“Sally” is now a Tropical Storm and remains a slow mover, with maximum sustained winds as of 2 p.m. EDT of 70 mph. The moisture from Sally will move across Georgia and the Carolina’s overnight and into Virginia on Thursday. There may be two waves of rainfall, the first occurring during the day Thursday with another area of rain, mainly across Southeastern Virginia late Thursday night into Friday morning. There is also a TIDAL FLOODING THREAT due to high pressure across the Northeast, which will provide a northeasterly flow.
The National Weather Service has issued Flood and Flash Flood Watches for South Central and Southeastern Virginia. These areas could see anywhere from 3 to locally more than 6 inches of rain.
The combination of the northeast flow off the Atlantic and the “leftovers” from Sally is going to produce tidal flooding. Right now, it’s too early to know the magnitude, however, I would say at least minor to low-end moderate flooding is on the table for locations along the Chesapeake Bay, Atlantic Ocean, and the Sounds across Eastern North Carolina, including the Outer Banks, with water inundation ranging 1 to 2 feet above ground level.
Rain will move into Southwestern Virginia by early Thursday morning. We’re not expecting much rainfall WEST of Interstate 77, generally one tenth to perhaps, locally one half inch of rainfall. Across the New River and Roanoke Valleys, up to one inch of rain is expected, with higher amounts possible mainly east of the Blue Ridge.
Locations along the Blue Ridge will need to monitor conditions from Thursday morning through early Thursday afternoon as heavy rain will cause rising creeks, streams, and even high water on some roads. Rain will move out of these areas by late Thursday afternoon.
By Thursday afternoon, much of the Commonwealth of Virginia is seeing rain, with the heaviest rain mainly along and SOUTH of Interstate 64. Locations along and NORTH of Interstate 66 will not see much rain from Sally, generally less than one half inch. We could see flash flooding issues as early as midday or early Thursday afternoon across Southern and Southeastern Virginia. Rainfall rates could exceed one inch an hour, especially in thunderstorms.
While the treat for severe weather is LOW, it’s not zero. The tornado risk is mainly confined across Eastern North Carolina. There is SOME concern for some severe weather across Far Southeastern Virginia, and a few isolated thunderstorms or an isolated tornado is not out of the question Thursday or Thursday night. However, this will NOT be a widespread severe outbreak and isolated. The main threat will be the heavy rainfall and flash flooding potential.
There will likely be a break in the rain by Thursday evening, with another batch of rain re-developing late Thursday evening into the overnight hours of early Friday morning, as what’s left of Sally moves off the Georgia and Carolina coast and moves northeast. Also, high pressure across the Northeast will provide a persistent northeast flow across much of the area.
COASTAL WIND: Breezy East/Northeast winds 20 to 25 MPH with gusts up to 35 MPH is LIKELY along coastal areas late Thursday Night through Saturday.
TIDAL FLOODING is a concern for ALL counties along the Chesapeake Bay, Atlantic Ocean, and Sounds and Atlantic side in North Carolina, including the Outer Banks. Generally 1 to 2 feet of water inundation can be expected starting late Thursday night and continuing through the weekend. This will be a PROLONGED tidal flooding event due to a East/Northeast wind flow.
RAINFALL FORECAST: 3 to locally more than 6 inches is expected across Southern Virginia and much of Hampton Roads. Across the Richmond Metro Area, generally 2 to 3 inches is expected with locally higher amounts possible. Across Northern Virginia, not much rain is expected, generally less than one half inch — some locations across Far Northwestern Virginia, such as Winchester, may see no rain from Sally. It will ultimately depend on the strength of high pressure building in across the Northeast.
Remember to TURN AROUND, DON’T DROWN. DO NOT attempt to cross flooded roads as you don’t know how deep the water may be. It only takes six inches of water to reach the bottom of most vehicles and one foot of water to stall a vehicle. Never take the risk.