World Grain - March 2012 - 81

FEATURE: NORTH AMERICA LOOKING FOR RELIEF

The odds also favor relief for the northern Plains and the upper Midwest during the next few weeks, but northern Canada and the far western United States will have to wait a while longer before sufﬁcient relief to dryness comes along. The 18-year cycle will promote a high pressure ridge in the middle of North America this late spring and summer. Early indications suggest the ridge will not be strong but signiﬁcant enough to suppress rainfall at times. The key to the high pressure ridge intensity and level of persistence will be linked to La Niña. The longer La Niña has inﬂuence on the world’s weather, the higher the probability for a strong ridge of high pressure that might block weather events from reaching the Great Plains or western Corn Belt, resulting in a threat of serious dryness and possibly drought. WILL EL NIÑO DEVELOP? Some computer forecast models are suggesting La Niña will dissipate by late spring, and a few others have gone on to predict the possible development of El Niño — a warming of sea surface temperatures in the equatorial region of the eastern Paciﬁc Ocean that changes the position of high and low pressure systems worldwide. El Niño produces weather patterns nearly opposite to those of La Niña, and if it evolves, the drier bias in the middle of North America could end up being a slightly wetter bias. If El Niño evolves by July, it could bring timely rainfall to the Great Plains and western U.S. Midwest, resulting in a better outlook for summer crop development. World Weather Inc. believes strongly that El Niño will not develop soon enough to bring an abundance of rain, but the weakening of La Niña will offer some support to the 18-year cycle, promoting a drier biased environment. That could lead to a little moisture stress at times in the Plains and Midwest, but a full blown drought is less likely to occur if La Niña is gone. A very close monitoring of the situation is warranted. The ofﬁcial forecast from World
www.World-Grain.com / World Grain / March 2012

Weather, Inc. suggests summer will have a drier than usual bias in the Plains and western Corn Belt, but a full blown drought may not evolve. The drier bias will put much dependency on the timeliness of rainfall since subsoil moisture will likely still be low in many areas after the long winter’s dryness. The tropics will be more active this year, and that should help ease the drought in Mexico and South Texas, but only when a tropical cyclone comes around. Until then, the summer months will trend drier in Texas. The more active tropical weather pattern will also bring greater rainfall to the southeastern United States later in the summer season. In Canada, a change

toward wetter weather is likely after the U.S. ridge of high pressure evolves during the late spring and summer. Canada will likely see a transition to wet conditions — like that in the southeastern United States and Mexico. Mexico’s greatest relief will occur in July and August.
Drew Lerner is senior agricultural meteorologist with World Weather Inc. He may be reached at worldweather@bizkc.rr.com. World Weather Inc. forecasts and comments pertaining to present, past and future weather conditions included in this report constitute the corporation’s judgment as of the date of this report and are subject to change without notice.
We want to hear from you — Send comments and inquiries to worldgrain@sosland.com. For reprints of WG articles, e-mail reprints@sosland.com.

http://www.World-Grain.com

World Grain - March 2012

Table of Contents for the Digital Edition of World Grain - March 2012