• Hello, please take a minute to check out our awesome content, contributed by the wonderful members of our community. We hope you'll add your own thoughts and opinions by making a free account!

Tropical Major Hurricane Florence

So, we want it to stay a strong cane now in order to curve out to sea, versus weakening now and a greater chance of hitting land and strengthening again before it does.
 
Last edited by a moderator:
So, we want it to stay a strong cane now in order to curve out to sea, versus weakening now and a greater chance of hitting land and straightening again before it does.

Exactly. A stronger cane increases the chance of it staying away from NC whereas the rapid weakening we are seeing right now, if it lasts awhile, could allow stronger ridging to build and push this more to the west. The next 36 hours will reveal which scenario is correct.
 
Exactly. A stronger cane increases the chance of it staying away from NC whereas the rapid weakening we are seeing right now, if it lasts awhile, could allow stronger ridging to build and push this more to the west. The next 36 hours will reveal which scenario is correct.

The shear is supposed to relax by tomorrow or Saturday.


Sent from my iPhone using Tapatalk
 
Barely looks like a hurricane anymore and new estimates have it barely one with only around 80 mph winds.

It's weakening much faster than the GFS indicated which leads me to believe the south/west tracks may have a higher chance of verifying going forward. Already the 12z NAM is coming in south and weaker with Florence and even though it's not a good model to use for the tropics the trends in it can be useful to get an idea for what the other models may do in the short term.
 
The shear is supposed to relax by tomorrow or Saturday.

Yep probably by tomorrow the shear should let up but this is barely a hurricane now and IMO probably a tropical storm now. Dry air has also penetrated the core and will take some time for Florence to rebuild from the shear and core disruption. A further west track is looking more likely at this time due to this rapid weakening.
 
Not only that, but with a mega ridge building over the top of it, it could rapidly restrengthen in it's final approach to the eastern U.S. Despite it's ghastly appearance now, Florence could once again blossom into a big-time storm before a potential landfall. Assuming the ridge is as strong as most NWP is currently suggesting, I think the odds are increasing by the hour that Florence is going to make an awfully close pass to the CONUS.
The thing that’s crazy is it made it to a major hurricane within a very hostile environment! It just cruises as weak storm for awhile and doesn’t get picked up, there’s plenty of good environment and of course the Gulf Stream, if it doesn’t recurve!
 
Not only that, but with a mega ridge building over the top of it, it could rapidly restrengthen in it's final approach to the eastern U.S. Despite it's ghastly appearance now, Florence could once again blossom into a big-time storm before a potential landfall. Assuming the ridge is as strong as most NWP is currently suggesting, I think the odds are increasing by the hour that Florence is going to make an awfully close pass to the CONUS.

The upper level pattern depicted is scary.. basically perfect outflow and absolutely 0 shear on the GFS with a massive anticyclone over Florence.
gfs_shear_atl_25.png
 
The thing that’s crazy is it made it to a major hurricane within a very hostile environment! It just cruises as weak storm for awhile and doesn’t get picked up, there’s plenty of good environment and of course the Gulf Stream, if it doesn’t recurve!

Makes me think what will happen when she gets into the primo environment.


Sent from my iPhone using Tapatalk
 
The upper level pattern depicted is scary.. basically perfect outflow and absolutely 0 shear on the GFS with a massive anticyclone over Florence.
gfs_shear_atl_25.png

Even if it does miss you could have 40ft swells generated just off shore.


Sent from my iPhone using Tapatalk
 
Florence is currently under ~30 KT of westerly-southwesterly shear according to both the CIMSS and the GFS vortex averaged skew Ts at initialization and most of this shear is in the mid-levels. You can also see that as Florence's rossby penetration depth becomes shallower due to weakening & asymmetrization of the storm's warm core, a larger proportion of the total integrated steering flow will be comprised of east-southeasterly flow at/below 600 hPa, hence the expected turn to the W or WNW in the next day or two. The evolution of the s/w trough associated w/ Gordon's remnants near the lower MS valley will be crucial to monitor going forward because in order to get stronger flow reversal under the building ridge to its north, a prolonged NW track like Hugo, Isabel, et al vs a broader recurvature, this feature usually needs to be present and in relatively close proximity to the storm. This remnant upper level trough being over the Gulf coast for example while our storm is offshore the SE US is often sufficiently close in instances like this.


gfs_vortex_sounding_06L_2.png
 
Florence is currently under ~30 KT of westerly-southwesterly shear according to both the CIMSS and the GFS vortex averaged skew Ts at initialization and most of this shear is in the mid-levels. You can also see that as Florence's rossby penetration depth becomes shallower due to weakening & asymmetrization of the storm's warm core, a larger proportion of the total integrated steering flow will be comprised of east-southeasterly flow at/below 600 hPa, hence the expected turn to the W or WNW in the next day or two. The evolution of the s/w trough associated w/ Gordon's remnants near the lower MS valley will be crucial to monitor going forward because in order to get stronger flow reversal under the building ridge to its north, a prolonged NW track like Hugo, Isabel, et al vs a broader recurvature, this feature usually needs to be present and in relatively close proximity to the storm. This remnant upper level trough being over the Gulf coast for example while our storm is offshore the SE US is often sufficiently close in instances like this.


