(9/15/24, 4 pm) Coastal Low to Spread Moisture Across North Carolina

Good Sunday afternoon,

Never a dull moment for us trying to forecast the weather across North Carolina. That said, we appear to have increasing support that a coastal low will help throw Atlantic moisture back across the western 2/3rds of North Carolina. We have a very complex weather pattern across the Eastern United States and it has resulted in everything getting blocked up. On the water vapor image below a massive area of high pressure over the Northeast is preventing anything from moving out over the Atlantic. Deep easterly flow continues and now we finally have a non-tropical system organizing off the South Carolina Coast.

A consensus has been reached that a non-tropical low will move west-northwest from the coast of South Carolina to a position across western North Carolina. The one item to nail down is the exact timing as there are some differences still. Regardless, deep Atlantic will work its way across the northern side of the low track and wrap its way into western North Carolina by late Monday.

GFS Model

Looking at the global model guidance, the GFS has our feature coming ashore the Grand Strand Region in South Carolina tomorrow morning with deep moisture wrapped around the surface low, more like something you would see in a truly tropical cyclone.

Sunday 8 pm:

Monday 8 pm: Low positioned near Charlotte with deep moisture working back through the Blue Ridge

European Model

The good news is that the track with both the Euro and GFS has consolidated, on this afternoon’s run it shows a similar push inland across The Grand Strand but the overall movement inland is a slower process. Infact, the Euro hints at a our feature stalling out across North Carolina as compared to the GFS that moved it as far west as the Lower Ohio Valley.

Monday 8 am:

Tuesday 8 am: Broad surface low still over South Carolina and moving toward the Western Piedmont of North Carolina.

Forecaster Analysis:

Just going off the global models, the GFS may indeed be a big quick in accelerating our coastal low back into the Western Carolinas as soon as Monday, so therefor we are trending our forecast today toward a slower overall evolution of this storm system.

Short range guidance such as the HRRR lies in between the GFS and Euro timing as it has the coastal low moving across the North Carolina Foothills Tuesday morning.

Also to note, this storm was given INVEST status which has allowed storm specific models to begin and those have helped with confidence of the track.

The Bottom Line…

Anytime you deal with a coastal low moving in from the east, some uncertainty in precipitation amounts can occur due to the northeasterly flow on the front end of the storm. But right now with the low track coming into better agreement, the expectation is for a 1.5 – 3 inch rainfall event from roughly US 221 (Marion to Rutherfordton) and east. Once you get over toward I-26 and US 74 in Polk County, amounts will begin to tail off. Rain will begin late Monday and peak early Tuesday before slowly winding down from there.

We will continue to monitor this through the next few days…