LAT
LAT turns up in 2 fields: tides, fire & safety. Here is what it means to the people in each one.
LAT in tides
Lowest Astronomical Tide: the lowest level that tide predictions reach when the weather is held at average.
Lowest Astronomical Tide is the lowest level the tide reaches in predictions from astronomy alone, with weather held at average, found by computing predictions across at least one full nodal cycle of about 19 years. Many countries use it as chart datum because the tide almost never falls below it without help from the weather. Its counterpart, Highest Astronomical Tide, often marks the upper limit for vertical clearances.
"Charts here are on LAT, so the tide table never shows a minus figure; you only get below datum with a strong offshore blow."
LAT in fire & safety
A Large Air Tanker used to drop water or fire retardant on wildland fires.
A Large Air Tanker is a fixed-wing aircraft capable of carrying between 2,000 and 4,000 gallons of water or fire retardant. These aircraft are critical in wildland firefighting for building retardant lines ahead of an advancing fire front. They are typically converted commercial airliners or military transport planes equipped with specialized gravity-drop or pressurized tank systems.
"Air attack is requesting two LATs to lay retardant on the northern ridge before the wind shifts."