Plain English Meaning
Thunderstorms hidden inside a larger blanket of cloud. You can't see them coming because the surrounding cloud hides them from view.
Full Definition
Thunderstorms that are obscured within other cloud layers, typically widespread stratiform or layered cloud, so they cannot be seen and visually avoided by a pilot in flight.
Context Anchor
Pilots encounter this term in weather briefings, risk management discussions, and flight planning when deciding whether a route through cloudy or rainy weather is safe.
Derivation
Embedded' comes from the idea of something being set firmly within something else, like a stone set into concrete. Here, the thunderstorms are set inside other clouds and hidden by them.
Why Pilots Care
They create sudden severe turbulence, , and with no warning, raising the chance of .