Non-tropical low off the Iberian coast

[WalterWhite]

Models indicate that a non-tropical low embedded within a stationary front in the temperate region of the North Atlantic will move southward to the coast of Iberia in a few days. Currently this low is situated over 46 N 27 W.

NOAA 12Z surface analysis:


The GFS, ECMWF, and ICON all expect this low to move southward towards the coast of Iberia where they indicate development of a subtropical cyclone is possible. On the GFS and ECMWF, model sounding also indicates a thermal pattern more akin to a tropical cyclone, where the equivalent potential temperature is higher at sea level than at 700 mb.

GFS 12Z run:


ECMWF 12Z run:


ICON 18Z run:


There is also heavy ensemble support for this system developing on the coast of Iberia, with both the GEFS and the EPS ensembles showing strong support for this system.

GEFS 12Z run:


EPS 12Z run:
photo hosting

[WalterWhite]

GFS 18Z run:


The sounding for this model run again shows a thermal pattern reminiscent of a tropical/subtropical cyclone. This could be Subtropical Storm Ophelia.

[WalterWhite]

This still has no mention on the 8 PM Tropical Weather Outlook. I hope the NHC mentions this on the 2 AM Tropical Weather Outlook tomorrow.

[WalterWhite]

18Z surface analysis shows that the non-tropical low is moving ESE and that it is now situated at approximately 46 N 26 W.

[WalterWhite]

GFS 00Z model run:


ECMWF 00Z model run:

[WalterWhite]

NOAA 00Z surface analysis indicates that the low has moved to 47 N 24 W.

[WalterWhite]

NOAA 06Z surface analysis is indicating that the low is situated at approximately 47 N 23 W.

[WalterWhite]

According NOAA 12Z surface analysis, the low has moved to ESE to 46 N 21 W.

[WalterWhite]

As of now, here is what my best track estimate of this system would be:

2023/09/13 12Z: 46 N 27 W 1016 mb 25 kt: Non-tropical low
2023/09/13 18Z: 46 N 26 W 1016 mb 25 kt: Non-tropical low
2023/09/14 00Z: 47 N 24 W 1014 mb 25 kt: Non-tropical low
2023/09/14 06Z: 47 N 23 W 1013 mb 30 kt: Non-tropical low
2023/09/14 12Z: 46 N 21 W 1014 mb 30 kt: Non-tropical low

[WalterWhite]

The 12Z GFS and CMC runs still both see this system becoming a subtropical/tropical storm off the coast of the Iberian Peninsula. Model sounding data is not available for the CMC, but the GFS still shows the thermal pattern for a tropical cyclone.





The GEFS and EPS ensemble support for this system is still very strong.

[WalterWhite]

18Z surface analysis indicates that the non-tropical low has moved to 46 N 19 W. The low has also deepened to 1010 mb over the past 6 hours.


Models still indicate development of this system into a subtropical cyclone over the Iberian coast on September 17. The GFS and ECMWF model sounding still indicate the temperature profile of a tropical/subtropical cyclone.




18Z GEFS still indicates strong support for the development of this system.


As of now, my best track estimate of this system would be:

2023/09/13 12Z: 46 N 27 W 1016 mb 25 kt: Non-tropical low
2023/09/13 18Z: 46 N 26 W 1016 mb 25 kt: Non-tropical low
2023/09/14 00Z: 47 N 24 W 1014 mb 25 kt: Non-tropical low
2023/09/14 06Z: 47 N 23 W 1013 mb 30 kt: Non-tropical low
2023/09/14 12Z: 46 N 21 W 1014 mb 30 kt: Non-tropical low
2023/09/14 18Z: 46 N 19 W 1010 mb 35 kt: Non-tropical low

[WalterWhite]

According to 00Z surface analysis, the low has moved to 45 N 17 W and has deepened to 1009 mb.


According to 06Z surface analysis, the low has moved to 45 N 15 W and has deepened to 1006 mb.


Models, such as the GFS, ECMWF, CMC, and ICON, and ensembles, such as the GEFS and ECENS, are still insistent upon the development of this system into a subtropical storm.

As of now, my best track estimate of this system would be:

2023/09/13 12Z: 46 N 27 W 1016 mb 25 kt: Non-tropical low
2023/09/13 18Z: 46 N 26 W 1016 mb 25 kt: Non-tropical low
2023/09/14 00Z: 47 N 24 W 1014 mb 25 kt: Non-tropical low
2023/09/14 06Z: 47 N 23 W 1013 mb 30 kt: Non-tropical low
2023/09/14 12Z: 46 N 21 W 1014 mb 30 kt: Non-tropical low
2023/09/14 18Z: 46 N 19 W 1010 mb 35 kt: Non-tropical low
2023/09/15 00Z: 45 N 17 W 1009 mb 35 kt: Non-tropical low
2023/09/15 06Z: 45 N 15 W 1006 mb 35 kt: Non-tropical low

[Extratropical94]

GFS shows the low to transition into a symmetric warm-core cyclone. Little temperature advection and no frontogenesis, and it might lose its frontal structure just quick enough to become subtropical before landfall.

