Bureau four day rainfall forecast.
Bureau four day rainfall forecast. BoM

Storms border to border bringing 100km/h gusts, heavy rain

UNSTABLE weather across the state has forecasters on their toes, with widespread severe weather forecast for the next few days.

The Bureau of Meteorology has issued a Flood Watch and Severe Weather Warning as a weather system begins to impact large parts of New South Wales.

They issued a Severe Thunderstorm Warning for destructive winds, giant hailstones and heavy rainfall today for a large part of the state stretching from border to border that currently includes the Northern Tablelands.

More bad weather on the way

A large slow-moving trough and low pressure system are moving across the region bringing widespread thunderstorms and heavy rain to parts of the state, mostly through Thursday afternoon and into Friday.

BoM said while the nature of the system means rainfall totals will vary greatly from area to area, some parts of the region could experience falls that trigger localised flash flooding.

This will mainly be associated with thunderstorm activity.

In addition, some thunderstorms may become severe, producing strong to destructive winds that could bring down trees and power lines, as well as large or even giant hail.

"Thunderstorms by nature are very localised, quickly forming and moving over a location, so it is vital people remain aware of local conditions and closely monitor the warnings and radar from the Bureau of Meteorology" Forecaster Anita Pyne said.

The system may also bring dangerous conditions along beaches and further out to sea.

"We are regularly briefing emergency services in New South Wales, and both the NSW/ACT Regional Forecasting Centre and Flood Warning Centre are monitoring the situation," she said.

BoM has issued a Strong Wind Warning for the Byron Coast for tomorrow.

North Coast Storm Chasers Antonio Parancin said the category 3 Cyclone Owen could track as far south to NE NSW over the next few days.

He said they were checking weather models day by day as forecasts change.

He said "the latest weather models forecast on where Owen "might" be on Sunday night / Monday which is right on the shores of SE QLD / Gold Coast / Byron."

"(In one instance) we can see the projected wind speeds on Sunday evening are very severe in SE QLD and then starting to creep south into NE NSW although a lot more coastal / elevated areas at risk.

"(In the second instance) we have models predictions on how much rain we "might" see from this system and we can see here places like the river catchments for Lismore, Brunswick and surrounds sitting near or over 200mm which mostly will fall from Sunday - Tuesday."

Updates on the Northern Rivers to come tomorrow.

Full details of current Warnings and Flood Watches are available at bom.gov.au.