AR 95-1 "Army Regulations"

Aircraft will not be intentionally flown into known or forecast extreme turbulence or into known severe turbulence. Aircraft will not be intentionally flown into forecast severe turbulence unless ACOM, ASCC, DRU, or NGB commander has established clearance procedures and— (a) Weather information is based on area forecasts. (b) Flights will be made in areas where encountering severe turbulence is unlikely. (c) Flights are for essential training or essential missions only. (d) Flights are considered extremely high risk. (e) Flights are terminated or depart turbulence if severe turbulence is encountered.

Aircraft will not be flown into known or forecast severe icing conditions. If a flight is to be made into known or forecast moderate icing conditions, the aircraft must be equipped with adequate
operational deicing or anti-icing equipment.

Destination weather must be forecast to be equal to or greater than VFR minimums at estimated time of arrival (ETA) through 1 hour after ETA. When there are intermittent weather conditions, predominant weather will apply.

Destination weather must be forecast to be equal to or greater than the
published weather planning minimum for the approach procedure to be flown at ETA through 1 hour after ETA. When
there are intermittent weather conditions, predominant weather will apply.

1 hour and 30 minutes from the time the forecast is received provided the aircraft has not departed.