National Weather Service at GSP is saying that a Flood Watch will likely be issued in advance of our next system. It's the same cold front that has been producing severe weather and flooding to our west from Michigan to Texas. As the front approaches Wednesday night, the Gulf of Mexico will open up and provide ample moisture for us to receive 2+ inches of rain in many spots.
Now last time we had a forecast like this, it didn't pan out... I'll say that our models are in really good agreement that heavy rain will push in Wednesday night, so my confidence is pretty high in this forecast validating. I don't expect storms to our south to rob us of moisture this time. You can never be certain, but for now it looks like heavy rain is a high likelihood.
Here's a timeline for what you can expect through Thursday:
Tonight: Isolated showers for the Upstate, with scattered storms in the mountains. Most areas will remain dry.
Wednesday: Only about a 20-30% chance of pop-up storms through the day. The best moisture starts to push in during the evening.
Wednesday night: Heavy rain develops to our west in GA by midnight, then pushes into the Carolinas between 3-5am. Isolated storms will be possible, with the main threat being torrential downpours.
Thursday: The front moves through during the day, and we'll continue to see showers and heavy storms. Any storm that develops will have the potential to put down damaging wind, hail and even a tornado. I think tornado threat is fairly minimal, but with so much shear in place it can't be ruled out. Localized flooding in low lying areas will be possible through the day. Especially around lunchtime.
Thursday night: Skies clear and it gets MUCH cooler! Overnight lows will drop back into the 50s for the Upstate and 40s in the mountains.