Tag Archives: Cone of Uncertainty


In the course of just over one week since SANDY generated from a tropical depression in the Caribbean, became a tropical storm and reached hurricane strength as it hit Jamaica and then Cuba, also affecting Haiti and the Dominican Republic. It then continued over the Bahamas, creating concerns among residents of Florida as all of the peninsula’s east coast found itself within the “cone of uncertainty used by The National Hurricane Center to surround the predicted track of a tropical cyclone.

Atlantic wide satellite view (NOAA) on 28 October 2012 showing water vapor in the atmosphere to highlight Tropical Cyclone SANDY, other areas of disturbed weather, as well as vast regions of mainly dry air

In moving over The Bahamas hurricane SANDY began following what could best be  described as a zigzagging track, first aiming toward the northwest paralleling the coast of Florida, but then turned north and later on toward the northeast paralleling the coast of Georgia and South Carolina, only to start describing another turn to the north and then the northwest aiming toward the mid-Atlantic and northeastern coastline of the USA.

Projected track for Hurricane SANDY as of 28 October 2012 developed by the U.S. Navy Research Laboratory on the basis of observational data from NOAA

In the process of meandering over the western Atlantic following the USA coastline Hurricane SANDY also began growing in size until it has become quite a large storm menacing hundreds of miles of USA coastline from North Carolina to Maine. It appears storm surge will be the main hazard as this behemoth of a tropical cyclone interacts with the numerous bays, sounds, inlets and other topography along the coastal region, which generate a funneling effect on the rushing waters contributing to storm surge and waves of enormous height. However, inland flooding and strong winds will also add to the impact, and could cause sever damage and human suffering.

GOES color-enhanced infrared satellite image (NOAA) showing Hurricane SANDY on 28 October 2012 as it approaches the coast of the USA

With SANDY being the 19th named storm of the 2012 Atlantic Hurricane Season are we already seeing the last of the season? Is this the 2012 Atlantic Hurricane Season going out with a bang, or is there more fuel left in the tropics so that we may still see additional cyclonic activity in days and weeks to come? After all the “official” season, as if Mother Nature really pays attention to this,  still has more than four weeks left to go.

Satellite image (NOAA) showing two tropical waves over hurricane alley and the eastern Atlantic on 28 October 2012

Regarding the possibility of more fuel left in the tropics to support additional tropical cyclone activity in the Atlantic, there are currently two tropical waves moving along hurricane alley that may warrant paying attention to over coming days, for any signs of potential further development.

Color-enhanced infrared satellite image on 28 October 2012 showing Typhoon SON-TINH over the Gulf of Tonkin about to make landfall in Viet Nam near Haiphong and Hanoi

Elsewhere in the world, there is tropical cyclone activity in the South China Sea at the northwestern extreme of the Pacific Ocean, where Typhoon Son-Tinh is making landfall over Viet Nam over the Gulf of Tonkin near Haiphong and Hanoi. Also in the Pacific there is a good sized tropical wave half way between Hawaii and the Philippines while closer to our region, over the Eastern Pacific,  there is a large elongated cell of disturbed weather and low pressure extending from just off-shore Central America to about 1,000 kilometers SSW of Acapulco, Mexico, which may show some potential for cyclonic development.

Color-enhanced infrared GOES satellite (NOAA) image on 28 October 2012 showing a region of low pressure and disturbed weather off the coast of central America and Mexico

There is also plenty of stormy weather over the northern Indian Ocean where we see a large cell of low pressure, showing some signs of potential cyclonic activity, over the southern end of the Bay of Bengal, off the coast of India near Madras and the nation of Sri Lanka, which may warrant close monitoring over the next couple of days. On the other side of the subcontinent, off the west coast of India over the Arabian Sea there are some areas of disturbed weather that may warrant monitoring.

Color enhanced infrared satellite image showing a potential tropical cyclone near India and other regions of disturbed weather over the Indian Ocean on 28 October 2012

The southern hemisphere is relatively quiet at this time, except for a couple of areas near New Zealand and over Australia, although there are large areas of disturbed weather and strong winds near the extreme southern latitudes.

