ATL: FLORENCE - Post-Tropical - Discussion

[toad strangler]

 https://twitter.com/TropicalTidbits/status/1038611733328343041

[artist]

[LarryWx]

Looking at satellite loops just now, it does appear that the center may have dipped to near 24.4N from the 24.6N of the 5PM advisory. Just something to monitor as what may seem like a minor move south can have a much larger domino effect down the road.

[Blown Away]

The SW dip appears to be happening...

[drewschmaltz]

The SW dip appears to be happening...

It seems like all the steering layers want to influence Flo south short term. But I'm still learning how to read/interpret these maps...

http://tropic.ssec.wisc.edu/real-time/dlmmain.php?&basin=atlantic&sat=wg8&prod=dlm1&zoom=&time=

[cycloneye]

BULLETIN
Tropical Storm Florence Advisory Number 39
NWS National Hurricane Center Miami FL AL062018
1100 PM AST Sat Sep 08 2018

...FLORENCE STILL MOVING SLOWLY...
...EXPECTED TO BECOME A HURRICANE AT ANY TIME SOON...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...24.6N 55.2W
ABOUT 790 MI...1270 KM SE OF BERMUDA
ABOUT 675 MI...1085 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...989 MB...29.21 INCHES




Tropical Storm Florence Discussion Number 39
NWS National Hurricane Center Miami FL AL062018
1100 PM AST Sat Sep 08 2018

Satellite images indicate that the cloud pattern has continued to
gradually become better organized with an eye feature trying to
form. An average of all of the Dvorak satellite intensity estimates
tonight suggest that Florence is not a hurricane yet, but is close
to being one. The initial intensity is kept at 60 kt in this
advisory. The recent ASCAT data showed less winds than previously
observed by the NOAA plane when the cloud pattern was less
organized.

There is a band of convection trying to wrap around a possible eye
feature, and that is an indication that Florence has continued to
recover from the hostile shear environment, which brought the
hurricane from Category 4 to a tropical storm in a matter of a day
or so. The presence of developing upper-level outflow is a
good indication that the shear has decreased, and with the presence
of a warm ocean ahead, strengthening is anticipated. As indicated
by my predecessor, the official forecast continues to call for a
period of rapid intensification in about 12-24 hours, and Florence
is expected to reach major hurricane intensity between 36-48 hours
with additional strengthening thereafter. Florence is forecast to
be an intense hurricane on days 3 through 5 as it moves across the
warm waters of the southwestern Atlantic Ocean between the Bahamas
and Bermuda, and then as it heads toward the southeast United States
coast.

Florence is still trapped within very light steering currents,
and is slowly moving toward the west or 270 degrees at 5 kt.
All indications are that this is about to change, as a strong ridge
of high pressure builds to the north of the hurricane. This
forecast flow pattern predicted by the global models will force
Florence on a general west-northwest to northwest track with an
increase in forward speed. The NHC forecast is basically on top of
the previous one, and is in the middle of the narrow guidance
envelope mainly for the next 3 to 4 days. By the end of the
forecast period, when the hurricane is approaching the U.S. coast,
the guidance envelope is wider and becomes bounded by the
northernmost GFS and the southernmost HCCA and the FSSE ensembles.
One thing all models coincide at the longer range is with the
collapsing of the steering currents, resulting in a significant
reduction of the forward speed of the hurricane.

Key Messages:

1. Florence is forecast to be a dangerous major hurricane near the
southeast U.S. coast by late next week, and the risk of direct
impacts continues to increase. However, given the uncertainty in
track and intensity forecasts at those time ranges, it's too soon to
determine the exact timing, location, and magnitude of those
impacts.

2. Interests along the U.S. East Coast, particularly from north
Florida through North Carolina, should closely monitor the progress
of Florence, ensure they have their hurricane plan in place, and
follow any advice given by local officials.

3. Large swells affecting Bermuda and portions of the U.S. East
Coast will continue into next week. These swells will result in
life-threatening surf and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT 09/0300Z 24.6N 55.2W 60 KT 70 MPH
12H 09/1200Z 24.5N 55.9W 70 KT 80 MPH
24H 10/0000Z 24.8N 57.4W 80 KT 90 MPH
36H 10/1200Z 25.2N 59.3W 100 KT 115 MPH
48H 11/0000Z 25.8N 61.8W 110 KT 125 MPH
72H 12/0000Z 27.5N 67.5W 125 KT 145 MPH
96H 13/0000Z 30.0N 73.5W 125 KT 145 MPH
120H 14/0000Z 33.8N 77.8W 115 KT 130 MPH

$$
Forecaster Avila

[supercane4867]

