Which type of weather briefing is recommended for a pilot departing within the hour if no prior information has been received?

A standard briefing is the most appropriate type of weather briefing for a pilot who is preparing to depart within the hour without having received any prior weather information. This type of briefing provides comprehensive and up-to-date weather information, which includes current conditions, forecasts, significant weather, and any relevant notices to airmen (NOTAMs).

Given the urgency associated with a flight that is set to depart shortly, the standard briefing ensures that the pilot is fully informed of any factors that could impact their flight. This includes crucial data such as turbulence, thunderstorms, low visibility, or other severe weather that might affect their route and safety.

The other types of briefings, while useful in different contexts, do not provide the thoroughness required when time is of the essence. An outlook briefing focuses on forecasts beyond a 2-hour timeframe, an abbreviated briefing is for pilots who have already received some information and need specific updates, and a routine briefing is intended for non-time-critical flights. Therefore, a standard briefing is the best choice in this situation to ensure safety and preparedness before departure.