ATL: FLORENCE - Post-Tropical - Discussion

[cycloneye]

BULLETIN
Tropical Storm Florence Advisory Number 17
NWS National Hurricane Center Miami FL AL062018
1100 AM AST Mon Sep 03 2018

...FLORENCE A LITTLE STRONGER AS IT CONTINUES MOVING ACROSS THE
CENTRAL TROPICAL ATLANTIC...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...18.3N 38.7W
ABOUT 980 MI...1580 KM W OF THE CABO VERDE ISLANDS
ABOUT 1505 MI...2425 KM E OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...997 MB...29.44 INCHES



Tropical Storm Florence Discussion Number 17
NWS National Hurricane Center Miami FL AL062018
1100 AM AST Mon Sep 03 2018

While Florence's structure improved overnight, the cloud tops have
warmed and the deep convection has thinned during the past several
hours. The 12Z satellite intensity estimates range from 55 to 65 kt,
but given recent trends the initial intensity is set at the low end
of that range at 55 kt, although this is quite uncertain given the
recent fluctuations in the cloud pattern.

UW-CIMSS satellite diagnostics indicate that around 20 kt of
southwesterly shear is affecting Florence, while the SHIPS analysis
based on the GFS fields shows only about 10 kt. SSTs warm from this
point forward along the forecast track, but shear is expected to
be steady or strengthen, and the mid-level relative humidity values
decrease to around 50 percent during the next 48 to 72 hours. Given
these mixed factors, the NHC intensity forecast shows some
possibility for strengthening in the next 12 hours, followed by a
slow decay through 72 hours. Some restrengthening is forecast late
in the period as SSTs warm above 28C and the atmospheric moisture
increases. The NHC forecast is close to or a bit above the latest
IVCN consensus aid and about 5 kt above the previous NHC forecast
through 96 hours.

The initial motion estimate is 285/14. Florence will be steered
generally west-northwestward for the next 72 hours by the Atlantic
subtropical ridge, followed by a northwestward turn at days 4 and 5.
While there is large spread in the guidance between the HWRF on the
right and the UKMET on the left, the GFS, ECMWF, and their ensemble
means are more tightly clustered near the middle of the guidance
envelope. Since the overall track forecast reasoning has not
changed, the new NHC forecast remains near the middle of the
guidance. This forecast is a bit north of the previous NHC track
given the initial position and lies a little south of the consensus
aids to reflect less influence of the outlier HWRF model to the
north.

FORECAST POSITIONS AND MAX WINDS

INIT 03/1500Z 18.3N 38.7W 55 KT 65 MPH
12H 04/0000Z 18.6N 40.7W 60 KT 70 MPH
24H 04/1200Z 19.1N 43.0W 60 KT 70 MPH
36H 05/0000Z 19.9N 45.3W 55 KT 65 MPH
48H 05/1200Z 20.8N 47.6W 50 KT 60 MPH
72H 06/1200Z 23.0N 52.2W 45 KT 50 MPH
96H 07/1200Z 25.0N 55.0W 50 KT 60 MPH
120H 08/1200Z 27.0N 58.0W 55 KT 65 MPH

$$
Forecaster Brennan

[plasticup]

Impressive outflow to the north. Am I imagining a little central clearing? I would have thought better than 55 kts.

[chaser1]

Florence certainly looking a good deal healthier then her Gulf counter-part

[Hypercane_Kyle]

Florence certainly looking a good deal healthier then her Gulf counter-part

Inverse is true now, about to become a naked swirl again:

[chaser1]

Yep, looks like Florence might just be getting a case of "dry-mouth"

[Shell Mound]

Based on the tracks of storms up to this point (including Gordon’s projected), 1880 and 1932 come up as analogs, followed by 1863 and 1964. Florence could well continue westward into FL in the very long range, given sufficiently deep-layered ridging over the Mid-Atlantic region. Given favorable conditions by then, Florence could threaten the Southeast as a powerful hurricane. Anywhere from FL through the Carolinas would be at potential risk. The 00Z ECMWF actually takes major hurricane Florence due westward into NC – something that has never happened historically (strong hurricanes have moved NW or WNW into the Carolinas, but not due W). The due-W movement could give some credence to southern solutions of the 00Z EPS suite, several of which now take a strong Florence into the FL peninsula (for the first time). There have been several such historical examples on record, e.g., Storm #4 (1880) and Dora (1964). A few others to mention: Frances and Jeanne (2004). Clearly, Florence needs to be watched rather closely, given the upcoming steering pattern. Residents of the Southeast and Bermuda should keep watch and be prepared. And there is more to come behind Florence...

