core winds. I could see a 950 slp with max sustained winds at 60kts....

With the exception of the 1938 hurricane, all of the important* ones that hit Long Island made landfall with pressures in the low 960s, and those 'canes had winds ranging from 75 kt (Gloria) to 100 kt (Carol). Given that, I don't think a 950 mb system would have winds that low, even when taking into account the fact that higher-latitude wind-pressure relationships are very different than in the tropics.

(* Belle was 980 mb/65 kt.)

HurricaneJosh,

all salient points - can't say I disagree. There are just 2 caveats here ...with probably less than even concern but on the table nonetheless.

1) We are at the apex SST of the year. The shelf waters N of the Gulf Stream are in the mid to upper 70s. Obviously the standard model says that's not going to cut it, but, under certain circumstances, such as having very good deep layer mechanics, it would be interesting to see if this assists some robustness.

2) This situation appears to be modeled somewhat unusually in that upper level divergence over the TC and lower overall shear exists pretty far up the coast.

Definitely will be interesting... In the end, it would definitely be better if one is in the business of experiencing a big even to have Irene moving faster.

Yep-- we'll just have to wait and see! I'm curious to see how it plays out.

[TheWeatherPimp]

[phil882]

http://philstropical...l-on-the-table/

My Updated Thoughts, where I give a simple explanation for why the models have trended farther right in the last 48 hours. Believe it or not, it seems like the GGEM had the right idea at the time with the weak s/w that is off the east coast currently helping to weaken the ridge more than expected and allowing a more poleward movement initially. However, I think the models in the longer range are a bit too weak with the ridge to the west mainly because of trying to redeveloping Invest 98L more than what will likely occur in reality which beats down the ridge more what might happen in reality. My forecast is very close to the NHC in the longer range intervals.

[winterymix]

[ My Updated Thoughts,

Nice presentation, Phil. I have a question;

Do you have any thoughts about biases innate to the Canadian model? I seem to recall that it would

typically place low pressure systems too far east off of the East Coast. Is that the case and is it a factor

here?

[Mitchel Volk]

Looking at the latest recon report Irene is deepening rapidly and I would estimate the surface winds around 100-110MPH. The current computer models and NHC keep shifting the track further east, I think that Long Island and southeastern New England are at greatest risk for a cat 1-3 storm. I could only hope it keeps trending east, but at this point I am worried that there could be considerable damage. With this economy and the government unwilling to spend on anything we do not need this.