ATL: KARL - Post-Tropical - Discussion

[Gustywind]

A noticeable southward shift in the track...

Us in the Leewards should keep an eye on this one if this soutward trend continues...

[ronjon]

Hmmm....nobody posted the 00z ECM? Shows a strengthening tropical cyclone headed W-NW toward the Bahamas at the end of its run. I know it's 10 days out but can't quite call it a recurve into open Atlantic just yet.

[SouthFLTropics]

Hmmm....nobody posted the 00z ECM? Shows a strengthening tropical cyclone headed W-NW toward the Bahamas at the end of its run. I know it's 10 days out but can't quite call it a recurve into open Atlantic just yet.

I looked at the overnight Euro and noticed that as well but didn't have time to post it this morning. Looking at the ridge over the SE CONUS and Atlantic at 240 hours it appears that movement from 240 hours+ would be continued west or WNW. The GFS keeps coming west as well, albeit weak. I'm actually leaning more towards the GFS solution given the past runs for Hermine and Julia. Both stayed weak and waited to develop until very close in, which is what everyone has been looking out for all along this season. I could see this remaining weak until the Bahamas, Caribbean, or points further west and then developing.

[blp]

Hmmm....nobody posted the 00z ECM? Shows a strengthening tropical cyclone headed W-NW toward the Bahamas at the end of its run. I know it's 10 days out but can't quite call it a recurve into open Atlantic just yet.

I looked at the overnight Euro and noticed that as well but didn't have time to post it this morning. Looking at the ridge over the SE CONUS and Atlantic at 240 hours it appears that movement from 240 hours+ would be continued west or WNW. The GFS keeps coming west as well, albeit weak. I'm actually leaning more towards the GFS solution given the past runs for Hermine and Julia. Both stayed weak and waited to develop until very close in, which is what everyone has been looking out for all along this season. I could see this remaining weak until the Bahamas, Caribbean, or points further west and then developing.

I agree with you and Wxman57 this looks like it will be another sleeper staying weak for a while. My impressions of the models this year has been to trust the Euro for the Steering environment and the GFS for the conditions pertaining to the development of the system. Right now both the Euro and GFS have ridging building over top of the system later in the period so I think this one will need to be watched. Certainly not an automatic fish at this time. As for the strength I have to side with the GFS.

[Alyono]

looks like the MDR has struck again.

This has been sheared apart

[AutoPenalti]

It has a sexy naked swirl

[Blown Away]

Naked LLC, but intact...

[sma10]

Once AGAIN, it becomes GFS vs Euro (wouldn't you think these two models would agree one time, even by accident?)

They both are at least relatively in agreement for the next few days that TD12 will struggle mightily, but thereafter GFS says it will completely dissipate while Euro thinks it comes back in SW Atlantic. In the past, you'd have to give credence to the Euro option, but maybe not this year.

[centuryv58]

Once AGAIN, it becomes GFS vs Euro (wouldn't you think these two models would agree one time, even by accident?)

They both are at least relatively in agreement for the next few days that TD12 will struggle mightily, but thereafter GFS says it will completely dissipate while Euro thinks it comes back in SW Atlantic. In the past, you'd have to give credence to the Euro option, but maybe not this year.

I think most of these storms have made it across the ATL this season. After that point is the real question, IMO.

[PTrackerLA]

I know we are all struggling with autocorrect but for the newbies, it's the Hebert Box. Not the Herbert Box.

https://en.wikipedia.org/wiki/Hebert_Box

That Wikipedia article is wrong. The Hebert Box is NOT a predictor. Paul Hebert noted that most hurricanes that eventually impacted Florida did go through that area. However, just because a storm moves through that area does NOT mean it is likely to hit Florida. As for Twelve, it may be struggling all the way across the Atlantic, as did Hermine.

IF it struggles across the Atlantic like that, could it be a potential threat to the East coast? The 00z Euro takes it pretty far west by day 10 on WNW heading but looks like a trough could possibly sweep it up after day 10 looking at the 500mb pattern. We'll see.

[gatorcane]

it's actually more concerning to me that it is getting sheared and staying shallow since it could make it quite a bit west and it might find better conditions down the road.

[JaxGator]

it's actually more concerning to me that it is getting sheared and staying shallow since it could make it quite a bit west and it might find better conditions down the road.

