Islip made national headlines when more than a foot of rain flash flooded the area last week, but there’s a big difference between precisely where the most precipitation fell and where the most dramatic damage occurred.

That’s because the Town of Islip and the unincorporated hamlet of the same name that was flooded with water and storm-chasing reporters are often confused with the location that the National Weather Service (NWS) uses as a reference point for Long Island: Long Island MacArthur Airport (LIMA) in Ronkonkoma. As a result, Islip the town, hamlet and LIMA are often used interchangeably in weather forecasts. But, the flood underscored how much of a difference is in the distinction.

“These are not little towns,” U.S. Sen. Charles Schumer (D-NY) said while explaining the term to reporters during a recent news conference on the flood. “They call them towns here on Long Island, but they each have over 200,000 people.”

Islip town actually has a population of 335,543, according to the 2010 census, while the hamlet of Islip is home to 18,689, as well as town hall. Although the hamlet saw more than 10 inches of rain, it’s nearly 10 miles southeast of the town-run airport, which was widely reported as setting a New York State record for most rain in one day: 13.73 inches. The likelihood of that much rain falling in one day is once every 200 years.

The weather service uses LIMA as a reference point for LI forecasts because that’s the location of its climate records and its observation equipment, or Automated Airport Weather Stations, aka AWOS machines. NWS references to LIMA as Islip are a carryover from when it was previously known as Islip Airport. Aviators still abbreviate the airport as ISP.

The Weather Channel and New York City-based TV news meteorologists were among those that reported that Islip got 13 inches of rain instead of 10 while citing the NWS data. So, what’s the difference in three inches of flood water when the entire Town of Islip—Ronkonkoma and Islip hamlet included—were under a state of emergency?

“If a major airport like MacArthur in the middle of the Island can have flooding you can imagine as you get to the low-lying areas how much worse it got,” Schumer said, noting that he saw LIMA crews pumping out flooded bathrooms when his plane landed that day.

Ronkonkoma, near the middle of the Island, is 112 feet above sea level versus the coastal hamlet of Islip, which sits at 16 feet. While it formed ponds when trapped in places like the Southern State Parkway, the water rushed from points north to the South Shore, including the hamlets of Islip and Bay Shore, where news crews broadcasted dramatic scenes of a 24-foot sinkhole at Bay Shore Commons shopping center, a colvert washout nearby off Montauk Highway and another on Manituck Lane, where Schumer visited.

“The water that was falling didn’t have anywhere to go,” added Joey Picca, an Upton-based NWS meteorologist. He noted that the timing of the storm also contributed to the flooding because it arrived around the same time as a full moon. As a result, tides were already astronomically higher than usual when the floods came.

That was a similarity this storm had with Sandy, which hit during a blue moon. The difference was that the 2012 superstorm flooded coastal areas with saltwater that surged inland from the Atlantic and its bays. But, in the latest storm, freshwater rushed toward the bay from inland—often turning roads into rivers when creeks and drainage systems overflowed.

The names of locations cited by meteorologists weren’t the only source of confusion. It was hard to tell who was caught more by surprise by the storm: those living in the flood zone, or those who traveled into it after the rain.

When Long Island Rail Road trains were forced to reduce their speed because the tracks were under water between the Islip and Bay Shore stations, one LIRR rider wowed by the sight of the flood was overheard asking: “Did it rain last night?”