Prolonged rainfall in Australia’s coal-producing Hunter Valley has slowed output and could jeopardise shipments by the world’s second-largest thermal coal exporter, producers and traders said on Friday.Heavy rains in the Hunter Valley over the last two weeks have hurt output and forced some producers to delay shipments, although no force majeure has been declared, major exporters and traders said.With many Indonesian exporters already delaying shipments due to wet weather, any serious disruption of Australia’s thermal coal shipments would sharply tighten bituminous coal supplies in the Pacific market and potentially push up prices, which have languished over the past month as China cut back import demand."The Hunter Valley has had lots of rain over the past two weeks," said a manager at one of the mines. "The mines are really wet and production has been affected big time."The rail operator is chasing anyone who has extra coal to get it down to Newcastle port but a lot of the mines just haven’t got enough coal to rail and their stockpiles are falling low."As evidence that rains have dented output, total stockpiles at Newcastle Port fell nearly 7 percent this week to 1.06 million tonnes from a week ago, making for the lowest level since June 6.Coal exports at Newcastle, the world’s largest export terminal for thermal coal, fell 5.7 percent to 2.1 million tonnes in the week to Aug. 2 from the preceding week, port data showed. [NEWC/COAL]Xstrata Plc (XTA.L), Rio Tinto (RIO.AX)(RIO.L) and BHP Billiton Ltd (BHP.AX)(BLT.L) are among the coal majors with mines in the Hunter Valley region, but were not immediately available for comment.Still, most producers and traders say wet weather in Indonesia and Australia has supported Asian thermal coal prices and cushioned them from the full impact of China’s fading demand.Slower economic growth combined with stricter measures imposed on energy-guzzling sectors have worked together to cut China’s coal consumption, analysts and traders said.Australian thermal coal prices on the Asian benchmark globalCOAL index have fallen for five consecutive weeks to a five-month low of around $93 a tonne amid concerns that China’s import appetite will fade further over the coming months as its economy cools.Thermal coal exports from South Kalimantan in Indonesia are being delayed or cancelled by several mining companies because heavy seasonal rains have caused production cuts.Last week, miner PT Bayan Resources (BYAN.JK) said rains had forced it to declare force majeure on an August loading coal shipment from a mine in South Kalimantan, while PT Adaro Energy, Indonesia’s biggest coal miner by market value, said heavy rains could hit its full-year output target of 45 million tonnes.With wet weather hindering shipments from Indonesia, the world’s largest thermal coal exporter, Australian producers said they have started to receive appeals by some customers to send shipments ahead of schedule."We’ve started to see requests from Taiwanese and South Korean buyers to bring a few vessels forward, while some customers are asking for additional coal. But it is hard to do because we’re also suffering from rain," said a second producer source.