In stormy weather, words for the wise Long Islander

Long Island's thunderstorms, floods and overall wild weather since Saturday have brought words like “advisory," “warning” and "watch" back into everyday conversation.

But for the uninitiated, the question could be “what’s the difference?”

The answer: "a lot."

When rainfall includes the threat of flash flooding, the National Weather Service issues guidance so people who live in or travel through areas prone to flooding can best prepare.

The lowest level alert, a flash flood “watch,” means “the environment is capable of producing rain rates high enough to see flash flooding,” weather service meteorologist James Tomasini told Newsday. In other words, flooding is possible, but not happening just yet.

The flash flood “advisory,” on the other hand, indicates "nuisance flooding is either imminent or ongoing,” Tomasini said. This often means there is “ponding on roads, but roads are still passible.”

Then there is the flash flood “warning,” which means that “flash flooding is imminent or ongoing,” and can alert motorists that “flooding is bad enough that roads become impassible.” Anyone walking through such conditions could be swept off their feet by the moving water.

And that’s only the “base” level guidance — the alerts most commonly issued, Tomasini said. Beyond those tiers, the weather service can issue two higher-level flash flooding alerts — the kind that broadcast directly to cell phones — neither of which were issued on Monday.

The weather service can send out a “considerable flash flood warning,” which means people must act immediately to protect their property and — more importantly — their lives. There is also the rarely issued “flash flood emergency,” when “catastrophic flooding” of extreme heights is ongoing, Tomasini said.