The following content was provided by meteorologist Gail Martell of MartellCropProjections.com:
Southern Jet Stream Strengthening
A strong wave of showers pushed through the Southern Plains over the weekend producing welcome rainfall in Texas and Oklahoma. The satellite images indicate the subtropical jet stream was responsible. You can see a moisture feed from the Mexico tropics northeastward into Texas on the satellite imagery. This is noteworthy because the southern jet stream indicates an El Nino influence.
If the El Nino signal strengthens in the weeks ahead, hard red winter wheat in the Southern Plains would receive beneficial rains. Parched pastures and ranges would also improve livestock feeding conditions.
A sharp cold wave is coming to the U.S. heartland. Frost is anticipated tonight in North and South Dakota and Minnesota, and tomorrow night in Wisconsin, northern Illinois and eastern Iowa. Freezing temperatures would not harm corn and soybeans, as crop maturity is already well advanced.
El Nino Development Questioned
Sea surface temperatures in the key Nino 3.4 region of the equatorial Pacific were 0.8 C in the last report from the Climate Prediction Center, slightly above the 0.5 threshold for El Nino. Controversy exists over whether a full-blown El Nino is in the cards.
The Australia Bureau of Meteorology claims that while sea surface temperatures are close to El Nino thresholds, other indicators such as the trade winds and tropical cloud patterns point to ENSO-neutral conditions. The U.S. Climate Prediction Center September 17 report shows net cooling in the eastern equatorial Pacific Ocean recently, opposite of El Nino warming.
The development of El Nino (or not) has major implications for weather conditions in South America, where spring planting is due to start soon. Argentina typically produces high-yielding corn and soybeans with the El Nino, due to the wet signal it causes in the grain belt. South Brazil often is wet also with the El Nino, though the signal there is less-strong.
The absence of El Nino may lead to ENSO–neutral weather. That implies "average" growing season rainfall as periods of dryness alternate with heavy rains.