View attachment 5870

You mean like Fran?


Sent from my iPhone using Tapatalk
 
Exactly. A stronger cane increases the chance of it staying away from NC whereas the rapid weakening we are seeing right now, if it lasts awhile, could allow stronger ridging to build and push this more to the west. The next 36 hours will reveal which scenario is correct.
And all depends how far west she travels before Flo feels the effects to start pulling a wnw or nw motion again. If Flo stays strong on a due west movement or even a wsw/sw as some models are saying, could she miss the pull and put her in a new ballgame as in the track?
 
You mean like Fran?


Sent from my iPhone using Tapatalk
Fran is also a good example. The placement of that upper level trough and it’s general presence are important, if it’s over the east-central Gulf Coast, or Deep South, it could drag Florence further into the southeastern US overall. Obviously, this doesn’t mean Florence wouldn’t be capable of doing this w/o it but the odds definitely would increase a lot. Lots of time left to sort this out.
 
Don't know how to post this to run but click the link and look at the worrisome evolution of the NHC track.

https://www.nhc.noaa.gov/archive/2018/FLORENCE_graphics.php?product=5day_cone_no_line

Sent from my SM-G920V using Tapatalk
The archives really won't let you save them as a .gif; it takes 3rd party software.
This is one of the most telling links regarding 'canes; it's in our Wiki by the way, so that any storm's NHC model history can be viewed. The "parent" link is here ... https://www.nhc.noaa.gov/archive/ or better yet, go to our Wiki for this and many other useful tools!

The evolution is a bit disconcerting, btw ... :eek:
 
Question. So the weaker this thing is, the further west it will track. I understand that, but the second this thing ramps back up will it start to recurve? I mean is there any way this thing makes a b line for the eastern shore as a Cat 3-4? Seems to me like if this thing wants to be a major hurricane then, at best (or worst), it’s going to ride the shoreline and pull back it to sea. Impacts would still be heavy nonetheless (Disclaimer: this is mostly opinionated)
 
Question. So the weaker this thing is, the further west it will track. I understand that, but the second this thing ramps back up will it start to recurve? I mean is there any way this thing makes a b line for the eastern shore as a Cat 3-4? Seems to me like if this thing wants to be a major hurricane then, at best (or worst), it’s going to ride the shoreline and pull back it to sea. Impacts would still be heavy nonetheless (Disclaimer: this is mostly opinionated)
The weaker it is the further south and west it will go. It's almost down to a weak cat 1 per Dvorak estimates now and the NHC mentions the ridge building in from the north. I believe, just a thought, that if it remains weak in this time period it will start going due west since it's slowed down now, and usually indicates a change in course. It may even veer WSW a bit more than the NHC cone has it in response to the heavy ridge. However, once the ridge builds and it restrengthens, it'll be ridge VS storm. As soon as the ridge moves past the storm should pull northward unless another one builds in faster. Any speed changes will be extremely influential as well whether it be now or down the road. If it's flying towards the coast it'll be slower to turn unless it hits something to pull it north. Certainly worrying if it doesn't make any turn down the road.
 
Question. So the weaker this thing is, the further west it will track. I understand that, but the second this thing ramps back up will it start to recurve? I mean is there any way this thing makes a b line for the eastern shore as a Cat 3-4? Seems to me like if this thing wants to be a major hurricane then, at best (or worst), it’s going to ride the shoreline and pull back it to sea. Impacts would still be heavy nonetheless (Disclaimer: this is mostly opinionated)

The key is how the ridge builds in. A stronger storm that tracks to the north forces the ridging to build further north and it's weaker as the GFS shows. A weaker storm allows stronger ridging to build in and push this a good deal further west. The GFS solution displaces the ridging to the north while the Euro/UK solution allows it to build further south thus resulting in a longer amount of time it is under the influence of the ridging for a westerly motion. It would all depend on timing and any weaknesses in the ridging if we get a cat 4 or 5 as to how close to the coast it comes... but a weaker storm will significantly increase the chances for a land threat IMO. This is likely a TS now and not a hurricane.
 
Now the west turn is occurring though it is as has been mentioned further north than the far south UKMET has been showing. Will this lead to somewhat further north UKMET adjustments or not? We should finally know the answer over the next few runs now that the west turn (and possibly WSW for a time) is occcuring. I’ll continue to follow the UKMET initializations closely.
 
Here is why Florence is weakening so rapidly and why I expect it to continue, possibly to weak TS strength later today. Mid-level shear is very strong over Florence and it's been my observation over the years that this type of shear is far more destructive to well established and powerful hurricanes like Florence was. Once she gets past this she should flare up and restrengthen considerably but I don't expect that to happen for another 18-30 hours. Also of note the GFS only weakens her to about 978mb on the newest run which is way too strong IMO. It will probably start adjusting this afternoon and tonight and shifting west as a result.
wg8midshr.GIF
 
Gfs picked up on it being weaker. 22mb weaker at hour 12. Let’s see what changes that leads to!

