By Peter Murphy
BRASILIA (Reuters) - Prospects for an abundant, high-quality 2013 Brazilian coffee crop look good, thanks to some of the most cooperative weather in at least two years, said a meteorologist at Somar, a Brazilian forecasting service.
About six weeks of dry weather created hydric stress, or a hibernation-like phase for trees, that boosts flowering when rains return, forecaster Olivia Nunes told Reuters late Wednesday.
At the same time the rains needed for the coffee trees to flower evenly and at the right time are expected to arrive on schedule in late September, she said.
Weather patterns have also increased the chance for the rains to continue with the frequency and intensity necessary to ensure optimal development of the tiny coffee fruit until Brazil's harvest, the world's largest, begins in May, Nunes added.
"Rains won't be late like in the last two years," Nunes said adding that a mild rain-bringing "El Nino anomaly" would create wetter conditions in the last three months of 2012, securing moisture supplies during the crop's thirsty early development.
The El Nino weather phenomenon is part of a three-to-seven-year warming and cooling cycle in the Pacific Ocean off South America that has a powerful impact on rainfall patterns.
Brazil's government expects the 2012 crop, which is near the end of an "on-year" harvest, to be 50.45 million 60-kg bags. The 2011 crop, an "off-year", was 43.5 million bags, the government said. The government will update its 2012 estimate, on September 6.
On-year crops are larger than off-year crops as the coffee plant's growth potential rises and falls in a two-year cycle. The 2013 crop will be a smaller off-year harvest.
While the chances of cooperative weather are good, there are still risks, Nunes warned.
One of them is that light showers will trigger flowering and then stop, leaving trees without enough moisture. This could cause them to wither and lessen yields.
Nunes said that any dry gap between the late September rains and before the arrival of more consistent rainfall is likely to be narrower this year than in recent years.
"The first rains will be isolated," she said. "There could be higher intensity rain that would open flowers, but it may not last long so the trees may not be able to hang on to the flowers."
"It won't be like in the last couple of years where the rain arrived in November," she added.
Despite Nunes' expectation of cooperative weather, it is still too early to make an estimate for the 2013 crop before flowering takes place and with the 2012 crop is still being picked.
About the only thing that can be reliably said about the 2013 crop is it will be an "off-year" in the two-year coffee cycle, making it almost certain that the crop will be smaller than this year's.
The key to the crop will be rain. Timely and consistent rainfall can boost the proportion of cherry-ripe fruit that can be wet-processed into higher-value washed, gourmet coffees.
Three-quarters of Brazil's coffee production is so-called arabica coffee, the more valuable, smoother-tasting of the two, principal coffee varieties. The rest of the crop is robusta, the cheaper but more astringent variety that is commonly processed into instant coffee or sold under low-cost brand names.
Arabica coffee prices are about 40 percent lower than they were a year ago when shortages of high quality beans and fund investments pushed prices rates above $2.80 per lb.
December arabica futures on New York's ICE exchange fell for a second day, shedding 0.4 percent to 1.66 per lb on Thursday.
(Reporting by Peter Murphy; Editing by Jeb Blount and Bob Burgdorfer)