Category Five Hurricane Lee

[NJwx85]

12z GFS is about 50-75 miles SW of the 06z position valid 00z Thursday.

[Hotair]

Initialized Lee at 991 mb Where  do they get these #s ?  

[MJO812]

[NJwx85]

12z GFS looks headed for a landfall in either down east Maine or Nova Scotia. 

[OSUmetstud]

Westward short term adjustments to Lee don't increase US landfall probabilities much if it at all because they also delay latitude gain with the Great Lakes trough trending eastward and having a tendency to pull out of the northeast with time. 

[Derecho!]

4 minutes ago, Hotair said:

Initialized Lee at 991 mb Where  do they get these #s ?  

 

Was already explained to you earlier in the thread. Global models lack the resolution (and it's worse the less sophisticated they are, like the GEM)  to deal with the pressure differentials across small distances from a tropical cyclone.  Would break the model with a true pressure init. 

[MJO812]

1 minute ago, NJwx85 said:

12z GFS looks headed for a landfall in either down east Maine or Nova Scotia. 

High pressure popped up to the north where 6z had a low.

[NJwx85]

1 minute ago, MJO812 said:

High pressure popped up to the north where 6z had a low.

The second trough lifted out faster but it's still moving North due to the flow around the high to the East.

[mob1]

4 minutes ago, OSUmetstud said:

Westward short term adjustments to Lee don't increase US landfall probabilities much if it at all because they also delay latitude gain with the Great Lakes trough trending eastward and having a tendency to pull out of the northeast with time. 

Correct, though speed/timing of both Lee and through/front/HP could have a bigger impact on where it ultimately ends up. 

[MJO812]

1 minute ago, NJwx85 said:

The second trough lifted out faster but it's still moving North due to the flow around the high to the East.

Agree 

 

[MJO812]

[MJO812]

Cmc further offshore

[NJwx85]

7 minutes ago, OSUmetstud said:

Westward short term adjustments to Lee don't increase US landfall probabilities much if it at all because they also delay latitude gain with the Great Lakes trough trending eastward and having a tendency to pull out of the northeast with time. 

The runs which hit land mostly have have the second trough lifting out and then the steering currents are left to the clockwise rotation around the high to the East. 

This run would be a big hit in Eastern Maine and Nova Scotia. 

[NJwx85]

1 minute ago, MJO812 said:

Cmc further offshore

Still makes landfall in Nova Scotia. A little East of the GFS. 

[Hazey]

Damn. That's like multiple gfs runs that are zeroing in on sw Nova Scotia. Still a long ways off but that's a bad track for up here. Lee better have crap beat out of it before it gets to this latitude. Yikes.

[NotSureWeather]

Still too close to the cape and SEMA for my liking.

[guinness77]

19 minutes ago, MJO812 said:

Regardless of where it eventually ends up, what a monster of a storm, wow, the size alone. 

[olafminesaw]

1 minute ago, Hazey said:

Damn. That's like multiple gfs runs that are zeroing in on sw Nova Scotia. Still a long ways off but that's a bad track for up here. Lee better have crap beat out of it before it gets to this latitude. Yikes.

Yeah, it's been rock steady for several days now (keep in mind the heavy precip is west of the track). 

[Hotair]

21 minutes ago, Derecho! said:

Was already explained to you earlier in the thread. Global models lack the resolution (and it's worse the less sophisticated they are, like the GEM)  to deal with the pressure differentials across small distances from a tropical cyclone.  Would break the model with a true pressure init. 

Ok it was not clear from previous response that it would actually break the model if they used real values.  It just seemed like a capricious choice 

[Derecho!]

7 minutes ago, Hotair said:

Ok it was not clear from previous response that it would actually break the model if they used real values.  It just seemed like a capricious choice 

Think about and ECMWF model run predicting a tornedo outbreak. The air pressure within an individual tornedo might be 850 mb; when you look at the model run you aren't going to see any 850 mb pressures within actual tornadoes - tornadoes are far tinier than the 9 km grid spacing of the ECMWF. 

