Updated: Thursday, October 17, 2019
By: Denver Murray, Peter Forister
Potential Tropical Cyclone Sixteen is expected to become either a Sub-tropical or Tropical Storm tonight and make landfall along the Florida Panhandle early Saturday morning.
This system will interact with an upper-level low and a frontal system along the Gulf Coast, with cold, high-pressure building across the Northeast. This will create gusty winds anywhere from 25 to 35 mph (possibly higher) along coastal areas and the potential for moderate coastal flooding (1 to 3 feet above ground level.)
These features (circled in the image above) are making the forecast rather complicated. High-pressure building in from the north will keep the system from moving north. However, as high-pressure shifts eastward, a huge upper-level low and front in the Midwest could help to pull the storm back towards the coast.
The European model takes the system pretty far off the Mid-Atlantic coast, while the American and Canadian models keep it closer to the coast. Hurricane models are “split” in the middle.
This disturbance could become “Nestor” but quickly turn into an extratropical system or large low-pressure system by the time it reaches the Gulf Coast on Saturday. The combination of high-pressure to the north and low-pressure across the Southeast. Also, in extratropical systems, colder, drier air can help to expand these systems, which is why we think there will be much more rain on the north and west side of the storm, compared to what models are suggesting.
It’s worth noting that the ensembles of these global models are trending wetter across the Mid-Atlantic and global models are trending precipitation further north and west with each run.
Latest Global Models
The latest GFS (American) model shows moderate rain along US Route 360 with the heaviest rain across Central and Eastern North Carolina and Hampton Roads.
NAM 12 km (North American)
The 12 km NAM is usually not the most reliable model, but is similar to other ensembles in regards to the northward extent of the precipitation shield.
The HIRES NAM 3 km looks pretty similar to other ensembles and the NAM 12 km model. This may be taking account of it not being a tropical system and interacting with colder air to the north and west, or in other words, overrunning precipitation.
If low pressure is closer to the Mid-Atlantic coast, (compared to the European model further offshore,) then this will increase the coastal flooding and wind, potentially by a lot. This would also spread precipitation further north and west.
VWN FORECAST: Sunday
While we do not have “numbers” on our forecast map at this time, areas labeled in the “Steady Rain, Moderate to Heavy” area could see anywhere 1 to 3 inches, with locally higher amounts 3 to 4 inches across Southeast Virginia and Central and Eastern North Carolina.
Areas in the “Light, Scattered” shading can expect rainfall amounts up to one half inch possible.
VWN WIND FORECAST: SUNDAY – MONDAY MORNING
Occasional wind gusts over 40 mph will be possible along the immediate coast, including the Chesapeake Bay area. Scattered power outages are possible. Across the Piedmont and higher elevations in the Blue Ridge, wind gusts could gust up to 30 mph at times.