Category Archives: Tropical Cyclones

The Northern Tropics in May 2011

Gradually with the onset of spring in the northern hemisphere  we have seen that tropical band just north of the equator get active with tropical waves, increased sea surface temperatures, rain, thunderstorms, and flaring areas of disturbed weather worldwide. 

Such tropical activity shows clearly within the belt of tropical activitygirddling Earth on the composite satellite view [courtesy of NASA] below:

Full disk composite satellite view of Earth's western hemisphere on 8 May 2011

 On the satellite image two areas are of especial interest to those of us in the United States: (a) One is the eastern-east Pacific just off and west of the coasts of Central America. This region, together with the junction of the isthmus of Panama with South America [Colombia] saw extraordinary rain an storm activity for a good portion of 2010, which was attributed to the effects of La Nina active off the coast of Peru, leading to a number of cyclonic events over Central America, Southern Mexico and the Gulf of Mexico and  above average rainfall over most of Central America, particularly Nicaragua, Costa Rica and Panama as well as portions of northern Colombia and Venezuela with several flooding events.  During the spring of 2011 La Nina is still active, although in a somewhat weaker mode than in 2010, and severe thunderstorms and rain have already affected that Panama – Colombia junction, raising the possibility that we might see more of the same during the summer and fall of 2010. The satellite image below [courtesy of NASA]:

of the Central American region on 8 May 2011″] (b) The other one is the eastern Atlantic, which marks the junction between mainland equatorial Africa and the so-called hurricane alley starting in the neighborhood of the Cape Verde Islands and then west by northwest toward the Antilles and the Caribbean. This area is the terminus for the tropical-wave assembly line that traverses equatorial Africa from east to west and serves as the transport for pulses of disturbed weather often originating over the Indian Ocean, which pick-up heat and moisture over equatorial Africa causing rain and thunderstorms. This activity generates tropical wavesthat emerge over the eastern Atlantic providing fuel fo potential tropical cyclone development. A satellite view of this region on 8 May 2011 already shows plenty of tropical wave activity giving way to cells of rain and thunderstorms south of the Cape Verde Islands moving west along ‘hurricane ‘alley’:

of the eastern Atlantic and western equatorial Africa region on 8 May 2011″]Completing the picture, also on 8 May 2011 a tropical low over the western Pacific became the first tropical cyclone of the the year in northern hemisphere. This is tropicl storm AERE moving toward landfall in the Philippines near the capital city of Manila. The forecast is for the storm to traverse the island and then make way toward Taiwan and possibly Japan under favprable ocean-atmospheric conditions. It would appear then that conditions for cyclogenesis are gradually congealing and becoming more favorable as spring rushes toward summer in Earth’s northern hemisphere. The satellite picture below shows the tropical cyclone on 8 May 2011 just east of the Philippines’ coastline:

showing tropical storm AERE on 8 May 2011 as it approached landfall in the Philippines.”]It is clear the northern tropics are being fueled by warming oceans and atmosphere as the Earth’s axis continues to tilt, bringing the northern hemisphere into full view of the Sun. Conditions are now in place that could soon generate tropical cyclone activity over the eastern Pacific and the eastern Atlantic; if we take into account the continued warming of surface waters in the Atlantic, Caribbean and Gulf, as well as in the eastern east Pacific plus the continuous presence of La Nina off the coast of Peru we may be looking at an active 2011 hurricane season in the Atlantic basin.  Relative to this the Colorado research duo of Bill Gray and Phil Klotzach recently presented their early forecast for the 2011 Atlantic hurricane season, calling for a total of 16 named-storms including 9 hurricanes, of which 5 may reach major hurricane strength (category 3 and above in the Saffir-Simpson scale of hurricane intensity).

Nature is sending us signals through this activity in key regions of the northern tropics. It behooves all of us in vulnerable coastal communities to pay attention to those signals, to be prepared and to practice mitigation to reduce the potential for damage from the impact of hurricanes, which will eventually come our way!

The Tropics are Growing Restless!

