Hybrid Eastern Atlantic storm ( 1-4 Feb 2010)

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stormympt
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Hybrid Eastern Atlantic storm ( 1-4 Feb 2010)

#1 Postby stormympt » Thu Sep 13, 2012 11:44 am

Hi everyone, this is my first post in s2k, and i´ll start with a very interesting storm that developed in an extremely rare context in the eastern Atlantic.

This storm started as an ULL, that detached from the westerlies on the 25th of January, well to the Southwest of Azores islands, in the central subtropical Atlantic.

The unusualy deep mid latitude trough from wich this ULL emerged had previously been pumping lots of tropical air from the S into the central Atlc.

In the next few days the sistem almost stalled, several thousand miles to the WSW of Canary islands, during that time the storm was able to extend its circulation trough the entire troposphere, and in the low levels a tropical/subtropical air mass wraped around the circulation.

Beneath the sistem, SST´s above 70ºF were observed.


As days passed the storm gained organization and deep convection was permanent around the center of circulation, as the storm remained sheltered from other extratropical sistems due to a large dynamic Anticiclone situated to the north of the Az islands.

Then, on Feb 1-2nd, the storm aproached the Canary islands...this after "marinating" over subtropical waters for 7 days...according to reanalysis from German Weather center the sistem had an obvious mid level warm core.

At this time the storm also presented a large CDO feature, with banding features around the main convective complex, that afected Canary islands directly with TS/TD force winds and copious amounts of rain, in excess of 100mm...also vigorous tstm activity was observed.

At this point the storm started recurving to the NE ahead of an aproaching upper trough.

The upper trough bypassed the storm as it mooved between Morocco and Madeira island, during the night from 2nd to 3rd of February.
Strong W shear shreded the storm´s convection and the storm became a swirl of low level clouds, but it was noticeable that the circulation was tight and closed.

Then something unbelivable happened...during the 3rd of Feb the shear eased and upper level difluence was present ahead of another upper trough, and over SST´s around 65-68ºF deep convection exploded all over the storm´s circulation, in such fury that the storm rappidly developd an impressive outflow cirrus feature with typical anticiclonic rotation.

Then the storm continued to the NE, and gradually tilted to a more easterly path as interecting with a low to mid level cold core high over Iberian Peninsula ( acting almost as a warm air bublble in the atmosphere).

The storm mantained a well defined inner core structure untill landfall near Cadiz Peninsula, in Southern spain, in the dawn of 4th of February.

The storm impacted cadiz peninsula with sustained tropical depression winds, moderate rain amounts of 1 to 3 inches and the lowest SLP readings near 1000Hpa.

Then the storm was then caught by a trough and it´s moisture fed a cold front that later caused minor flooding over S France.

Here we have the sattelite animation from Jan 30th to Feb 3rd:
http://www.youtube.com/watch?v=0HdV9lAOlW4

And data from a WU station about 20km to the north of landfall site, in Cadiz Peninsula, Spain:
http://www.wunderground.com/weatherstat ... &year=2010

Finaly, a page in the Spanish storm chasing forum, where you cand find some impressive images of the storm:
http://www.cazatormentas.net/index.php/ ... pical.html
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