Full-disk satellite image of Earth over the Pacific Ocean on 27 October 2012 showing the ‘belt of tropical activity’, spanning from just off the coast of Mexico to near the Philippines, as well as a cell of low pressure near Mexico
Full-disk satellite image of Earth’s western hemisphere on 28 October 2012 showing a discontinuous ‘belt of tropical activity, a couple of tropical waves along hurricane alley and in the eastern Atlantic, as well as Hurricane Sandy approaching the USA coastline

How damaging will the impact of Hurricane SANDY be over the USA? Is SANDY the last activity of the 2012 Atlantic Hurricane Season? How much more cyclonic activity will there be in the northern hemisphere? When will the southern hemisphere start to see more tropical cyclones? How will 2012 rate in terms of total tropical cyclone activity worldwide compared to previous years? Yes, there are a number of questions that we would like to have answered, but we will have to wait until after the end of the year for some of those answers.

Tropical Storm IRENE: Here we Go Florida!

Now that Tropical Storm IRENE, the ninth-named tropical cyclone of the 2011 Atlantic hurricane season, has generated in the extreme eastern Caribbean the data-crunching by the prediction models is is busy following the path of the storm trying to determine where it might go and where it could be five days from now. These models used by the National Hurricane Center require continuous input from satellite observations, from surface observations made by oceangoing ships in or near the path of the storm, and also from observations and data captured by especially equipped airplanes, the so-called hurricane hunters, which fly through the cyclone in a zig-zag pattern at an altitude of 3,000 meters and others that flight around the perimeter of the storm at much higher altitudes.

Visible light satellite image of Tropical Storm IRENE taking in the early morning on 21 August 2011 showing the storm as it moved over the French Antilles toward the Caribbean

The end result of these model runs is not only the graphic representation of the projected storm track as a cone of uncertainty which is used by emergency management and civil protection authorities to issue alerts, watches and warnings  for the public, but also  information about sustained wind speeds, potential wind gusts, minimum central atmospheric pressure, amount of precipitation, potential for strengthening or weakening as the storm progresses. Over the years predictions by the National Hurricane Center based on these models, especially the projected three-day track, have improved considerably becoming more accurate over recent years. Despite this improvement in track prediction, the five-day forecast still carries a high degree of uncertainty, which is why the cone of uncertainty gets rounder and wider toward the end of any given five-day prediction.

With respect to Tropical Storm IRENE the model runs have resulted in a track that has the tropical cyclone strengthening over the next 24-48 hours, perhaps even reaching hurricane strength as it approaches a predicted landfall in Hispaniola. At this point an assessment of the coupled ocean-atmosphere environment around and ahead of the storm suggest it may survive its interaction with topography as it traverses over Haiti and Cuba to reorganize, and perhaps strengthen again to hurricane strength, over the Bahamas and Florida straits for another landfall somewhere in south Florida.

Projected five-day track for Tropical Storm IRENE as of 21 August 2011, courtesy of the U.S. Navy Research Laboratory based on NOAA observations

Based f current projections Florida is a target for Tropical Storm IRENE, possibly as a hurricane by then, toward the end of this week. Because this projected impact on Florida is toward the end of the five-day track the degree of uncertainty as to the exact region of landfall, its intensity at the time, or whether there will be a land fall at all or not in South Florida, remains quite high. Such uncertainty notwithstanding, the prudent action for all South Florida interests is to monitor the progress of Tropical Storm IRENE closely over the next 2-3 days, be on the alert, make preparations and concentrate of ways to mitigate any potential impact if and when it takes place. In fact all interests around the Caribbean sub-basin, particularly along the eastern periphery of the Caribbean sea, and in the Bahamas and South Florida, will do well to pay close attention as IRENE evolves and moves over the next 24-72 hours.

Composite full-disk satellite image of Earth's western hemisphere taken in the afternoon of 20 August 2011, showing the 'belt of tropical activity' circling the planet just north of the equator.

Those of us who call South Florida home will do well to keep an eye on what happens with Tropical Storm IRENE over the next few days, especially when our region enters the three-day cone of uncertainty toward mid week. In the mean time Pay Attention! Be Prepared!! MITIGATE!!!

UPDATE: Sunday 21 August 2011 at 6:30 p.m.

Tropical storm IRENE has found a favorable environment and it has gotten better organized and strengthened during the day today. The most significant development with IRENE today is a slight shift of its track toward the north, which will bring it for a possible landfall in southwestern Puerto Rico and a more northerly track over Hispaniola and Cuba, and faster forward movement along its track. Should these changes hold the risk of landfall near the large urban area in southeast Florida increases, although the margin of error this far away is quite high, in the order of 320 – 400 kilometers either way.

Following is the modified track as published by the Navy Research Laboratory, which when compared to the one posted earlier [above] shows  what has been described.

Modified track for Tropical Storm IRENE on 21 August 2011 per the Navy Research Laboratory, based on changes that took place during the day