FIRST FLOODS: Grafton’s wettest December on record
GRAFTON has already experienced its wettest December on record dating back to 1867.
After the third driest November on record (7mm), by 2pm Tuesday Grafton had received 304.6mm of rain in December.
The total after just 15 days well exceeds the previous December high of 209.8mm recorded in 2014 and is more than triple the monthly average of 91.4mm.
More than 90 per cent of the current monthly total has fallen in the past five days.
"It is now the wettest December on record. With the whole month now at 304.6mm it beats all those records for December dating back to 1867," Weatherzone meteorologist Joel Pippard said.
"There has been 274.6mm at Grafton in the last five days which is a huge amount of rainfall. It is very unusual to get it all so close together.
"We've seen a very slow moving coastal trough which has almost stalled. There is a high pressure system off the coast of New Zealand that hasn't allowed it to move very much.
"This has resulted in a lot of moisture which has converted into rainfall across southeast Queensland and Northern NSW."
Grafton had 125.2mm to 9am Tuesday, including half that total after 6.30am.
Higher in the catchment, Dorrigo has had 522mm in the past five days including 162mm in the 24 hours to 9am Tuesday, plus another 86.6mm to 5pm.
The Orara River reached the moderate flood level of 9m at Glenreagh by 11am Tuesday, and had risen to above 10.3m by 5pm.
Water levels rose sharply in the Nymboida, Mann and Clarence rivers throughout today and were expected to continue rising.
Clarence River at Grafton is expected to rise above the minor flood level (1.9m) and peak at about 2.3m with the high tide at 2am Wednesday morning. It will be the first time the Clarence has ever reached minor flood levels at Grafton during the month of December.
While the Clarence River is not expected to reach moderate flood levels after the existing rainfalls, more showers are forecast which could lead to increased risk of flooding.
"We are expecting more precipitation, but in the form of showers and thunderstorms rather than persistent rain," Mr Pippard said.
"We may see 20 to 40mm in isolated parts, but more likely 5 to 10mm in widespread parts in coming days, and a similar pattern every day until at least Wednesday next week.
"Certainly we're hitting minor flooding levels in the Clarence River tonight, and it will go down tomorrow, but it will remain fairly high and if those thunderstorms keep topping up the rainfall it could bump it up quite quickly."