Flood Risk and Vulnerability Analysis Project - Atlantic Climate ...

Weather Bombs
This increasingly accepted term refers to low pressure systems that develop rapidly,
explosively deepening low pressure systems, and hence the word „bomb‟, in the Cape
Cod area off the coast of North America;
This is a favored area for cyclogenesis or re-envirogation of storms moving off of the
continent and encountering the warm waters of the Gulf Stream;
Storms occur especially in the fall and winter and deepen further as they move rapidly
north-east or north-north-east along the Gulf Stream skirting the island of Newfoundland;
Some storms can reach Hurricane or near Hurricane force sustained wind speeds (> 100
km/hr) and give rise to the strong „Nor‟easters‟ that Newfoundland is known for (counterclockwise
cyclonic circulation on the north side of these systems);
Typically tracking just off of Avalon or right over the Avalon Peninsula, these storms may
become more intense with warming oceans and a more marked Gulf Stream which
provides a main source of energy and moisture for their explosive development.
However, it is uncertain what will happen with events of this nature as they could also
become less intense given that the temperature gradients they draw energy from will
also weaken in the future;
An extensive area of strong and aligned northeast winds can sometimes be set up as
the storms move along the Gulf Stream and are absorbed by the semi-permanent
Icelandic low. This generates seas and waves over a long fetch area creating massive
waves which affect Eastern and Northeastern Newfoundland producing coastal flooding;
and
The frequency and intensity of such events will also likely change through this century as
a result of global warming. The most recent studies (Mizuta et al, 2011) suggest that
mid-latitude cyclones, in general, will become less frequent in a warmer climate, but will
be more intense on average.
Hurricanes and Tropical Storms
These are major cyclones developing over the warm (> 26ºC) waters of the equatorial
Atlantic Ocean;
The island of Newfoundland lies at the outer north west reaches of typical Atlantic
Hurricane tracks;
Hurricanes and Tropical Storms from the Atlantic, see Figure 3-27, can pass on either
side of the island of Newfoundland as has been seen in recent years by Chantal, Aug
2007, just east of the Avalon, and Earl, Aug 2010 through the Strait of Belle Isle though
clearly, the eastern regions of the island are more exposed to the higher intensity
storms;
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