Take a look a the central Atlantic ocean north of the equator, just to the southeast of Bermuda, and today 20 April 2011 you will see a huge area of storms moving in the general direction of mainland USA!!

for the aviation industry on 20 April 2011″]
The GOES [Geostationary]  satellite  over the eastern USA captured an image of a rather large region of disturbed weather covering some 2.5 million square kilometers over the central Atlantic ocean just southeast of Bermuda and northeast of the Virgin Islands.  With so much extreme weather activity causing tornado and flood damage in several states over the past couple of days and capturing our collective attention, it’s been easy to forget that with the advent of spring the waters north of the equator have warmed considerably over the past 30 – 60 days, and  we are seeing more and more signs that the tropics are growing restless as we the “official” start of the 2011 Atlantic hurricane season is less that six weeks away.
Color-enhanced infrared GOES satellite image [NOAA] on 20 April 2011 showing what could well be the first ‘salvo’ of the 2011 Atlantic Hurricane Season.Satellite imagery, such as the color-enhanced infrared GOES satellite photo taken earlier this afternoon of 20 April 2011, clearly show a region of low pressure over the central north Atlantic  where rain and storm activity are being generated over a large area while the system moves in a generally westward direction.  This satellite image also shows the areas of extreme weather that have been attacking large regions of the USA, causing death and damage over the last couple of days. Also shown are areas of storm activity over northern South America, Panama and Central America. These are all signs that as surface waters and the atmosphere to the north of the equator continue to warm up  as spring takes hold of the northern hemisphere, tropical cyclogenesis can not be too far off even if the start of the “official” 2011 Atlantic hurricane season is 5-/12 weeks away. Other signs of impending tropical cyclonic activity and potential contributos to the same can be seen on other satellite images such as the ones that follow:
Full Earth disk composite satellite image of the western hemisphere on 20 April 2011. The full Earth’s disk satellite image [NASA] on the left show once again the “belt” of tropical activity girdling the Earth around the equator as it slowly migrates northward. On the eastern [far right] extreme of the “belt” there are alreday signs of tropical waves emerging from over equatorial Africa over the eastern Atlantic to the south of the Cape Verde islands. So, here we see the outline of what is generally known as “hurricane alley”, lots of tropical activity near the equator, “pulses” of tropical waves moving westward over equatorial Africa toward the eastern Atlantic, and to top it all off, a large region of low pressure and disturbed weather in the middle of the Atlantic. It is clear the tropics are growing restless and tropical cyclones can not be too far off. Not seen here, but shown in additional images below, are the increasingly warmer waters of the Atlantic, Caribbean, Gulf and eastern Pacific, and the lingering La Nina [ENSO] off the coast of Peru, which are all potential contributign factors to cyclogenesis in the Atlantic in 2011.Map of sea surface temperatures on 19 April 2011.
This satellite-based [NOAA] temperature map of sea surface waters on 19 April 2011, already shows surface waters at or above 30 Celsius along “hurricane alley”, parts of the Caribbean and the Gulf and also off Central America and Mexico in the eastern Pacific. Also shown are the much cooler waters of the coast of Peru indicating the lingering effects of the La Nina event that was active in 2010.
Soon, during the National Hurricane Conference and the soon to follow Florida Governor’s Hurricane Conference both NOAA National Hurricane Center and the folks at Colorado State University will issue their predictions for tropical cyclone activity in the North Atlantic basin for 2011 and then Mother Nature will do what it pleases and humankind will be divided into suffering bystanders or active participants who manage their risk and mitigate the impacts of hurricanes in their own communities.
For starters there is that large glub of disturbed weather over the central north Atlantic, which may develop further or just blow over, but which nevertheless warrants close monitoring. Then we already have the ‘belt’ of tropical activity circling the globe around the equator, the initial waves of storms coming over equatorial Africa toward the eastern Atlantic and “hurricane alley”, increasingly warmer surface waters in the Atlantic, Caribbean, Gulf and eastern Atlantic, and weakened but still lingering La Nina event off the coast of Peru. So many of the potential triggers or contributors to cyclogenesis in the Atlantic and eastern Pacific basins are already in place or being assembled. Let us see what Mother Nature has in store for us. Let us pay attention. Be prepared! MITIGATE!!