El Niño Rolling Back Around?
Starting out with the current state of our El Niño-Southern Oscillation this morning, it appears Niño 3.4 sea surface temperature anomalies have reached the 0.5C threshold for the first time in several months. Already, the Climate Prediction Center has issued an "El Niño Watch" with the expectation that El Niño may develop sometime this summer. Recently, events have been taking place across the Pacific ocean that seem to signal a potentially quicker than anticipated onset of El Niño conditions.
One of these events has included several westerly bursts of wind across the western Pacific, associated with the eastward propagation of a strong oceanic Kelvin Wave. This "Kelvin Wave" has produced sinking motion in the upper layers of the ocean, resulting in a broad region of above-normal oceanic temperatures just under the surface of the key Niño 3.4 region. In fact, from 180W to 120W, sst anomalies in the 100-200m depth range have approached 5-6C above normal.
What does all this mean? For starters, warming of the Niño 3.4 region (the region we look to in order to classify ENSO), is likely to continue, supported by several consistent runs of the CFS model (Pacific SST anomalies can be seen on the image to the right). Very heavy rainfall across Argentina the next several days seems to be a potential indicator of an early transition to El Niño, and if conditions progress as forecast, El-Niño-related climate signals may begin affecting the U.S. Corn Belt as early as late spring.
A quick look at climatology tells us this should favor a wetter pattern for portions of the Midwest and Plains by the summer, which is generally a positive influence on crop yields. Many of our highest crop yields have occurred during El Niño summers (recently, 2004 and 2009), although considerable variability does exist in average yields when examining all El Niño years.
With that said, let's finish with a quick look at the current weather across the Midwest. Already, a broad E-W band of showers and thunderstorms is slowly drifting ESE across northern Missouri east through south/central Ohio. More showers and thunderstorms will develop this afternoon through Thursday night across the Corn Belt, with rainfall totals likely to average 1 to 3 inches for much of the central and eastern Midwest. In fact, some 3- to 5-inch totals are possible across portions of east/central Missouri into west-central Illinois, increasing the potential for localized flooding.
Across the southern Plains, rainfall will be considerably lighter through Friday with 0.5- to 1.0 inch across E HRW Wheat areas, decreasing to 0.5 inch or less for western HRW Wheat areas. Additional spotty rainfall chances will develop across HRW Wheat areas Saturday through Monday, with additional rainfall totalling 0.25 inch or less for the major production regions. Heading into next week, another rain-maker may cross the Delta/central and eastern Midwest Monday, with a few more showers possible Tuesday.
A warmer and drier pattern will then arrive for the middle to latter part of next week, with the potential for a day or two of 60°F. and 70°F. temperatures for the central and especially western Midwest, if current model forecasts verify.
Freese-Notis Weather/Weather Trades, Inc. Des Moines, Iowa Copyright 2012 - All Rights Reserved