Forecast of the Day • A National Weather Forecasting Contest

The two major computer models that the National Weather Service uses for weather prediction usually have fairly small differences for any given location and time. But occasionally they diverge, and one example is the Wednesday maximum temperature forecast for Hobart, a city in the southwest corner of Oklahoma, close to the Texas border. The GFS MOS Tmax forecast is a toasty 67 F for Wednesday afternoon, but the NAM MOS forecast is about 20 degrees less (that's a big difference). So let's predict Wednesday's Tmax for Hobart and see which model does better. Hobart is named for Garret A. Hobart, President William McKinley's first vice president (Theodore Roosevelt was his second).

Question: Can you speculate as to what weather factor could be significant enough to cause such a large difference in the temperature forecasts?