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EL NINO AND THE SUMMER AHEAD...


The evidence continues to mount that a weak El Nino is developing that will gradually increase in strength going into the fall. Ultimately it's likely to have impacts on the coming winter. It can also give us clues to the summer ahead.

For those of you not familiar with what constitutes an El Nino, it's basically pretty simple. It's a broad stretch of above normal sea surface temperatures that form over the tropical Pacific. Depending on the intensity of the warmth, it will dictate the position of the storm track for extended periods of time. That's important because it drives temperature and precipitation patterns over North America.

In the graphic below you can see where the warmer water currently resides

The actual sea surface anomalies look like this.

Below you can see the broad range of El Nino intensities that various models are predicting. The statistical average shows temperatures in region 3.4 running .5 to .7 degrees above normal from July through winter. That qualifies as a weak El Nino.

Using the El Nino as an indicator, it points towards a summer that is cooler and wetter than normal over the central Midwest. Here are the El Nino analogs.

Typical summer precipitation (June-August) in the corn belt is usually generous to begin with. As you can see parts of Iowa annually receive more than 14" inches of rain.

Interestingly enough, the EURO weeklies 46 day mean precipitation anomaly through mid summer shows much of the central Midwest with near to below normal precipitation the first half of summer. That's the opposite of what a developing El Nino signals for summer as a whole. That might not be out of line based on recent trends.

The 46 day temperature outlook came in this way on the weeklies. It also bucks the trend the El Nino suggests of below normal Midwest temperatures by showing most of the Midwest near to above. Time will tell.

Whatever happens the weekend is going to be a warm one. Highs will be in the 80s Friday through Sunday. Humidity levels will also jump substantially and summer will be in the air for everybody. Those swimming pools that just opened will finally get some takers. Have a great weekend and roll weather...TS

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