On September 1–2, 2021, Hurricane Ida affected much of the Northeastern United States as an extratropical cyclone, causing catastrophic river and flash flooding. Widespread flooding affected many areas, shutting down numerous roads, halting public transit, and cancelling hundreds of flights. Several rivers overflowed their banks, flooding farmlands, towns, and homes. Hundreds of cars were abandoned on roadways after being stranded in floodwaters and dozens of high-water rescues were performed. Several flash flood emergencies were issued due to the flooding.
The storm also produced a tornado outbreak that spawned seven tornadoes across Pennsylvania and New Jersey along with an additional weak tornado in Massachusetts. In Pennsylvania, an EF2 tornado caused severe damage and a fatality in Upper Dublin Township. One intense EF3 tornado passed near Mullica Hill, New Jersey damaging or destroying several homes. The same storm later produced EF1 tornado that tracked from Edgewater Park, New Jersey to Bristol, Pennsylvania and prompted a rare tornado emergency for both Bristol and Croydon, Pennsylvania, as well as Burlington, New Jersey. This was the first tornado emergency ever issued for a tropical cyclone as well as the first ever issued for the Northeastern United States.
At least 55 people died in the states of New Jersey, New York, Pennsylvania, Maryland, and Connecticut. CoreLogic estimated that Ida caused an estimated $16 to 24 billion in flooding damage in the Northeastern United States. The National Hurricane Center (NHC) estimated that Ida caused between $18 billion to $22.5 billion in damage in the Northeastern United States, with a median estimate of at least $20 billion in damages.
Background
Ida was the third tropical system in a time period of several weeks to affect the Northeastern United States, after Tropical Storm Fred and Hurricane Henri in August. These storms dropped heavy rainfall, saturating the soil. New York City recorded from August 16 to 30, which became the second largest amount of rain New York City had in the second half of August on record. Water levels in rivers were also higher than average, leaving much of the region susceptible to flooding.
Preparations
The Weather Prediction Center issued a High Risk of flash flooding for parts of West Virginia, Maryland, Pennsylvania, New Jersey, New York, and Connecticut.
Impact
Maryland
In Maryland, A 19-year-old man was confirmed dead after flooding at an apartment complex in Rockville. In Frederick County, 10 students and their bus driver had to be rescued when their school bus was caught in flooding. An EF2 tornado caused considerable damage to homes, businesses, schools, and other structures as well as trees, signs, and power lines in Annapolis. Two other EF0 tornadoes also touched down in the state.
Pennsylvania
At least five people were killed in Pennsylvania. In Bucks County, a man drowned in his vehicle in the Unami Creek. The flooding was particularly severe on portions of Interstate 676, leading the highway to take several days to reopen and causing $715,000 to repair. Parts of Pennsylvania Route 611 were closed for six months due to flooding. Four tornadoes touched down in the states while another one moved into the state out of New Jersey. A low-end EF2 tornado caused severe damage when it impacted the east side Oxford in Chester County. Another EF2 tornado caused severe damage in Fort Washington, Upper Dublin Township, and Horsham Township in Montgomery County, knocking down trees and power lines and tearing the roof off of the Upper Dublin Police Department. A woman was killed when a tree fell onto her house due to the tornado. Three EF1 tornadoes were confirmed in Bucks County, including one EF1 tornado that crossed the state line after striking Edgewater Park, New Jersey and struck Buckingham Township. In Pittsburgh, a bus with over 40 people had to be rescued. This tornado came from the same storm that produced the Mullica Hill, New Jersey EF3 tornado and this prompted the issuance of a tornado emergency for Burlington, New Jersey and Croydon, and Bristol, Pennsylvania, the first of its kind in the Northeast, as well as the first such alert associated with a tropical cyclone. Bucks County was also under a flash flood emergency at the time, marking one of the few times that these emergency alerts were issued for the same area. Damage in Pennsylvania amounted to anywhere between $2.5 billion and $3.5 billion.