US: Adverse weather prompts disruptions and flooding across northeast as the evening of June 30

As of the evening of June 30, severe weather accompanied by thunderstorms has prompted flight disruptions and flash flood warnings across multiple northeast regions. The US National Weather Service (NWS) issued severe thunderstorm watches and warnings across most affected areas. Flash flood warnings are in place across eastern Pennsylvania, central and southern New Jersey, southern Connecticut, and the New York metropolitan area. Authorities will likely issue new alerts as weather conditions change over the coming hours.

Flight disruptions, including delays and cancellations, will likely continue to affect northeast airports, including Boston, Massachusetts, into at least early July 1 amid thunderstorms impacting the region. The Federal Aviation Administration (FAA) has issued ground delay programs at LaGuardia (LGA) until at least 23:59 June 30 and John F. Kennedy International (JFK) airport until at least 01:00 EDT on July 1. Additional ground delay programs are in effect at Philadelphia International Airport (PHL) until 21:59 June 30 and Newark International (EWR) until 22:59 June 30. The FAA may modify or rescind the ground delays on short notice. As of the evening of June 30, departure delays at LGA average 135 minutes, while arrival delays average 75 minutes. Flights at JFK averaged 75-minute delays, and flights at BOS averaged 90 minutes. Flight disruptions are possible at other airports in the region.

Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rain has saturated the soil.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks.

The severe weather could contribute to transport disruptions throughout the region. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities may temporarily close low-lying routes that become inundated by floodwaters.

Localized business disruptions may occur in flood- or tornado-hit areas; some businesses might not operate at full capacity because of damage to facilities, possible evacuations, and employees' inability to reach work sites.