Areas from the mid-Atlantic to New England will be in the path of drenching downpours and locally gusty thunderstorms into Friday.
The bulk of the storms will occur during the afternoon and early evening hours, but there will be some exceptions.
The storms will focus along the I-81 and I-95 corridors and will bring the risk of flash flooding and isolated damaging winds. A couple of locations can also be hit with hail during the afternoon.
The storms are forecast to impact the afternoon and evening commutes for Roanoke, Virginia; Washington, D.C.; Baltimore; Philadelphia; New York City; Hartford, Connecticut; and Boston.
Those driving should be prepared for a sudden drop in visibility and seek another route if the road becomes flooded.
As the storms develop over or move through the major metro areas, a ground stop may be issued for a time at the airports.
People outdoors should be on the lookout for changing weather conditions and seek shelter as the storms approach. If you can hear thunder, you are at risk for being struck by lightning.
While direct effects on the weather by Arthur will be restricted to coastal communities into Friday, tropical moisture surrounding the system will contribute to the intensity of the downpours and thunderstorms in the I-95 corridor.
As Arthur accelerates to the northeast offshore in the Atlantic this weekend, much cooler and less humid air with a clearing sky will sweep eastward from the Appalachians to the East Coast spanning Friday into early Saturday.
Fireworks from Cleveland, Cincinnati and Pittsburgh to Washington, D.C., Philadelphia and New York City scheduled during the evening of July Fourth should not be affected by the weather. However, the rain will not depart fast enough in southeastern New England, such as in Boston.