Major Hurricane Irma

[NJwx85]

3 minutes ago, Windspeed said:

It did form from an African wave just like Harvey formed from an African wave. Is Harvey a Cape Verde hurricane? I understand your point. But the majority of systems develop out of African waves at some point and their interaction with the ITCZ. The idea here I am stressing is a "Cape Verde long-tracking major hurricane." I believe there is a difference.

 

Yes I would consider Harvey a CV storm, it was first designated East of the lesser antilies in the MDR. The fact that it dissipated and reformed is irrelevant since it was the same system.

[NJwx85]

Let's not drag this thread off topic, what constitutes a CV hurricane is a grey area.

[Windspeed]

18 minutes ago, NJwx85 said:

Let's not drag this thread off topic, what constitutes a CV hurricane is a grey area.

 

Quote

Cape Verde-type hurricanes are those Atlantic basin tropical cyclones that develop into tropical storms fairly close (<1000 km [600 mi] or so) of the Cape Verde Islands and then become hurricanes before reaching the Caribbean. (That would be my definition, there may be others.) Typically, this may occur in August and September, but in rare years (like 1995) there may be some in late July and/or early October. The numbers range from none up to around five per year - with an average of around 2.

 

I'll take the NOAA Hurricane Research Division's definition and we'll just have to agree to disagree.

 

[Drz1111]

Environmental conditions for an annular hurricane are going to be in place for this in 3 days or so.

[bluewave]

If Irma can make it all the way to the US, then it will be first storm named near 30W to make it since Ivan in 2004.

[Windspeed]

Environmental conditions for an annular hurricane are going to be in place for this in 3 days or so.

 

27° SSTs, perhaps 28° if it loses some latitude. But certainly the potential exists that current banding features around Irma could dissipate. If Irma has a strong core, it could very well evolve into a donut. It might still have a moist enough envelope on the southern extent to maintain banding out of the ITCZ. Again, just depends on how much latitude it gains as it crosses the MDR and how much dry air persists in the mid-levels.

 

Good call!

 

[jburns]

1 hour ago, NJwx85 said:

Not really. Matthew 2016.

 "So the last shall be first, and the first last: for many be called, but few chosen."  Not sure what that has to do with Irma, but OK.

[SnowGoose69]

I always say with these the faster it goes crazy the better since they just don't maintain cat 4 or 5 status for long.  If it struggles for the first 3-4 days that could be trouble when and if it reaches the islands  

[NJwx85]

2 minutes ago, SnowGoose69 said:

I always say with these the faster it goes crazy the better since they just don't maintain cat 4 or 5 status for long.  If it struggles for the first 3-4 days that could be trouble when and if it reaches the islands  

NHC says it could encounter slightly cooler water and drier air beyond day 3, however that would be short lived. Upper level winds are expected to remain relatively favorable throughout the track, so who knows.

[jbenedet]

1 hour ago, NJwx85 said:

That's a really deep trough on the GFS near the East coast days 8-9. I wouldn't be shocked if a few ensemble members showed a capture.

Timining is off by 24-48 hrs for a capture. Base of the trough is off the east coast before Irma makes it past Bermuda's longitude. Euro shows this as well.  

With the strength of the ridge over the western Atlantic and the missed timing of the deep trough over the eastern CONUS around day 9, I'm leaning that Irma heads west into Fla or the Keys.

Plenty of time obviously, but based on current guidance I don't see her getting picked up around day 9--I need to see big timing changes on guidance first. And if that's the case, that ridge is taking her west.

[Vice-Regent]

[MJO812]

7 minutes ago, Vice-Regent said:

That's pretty far south

[Vice-Regent]

1 minute ago, Snow88 said:

That's pretty far south

The hallmarks or classic signs are all there if you are looking for a conus landfall.

[NJwx85]

1 minute ago, Vice-Regent said:

The hallmarks or classic signs are all there if you are looking for a conus landfall.

It could also take a poor track and end up getting shredded by Hispanolia, Cuba or both.

[Vice-Regent]

16 minutes ago, NJwx85 said:

It could also take a poor track and end up getting shredded by Hispanolia, Cuba or both.

Usually a consensus track between the Euro and GFS ends up verifying. With Irma being so strong, hard to envision without a historically strong ridge.

[SN_Lover]

The 18z scares the ###t out of me. Trend that trough more negatively and you got major issues. 

 

[Vice-Regent]

The best part of the 18z GFS was that it's a non-phased TC impact in New England. That's quite unprecedented imo.

[Windspeed]

The hallmarks or classic signs are all there if you are looking for a conus landfall.

 

 

 

Obviously, the "what ifs" for the CONUS that will play out will drive the bulk of attention for Irma on this forum, but we should not downplay attention to a possible more immediate threat to the islands. Not that you are, I am just concerned that Irma could be a threat to the northern Lesser Antilles as a major hurricane first and foremost regardless of what happens beyond any long range forecast uncertainty. Which, of course, would put territory under U.S. responsibility at risk along with the UK and France. Obviously, still way too early even with respect to the Antilles, but the south of west to WSW track in the model consensus is concerning. Will be interesting to see how the models handle that motion and what actually plays out.