[AxaltaRacing24]

Florence certainly looking a good deal healthier then her Gulf counter-part

Inverse is true now, about to become a naked swirl again:

The GFS is onto something if it thinks that is going to be a cat 2 tomorrow.

[Hurricaneman]

Florence certainly looking a good deal healthier then her Gulf counter-part

Inverse is true now, about to become a naked swirl again:

The GFS is onto something if it thinks that is going to be a cat 2 tomorrow.

More like on something

[chaser1]

[mitchell]

Sorry if this has already been said....it looks on recent runs like Gordon tracks northward through Ohio Valley, eastern Canada and could create a weakness that lifts Florence northward? Or maybe Florence misses it and keeps heading westward? 12 z Euro looks like it misses the trough and just steams westward

[lando]

I know 10 day models don’t verify, and you can see the huge swing in just 24hrs, but last nights 00z euro ensemble run did have one head into Jax as a cat 3, and the latest operational run at 12z is showing something similar. It’s interesting. Jacksonville saw ALOT of flooding with Irma last year, and didn’t even take a huge direct hit. A cat 3 steaming in would potentially cause Katrina like flooding depending on the tide. Jacksonville has the largest population in the South East with over 850k residents

[cycloneye]

BULLETIN
Tropical Storm Florence Advisory Number 18
NWS National Hurricane Center Miami FL AL062018
500 PM AST Mon Sep 03 2018

...FLORENCE JUST BELOW HURRICANE STRENGTH...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...18.6N 39.8W
ABOUT 1055 MI...1700 KM WNW OF THE CABO VERDE ISLANDS
ABOUT 1435 MI...2310 KM ENE OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...995 MB...29.39 INCHES


TAA00 KNHC DDHHMM

Tropical Storm Florence Discussion Number 18
NWS National Hurricane Center Miami FL AL062018
500 PM AST Mon Sep 03 2018

Florence appears a little better organized than earlier today. Deep
convection is slightly stronger near and to the north of the center,
and the cloud pattern still resembles a central dense overcast. A
blend of the latest Dvorak classifications suggests a slightly
higher wind speed, and accordingly, the initial intensity is nudged
upward to 60 kt.

The strong tropical storm is moving westward, or 280 degrees, at 13
kt steered by a subtropical ridge to its north. The global models
all show a persistent weakness in the subtropical ridge during the
next several days due to a series of troughs moving across the
Atlantic. In response, Florence is expected to gradually turn
northwestward with a slight reduction in forward speed during the
next several days. While there remains a fair amount of spread in
the models from 72 to 120 h, there has been a notable trend to the
right, or north, during the past few model cycles. The official
track forecast is adjusted slightly to the right as well, trending
toward the latest consensus aids.

Little change in strength is expected through tonight as Florence
remains over marginally warm waters and in moderate wind shear
conditions. However, nearly all of the intensity models show a slow
weakening trend during the next few days. This weakening is in
response to a gradual increase in southwesterly or westerly shear.
Beyond a few days, however, the shear is expected to decrease and
Florence will be over much warmer waters. Therefore, slow
strengthening is shown in the 3 to 5 day period. This forecast is
slightly higher than the previous one at the longer range, but is
otherwise unchanged.

FORECAST POSITIONS AND MAX WINDS

INIT 03/2100Z 18.6N 39.8W 60 KT 70 MPH
12H 04/0600Z 19.0N 41.6W 60 KT 70 MPH
24H 04/1800Z 19.6N 43.9W 55 KT 65 MPH
36H 05/0600Z 20.4N 46.1W 55 KT 65 MPH
48H 05/1800Z 21.5N 48.4W 50 KT 60 MPH
72H 06/1800Z 23.7N 52.5W 50 KT 60 MPH
96H 07/1800Z 26.0N 55.3W 55 KT 65 MPH
120H 08/1800Z 28.0N 57.5W 60 KT 70 MPH

$$
Forecaster Cangialosi

[Highteeld]

Could be a hurricane with recon.

