Gales,
flood rains as cyclonic low crosses NSW North Coast |
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| The synoptic
chart for 5pm EDST today (above, BOM)
shows the small low shortly before it crossed the coast near Ballina. The visible light satellite image (above right, CIMSS) for the same time shows a distinct eye. The wind arrows show wind direction and speed at a height of about 3km, with strong winds in the southwestern quadrant. The infrared image for 9.30pm EDST (below right, NPMOC), shows an eye structure still in place, moving north of Ballina close to the coast. The rapid rise of the Bellinger River (below, MHL) followed torrential overnight rain. |
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The low, with a distinct eye visible on satellite and radar images, crossed the coast near Ballina around 6pm, dropping the pressure at the airport to 992.5hPa. It then moved slowly north close to the coast before moving into SE Qld. Because it has been so slow moving, the low has had time to entrain copious amounts of warm, humid, tropical air down its eastern flank. This, coupled with strong divergence, or outflow, aloft and high vorticity, or rotation imparted by the surrounding atmosphere, at lower levels, has set the scene for a major east coast flood event.
Squally, galeforce winds reached cyclonic speeds, with Evans Head automatic weather station, 30km south of Ballina, recording a top gust of 139km/h at 5.15pm. Around 100 buildings at Yamba, 60km south of Ballina, were damaged, and State Emergency Services attended 350 calls for roof damage and downed trees in the North Coast area. Large trees were snapped off or uprooted near the coast, where the winds were strongest, and 70 power lines were cut, blacking out over 10,000 homes between Kempsey and Ballina. SES advised against all non-essential road travel in the Lismore area because of the extensive storm damage, and the severe winds made travel and work close to impossible for repair crews. Caravan parks were evacuated because of the threat of caravans being overturned, and one man was injured by a falling tree.
Rain generated by the low intensified overnight along 500km of the NSW Mid North and North Coasts stretching from the northern Hunter Valley to Byron Bay. Warnings ranging from minor to major flooding were issued for all rivers from the Paterson River north of Newcastle to the Richmond River near Lismore as heavy rain fell throughout the day and was forecast to continue.
The heaviest falls were in the ranges behind Coffs Harbour, where Dorrigo registered over 500mm in the two days ended 9am Friday (see AWN for 9 March for an analysis of rainfall in this event). This resulted in a dramatic rise in the Bellinger River to its highest levels in over 20 years, prompting declaration of the Bellingen Shire as a disaster area. The town, and the upstream community of Thora, were isolated. The neighbouring communities of Darkwood and Kalang have been isolated for 3 days, and the upper Bellinger valley has no power. Helicopters began making food drops this afternoon.
Elsewhere on the coast
- Bridges and roads were cut by floodwaters, landslides and downed trees, with the main Pacific Highway reduced to one lane north of Taree and north of Coffs Harbour
- Two men were rescued from a car washed into a creek in Kempsey
- Coffs Harbour residents sandbagged homes and businesses against local flooding, while SES workers were sandbagging the main street of Ballina in anticipation of high tides banking up the flooded Richmond River
- Heavy seas pounded the North Coast, causing beach erosion.