MED: SubTropical Storm near Sicily/southern Italy ("Louis")

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Derek Ortt

Re: MED: Subtropical Storm near Sicily/southern Italy

#21 Postby Derek Ortt » Tue Mar 10, 2009 1:39 pm

I think I was forwarded an e-mail on the tropical storms mailing list that showed it was subtropical

If I recall correctly, there was a flat pressure pattern and little temperature gradient. However, it was clearly detached from any frontal features.

Maybe it was a TC or STS underneath an upper low like Hurricane 8 in 1991 or Olga in 2001
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Re: MED: Subtropical Storm near Sicily/southern Italy

#22 Postby Aslkahuna » Wed Mar 11, 2009 9:34 pm

What is needed is some idea of the vertical temperature profile and the upper air pattern to see what the situation was. The Med is pretty far north for winter time TC's and with a cold continent just to the north the conditions don't seem that favorable. There is a lot of terrain surrounding the Med that can trigger medium sized eddies in the lower level flow. Unless my eyes were crossed, I didn't notice any higher level outflow so characteristic of TC's.

Steve
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Re: MED: Subtropical Storm near Sicily/southern Italy

#23 Postby Pedro Fernández » Fri Mar 13, 2009 1:54 pm

Certainly, winter 'medicanes' couldn't be consider as cyclones fully tropicals, as deep warm core is not present. It is quite common to find a shallow warm core in the center of those active low pressure systems, from the extensive convection activity (latent heat). Nevertheless, there is a very well consolidated studies on mediterranean cyclones (it is not difficult to find some at Internet) and some study cases are very interesting, with quite deep warm core, the strongest winds field located very close to the center... and some other characteristics which can be found in a cyclone fully tropical.

Great work again, Danielle. I would like to thank you to keep your eyes on those systems ;)
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Re: MED: Subtropical Storm near Sicily/southern Italy

#24 Postby senorpepr » Sun Mar 15, 2009 3:27 pm

Here are some soundings as the system passed between Corsica and Sardinia:

Image
Image
Image
Image
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Re: MED: Subtropical Storm near Sicily/southern Italy

#25 Postby senorpepr » Sun Mar 15, 2009 3:35 pm

Upper air charts from 27 Jan 09 00Z:

100 hPa
200 hPa
300 hPa
500 hPa
700 hPa
850 hPa
925 hPa
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Re: MED: Subtropical Storm near Sicily/southern Italy

#26 Postby Aslkahuna » Sun Mar 15, 2009 10:46 pm

Definitely nothing tropical about the system. Very familiar looking-sort of like the Closed ULLs that develop when a trough digs off the SoCA coast and kicks inland across AZ. Very convective and a perfect setup for cold air funnels. The TT's at 58 were pretty high for the time of year. Could this have been a remnant MCV or did we have a digger on our hands. The -30C H5 temperature definitely shows that this was a cold core ULL. That said, we have looked at other instances and there are cases where one can make a very strong case for a TC in the Med but they occurred in the Summer and early Fall.

Steve
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Re: MED: Subtropical Storm near Sicily/southern Italy

#27 Postby Derek Ortt » Sun Mar 15, 2009 11:47 pm

I dont think this was a ULL

the weather charts had a surface low, albiet with a flat pressure pattern. That is why I was thinking something subtropical underneath an upper low, as we sometimes get in the Atlantic late in the season
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Re: MED: Subtropical Storm near Sicily/southern Italy

#28 Postby Aslkahuna » Tue Mar 17, 2009 2:41 am

The H5 charts posted above show a closed 534 contour with lowest height value of 531 dm and a -30C cold core. on the 27th of January with the upper center located in the Sardinia/Corsica area. I would say that qualifies as a ULL.

Steve
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Re: MED: Subtropical Storm near Sicily/southern Italy

#29 Postby HURAKAN » Tue Mar 17, 2009 6:18 am

What makes these systems interesting is that they don't look like your typical ULL. Still, looks can be deceiving.
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Re: MED: Subtropical Storm near Sicily/southern Italy

#30 Postby Derek Ortt » Tue Mar 17, 2009 4:31 pm

Aslkahuna wrote:The H5 charts posted above show a closed 534 contour with lowest height value of 531 dm and a -30C cold core. on the 27th of January with the upper center located in the Sardinia/Corsica area. I would say that qualifies as a ULL.

Steve


However, there have been TCs and STCs underneath ULs (Hurricane 8 (1991) Michael, and Olga come to mind... also likely Catarina from 2004 at least initially)

We'd need to take a look at some of the low level charts and temperature profiles to determine if a shallow warm core existed
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Re: MED: Subtropical Storm near Sicily/southern Italy

#31 Postby Aslkahuna » Wed Mar 18, 2009 9:38 pm

The 925mb and H85 analyses posted above showed cooler temperatures in towards the center with temperatures of +4 to +5C at 925 and 0 to -1C at H85 in the Corsica/Sardinia area. No evidence of a warm core and the soundings posted above looked like fairly typical mPk soundings.

Steve
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Re: MED: Subtropical Storm near Sicily/southern Italy

#32 Postby Pedro Fernández » Fri May 01, 2009 9:09 am

I would like to leave here a link to a post in our forum, with the most notable cases of MEDICANES I found some months ago (High Resolution Images). Thank to Dundee Satellite Receiving Station:

http://www.cazatormentas.net/foro/segui ... #msg317792
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