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Tropical Major Hurricane Florence

Well, my office is closing tomorrow at 12 and will be closed Friday.
 
Anyone like to elaborate on the this comment in the NHC discussion? Is this what was expected and the reason for the southward shift or something new, they sound as if this is another wrinkle in the forecast...

The shortwave trough over the southern Plains seen in water vapor
imagery could end up being a significant factor as it rounds the
narrow ridge over the Tennessee Valley and is expected to erode the
ridge along the U.S. mid-Atlantic coast on days 3-5. At this time,
little change has been made to the NHC track forecast, which remains
very close to the aforementioned consensus aids through 72 hours.
 
metwannabe said:
Anyone like to elaborate on the this comment in the NHC discussion? Is this what was expected and the reason for the southward shift or something new, they sound as if this is another wrinkle in the forecast...

The shortwave trough over the southern Plains seen in water vapor
imagery could end up being a significant factor as it rounds the
narrow ridge over the Tennessee Valley and is expected to erode the
ridge along the U.S. mid-Atlantic coast on days 3-5. At this time,
little change has been made to the NHC track forecast, which remains
very close to the aforementioned consensus aids through 72 hours.
Click to expand...


Sounds like they don’t know where TF to draw the lines & cones because this model output is unlike anything we’ve ever seen. Seems like they want a few more model suites before they draw loops and stalls in....JMO, but I don’t do this for a living.


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I'm an amateur (hence the name metwannabe) but seeing that ridge to her east and that trough to the west and the current quick NW motion, I'm not buying this southward thing until it happens.... yeah yeah I'm an idiot I know but sure a long way to go with her just yet imo
 
metwannabe said:
Anyone like to elaborate on the this comment in the NHC discussion? Is this what was expected and the reason for the southward shift or something new, they sound as if this is another wrinkle in the forecast...

The shortwave trough over the southern Plains seen in water vapor
imagery could end up being a significant factor as it rounds the
narrow ridge over the Tennessee Valley and is expected to erode the
ridge along the U.S. mid-Atlantic coast on days 3-5. At this time,
little change has been made to the NHC track forecast, which remains
very close to the aforementioned consensus aids through 72 hours.
Click to expand...

It sounds to me like they might be expecting less of a stall and more of a west motion or northwest motion as the shortwave breaks down the ridging allowing her to pull more to the north... but that's just a guess.
 
Any erosion or changes to the ridge will effect how long she sits and where she eventually goes. She'll follow the path of least resistance.. and with the steering pattern being virtually nill (as modeled), anything will nudge her around given the opportunity. NHC is just introducing the idea that there could be a change to the ridge based on a shortwave trof and to keep the option on the table that the track may start to change on modeling day 3+.
 
Of note the ICON stalls to the east of it's 06z run and then drifts it west into the Wilmington area through hour 72.
 
South AL Wx said:
092830_5day_cone_no_line_and_wind.png
Click to expand...
Upstate track? Great...
 
Yeah, at 81, the ICON is slightly east of its 87 hour 6z location.
 
It would seem from the 12z models so far that the bend to the sw or wsw isn't as pronounced and the stall is shorter... Let's see if the globals show the same or different.
 
ICON substantially farther north than 6z. Never gets into SC. Ruh Roh.
 
The one thing I’m fairly confident of is that should there be a stall of ~24 hours while still offshore, the likelihood of significant weakening then would be high. I don’t recall off the top of my head a single instance of a very strong storm like this in the Atlantic stalling or even just slowing down to a crawl not weakening substantially. As I understand it, this is possibly due to a combo of 1) energy being extracted from the top layers of the ocean to feed the storm in the general vicinity of the center....conservation of energy concept (a principle stating that energy cannot be created or destroyed, but can be altered from one form to another) and 2) The rain cooled air for such a long period with no warming sunshine over a larger portion of the ocean (diameter of several hundred miles for this big of a storm) covered by the rain shield, would itself, likely cause cooling of a few degrees on its own. Perhaps these 2 things are interdependent/overlapping to some extent.

So, if it were still a major when this potential 24+ hour slow down and/or stall were to start, I’d bet on a weakening at least down to category 2 and possibly even down to a cat 1 as of the end of the 24 hours. I suppose she could restrengthen some once she started moving again but I wouldn’t expect her to come close to her pre-stall strength if for no other reason that a good portion of her would likely be over land then. The caveat though to the chance for restrengthening much after the weakening is a stall a good bit further offshore than even the 0Z Euro showed. That possibility also needs to be considered since that may be the trend going forward.

In talking about this likely weakening during any prolonged crawling/stalling, I’m not trying to downplay if she were to weaken to a cat 2 or even to a cat 1 as the effects on land would likely still be major all around her wherever she ends up going mainly due to her large size.

Any thoughts? By the way, I realize the waters right over the Gulf Stream would likely remain warmer than surrounding areas, regardless.

(PS, yes I still have reservations just in case)
 
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