Tropical Depression Bonnie And Storm Timeline Into Memorial Day

Sunday May 29 – The heat is still with us, but the influence of more moisture and a tropical cyclone will be as well. On Saturday The National Hurricane Center officially named Tropical Storm Bonnie off of the South Carolina coast. But shortly after it reached the winds needed, it weakened a little back to a tropical depression. It is no longer a tropical storm and I’ve seen that error on a few TV stations this morning.  This is more academic than anything else as the winds are holding at 35 mph and it is not a large system. As the morning visible satellite shows, the center is along the coast near Charleston, SC. There seems to be a void of clouds on the stronger east side up the coast, but it will spend the next few days crawling up the coast.

The storm will influence the local beaches with increased rip currents. It is also feeding moisture aloft that will interact with a front to give us some locally heavy rain tonight into Memorial Day Monday far away from the storm as it interacts with another system aloft. The timing of this is the tricky part. One solution brings the rain in tonight, another by tomorrow morning. This might determine if the rain will depart and dry out part of Monday or keep it stormy all day.  See the timelines below.

First,

Tropical Depression Bonnie

The main things about this storm is that this storm is small and it will be a slow mover.  This will spend a few days creating gusty winds and rip currents along the Carolina coastline. It is a shallow storm with not much potential for development.

Rain influence

The convergence of moisture from the storm and a cold front inland will max out of Virginia and Maryland. So the heaviest rain will be well away from the core and the coast.

Our Rain: When and Where

The one thing I see as agreement is that the core of rain will move over our region, between I-95 and I-81. So west of the Chesapeake Bay to the mountains will see some moderate to heavy rain as the cold front gets a boost like an energy drink. The big question will be the precise timing. Here is the wide view of the GFS Model showing it. But while this model is being applauded by the National Hurricane Center for the storm track, I think it is a little slow. In fact, the storm not being purely tropical, the short range models might be doing a better job. The difference is that our heaviest rain either falls overnight into Monday morning, or lasting most of Monday. Here is the comparison

Faster Arrival By HRRR Model –> slider

This shows the arrival of rain from the south this evening. If this verifies, then we will have more rain overnight, and an improvement Memorial Day.