ATL: NADINE - Post-Tropical - Discussion

[AnnularCane]

Where's Nadine's floater?

[littlevince]

Where's Nadine's floater?

Was removed, the same thing happened during Hurricane Gordon in this area, SSD use images from GOES to their floater imagery, Nadine has moved into the area covered by METEOSAT and they are restricted to using only imagery every six hours from METEOSAT.
Unfortunately in Europe EUMETSAT (supported by taxpayers) don't have the same policy of providing free satellite imagery as in U.S., they charge money.
You can use this alternative: http://rammb.cira.colostate.edu/product ... r=AL142012

[Hurricane_Luis]

Tropical Storm Nadine

[Hurricanehink]

I agree with the NHC, it looks much better today. Nadine doesn't want to see us in 2018 quite yet.

[cycloneye]

00z Best track up to 55kts because of an ASCAT pass that show stronger winds.

AL, 14, 2012092100, , BEST, 0, 359N, 280W, 55, 981, TS

[DukeDevil91]

That is the wind field of a cat 1 hurricane.

[DukeDevil91]

She's been around for a long time.

[wxman57]

Looks more like the wind field of a 50kt extratropical storm. Strongest winds are not near the center.

[DukeDevil91]

Looks more like the wind field of a 50kt extratropical storm. Strongest winds are not near the center.

Meh.............
Those winds on the left front quadrant could be sustained at 65 knots for all we know. Granted no eye wall is there.

[cycloneye]

BULLETIN
SUBTROPICAL STORM NADINE ADVISORY NUMBER 42
NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012
500 PM AST FRI SEP 21 2012

...NADINE TRANSITIONS INTO A SUBTROPICAL STORM...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...33.0N 27.0W
ABOUT 345 MI...555 KM S OF THE AZORES
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...SSE OR 160 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...982 MB...29.00 INCHES

[Macrocane]

Pretty interesting, has it happened before? from tropical to subtropical? Nadine doesn't give up.

[AnnularCane]

I don't think I've ever seen a TS transition into a subtropical storm. Usually it's the other way around. Has this ever happened before?

[Hammy]

I've seen this done post-analysis with a few systems, bit I do believe it is a first for operational advisories

[cycloneye]

Nadine has been very tenasious and she may go back to Tropical soon. Maybe one of our pro mets can answer the question about if this transition from Tropical to Subtropical has happened before.

[CrazyC83]

Yeah I don't remember the last time there was a backwards transition either operationally (the last in actual fact was Tropical/Subtropical Storm Lee last year, but that was not done operationally). I think they kinda wanted to make it post-tropical, but there is so much uncertainty (i.e. it is non-frontal, but lacks most tropical cyclone features).

There isn't much else to call it though, the only other thing a case could be made for is simply "low".

[CrazyC83]

Lee was never designated as a subtropical cyclone operationally. However, in the poststorm analysis, Lee is shown to have evolved from a tropical to a subtropical storm by 1200 UTC 3 September. By that time, Lee was located directly beneath the upper-level low and the radius of Lee’s maximum winds expanded from about 75 n mi to between 120 and 150 n mi by late on 3 September. After Lee became a subtropical cyclone, it continued to deepen despite having relatively weak convection near the center. This suggests that at least a portion of Lee’s energy source was related to baroclinicity associated with the upper-level low. Figs. 4 and 5 show the evolution of Lee’s structure in visible and microwave satellite imagery from 2 September when Lee was a tropical storm, through its period as a subtropical cyclone, and then its transformation to an extratropical low on 5 September. The transition from a tropical to a subtropical cyclone, while rare, has been previously observed. The last Atlantic basin tropical cyclone to evolve into a subtropical cyclone was Allison (2001). Hurricane Klaus (1984) made a similar transition.

That was from the TCR of Lee last year. In operational advisories, Lee was kept tropical, while Allison was treated as a post-tropical low. Not sure how Klaus of 1984 was treated.

[cycloneye]

BULLETIN
POST-TROPICAL CYCLONE NADINE ADVISORY NUMBER 43
NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012
1100 PM AST FRI SEP 21 2012

...NADINE BECOMES A POST-TROPICAL CYCLONE...
...REGENERATION POSSIBLE IN A COUPLE OF DAYS...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...31.9N 26.6W
ABOUT 420 MI...680 KM S OF THE AZORES
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...SSE OR 165 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...984 MB...29.06 INCHES

[brunota2003]

Wow...if everything holds, 5 am will be the first advisory time where we don't have an advisory issued in what? A month?

EDIT:

Here's the breakdown, from first advisory to last:

Nadine:
11 Sept 11 am – 21 Sept 11 pm

Michael:
3 Sept 5 pm – 11 Sept 5 pm

Leslie:
30 Aug 11 am – 11 Sept 11 am

Kirk:
28 Aug 5 pm – 2 Sept 5 pm

Joyce:
22 Aug 11 am – 24 Aug 11 am

Isaac:
21 Aug 5 am – 30 Aug 5 pm


So we've had continuous advisories since 21 Aug at 5 am to 21 Sept at 11 pm...or the last 32 days.

The last advisory time where an advisory was not issued would be 20 Aug 11 pm, which is bordered on either side by the last advisory for Gordon 20 Aug at 5 pm and Isaac's first advisory 21 Aug at 5 am.

[brunota2003]

Note that the above is just for Atlantic storms, obviously there currently is an EPac system that they just started issuing advisories for.

[CrazyC83]

Of course, Nadine may very well regain tropical characteristics as it moves southwest...was it ever subtropical or did they just want to play it safe and wait and see?

In the ultimate BT, I would think this part of the track will just go down as "low". It isn't extratropical since there is no front, just no deep convection.