[CheeselandSkies]

Think about and ECMWF model run predicting a tornedo outbreak. The air pressure within an individual tornedo might be 850 mb; when you look at the model run you aren't going to see any 850 mb pressures within actual tornadoes - tornadoes are far tinier than the 9 km grid spacing of the ECMWF. 

A couple of the high-res CAMs (NOT the HRRR!) actually appeared to quite accurately resolve* the mesocyclone associated with the Table Grove/Lewistown, IL tornadic supercell on April 4 nearly 24 hours in advance. Unfortunately I didn't put enough stock in them to catch it (ended up too late to the area and stuck on the wrong side of the storm near Monmouth when the warning went out, and I don't core-punch unless I am fairly confident that the conditions do not favor large, damaging hail). However even they couldn't resolve individual tornadoes, unless they were predicting something the size of El Reno '13.
*As in not just helicity tracks, but a localized pressure perturbation with extremely tightly packed isobars on the surface map.

[NeffsvilleWx]

41 minutes ago, Hotair said:

Ok it was not clear from previous response that it would actually break the model if they used real values.  It just seemed like a capricious choice 

 

1 hour ago, Derecho! said:

Was already explained to you earlier in the thread. Global models lack the resolution (and it's worse the less sophisticated they are, like the GEM)  to deal with the pressure differentials across small distances from a tropical cyclone.  Would break the model with a true pressure init. 

 

Cells are an average value of all their contents. If a cell has pressure values of 1024, 1028, 1010, 1015, and 948, then that cell will be given a value of 1005. Even though there's a 948 mb low in there.

There's probably some fancy math nuance to it that mets could chime in on, but I believe this is the gist of it (cell dimensions vary by model). 

 

[GaWx]

5 hours ago, Hotair said:

Model track accuracy for Lee 

 

This shows the UKMET having had the smallest mean absolute error for both 24 and 48 hours out and the Euro being second best for both timeframes.

[Amped]

This could end up being like Typhoon Mawar back in May which fell apart for a day and then rapidly strengthened back to a super Typhoon.

[GaWx]

 I saw no more direct US hits on the 0Z EPS after hour 240. So, the hit % for the US went down from 24% on yesterday's 12Z to 14% on today's 0Z. ME remains at the highest risk of any US state per the EPS:

Summary of recent EPS runs' US landfalls:

9/8 0Z: 7 (14%) 9/15-17 (6 ME, 1 NY)
9/7 12Z: 12 (24%) 9/15-19 (7 ME, 3 MA, 1 NY, 1 NJ)
9/7 0Z: 10 (20%) 9/15-18 (5 ME, 5 MA)
9/6 12Z: 3 (6%) 9/15-18 (2 ME, 1 MA)
9/6 0Z: 5 (10%)
9/5 12Z: 2 (4%)
9/5 0Z: 4 (8%) 
9/4 12Z: 1 (2%) 
9/4 0Z: 2 (4%)

[StantonParkHoya]

I’m confused as to what people are still looking for here? Whether it scrapes MA or ME? I think that’s going to be a gametime decision.

[cptcatz]

12z Euro initializing at 984, steady for the next 24 hours, and still brings it down to 924 north of Puerto Rico, a difference of 60 mb.  With it actually being 942 right now, does that mean it really gets down to 882?

[StantonParkHoya]

Euro almost hits Bermuda on the way NE

[GaWx]

The 12Z Euro at 192 is ~100 miles SSW of the 0Z Euro at 204 at the latitude of Cape Hatteras though many hundreds of miles OTS. The 12Z yesterday for the same time (216) was landfalling in E ME!

 It looks like Nova Scotia is going to be hit on this new run.

[NJwx85]

12z ECMWF with a Nova Scotia landfall on Sunday the 17th.