Labor Day’s One-Two Rain/Storm Punch

Yet again, the weather is throwing two punches at us during a holiday: early morning, late afternoon/early evening. Neither is certain.

Monday Morning – First Punch

“The main trough axis will inch closer to Middle Tennessee overnight, with scattered showers and storms occurring mainly during the 06z-12z period.” (NWS Area Forecast Discussion, 135 pm CDT Sun Sep 1 2013).

“Uh, what?  I just want to know if it’s going to rain in the morning. I’m running in the Franklin Classic, or otherwise doing something fun on my day off.”

I’ll let you decide. The “trough axis” is the main area of disturbed weather coming in from Illinois & Missouri. It should arrive while we’re sleeping in the tomorrow’s early morning hours:

Will it bring rain? Weather models disagree. Our favorite weather model, the HRRR (below at 4 a.m.), predicts only a few weak sprinklers.

HRRR Update:

The 4-km Hi-Res NAM sends in a LOT of rain. Here it is at 4 a.m.:

Our NWS forecasts “scattered showers and storms” for the morning.

The models (caution: use weather models for guidance, not Gospel) agree the rain will be gone by 7 a.m. Very close call for the Franklin Classic in the morning. Be thinking about what you’ll do if it’s raining when you wake up, and hope for the best. Temps will be in the low to mid 70s at race time.

Monday Afternoon – Second Punch

Chasing the aforementioned morning “trough axis” will be the beloved surface cold front. Scattered showers and thunderstorms will fire out ahead of and along the front as it arrives around late afternoon / early evening. The 4km Hi-Res NAM, below, predicts what the radar will look like around 7 p.m.:

Strong storms can’t be ruled out with this punch. The Storm Prediction Center thinks we have a 5% chance of a strong/severe downburst (high winds) inside any unruly thunderstorms.

More details coming on Twitter, like this:

Tuesday & Beyond

Humidity, temps, and rain chances drop off rather dramatically. This week’s high temps: Tuesday 82, Wednesday 84, Thursday 86, Friday 88, Saturday 88.

Full disclosure: I scoff at forecasts 72 hours away & beyond, but things are looking pretty good Saturday. (If it rains Saturday I will blame myself).