The US is set for more of the weather extremes which have left southern parts too dry and northern areas too wet - raising worries over the revival in crop production needed to replenish thin inventories.
The La Nina weather system, which official forecasters say has a 50% chance of lasting until June, will "reinforce" the pattern which has brought the US a string of rain belts – only for them to dump over the same more northerly areas, veteran meteorologist David Tolleris said.
"Areas that have not had rains and not going to get rain and areas that have had excess moisture, it is not stopping," Mr Tolleris, at WxRisk.com, told Agrimoney.com, in a forecast for the April-to-May period.
"If the La Nina collapsed, the story might see some change. But that's not happening. The weather pattern is just reinforcing itself."
The picture tallies with outlooks from some other private meteorological groups, such as AccuWeather.com, besides forecasts from America's official forecaster, the National Oceanic and Atmospheric Administration (NOAA).
The NOAA in an initial spring weather forecast, to be updated on March 17, warned that "a large swathe of the country is at risk of moderate-to-major flooding this spring", as fresh rainfall adds to water produced from the thaw of heavy snowpack in areas such as the upper Midwest.
The Red River valley was set for a third successive year of flooding, threatening spring sowings in a major spring wheat area in northern US states such as North Dakota, and southern areas of Canada's Prairies.
The Canadian Wheat Board warned last week that the Prairies needed"ideal conditions" to avoid losses of up to 5m acres in sowings.
Meanwhile, the NOAA forecast hotter and drier than normal conditions for the US South for the next three months – threatening cotton sowings besides adding further misery to the drought-tested hard red winter wheat crop already in the ground.
Between 21-25% of the US cotton area is classified as "in a severe drought", while more than 53% has some sort of moisture deficiency, Rabobank said.
"Soil moisture deficiencies could be an issue [for cotton]," the bank said.
"Because the US is the number one cotton exporter in the world, the reaction to delayed or constrained plantings would likely be significant."
For corn, further wet weather for areas such as the Midwest would be likely to favour sowings of soybeans over the grain, Michael Cordonnier at Soybean and Corn Advisor said, highlighting the oilseed's later planting window.
"Even though it appears that corn is winning the battle for acres compared with soybeans, the weather during April will the deciding factor," he said.
"Generally, it is assumed that warmer and drier conditions during April favours corn acres, and cooler and wetter conditions during April favours soybean acres."
Indeed, separately, academics at the University of Illinois at Urbana-Champaign warned that investors were underestimating the risks that weather posed to US corn crops.
"Many attribute the lack of a major shortfall in the US average yield since 1995 to the adoption of improved seed genetics," Darrel Good and Scott Irwin said.
However, their own research suggested that yield improvements reflected "an extended period of generally better-than-average weather".
"The risk of weather-induced shortfalls in corn production may be greater than generally perceived."