Same here. It did look nice the last 2 days though but still, most of the stormes this season that were sheared developed till they got to land, giving people little warning and time to adequately prepare (sometimes).

[cycloneye]

 https://twitter.com/TropicalTidbits/status/776413836551217152

[JaxGator]

 https://twitter.com/TropicalTidbits/status/776413836551217152

Interesting he brought up Irene and Elena too. Both powerful hurricanes.

[jlauderdal]

Hmmm....nobody posted the 00z ECM? Shows a strengthening tropical cyclone headed W-NW toward the Bahamas at the end of its run. I know it's 10 days out but can't quite call it a recurve into open Atlantic just yet.

I looked at the overnight Euro and noticed that as well but didn't have time to post it this morning. Looking at the ridge over the SE CONUS and Atlantic at 240 hours it appears that movement from 240 hours+ would be continued west or WNW. The GFS keeps coming west as well, albeit weak. I'm actually leaning more towards the GFS solution given the past runs for Hermine and Julia. Both stayed weak and waited to develop until very close in, which is what everyone has been looking out for all along this season. I could see this remaining weak until the Bahamas, Caribbean, or points further west and then developing.

I agree with you and Wxman57 this looks like it will be another sleeper staying weak for a while. My impressions of the models this year has been to trust the Euro for the Steering environment and the GFS for the conditions pertaining to the development of the system. Right now both the Euro and GFS have ridging building over top of the system later in the period so I think this one will need to be watched. Certainly not an automatic fish at this time. As for the strength I have to side with the GFS.

weak storms are dangerous..the ons that develop west of 50 are the ones to really watch

[cycloneye]

TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016
1100 AM AST THU SEP 15 2016

Visible satellite images indicate that the depression has a rather
impressive low-level circulation, although all the deep convection
is far removed from the center due to southwesterly shear. Given
such a well-defined circulation, the depression could have become a
tropical storm overnight. The initial wind speed, however, remains
30 kt using a blend of the TAFB/SAB estimates with any of the more
reliable ASCAT passes unfortunately missing the center during the
past 18 hours.

An upper-level trough to the northwest of the cyclone is expected to
cause an increase in shear during the next day or so, which will
likely cause the cyclone to weaken. Beyond 48 hours, most of the
models show the shear relaxing, with an upper-level high taking the
place of the trough, and the cyclone is forecast to move over warmer
waters. This will probably promote a restrengthening trend,
although guidance is in poor agreement on how much the winds could
increase. Thus, the official forecast is reduced a little bit for
Friday/Saturday due to the shear, then is the same as the previous
one, showing a slow restrengthening early next week. It is also
possible the cyclone will degenerate into a remnant low for a while
due to the shear, although this isn't the likeliest scenario.

The depression is moving westward at about 11 kt, and this general
motion should continue for a day or so while it moves around the
Atlantic subtropical ridge. This ridge is forecast by much of the
guidance to strengthen and build westward, which would force the
depression to the west-southwest over the weekend. Early next
week, the cyclone could begin to gain some latitude as it reaches
the southwestern periphery of the ridge. Guidance is in good
agreement on this scenario, except for the GFDL which appears to be
a northward outlier. The official forecast track is very close to a
blend of the other models in the TVCN consensus minus the GFDL, and
is basically an update of the previous forecast.

FORECAST POSITIONS AND MAX WINDS

INIT 15/1500Z 17.7N 30.4W 30 KT 35 MPH
12H 16/0000Z 17.8N 32.2W 30 KT 35 MPH
24H 16/1200Z 17.9N 34.8W 30 KT 35 MPH
36H 17/0000Z 17.7N 37.4W 25 KT 30 MPH
48H 17/1200Z 17.4N 40.1W 25 KT 30 MPH
72H 18/1200Z 16.5N 45.2W 30 KT 35 MPH
96H 19/1200Z 16.7N 50.3W 35 KT 40 MPH
120H 20/1200Z 17.5N 55.0W 40 KT 45 MPH

$$
Forecaster Blake

[Blown Away]

NE Caribbean could be in the path and it's rare for a CV storm to travel west all the way across the Atlantic and impact the CONUS during late September...

[cycloneye]

[SFLcane]

Weak storms are dangerous BUT the Atlantic is hostile just about every were you look. If not shear well dry air will get it. Not much to be concerned about here yet possibly never.

[gatorcane]

06Z NAVGEM as it heads W or WNW: