East Coast Lows [44]

By Nick Gill

Cast your mind back to Easter ’95.

Norm Sanders, Mark Pearson, a friend of mine from Adelaide and I huddle over a White Wings cheesecake in a dark tent on the Nadgee coast.

Outside the wind howls and threatens to uproot trees. The rain comes down by the truckload and houses are unroofed in coastal towns to the north. So much for the south coast paradise of Merrica River, normally a haven for weary paddlers.

This storm didn’t last long, by the next day it was pleasant again. Brevity and strength are features of one weather system that produces such conditions on the NSW coast – east coast lows. Whether this Easter storm was one such low I can’t remember. It’s nature, however, suggests that it likely was one of these so-called ‘bombs’.

Kayakers need to beware of the gale force winds and heavy seas that these lows bring, often at short notice. A 1986 east coast low brought 40 knot winds and in excess of 300 mm of rain to Sydney in 24 hours. They are the intense storms that in NSW bring easterly gales, flooding in coastal rivers, heavy seas and have caused the loss of small craft off the coast. While they tend to do their worst when we are most likely to be snug in bed, their danger lies partly in the sudden onset and in the fact that meteorological observations are at a minimum at the times they are most likely to occur. Added to this is the fact that they are rare beasts – on average only one or two occur each year.

There are a variety of types of east coast lows. The term refers to a range of intense low pressure systems that can develop at any time of the year (although, due to water temperatures, they tend to occur in late autumn or winter) over the NSW coast. They can originate in a variety of ways. In summer they can be the still intense remnants of tropical cyclones which have moved south. Others form over inland NSW from an easterly dip towards the coast, or are associated with cold fronts moving eastwards from South Australia. The low that we need to be most aware of for their sudden onset and intensity is the type that forms off the NSW coast itself.

The power and rapid onset of east coast lows is driven by circumstances in which there is a steep temperature gradient of the water from relatively warm offshore water to relatively cold inshore water. This gradient, in concert with the steep topography at the NSW coast, causes intensification of lows and a strong flow of moisture-laden air towards the coast, producing strong winds and heavy rain.

What can we do to avoid getting caught out in one of these monsters?

The simplest thing is to keep a close eye on weather forecasts. The Bureau of Meteorology issues regular bulletins for coastal waters which are available on the phone (1900 926 101) or fax. They are on the Internet at www.bom.gov.au. Weather forecasts are also available on VHF (Ch 67 for regular broadcasts from Telstra) or 27MHZ radio (from Royal Volunteer Coast Patrol or Volunteer Coast Guard Stations). On trips get the phone numbers of local Coast Patrols & Guards, and take an AM/FM radio and obtain frequencies for local stations before you set out.

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