Interesting forecast problem today

Thursday, July 7, 2016  11 A.M.

Looking at this morning’s forecast models and actual forecasts is almost a case of “What’s going on?”  Everything you look at has a different story to tell.  First, the NWS forecast includes a scant 20% chance for rain/t-storms today and another 20% chance tonight.  The backbone of our forecast system, the GFS produces a 1% chance today and about 40% tonight (LAMP) and a 4% chance today, 45% tonight (MOS).  Meanwhile, the NAM model output is also low…11% today and 53% tonight.  By the way, all of the “tonight” forecasts call for the rain after midnight.

On the other hand, the Storm Prediction Center gives us a 40% chance for thunderstorms today and just 10% tonight.   Then, the two primary short-term forecasts chime in with a slight different story.  Both the RAP and the HRRR predict a line of thunderstorms to reach the Louisville area between roughly 8 P.M. and Midnight.  Earlier today I saw WAVE TV’s in house model project a line of storms between 6 and 8 P.M..

What’s one to believe?  Good question!  First of all the GFS has been terrible lately as evidenced by a lot of forecasts we’ve heard recently.  Second, the short-term forecasts are better at picking up on the “outflow boundaries” created by previous storm systems, so they should be more reliable.  As a result, I’d lean toward the RAP/HRRR/WAVE forecast expecting a line of thunderstorms this evening.  We’ll see how it plays out.

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