Learn Hardcore Spanish (Latin America): El martes habrá un simulacro de huracán y sonará una alerta fuerte por el altavoz. - On Tuesday there will be a hurricane drill and a loud alert will sound over the speaker.

In Spanish, days of the week are normally preceded by the definite article when you specify “on” that day. So El martes literally means “on Tuesday.” Omitting el would sound unnatural in this context.

What does habrá mean, and how does it differ from va a haber?

Habrá is the simple future form of haber used impersonally to mean “there will be.”
• Habrá un simulacro = “There will be a drill.”
• Va a haber un simulacro is also correct (“there is going to be a drill”), but habrá is more concise and formal.

What exactly is a simulacro de huracán, and why not use simulación?

A simulacro in emergency-prep contexts means a “drill” or “exercise.” You practice procedures as if the real event were happening.
• Simulación usually refers to a “simulation,” a model or representation, and is more abstract.
• For safety drills—earthquake drill, fire drill, hurricane drill—Spanish uses simulacro.

In “y sonará una alerta fuerte,” why do we use sonará, and what is its subject?

Sonará is the third-person singular future of sonar (“to sound” or “to ring”). Here the subject is una alerta fuerte—the alert itself. In other words, “a loud alert will sound.”

Why is fuerte placed after alerta, and does it mean “strong” or “loud” here?

Most descriptive adjectives in Spanish follow the noun, so alerta fuerte is natural. Although fuerte literally means “strong,” when talking about sounds it usually means “loud.” So alerta fuerte = “a loud alert.”

Why is the preposition por used in por el altavoz instead of en or a través de?

Por indicates the medium or channel through which something happens.
• Por el altavoz = “through the loudspeaker.”
• You could say a través del altavoz, but por is shorter and more common in announcements.