FORECAST POSITIONS AND MAX WINDS

INIT 09/0300Z 24.6N 55.2W 60 KT 70 MPH
12H 09/1200Z 24.5N 55.9W 70 KT 80 MPH
24H 10/0000Z 24.8N 57.4W 80 KT 90 MPH
36H 10/1200Z 25.2N 59.3W 100 KT 115 MPH
48H 11/0000Z 25.8N 61.8W 110 KT 125 MPH
72H 12/0000Z 27.5N 67.5W 125 KT 145 MPH
96H 13/0000Z 30.0N 73.5W 125 KT 145 MPH
120H 14/0000Z 33.8N 77.8W 115 KT 130 MPH

[tolakram]

We are chatting in the Storm2K chatroom: https://discord.gg/VMktVYb while waiting for the 11:30 run of the GFS. 22 online at the moment, another 101 already signed up.

[Socalhurcnegirl227]

FORECAST POSITIONS AND MAX WINDS

INIT 09/0300Z 24.6N 55.2W 60 KT 70 MPH
12H 09/1200Z 24.5N 55.9W 70 KT 80 MPH
24H 10/0000Z 24.8N 57.4W 80 KT 90 MPH
36H 10/1200Z 25.2N 59.3W 100 KT 115 MPH
48H 11/0000Z 25.8N 61.8W 110 KT 125 MPH
72H 12/0000Z 27.5N 67.5W 125 KT 145 MPH
96H 13/0000Z 30.0N 73.5W 125 KT 145 MPH
120H 14/0000Z 33.8N 77.8W 115 KT 130 MPH

i wonder if this takes into account the southward dip

[AutoPenalti]

It does.

[HurricaneFrances04]

Looks like banding is becoming more pronounced, with another burst of convection over the center. Hurricane by 5 am tomorrow?

[Ken711]

Curious why the 11:00 PM NHC forecast discussion max winds are forecast to drop from 145 MPH at 96 hours to 130 MPH at 120 hours?

[floridasun78]

so by sunday will be moving more wnw because i bet Bahamas people dont like look been their east

[wkwally]

My concern is not much where landfall will be but how bad will it flood in the New England area down the road

[Ken711]

i wonder if this takes into account the southward dip

It appears to.

INIT 09/0300Z 24.6N
12H 09/1200Z 24.5N

[supercane4867]

Curious why the 11:00 PM NHC forecast discussion max winds are forecast to drop from 145 MPH at 96 hours to 130 MPH at 120 hours?

NHC's long term intensity forecasts usually have potential structural changes taken into account. It assumes fluctuations in intensity due to eyewall replacement cycles

[cheezyWXguy]

Looks like banding is becoming more pronounced, with another burst of convection over the center. Hurricane by 5 am tomorrow?

https://i.imgur.com/2eGHyyN.jpg

That's a pretty substantial blow-up right on top the center. It would be a tough call for me to say hurricane at 5am, because although it is improving, a storm with an appearance like this usually has winds closer to 50mph than 70. It's hard for me to wrap my head around the fact that this thing is already on the verge of hurricane status. That said, I think they'll keep it as a TS until they either send recon out or see an appearance more typical of a hurricane. If the latter happens before 5am though, I can see them bumping it up.

[LarryWx]

i wonder if this takes into account the southward dip

It appears to.

INIT 09/0300Z 24.6N
12H 09/1200Z 24.5N

But their initial latitude wasn’t changed from the 24.6 N of the prior advisory. So, maybe what appeared to be a slight dip on satellite pics is an illusion? I was estimating it dropped to 24.4N already. Any other opinions?

[toad strangler]

i wonder if this takes into account the southward dip

It appears to.

INIT 09/0300Z 24.6N
12H 09/1200Z 24.5N

But their initial latitude wasn’t changed from the 24.6 N of the prior advisory. So, maybe what appeared to be a slight dip on satellite pics is an illusion? I was estimating it dropped to 24.4N already. Any other opinions?

Possible but I would bet Levi Cowan wasn't fooled. We'll know soon enough.

[chaser1]

After long analysis of the steering flow, present motion, and satellite I sense that sometime today the storm appeared at its "apex" between a slight tear in a ridge to its northeast and to its west. I just believe that we'll soon see a little quicker forward motion (8-10 knots maybe). Not that the NHC 24 hr. forecast differs that much but it calls for Flo to be approaching 24.8 by 8:00p.m. tomorrow (Sunday) eve. While .2 or .3 tenths are negligible it does become a bit more interesting if additional small drop in latitude were to occur. It also potentially impacts forecast track if the storm were to move faster (or slower) then models take into present consideration. All in all, I just see no greater resolution toward a definative landfall yet and just think we need to wait and watch for any near term unexpected or anticipated change in motion.

By the way.... does ANYONE have access to the FSU super model? I understand it's one of the southernmost outliers but just how far south I have no clue.