Tag Archives: Madagascar

Seventeen and counting!

Saturday 13 October 2012! Almost 75% done with the ‘official’ 2012 Atlantic Hurricane Season, and there is plenty of cyclonic activity our there in the tropics.

In the larger Atlantic basin there is Tropical Storm RAFAELthe 17th named tropical cyclone of the 2012 Atlantic Hurricane Season,  over the Lesser Antilles moving generally to the northwest, but expected to make a gradual turn to the north and eventually the northeast as it interacts with a trough over the southeastern USA, the Gulf of Mexico and Florida.  With maximum sustained winds barely reaching 65 kph the storm had begun to show signs of getting better organized and becoming stronger, but the environment ahead contains strong wind shear and may not be too favorable for further development.

Color-enhanced infrared GOES satellite image (NOAA) of 13 October 2012 showing Tropical Storm RAFAEL and Tropical Depression PATTY on the periphery of the Caribbean Sea

Closer to Florida there is now Tropical depression PATTY, the weakened remnants of the tropical storm of the same name, moving generally southward over Cuba being pushed by the system that is descending over the Gulf of Mexico and the southeastern USA.

Atlantic-wide satellite image (NOAA) on 13 October 2012 showing water vapor in the atmosphere as a way of highlighting the complex interaction of various atmospheric features and both Tropical Depression PATTY and Tropical Storm RAFAEL

What is interesting to see with RAFAEL and PATTY is how they are getting closer to one another and yet they are tracking in opposite directions under the influence and interaction of several atmospheric components now over the Gulf, Caribbean and western Atlantic region.

Projected track for Tropical Depression PATTY on 13 October 2012 developed by the U>S> Navy Research Laboratory on the basis of observational data from NOAA
Projected track for Tropical Storm RAFAEL on 13 October 2012 developed by the U.S. Navy Research Laboratory on the basis of observational data from NOAA

Farther to east over the Cape Verde Islands there is a large tropical wave that may need monitoring as it moves generally toward the west and ‘hurricane alley’ in the next day or so.

Color-enhanced infrared satellite image (NOAA) of rhe eastern Atlantic Ocean on 13 October 2012 showing a large tropical wave over the Cape Verde Islands moving generally westward along ‘hurricane alley’

Continuing our outlook to the east, there is not much tropical activity along the ‘tropical wave assembly line’ over Equatorial Africa, but beyond the eastern coast of the African continent in the central Indian Ocean we find the first tropical cyclone to be generated in the southern hemisphere in a long time; a sign that after the ‘autumnal equinox’ the ocean waters and atmosphere south of the equator have started to grow warmer. This is Cyclone ANAIS, which has rapidly strengthened in the past 24 hours from tropical storm to a category 2 tropical cyclone. The storm is moving southwest toward Madagascar.

Color-enhanced infrared satellite image (NOAA) showing Cyclone ANAIS over the Indian Ocean on 13 October 2012 moving in the general direction of Madagascar

Far over the Philippines Sea, in the northwestern Pacific, Typhoon PRIPAROON a category 1 tropical cyclone is moving toward the northeast near the island of Okino-Tori-Shima (Japan) on a path that could take between Okinawa and Iwo-Jima.  This typhoon is being shadowed by a large cell of stormy weather to its southeast that exhibits some interesting characteristics and may warrant close monitoring for potential further development.

Color-enhanced infrared satellite image (NOAA) over the far northwestern Pacific on 13 October 2012 showing Typhoon PRAPIROON in the Philippine Sea moving toward the northeast, and its shadowing storm cell to its southeast
Color-enhanced infrared GOES satellite image (NOAA) on 13 October 2012 showing a strong tropical wave off the coast of Mexico, which warrants monitoring for potential further development

At the other extreme of the Pacific Ocean near the coast of Mexico a strong tropical wave is generating strong storms and plenty of rain some 1,000 kilometers to the WSW of Acapulco, Mexico, and it is being monitored for potential cyclonic development over the next 24-36 hours.

So, there is plenty of activity in the northern tropics even as the transition toward a regime of tropical cyclones over the southern hemisphere has already began.  While we have seen above average activity, in terms of number of tropical cyclones, over the Atlantic and Eastern Pacific basins, and plenty of activity also over the Northwestern Pacific, we are still below the historical average of the past 50 years on a calendar year-to-date basis worldwide. We will continue to monitor to see what else Mother Nature has in store in terms of tropical cyclone activity in what remains of 2012.

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!