Are you sure? Hour 12 it shows 975mb vs 982mb in the prior run at the same time. It's actually stronger and it doesn't seem it has yet picked up on the rapid weakening we are observing. By hour 48 it is 967mb vs 973mb in the previous run so the GFS is actually stronger so far and doesn't match up with what we are seeing right now... so it will likely have a N bias as a result.
 
Are you sure? Hour 12 it shows 975mb vs 982mb in the prior run at the same time. It's actually stronger and it doesn't seem it has yet picked up on the rapid weakening we are observing. By hour 48 it is 967mb vs 973mb in the previous run so the GFS is actually stronger so far and doesn't match up with what we are seeing right now... so it will likely have a N bias as a result.
Yea my bad my eyes are not working today. Saw 955 as opposed to 985. Smh lol
 
Here's the current steering map for a 970-989mb system. Shows a solid westerly track for the foreseeable future as Florence bumps against the ridging.
wg8dlm3.GIF
 
gfs_mslp_pcpn_atl_7.png
Hour 42 still wsw movement. But I bet that wsw happens before than and put Flo further sw than gfs is showing
 
Great post. It's pretty obvious based on today's developments that Florence is coming well west. Like you said, it'll take the GFS several more runs to catch up probably. The big questions are going to be how soon does it regain intensity, and what will the upper ridge do to it?
Have to watch the runs closely because the GFS and CMC keep wanting to merge Invest 92L and to be designated Invest 93L and shove them northward, which would definitely influence the speed at which the initial high moves out or even if this new low pops up east of that high as well.
 
Great post. It's pretty obvious based on today's developments that Florence is coming well west. Like you said, it'll take the GFS several more runs to catch up probably. The big questions are going to be how soon does it regain intensity, and how will the upper ridge and Gordon's remnants evolve?

At this point I'm thinking a blend of the Euro and UK may be pretty reasonable. I think the Euro has a pretty good handle on the evolution going forward and this would put SC/NC at risk of a potential strengthening hurricane if it verifies. Even with the GFS showing a stronger storm on today's run it is still south of the previous run and shows stronger ridging too. I expect the Euro to hold serve or adjust a touch south and the GFS to play catch up in the 18z and 00z runs later today.
 
If these ridiculously strong Flo runs in combo with Irma and other ones don’t finally convince the folks in doubt that the gfs has a ridiculously strong low SLP bias, then I don’t know what will.

Yep it's something they are working on fixing in the FV3 model but there are still a lot of refinements it needs. The CMC and GFS are both coming in south so far through 72 hours, not a good sign...
 
Not good.. the UK has shifted north in line with the Euro pointing to a NC landfall. Here is the text output.
HURRICANE FLORENCE ANALYSED POSITION : 24.1N 48.6W

ATCF IDENTIFIER : AL062018

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 06.09.2018 0 24.1N 48.6W 1001 57
0000UTC 07.09.2018 12 25.0N 49.9W 998 62
1200UTC 07.09.2018 24 25.2N 51.5W 994 64
0000UTC 08.09.2018 36 25.0N 52.7W 989 68
1200UTC 08.09.2018 48 24.8N 54.1W 984 61
0000UTC 09.09.2018 60 24.7N 55.1W 981 56
1200UTC 09.09.2018 72 24.8N 56.5W 980 55
0000UTC 10.09.2018 84 25.2N 58.0W 975 63
1200UTC 10.09.2018 96 26.0N 60.4W 973 63
0000UTC 11.09.2018 108 27.2N 63.5W 971 69
1200UTC 11.09.2018 120 28.3N 67.7W 965 71
0000UTC 12.09.2018 132 29.2N 71.3W 960 71
1200UTC 12.09.2018 144 30.6N 74.3W 957 81
 
Not good.. the UK has shifted north in line with the Euro pointing to a NC landfall. Here is the text output.
HURRICANE FLORENCE ANALYSED POSITION : 24.1N 48.6W

ATCF IDENTIFIER : AL062018

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 06.09.2018 0 24.1N 48.6W 1001 57
0000UTC 07.09.2018 12 25.0N 49.9W 998 62
1200UTC 07.09.2018 24 25.2N 51.5W 994 64
0000UTC 08.09.2018 36 25.0N 52.7W 989 68
1200UTC 08.09.2018 48 24.8N 54.1W 984 61
0000UTC 09.09.2018 60 24.7N 55.1W 981 56
1200UTC 09.09.2018 72 24.8N 56.5W 980 55
0000UTC 10.09.2018 84 25.2N 58.0W 975 63
1200UTC 10.09.2018 96 26.0N 60.4W 973 63
0000UTC 11.09.2018 108 27.2N 63.5W 971 69
1200UTC 11.09.2018 120 28.3N 67.7W 965 71
0000UTC 12.09.2018 132 29.2N 71.3W 960 71
1200UTC 12.09.2018 144 30.6N 74.3W 957 81

There we go. UKMET finally adjusting back north.
 
Back
Top