When the weather is just out there to get at you, you need to be wearing the Mountain Equipment Triton Jacket. It is designed to be completely waterproof with an added layer of really warm down to give your core the boost it needs to keep you going when out in rough conditions. Hem draw cords, adjustable cuffs and hood will help keep precious heat inside and the water resistant YKK Aquaguard central zip has an internal storm flap so there is no cold spots there either. This is the jacket to rely on in the worst of days.
A Mountain Equipment base layer under the Triton jacket would make an great combination for superb comfort and breathabilty.