The cyclone that won’t go away!

Just about two weeks ago the tropical storm that became cyclone Giovanna generated over the central Indian Ocean near the equator. Since then this storm grew in size and strength reaching category 4 intensity one week ago before making landfall in Madagascar on 13 February, near the capital of Antananarivo. Weakened by its interaction with the topography of the island the cyclone still managed to traverse it to emerge over the Mozambique Channel the next day as a tropical depression.

Color-enhanced infrared satellite image showing two tropical cyclones active over the southern Indian Ocean on 20 February 2012

Once over the warm waters between the African continent and Madagascar the cyclone strengthened once again becoming a tropical storm and reaching category 1 strength on 19 February, which it maintained until earlier today 20 February 2012. The cyclone has been downgraded to tropical storm category and late in the day was moving generally south by southeast some 500 kilometers south of Reunion in the southern Indian Ocean. While it appears Giovanna will continue to weaken as it tracks over progressively colder waters, this storm has traveled close to 7,000 kilometers over the past 14 days.

Tropical storm Giovanna is being chased by a cyclone currently designated as Tropical Storm 13, which formed as a tropical depression over the south-central Indian Ocean some 4-5 days ago, and is near the island of Rodrigues in the Mauritius archipelago on 20 February 2012 moving in a generally southward track toward the course being followed by Giovanna.

Current cyclonic activity and the long lasting course of cyclone Giovanna are testimony of the coupled ocean-atmosphere condition that prevail over most of the Indian Ocean and the tropical South Pacific. Evidence of this cyclogenesis-favorable environment is apparent in the satellite image above, in the form of very cold cloud tops over a vast region of disturbed weather and rainfall reaching from the western Pacific across the Indian Ocean all the way to just off-shore eastern Africa.

Elsewhere in around the world the Caribbean and most of the tropical Atlantic basin north of the equator are calm and cool on20 February, but both the northeastern Pacific and Northern Atlantic are different stories. Over the Pacific it appears the Pineapple Express is quite active interacting with a polar jet stream near Alaska to create pulses of disturbed winter weather over large regions of North America reaching all the way into Texas and the southeastern USA. The satellite image below illustrates these conditions on 20 February 2012.

Satellite view for the aviation industry showing the calm, mostly col and dry Caribbean, Gulf and a good portion of the tropical Atlantic basin on 20 February 2012

Color enhanced infrared satellite image showing stormy conditions over portions of the northeastern Pacific Ocean and North America on 20 February 2012

These pulses of winter stormy weather are pushed beyond North America over the northern Atlantic and Europe beyond, where extreme weather events over the past few weeks have caused considerable damage and death in many areas. The satellite image below partially illustrates some of those prevailing conditions over Europe and beyond.

Color-enhanced infrared satellite image showing large regions of disturbed winter weather over the North Atlantic and Europe on 20 February 2012

The reality of this northern hemisphere winter in 2011/2012 is that it has been anything, but typical. Late in coming in some regions, extreme in others, warmer than usual, wetter than usual, rare etc. It is clear that patterns have been changing as the effects of global climate change are becoming more apparent.

What will the rest of 2012 brings us in terms of climatic conditions? What will happen by way of cyclogenesis around the various basins worldwide? Only time will tell, but if current and recent activities are any indication, it is certain to be interesting! Keep watching!


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