ATL: FLORENCE - Post-Tropical - Discussion

[supercane4867]

5PM advisory now brings forecast intensity up to 130kt, the same as the bold prediction I made days ago when Flo was still struggling

[somniture]

MIMIC shows the center still moving just S of due west.

[CrazyC83]

How did you come up with that estimate?

What estimate?

It is pretty clear Florida is in the clear. I just think it is possible for WSW when the ridge fills in and Florence will be on SE side of the high.

That is too bold of a statement to say, the likely hood is now for a SC/NC landfall, but with this system still not making the turn the likely hood is slowly converging to a Ga/SC landfall, and I say people from Daytona all the way up to NYC need to keep an eye on this system, this ridge building in will have a major effect and then it retrograding will also have an effect later on

Climatology is always meant to be broken.

Consider that it will be in a similar position soon as where Joaquin in 2015 formed. That ended up in the southern Bahamas!!! Some ensembles still go as far south as Florida, and as far north as the Northeast. No one is off the hook yet.

[Kazmit]

5PM advisory now brings forecast intensity up to 130kt, the same as the bold prediction I made days ago when Flo was still struggling

That's getting close to cat 5 strength. And the NHC tends to be on the conservative side with intensity forecasts.

[supercane4867]

FORECAST POSITIONS AND MAX WINDS

INIT 09/2100Z 24.4N 57.0W 75 KT 85 MPH
12H 10/0600Z 24.6N 58.3W 90 KT 105 MPH
24H 10/1800Z 25.1N 60.4W 105 KT 120 MPH
36H 11/0600Z 25.9N 63.1W 115 KT 130 MPH
48H 11/1800Z 27.0N 66.2W 125 KT 145 MPH
72H 12/1800Z 30.3N 72.6W 130 KT 150 MPH
96H 13/1800Z 33.5N 77.5W 120 KT 140 MPH
120H 14/1800Z 35.0N 79.0W 60 KT 70 MPH...INLAND



Forecast track starts to show the slowing at day 5

[plasticup]

About the NHC cone from the NHC website (the bold is mine):

"Historical data indicate that the entire 5-day path of the center of the tropical cyclone will remain within the cone about 60-70% of the time.

To form the cone, a set of imaginary circles are placed along the forecast track at the 12, 24, 36, 48, 72, 96, and 120 h positions, where the size of each circle is set so that it encloses 67% of the previous five years official forecast errors.

The cone is then formed by smoothly connecting the area swept out by the set of circles."

That is the average error over all storms. Sometimes, like last week, they have particularly low confidence in a forecast. At the moment, however, the Discussion seems to imply fairly high confidence. I think it is reasonable to assume >67% chance than the storm lands within the cone.

[PandaCitrus]

NHC forecast takes it to 150MPH but may still be conservative according to the 5PM discussion. It's very possible this may max out at Cat 5 strength.

The new forecast continues to show rapid
intensification and is increased 5 or 10 kt at most time periods,
but it is still not as high as the Florida State Superensemble or
the NOAA corrected consensus models. It is worth noting that the
model guidance is also significantly increasing the size of
Florence's wind field over the next few days, and the official
forecast reflects this trend.

[GeneratorPower]

This is about worst case scenario for Wilmington and surrounding areas. Almost a Cat 5 which is tough to do at that latitude. And then slow moving and stalling out, on top of it.

This is really a situation where evacuation is the best option.

[Hurrilurker]

Looking to me like a new fully circular eye wall feature beginning to take shape; not like it won't be about the 3rd or 4th time in recent days. Flo seems to be having a hard time maintaining organization. Lets see.... vertical shear - check, dry air - check.... no reason to think she'll continue to ramp up then. Assuming what I'm seeing is correct then, she's still riding west at about 24.4 N.

From the last pic I saw, the dry air is pretty much gone, except well south of Flo. Now Isaac, that's a different story, it's surrounded.

From 2PM discussion WRT dry air:

Code: Select all

Radar data from the NOAA Hurricane Hunter indicated that there were still a few breaks in the eyewall, possibly allowing some dry air to mix into the core.  This structure has potentially kept Florence from intensifying rapidly so far.  It is likely, however, that the eyewall will close soon with low environmental shear present, resulting in a faster intensification rate.

[rickybobby]

When is it suppose to start turning north?

[plasticup]

72H 12/1800Z 30.3N 72.6W 130 KT 150 MPH

What an insane prediction. That is a top-end Category 4 they are predicting. Cat 5 starts at 137 knots.

Unreal that they see enough potential out there to justify that. Absolutely terrifying.

[Aric Dunn]

When is it suppose to start turning north?

tonight into tomorrow morning. so any continued west movements will cause future track adjustments.

[Cyclenall]

With that floater image posted a few pages back I looked myself at the SSD floater page and found Florence on it! Up to now all the Atlantic systems were blackened blanks on their respective floater pages. When did that start for Flo? Its about time because I don't enjoy using the alternatives and why they haven't all started on the new satellite is beyond me. The loops are in 15 min intervals though.

[pgoss11]

I noticed the 5PM track map shifted south a little. Not too surprised with Florence staying at the same latitude for over a day now. You called it Aric! Kudos!

[Blinhart]

When is it suppose to start turning north?

it should of started a WNW turn already.

[CrazyC83]

72H 12/1800Z 30.3N 72.6W 130 KT 150 MPH

What an insane prediction. That is a top-end Category 4 they are predicting. Cat 5 starts at 137 knots.

Unreal that they see enough potential out there to justify that. Absolutely terrifying.

The only storms that have had a similar intensity in that position that I know of are Helene (1958) and Hugo. There has never been a cat 5 in the open Atlantic north of 28N (the latitude of central Florida) - the northernmost was Camille in the GOM.

[Blinhart]

72H 12/1800Z 30.3N 72.6W 130 KT 150 MPH

What an insane prediction. That is a top-end Category 4 they are predicting. Cat 5 starts at 137 knots.

Unreal that they see enough potential out there to justify that. Absolutely terrifying.

And if you read the Disco, they are saying they are being conservative, other models are saying it could get stronger.

[Hypercane_Kyle]

[dspguy]

I noticed the 5PM track map shifted south a little. Not too surprised with Florence staying at the same latitude for over a day now. You called it Aric! Kudos!

I'm guessing that for every few hours the storm doesn't start making the north turn, the track will begin shifting from OBX/Wilmington towards Myrtle Beach, then Charleston, then Savannah. I have no idea what the confidence levels are for when it will turn. Someone had a graphic earlier that was very telling. While I think the OTS solutions are likely minimal (even the stalling off the coast ones), those slim chances probably turn into absolute no chance if this storm doesn't make the WNW turn soon.

[pgoss11]

I noticed the 5PM track map shifted south a little. Not too surprised with Florence staying at the same latitude for over a day now. You called it Aric! Kudos!

I'm guessing that for every few hours the storm doesn't start making the north turn, the track will begin shifting from OBX/Wilmington towards Myrtle Beach, then Charleston, then Savannah. I have no idea what the confidence levels are for when it will turn. Someone had a graphic earlier that was very telling. While I think the OTS solutions are likely minimal (even the stalling off the coast ones), those slim chances probably turn into absolute no chance if this storm doesn't make the WNW turn soon.

I'm hoping the south shifts end but I have a feeling they've just begun. I'm sure they'll be very small shifts but I'm in Charleston and getting veery concerned. The 5PM discussion was terrifying.