* Stocks seen at 10-20 pct of output -traders
   * Rains help trees in producing region
   
   By Ho Binh Minh
   DALAT, Vietnam, July 20 (Reuters) - Vietnam coffee stocks have thinned in the past two weeks on good international quotes, leaving between 10-20 percent of the country's spring harvest in warehouses and few sellers as prices dip, traders said.
   "Stocks held by farmers are very thin while most of those who now hold beans have good financial stance, so they don't rush to sell," said a dealer in the central highland province of Lam Dong, Vietnam's second-largest coffee growing region after Daklak.

An agent buying arabica and robusta beans in Dalat, the capital of Lam Dong, said she did not expect to find more beans from local growers even though she offered high prices. The province is Vietnam's top producer of arabica variety.
   "Despite a good price, Vietnamese growers did not sell too much in recent weeks, which probably means speculators are holding back until the next harvest" starting in October, a Vietnamese trader with a foreign company in Ho Chi Minh City said.
   
   STOCKS VARY, RAINS BRING PROMISE
   However, estimates of the current volume of coffee stocks available in Vietnam, the world's second-largest producer of coffee after Brazil, vary widely because of a lack of any official data.
   Trader stock estimates are based on a crop of around 1 million tonnes, or 16.7 million bags.
   A Reuters poll in late January at the end of the four-month harvest showed output at 18 million 60-kg bags, down from 19.5 million bags in the previous crop. [ID:nSGE60H080]
   Just outside Dalat, green arabica trees were washed clean by a shower late on Monday, with branches bending down under the weight of new cherries.
   Another shower fell on Tuesday in Dalat and rains were also forecast in other areas of the coffee belt as the wet season peaked.
   Vietnam is also expected to escape a tropical storm now approaching the Paracel archipelago in the South China Sea as it expected to head northwest to China, Vietnamese forecasters and the Tropical Storm Risk site (www.tropicalstormrisk.com) said.
   The current rains are helping the coffee crop but if heavy rains from a storm hit the region between now and September, output will fall as cherries have not been fully mature. The region produces 80 percent of Vietnam's total coffee.
   "We will know more about the next output in September, because, with weather uncertainty, any forecasts now are still too early," Director Pham Van An of Lam Dong's Agricultural Department told Reuters.
   
   PRICES EASE
   Robusta eased to 29,400-29,700 dong ($1.54-$1.56) per kg on Tuesday from 30,100 dong on Monday in the Central Highlands, tracking a fall of London's futures market where September contract <LRCc2> lost $34 to end at $1,730 per tonne, weakened partly by a pick-up in origin selling. 
   Discounts to London September for robusta grade 2, 5 percent black and broken widened to $70-$100 a tonne, from $90-$100 a tonne early last week, while foreign buyers bid at discounts of $110-$120 a tonne, against $100-$140 last Tuesday.
   Free-on-board price therefore stood at $1,630 and $1,660 a tonne <COFFEE/ASIA1>. Several companies also quoted a discount of $100 a tonne for beans from the new 2010/2011 harvest, but buyers have not been interested, traders said.
   Vietnam may not see a rise in coffee output in the 2010/11 season, according to the International Coffee Organization's (ICO) June report that pegs production for the next crop year at 16 million to 18 million 60-kg bags.  (Editing by Ed Lane)