DES MOINES, Iowa — Our average high this time of year is around 70 degrees in Des Moines, and it’s felt a lot more like June lately than average. However, it appears we’ll balance things out as we head into the second half of May. While models become less reliable at this range, they can give us an idea of general trends.

Above and below, the raw temperature forecasts from the National Blend of Models and the European computer model (which tends to be a little cool). Both give us less heat as we head into the second half of May.

The European model’s 50 ensemble members take us through May 25th and, in general, give us better rain chances beyond May 18th.

Regarding the May 19th stormy forecast in particular, the GFS computer model shows us a decent chance to see stronger thunderstorms in the central U.S.

Our 8-to-14-day outlook, below, finally trends cooler than average and indicates above-average precipitation chances.

The North American Ensemble Forecast System (NAEFS) is a collaborative weather forecasting project involving the Meteorological Service of Canada (MSC), the United States National Weather Service (NWS), and the National Meteorological Service of Mexico (NMSM). Launched in November 2004, NAEFS combines state-of-the-art ensemble forecasts from the MSC’s Global Environmental Multiscale Model and the NWS’s Global Forecast System to provide probabilistic weather guidance for North America, covering forecast periods from 0 to 384 hours (up to 16 days). Its output below is similar to the Climate Prediction Center’s above.

Finally, the Pacific-North American Oscillation forecast indicates a trough of low pressure in the western/central U.S. may be in place during the latter part of May, also increasing our thunderstorm chances. Possible good news for farmers and gardeners.