Based on questions we’ve seen on social media and online chats, there is a lot of confusion about what Hurricane Florence will mean for the D.C. area through the weekend. It won’t mean much.
When the storm probably makes landfall in southeast North Carolina on Friday, the most we’ll probably see are some showers and a bit of a breeze. The heaviest and most numerous showers are likely to fall in our far southern areas (toward Fredericksburg), but even there, we don’t expect it to amount to enough to cause flooding or significant disruption.
For interests along the Chesapeake Bay and Tidal Potomac, winds from the south and east could cause some minor coastal flooding Friday into the weekend, but we do not anticipate a big surge (like in Hurricane Isabel, for example).
The Virginia Tidewater is the closest area to the Washington region that may experience heavy rain, strong winds and some storm surge in coastal areas, mainly Friday, although it’s possible that area, under a hurricane watch, also misses the brunt of it.
As the storm shifts south through South Carolina during the weekend, we may see little or no rain in the Washington region. Unless the forecast changes markedly, there is no need to cancel outdoor plans, events or travel in the Washington region this weekend because of Hurricane Florence. While we can’t totally rule out some widely scattered showers, not unlike what we’ve seen in the past few days, the weather may end up being pretty benign.
Rain chances from Florence's remnants increase next week
The wild card is what happens with the storm early next week. It is predicted to take an unusual path, traveling south along the South Carolina coast, then inland near the border with Georgia, then turning back to the north.
Between Monday and Wednesday next week, there is some potential for us to see rain from former Hurricane Florence. As the region is waterlogged, having endured the fourth-wettest year on record to date (nearly 46 inches in Washington), it won’t take much rain to cause flooding. Even at this time, parts of the Potomac River downstream from Shepherdstown are flooding from all of the recent rain.
Because Florence will have spent several days over land by the time it nears our region, we do not expect widespread strong winds although some locally strong gusts cannot be ruled out. Because soils are saturated, trees will be more vulnerable to the wind than normal.
There are a few different scenarios for the storm's remnants in our region, depending on exactly where it turns to the north.
Scenario 1: A period of heavy rain and storms as Florence’s remnants pass near or over our region (40 percent chance)
The European model presents this scenario. It brings former Florence up the Southern Appalachians into Northern Virginia. We’d see a slug of heavy rain come through between Monday night and Tuesday, which would probably cause areas of flooding. These storm remnants will be moving along, which should prevent a widespread, very serious flooding situation.
We'd have to watch for the slight risk of brief tornadoes forming within some of the passing rain bands, which is common in remnant tropical systems.
Rainfall potential: 2-4 inches with some locally higher amounts
Scenario 2: Scattered showers and storms as Florence’s remnants pass well west of region (40 percent chance)
The American model presents this scenario. It brings the storm's remnants through eastern Tennessee, Ohio, and western Pennsylvania, and eventually through western New England. It passes far enough west of our region, that we stay out of the zone of heavy rainfall.
However, some of its moisture would still get drawn into a front moving toward the region that would probably set off showers and storms, which could be locally heavy. As in Scenario 1, we’d need to monitor the small risk for a tornado in any storms given added spin in the atmosphere.
Rainfall potential: Less than an inch with some locally higher amounts. Up to several inches in the mountains.
Scenario 3: Something else . . . (20 percent)
The path of Florence three to five days from now is highly uncertain, so it’s not hard to envision some set of circumstances different from what we’ve outlined. The storm’s track could change (again) as could its timing. So it’s best to leave some wiggle room for other possibilities.
We’ll reevaluate these scenarios again Thursday.