 

[yoda]

Tropical Storm Irma Discussion Number   3
NWS National Hurricane Center Miami FL       AL112017
1100 PM AST Wed Aug 30 2017

Irma continues to become better organized, with the development of
a small CDO feature and increased banding near the center.  An
earlier high-resolution Windsat microwave overpass showed that Irma
has a tight inner core and a low-level eye-like feature was
present.  A Dvorak classification of T3.5 from TAFB is the basis
for the initial intensity of 55 kt.  Irma is expected to steadily
strengthen during the next couple of days while it moves through a
low-shear and moist environment, and remains over warm sea
surface temperatures.  After that time, slightly cooler SSTs and
lower mid-level moisture may temper the intensification process.
However, the statistical aids, HWRF, and most of the consensus
models make Irma a major hurricane by the end of the forecast
period.  The NHC forecast is fairly similar to the previous advisory
through 48 hours, but is above the earlier forecast thereafter.  The
new official intensity forecast could still be a little conservative
as it remains a little below the SHIPS/LGEM guidance and the ICON
consensus at days 4 and 5.

Irma is moving westward at about 10 kt to the south of deep-layer
ridge over the eastern Atlantic.  The track forecast reasoning is
about the same as the previous advisory, with Irma expected to turn
west-northwestward on Thursday, then continue on that heading
for a couple of days.  The high pressure ridge over the central
Atlantic is forecast to strengthen later this week, which is
expected to result in Irma turning west-southwestward by the
weekend.  There is still some spread among the track models, so the
NHC forecast lies near a blend of the typically reliable GFS and
ECMWF, and the HFIP corrected consensus.


FORECAST POSITIONS AND MAX WINDS

INIT  31/0300Z 16.4N  32.2W   55 KT  65 MPH
 12H  31/1200Z 16.8N  33.6W   65 KT  75 MPH
 24H  01/0000Z 17.3N  35.5W   75 KT  85 MPH
 36H  01/1200Z 17.7N  37.3W   85 KT 100 MPH
 48H  02/0000Z 18.0N  39.5W   90 KT 105 MPH
 72H  03/0000Z 17.6N  44.3W   95 KT 110 MPH
 96H  04/0000Z 16.8N  49.0W  100 KT 115 MPH
120H  05/0000Z 16.2N  53.5W  105 KT 120 MPH

$$
Forecaster Brown

[LandofLincoln]

Beat me to it. 

Did not take long for that to reach hurricane status..

[hlcater]

2 hours ago, Windspeed said:

 

Obviously, the "what ifs" for the CONUS that will play out will drive the bulk of attention for Irma on this forum, but we should not downplay attention to a possible more immediate threat to the islands. Not that you are, I am just concerned that Irma could be a threat to the northern Lesser Antilles as a major hurricane first and foremost regardless of what happens beyond any long range forecast uncertainty. Which, of course, would put territory under U.S. responsibility at risk along with the UK and France. Obviously, still way too early even with respect to the Antilles, but the south of west to WSW track in the model consensus is concerning. Will be interesting to see how the models handle that motion and what actually plays out.

 

When was the last time the Lesser Antilles had a major hurricane? I remember an awful lot of TSs and weak hurricanes recently, but nothing too significant.

[Windspeed]

When was the last time the Lesser Antilles had a major hurricane? I remember an awful lot of TSs and weak hurricanes recently, but nothing too significant.

Omar was the last major in 2008. Earl was very close in 2010, becoming a major as it left the Virgin Islands.

[Chinook]

I believe Hurricane Ivan of the 2004 season may have been the most recent Cat-3 or greater at the Lesser Antilles. It passed near Granada, and Trinidad and Tobago, as Cat- 3. Hurricane Dean of 2007 was close. It reached the Category 3 status was reached as it was departing the Lesser Antilles area.

 

Edit: I was wrong, but at least I posted some good info.

[SN_Lover]

Another GFS run below. The Euro has been more consistent IMO. 

 

[Chinook]

Has the GFS ever predicted an 894mb pressure?

[SN_Lover]

Just now, Chinook said:

Has the GFS ever predicted an 894mb pressure?

Context? 

[LandofLincoln]

Euro has been consistent with it being further south, but I wouldn't necessary say it's been more consistent than the GFS with its own solution.

Like, the Euro at HR 216 on the 12z:

Compared to what it was like on the 00z:

I wouldn't really expect any of the models to be too reliable at this point in time anyway.

[brooklynwx99]

3 minutes ago, SN_Lover said:

Context? 

 

[SN_Lover]

Just now, brooklynwx99 said:

 

didn't know the site had that. 

 

All ill say is that the phasing is similar to sandy on the 0z and that scares the crap out of me. I pray the next run changes, and im sure it will. This county can't afford to be hit twice in 1 year like that. 

[brooklynwx99]

Wow. Eventual full capture over Maine per 00z GFS. Just another possible outcome on the table.