Trip planning the night before: the hour that saves the day

The decisions you make on a slope are made cold, tired, at altitude, with a group looking at you and a beautiful line in front of you. The decisions you make the night before are made warm, fed, calm, with a map, and with nothing at stake.

Those are not equally reliable conditions. So do as much of the deciding as possible the night before.

Start with the forecast, properly

Not the danger rating. The rating is a summary and summaries lose the useful part.

Read the avalanche problems: what type, on which aspects, at which elevations, and what size. "Persistent slab, north through east, above tree line, size two to three" is an instruction about where not to go. It defines the terrain to avoid with far more precision than a colour on a scale.

Then read the discussion section, which is where forecasters put the reasoning and the uncertainty. When a forecaster writes that they are unsure how a particular layer is behaving, that uncertainty should propagate into your plan as extra margin.

Read yesterday's forecast too, and the day before. The trend tells you whether things are healing or getting worse, and a single day's snapshot hides that entirely.

Then the weather

New snow amount and rate. Wind speed and direction, which determines which aspects are being loaded — the lee side of a ridge collects the snow the windward side loses. Temperature, especially rapid warming or rain on snow, both of which destabilise things quickly. Freezing level. Visibility, because navigating and reading terrain in a whiteout is a different sport.

Draw the route on a map with slope shading

Modern mapping with slope-angle shading is the most significant safety development in backcountry travel in decades, and it costs almost nothing. Turn it on and look at your intended line.

Mark where you enter terrain steeper than your limit for the day. Mark where you travel underneath terrain steeper than your limit — this is the one people miss, and overhead hazard has caught a lot of parties in flat places.

Identify safe regrouping spots: ridges, dense trees, wide flat areas well clear of runouts. Plan to stop at those, not wherever people happen to get tired.

Set the numbers now

Two numbers, agreed in advance, written down.

A terrain limit — the maximum slope angle you will travel on or beneath today. Derive it from the forecast, not from ambition.

A turnaround time — the time at which you head down regardless of how close the summit is. Derive it from daylight, the descent time, and the weather window, with a buffer.

Numbers set in a kitchen are far more robust than numbers negotiated on a ridge at two in the afternoon by people who have driven a long way. That is the entire point of setting them early.

Have a plan B and a plan C

Not vaguely — actually drawn. A lower-angle tour, and a treeline day that works if it is snowing hard and blowing.

Groups without alternatives do not turn around; they proceed, because the only options on the table are the objective or driving home. Giving people a genuinely good alternative removes most of the pressure to push a bad plan.

Check the group, honestly

Who is coming? What is their actual experience — not their claimed experience? Does everyone have transceiver, probe and shovel, and has everyone used them this season?

Is there a fitness or skill spread that means someone will be exhausted by midday? A tired member changes every subsequent decision, including the ones about hazard.

Say out loud who is making the call if opinions differ, and say that anyone can stop the group at any time for any reason without needing to justify it.

Leave a plan behind

Someone not on the trip should have: where you are going, the route, the vehicle and where it is parked, who is with you, and the time at which they should start making phone calls. Being specific about that last one matters — "if you have not heard from me by nine" is actionable, "sometime tonight" is not.

Then, in the morning

Re-read the forecast. It updates, and overnight weather can change things substantially. If the new forecast contradicts your plan, believe the forecast, not the plan you are already attached to.

The hour at the table is the highest-leverage hour of the trip. Everything after it is execution.