I should emphasize now is not the time to let your guard down. The National Hurricane Center is stressing that forecast confidence is low and that the hurricane, with 130 mph peak winds and growing stronger, could still significantly affect the Mid-Atlantic.
If Joaquin directly impacts the D.C. region, it would be in the Sunday-to-Monday time frame. The National Weather Service sums up the situation this way: “The weather Sunday and Monday remains highly uncertain with heavy rain…strong gusty winds…tidal flooding and erosion remaining a concern…though it could just turn out to be a partly sunny and breezy day.”
Irrespective of whether Joaquin steamrolls into the Mid-Atlantic or curves harmlessly out to sea late this weekend, heavy downpours are likely in the D.C. region Friday into early Saturday from its predecessor rain event.
Two to four inches of rain may fall through Saturday morning, and a flash flood watch is in effect for the region starting Friday. The heaviest rain is anticipated Friday afternoon into Friday night. Along with the heavy rain, winds may gust up to 30 mph or so.
Showers may linger into Saturday morning, before a likely break in the action Saturday afternoon and night.
Sunday and Monday present the most challenging part of the forecast, so I’ll try to break it down into three possible scenarios:
SCENARIO A: Joaquin stays out to sea or makes landfall north of the Mid-Atlantic (60 percent chance)
- Breezy with showers on Sunday; becoming partly sunny by Monday.
- Atlantic beaches have high surf, some beach erosion, minor coastal flooding.
SCENARIO B (worst case): Joaquin makes landfall in Mid-Atlantic and tracks northeast through Virginia (20 percent chance)
- Tropical storm-force winds and heavy rain develop Sunday and last into Monday.
- Potential for four to eight inches of additional rain. Flooding of river, streams and low-lying areas likely, the risk elevated by saturated ground from previous rain.
- Damaging winds and power outages possible — risk also elevated due to wet ground.
- Significant storm surge possible up the Chesapeake Bay and Potomac, with tidal flooding in Annapolis, Old Town and Georgetown.
- Atlantic beaches have hurricane-force winds, extremely high surf, major coastal flooding and severe beach erosion.
SCENARIO C: Joaquin makes landfall in North Carolina but tracks well south of D.C. (20 percent)
- Showers, heavy at times, developing Sunday and tapering off Monday.
- Isolated but unlikely widespread flooding; heaviest rain south of the region.
- Breezy conditions but damaging winds probably remain south of the region.
- Atlantic beaches have tropical storm-force winds, high surf, moderate coastal flooding and significant beach erosion.
Tomorrow, we will try to narrow down these scenarios further and add more detail.