[WalterWhite]

NOAA 12Z surface analysis has indicated that the low has moved SE to 44 N 14 W and has stayed at 1006 mb. Models still indicate development for this system into a subtropical cyclone.


As of now, my best track estimate of this system would be:

2023/09/13 12Z: 46 N 27 W 1016 mb 25 kt: Non-tropical low
2023/09/13 18Z: 46 N 26 W 1016 mb 25 kt: Non-tropical low
2023/09/14 00Z: 47 N 24 W 1014 mb 25 kt: Non-tropical low
2023/09/14 06Z: 47 N 23 W 1013 mb 30 kt: Non-tropical low
2023/09/14 12Z: 46 N 21 W 1014 mb 30 kt: Non-tropical low
2023/09/14 18Z: 46 N 19 W 1010 mb 35 kt: Non-tropical low
2023/09/15 00Z: 45 N 17 W 1009 mb 35 kt: Non-tropical low
2023/09/15 06Z: 45 N 15 W 1006 mb 35 kt: Non-tropical low
2023/09/15 12Z: 44 N 14 W 1006 mb 35 kt: Non-tropical low

[WalterWhite]

18Z surface analysis has shown the low moving E to 44 N 13 W and has deepened to 1004 mb.



As of now, my best track estimate of this system would be:

2023/09/13 12Z: 46 N 27 W 1016 mb 25 kt: Non-tropical low
2023/09/13 18Z: 46 N 26 W 1016 mb 25 kt: Non-tropical low
2023/09/14 00Z: 47 N 24 W 1014 mb 25 kt: Non-tropical low
2023/09/14 06Z: 47 N 23 W 1013 mb 30 kt: Non-tropical low
2023/09/14 12Z: 46 N 21 W 1014 mb 30 kt: Non-tropical low
2023/09/14 18Z: 46 N 19 W 1010 mb 35 kt: Non-tropical low
2023/09/15 00Z: 45 N 17 W 1009 mb 35 kt: Non-tropical low
2023/09/15 06Z: 45 N 15 W 1006 mb 35 kt: Non-tropical low
2023/09/15 12Z: 44 N 14 W 1006 mb 35 kt: Non-tropical low
2023/09/15 18Z: 44 N 13 W 1004 mb 35 kt: Non-tropical low

[WalterWhite]

GFS shows the low to transition into a symmetric warm-core cyclone. Little temperature advection and no frontogenesis, and it might lose its frontal structure just quick enough to become subtropical before landfall.

https://i.imgur.com/mRX1WV2.png

https://i.imgur.com/91YbiK0.png

https://i.imgur.com/V4PmoQo.png

From where did you get the first image?

[WalterWhite]

The GFS, CMC, ECMWF, and ICON still insist upon the formation of a subtropical storm off the coast of Iberia. GFS and ECMWF still indicate thermal patterns reminiscent of a subtropical cyclone as opposed to those of an extratropical cyclone.









The GEFS, GEPS, and ECENS ensembles all still indicate development of this system as well.







The NHC should mark this in their next Tropical Weather Outlook.

[WalterWhite]

Even NAVGEM is on board for the development of this system.

[weeniepatrol]

GFS shows the low to transition into a symmetric warm-core cyclone. Little temperature advection and no frontogenesis, and it might lose its frontal structure just quick enough to become subtropical before landfall.

https://i.imgur.com/mRX1WV2.png

https://i.imgur.com/91YbiK0.png

https://i.imgur.com/V4PmoQo.png

From where did you get the first image?

https://moe.met.fsu.edu/cyclonephase/

[WalterWhite]

00Z surface analysis indicates the low has moved to 43 N 12 W and has deepened to 1002 mb.



06Z surface analysis indicates the low has moved to 42 N 12 W and has deepened to 999 mb. Signs are also indicating that the low is detaching itself from the frontal structure, which could indicate subtropical development.



The GFS, ECMWF, and CMC all indicate this low will have more time to acquire tropical characteristics and potentially become a subtropical cyclone.







As of now, my best track estimate of this system would be:

2023/09/13 12Z: 46 N 27 W 1016 mb 025 kt: Non-tropical low
2023/09/13 18Z: 46 N 26 W 1016 mb 025 kt: Non-tropical low
2023/09/14 00Z: 47 N 24 W 1014 mb 025 kt: Non-tropical low
2023/09/14 06Z: 47 N 23 W 1013 mb 030 kt: Non-tropical low
2023/09/14 12Z: 46 N 21 W 1014 mb 030 kt: Non-tropical low
2023/09/14 18Z: 46 N 19 W 1010 mb 035 kt: Non-tropical low
2023/09/15 00Z: 45 N 17 W 1009 mb 035 kt: Non-tropical low
2023/09/15 06Z: 45 N 15 W 1006 mb 035 kt: Non-tropical low
2023/09/15 12Z: 44 N 14 W 1006 mb 035 kt: Non-tropical low
2023/09/15 18Z: 44 N 13 W 1004 mb 035 kt: Non-tropical low
2023/09/16 00Z: 43 N 12 W 1002 mb 035 kt: Non-tropical low
2023/09/16 06Z: 42 N 12 W 0999 mb 035 kt: Non-tropical low