[LarryWx]

So, the 12Z Euro, which is obviously a SW outlier of the less threatening (vs 0Z EPS) 12 EPS, has Florence hit the CONUS from 30N, 60W. This would be a very highly anomalous track to say the least and one not to place bets on right now although it wouldn't be unprecedented to have a TC move from N or E of 30N, 60W and later hit the CONUS:

1) Kyle of 2002 came from 33/50 and hit the SE US: https://www.nhc.noaa.gov/data/tracks/tracks-at-2002.png

2) H Ginger of 1971 moved ENE to near 33/48 before turning around and coming all of the way back to NC:
https://www.wunderground.com/hurricane/ ... ane-Ginger

3) The Yankee Hurricane of November of 1935 went from near 32.5/61 to hit S FL moving SW:
https://www.wunderground.com/hurricane/ ... -Hurricane

-------------------------------------------------------------

So, over the last 100 years, they have been recorded about once very 30 or so years. So, very, very highly anomalous but not impossible.

[gatorcane]

So, the 12Z Euro, which is obviously a SW outlier of the less threatening (vs 0Z EPS) 12 EPS, has Florence hit the CONUS from 30N, 60W. This would be a very highly anomalous track to say the least and one not to place bets on right now although it wouldn't be unprecedented to have a TC move from N or E of 30N, 60W and later hit the CONUS:

1) Kyle of 2002 came from 33/50 and hit the SE US: https://www.nhc.noaa.gov/data/tracks/tracks-at-2002.png

2) H Ginger of 1971 moved ENE to near 33/48 before turning around and coming all of the way back to NC:
https://www.wunderground.com/hurricane/ ... ane-Ginger

3) The Yankee Hurricane of November of 1935 went from near 32.5/61 to hit S FL moving SW:
https://www.wunderground.com/hurricane/ ... -Hurricane

-------------------------------------------------------------

So, over the last 100 years, they have been recorded about once very 30 or so years. So, very, very highly anomalous but not impossible.

Check out the 18Z FV3 GFS. Almost hits Florida after taking Florence up to like 38N.

That track is crazy, maybe something like Kyle?

[pgoss11]

So, the 12Z Euro, which is obviously a SW outlier of the less threatening (vs 0Z EPS) 12 EPS, has Florence hit the CONUS from 30N, 60W. This would be a very highly anomalous track to say the least and one not to place bets on right now although it wouldn't be unprecedented to have a TC move from N or E of 30N, 60W and later hit the CONUS:

1) Kyle of 2002 came from 33/50 and hit the SE US: https://www.nhc.noaa.gov/data/tracks/tracks-at-2002.png

2) H Ginger of 1971 moved ENE to near 33/48 before turning around and coming all of the way back to NC:
https://www.wunderground.com/hurricane/ ... ane-Ginger

3) The Yankee Hurricane of November of 1935 went from near 32.5/61 to hit S FL moving SW:
https://www.wunderground.com/hurricane/ ... -Hurricane

-------------------------------------------------------------

So, over the last 100 years, they have been recorded about once very 30 or so years. So, very, very highly anomalous but not impossible.

Check out the 18Z FV3 GFS. Almost hits Florida after taking Florence up to like 38N.

That track is crazy, maybe something like Kyle?[/quotes

That 18Z FV3 GFS run is the craziest run I have ever seen!

[AnnularCane]

So, the 12Z Euro, which is obviously a SW outlier of the less threatening (vs 0Z EPS) 12 EPS, has Florence hit the CONUS from 30N, 60W. This would be a very highly anomalous track to say the least and one not to place bets on right now although it wouldn't be unprecedented to have a TC move from N or E of 30N, 60W and later hit the CONUS:

1) Kyle of 2002 came from 33/50 and hit the SE US: https://www.nhc.noaa.gov/data/tracks/tracks-at-2002.png

2) H Ginger of 1971 moved ENE to near 33/48 before turning around and coming all of the way back to NC:
https://www.wunderground.com/hurricane/ ... ane-Ginger

3) The Yankee Hurricane of November of 1935 went from near 32.5/61 to hit S FL moving SW:
https://www.wunderground.com/hurricane/ ... -Hurricane

-------------------------------------------------------------

So, over the last 100 years, they have been recorded about once very 30 or so years. So, very, very highly anomalous but not impossible.

