FLOOD WARNING: Major flooding likely at Gravesend, Moree; Pallamallawa to be cut off

The Bureau of Meteorology (BoM) alert said major flooding is likely at Gravesend Road Bridge and Moree.

SES has said Pallamallawa is likely to be cut off from both Moree and Warialda.

Up to 50 to 150mm of rain has been recorded in the Gwydir catchment since 9am Monday morning.

And it's not going to stop anytime soon, with more heavy rain set to come down for the catchment across the next few days.

Emergency services are predicting that Pallamallawa will be cut off on Tuesday.

The SES has said overland flooding may occur between the Gwydir and Mehi Rivers, and roads from the Gwydir Highway to Pallamallawa may close.

The Gwydir River at Pallamallawa is currently below minor at 1.42m and remains steady, but is expected to reach minor flood levels late Tuesday morning, exceeding moderate by the time evening rolls around.

Water is likely to cover the stretch of road on the Gwydir Highway east of Moree, cutting off the road.

Road access for Pallallamallawa between both Moree and Warialda is likely to be cut, the SES has warned.

The Gwydir River at Yarraman Bridge is likely to reach moderate flooding levels early Tuesday evening.

Overland flooding will occur in the Gingham and Big Leather Watercourses to the west of the Gwydir Raft.

The low level, single lane concrete bridge at Brajeen Crossing may close.

Major flooding is also likely along the Mehi River.

The Mehi River at Moree was at at 4.16m early on Tuesday morning and continuing to rise.

The BoM said the river would exceed the minor flood level, 5.50m, late on Tuesday morning.

The river level is expected to exceed the moderate flood level, 7.60m, by the evening and is likely to exceed the major flood level on Wednesday morning.

Moree has received 150mm in the past 24 hours. This has broken the record from the Post Office of 142mm in 1894 and was only 12mm short of the all-time daily record from the Post Office in February 1888.

A number of roads are either closed or have water over them.

So far the Moree to Queensland border via Carnarvon Highway and Moree to Queensland border via the Newell Highway are shut along with the Gwydir Highway near Biniguy, two kilometres east of Gretai Road.

You can find more information about local roads via Moree Plains Shire Council.

"Please be vigilant and very aware that we have a large amount of unmetered local water flowing off the slopes into our creeks, gullies and tributaries, and ultimately into our Gwydir/Mehi system.

"This water may cause serious local flooding with not a lot of warning as it is coming in between and below metered sites, and we may not have accurate readings until it hits Pallamallawa, Tareelaroi and Chinook gauges, and these are only the sites east of Moree.

"There is serious water coming across the plains south of Moree which will feed into the Mehi below Moree.

"Please prepare now as we have a lot of unknowns and up to 100mm forecast for today." - Cr Katrina Humphries

In life threatening emergencies, call 000 (triple zero) immediately. If you require rescue, assistance to evacuate or other emergency help, ring NSW SES on 132 500.

For more emergency information, advice, and access to the latest river heights and rainfall observations and forecasts:

* NSW SES: www.ses.nsw.gov.au

* RMS Live Traffic: www.livetraffic.com

* Latest River Heights and Rainfall Observations: www.bom.gov.au/nsw/flood/northwest.shtml

* Latest NSW Warnings: www.bom.gov.au/nsw/warnings/

* Rainfall Forecasts: www.bom.gov.au/australia/meteye/

* BOM NSW Twitter: www.twitter.com/BOM_NSW