Check out the 18Z FV3 GFS. Almost hits Florida after taking Florence up to like 38N.

That track is crazy, maybe something like Kyle?[/quotes

That 18Z FV3 GFS run is the craziest run I have ever seen!

How do I find that crazy track?

ETA: Never mind, I found it. Probably too interesting to actually happen.

[AxaltaRacing24]

So, the 12Z Euro, which is obviously a SW outlier of the less threatening (vs 0Z EPS) 12 EPS, has Florence hit the CONUS from 30N, 60W. This would be a very highly anomalous track to say the least and one not to place bets on right now although it wouldn't be unprecedented to have a TC move from N or E of 30N, 60W and later hit the CONUS:

1) Kyle of 2002 came from 33/50 and hit the SE US: https://www.nhc.noaa.gov/data/tracks/tracks-at-2002.png

2) H Ginger of 1971 moved ENE to near 33/48 before turning around and coming all of the way back to NC:
https://www.wunderground.com/hurricane/ ... ane-Ginger

3) The Yankee Hurricane of November of 1935 went from near 32.5/61 to hit S FL moving SW:
https://www.wunderground.com/hurricane/ ... -Hurricane

-------------------------------------------------------------

So, over the last 100 years, they have been recorded about once very 30 or so years. So, very, very highly anomalous but not impossible.

Check out the 18Z FV3 GFS. Almost hits Florida after taking Florence up to like 38N.

That track is crazy, maybe something like Kyle?[/quotes

That 18Z FV3 GFS run is the craziest run I have ever seen!

The Euro might be onto something then.

[galaxy401]

So Florence pulls a more extreme version of Kyle back in 2002? That would be ridiculous if that happens.

[cycloneye]

Tropical Storm Florence Discussion Number 19
NWS National Hurricane Center Miami FL AL062018
1100 PM AST Mon Sep 03 2018

Although Florence continues to produce a fairly circular area of
deep convection, microwave images have revealed that there is a
significant southwest-to-northeast vertical tilt of the
circulation due to southwesterly shear. The initial intensity is
held at 60 kt, using a blend of the Dvorak CI-numbers from TAFB and
SAB. This estimate is a little below the latest automated Dvorak
values from CIMSS at the University of Wisconsin.

The strong tropical storm is moving west-northwestward, or 285
degrees, at 12 kt steered by a subtropical ridge to its north. The
storm is expected to gradually turn northwestward with a decrease
in forward speed during the next several days as it moves
toward a persistent weakness in the subtropical ridge. There
remains a fair amount of spread in the guidance, especially in the
3- to 5-day time period, but the consensus aids have changed little
this cycle. Therefore, no significant changes were made to the
previous forecast, and this one lies near the middle of the guidance
envelope.

Little change in strength is expected through early Tuesday as
Florence remains over marginally warm waters and in moderate wind
shear conditions. Slight weakening is expected during the middle
part of the week due to a gradual increase in southwesterly or
westerly shear. Beyond that time, however, the shear is expected to
decrease and Florence will be over much warmer waters. Therefore,
slow strengthening is shown at the end of the forecast period.
This forecast is unchanged from the previous one, and is in good
agreement with the HCCA guidance.

The 34- and 50-kt initial wind radii have been expanded outward
based on recent ASCAT passes.

FORECAST POSITIONS AND MAX WINDS

INIT 04/0300Z 18.9N 41.0W 60 KT 70 MPH
12H 04/1200Z 19.4N 42.7W 60 KT 70 MPH
24H 05/0000Z 20.1N 44.9W 55 KT 65 MPH
36H 05/1200Z 21.1N 47.2W 55 KT 65 MPH
48H 06/0000Z 22.1N 49.5W 50 KT 60 MPH
72H 07/0000Z 24.5N 53.1W 50 KT 60 MPH
96H 08/0000Z 26.8N 55.8W 55 KT 65 MPH
120H 09/0000Z 28.4N 57.8W 60 KT 70 MPH

$$
Forecaster Cangialosi