Walking in different weather conditions

Rain, mud and shine is all part of bushwalking and are some of joys of going bush. There are, of course, some conditions that are simply too extreme to walk in, and we’ll run through some of them here along with ‘go’ or ‘no go’ decision making. As well as how to enjoy walking in mud, rain, cold/hot conditions and so on.

Of course, no weather forecast is 100% reliable. Weather patterns can change quickly, and dramatically, especially in high alpine areas. It not always possible to avoid these conditions, or to walk out before the storm hits. That’s why it pays to have some strategies for handling unexpected weather patterns.

We’ll run through a few key scenarios below, including how to forecast these conditions, how to decide whether to ‘go bushwalking’ or not, and what to do if you get caught out in these conditions.

Definition
Wind is the movement of air between regions of different pressure. These pressure gradients arise out of temperature differences caused by uneven heating of the earth by the sun (for example, water heats up slower than soil). Wind direction is also affected by the rotation of the earth, whereby the movement of air follows a curved path. In the northern hemisphere, air curves to the right, whereas in the southern hemisphere, it’s the opposite.

Changes in latitude and composition of the earth’s landforms and water give rise to local wind patterns. Also, there are global winds patterns that come from larger-scale heating patterns. For instance, the Hadley Cell is the outcome of consistent the consistent heat differential between the equator and the poles. The wind patterns that we feel on a bushwalk are the combination of both local and global influences.

Enjoying walking in windy conditions
Walking in moderately windy can be refreshing and enjoyable as long as you have appropriate gear and keep an eye on the conditions.

Here are some of the issues to be aware of, why they are important, and how to reduce risks.

‘Go’ or ‘No go’ decisions
The Beaufort Scale is a categorisation system that describes wind conditions, from a gentle breeze right through to a hurricane.

Conditions less than 40 km/h are generally ok to walk in, and while small trees will move around, the risks are relatively low. Walking in these conditions are refreshing and generally quite enjoyable. Conditions less than 40km/h occur for the majority of days throughout the year in Sydney.

Winds higher than 60 km/h are serious: you should seriously consider postponing the walk if these conditions are forecast.

If wind conditions between 40-60 km/h are forecast, consider the terrain and conditions you are entering. For instance, if the bushwalk is through a gorge or canyon area, it’s likely to be relatively sheltered, and therefore less impacted by wind conditions. But if the walk is exposed, close to high cliff edges, you may wish to reconsider.

Before heading out on a bushwalk, check the following to make a decision on whether to ‘go’ or not:

• Check weather reports for predicted conditions including high wind and storm predictions and weather warnings.
• Also, check in with another bushwalker that is familiar with that region. It pays to understand the typical weather patterns in that area from someone who has walked there before. For instance, in some regions, high winds are more likely in the afternoon, and bushwalkers select early morning starts and finishes in these regions.
• Plan ahead and know the logical exit points along the track in case the group needs to exit early.
• If there are winds higher than 40km/h, consider changing bushwalking route to somewhere that avoids areas impacted by the wind such as open ridgelines and cliff-edges. If winds are forecast for higher than 60km/h, seriously consider postponing the walk.

How to minimise the risks if caught out unexpectedly in high winds:
Weather systems can change quickly, and it is possible to get caught out in windy conditions on a bushwalk. Depending on the force of the wind, it may be critical to seek shelter.

When bushwalking, tree movements are a great indicator of wind speed and direction (see Beaufort table above). When walking among trees, watching how the trees move is a great way of determining how windy the conditions are, and monitor conditions change over the course of the day. If conditions change, and you start to notice an increase in wind conditions, monitor nearby trees carefully to get an idea of how fast the wind speed is and determine if you need to change route or seek shelter. You can see from this table that a tipping point from safer to riskier conditions occurs around 40 km/h wind. This is where walking conditions become increasingly challenging, and the risks of falling objects (e.g trees, twigs, branches), slips, trips and falls, and over-exposure to cold, gusty conditions, causing fatigue and/or loss of body temperature increase.

Bear in mind that even if the overall wind conditions are less than 40 km/h, you could experience short, fast gusts of wind, which can be dangerous and uncomfortable, especially if people lose footing, or slip on uneven or wet surfaces. Monitor gusts as well as overall wind conditions with regular observations of tree movements.

Only attempt to go into an area without trees (e.g. above the treeline or onto an exposed open ridge) if wind conditions are less than 40 km/h. And while it’s tempting to stay at a summit above the treeline to enjoy the views, be mindful that conditions can change rapidly. Stay perceptive of wind conditions, and start your descent well before conditions change for the worse.

If you get caught out and need to seek shelter, follow these basic principles:

• Higher elevations are more exposed than low elevations. Often dropping down in elevation can dramatically reduce exposure to windy conditions. Sometimes, this may mean not making it to the summit of the walk (but that’s ok, you can come back another day!)
• Open ridgelines are more exposed than forests. While it’s dangerous to be beneath trees in high winds because of the risk of falling trees and branches, often you’ll find that trees provide a great wind-break and pleasant walking conditions. In windier conditions, avoid open ridgelines and cliff edges in favour of low-elevation forest walks.

Definition
During a thunderstorm, a lightning strike is a sudden electrostatic discharge that occurs when there is an overaccumulation of charged particles within a cloud. The discharge process is a lightning flash, and a single lightning strike discharges an incredible amount of energy: about 1-10 billion joules of energy, producing a current of 30,000 – 50,000 amps.

Getting caught in a lightning storm is extremely dangerous because of the risk of being struck with potentially fatal consequences.

‘Go’ or ‘No go’ decisions
Before heading out on a bushwalk, check weather reports for predicted conditions including storm predictions and weather warnings to help decide if conditions are safe to walk in.

The likelihood of a thunderstorm is different throughout the year in NSW. Long-term thunderstorm data from the Bureau of Meteorology shows that the number of severe thunderstorms quickly rise in NSW during November and stay high through summer, also that the severe thunderstorms are much more likely in the afternoon and early evening. These patterns can be helpful in assessing the likelihood of getting caught out in a thunderstorm, and you may choose to start and finish early to avoid late-afternoon storms.

It is also useful to check in with another bushwalker that is familiar with that region. It pays to understand the typical weather patterns in that area from someone who has walked there before. For instance, in some regions, storms are more likely in the afternoon, and bushwalkers select early morning starts and finishes in these regions. Plan ahead and know the logical exit points along the track in case the group needs to exit early.

If there is a reasonable chance of thunderstorms or lightning forecast, the safest option is to avoid bushwalking. Thunderstorms usually very localised but can be very fast moving so can move across a large area. Even if there are no storms or lightning forecast, remain vigilant and check for signs of storms brewing.

When you’re out on the track, follow these guidelines to keep an eye on conditions and how they are changing:

• Look at the horizon regularly (every 15 minutes) for large cumulous cloud formations and lightning flashes.
• Listen for thunder (if you can hear thunder you should already be on your way to shelter as the lightning could already be dangerously close and approaching fast).
• Calculate the distance that the lightning is away by counting the seconds between seeing the lightning strike and hearing thunder. Since sound travels at 340 m/s, simply multiply the number of seconds you counted by 340, and you’ll get the distance of how far the lightning is away in metres. For example, if you count 4 seconds between seeing the lightning and hearing thunder, then the lightning is 1360m or 1.36km away.

How to minimise the risks if caught out unexpectedly in lightning
A lightning strike follows a buildup of electrostatic current in thunderstorm clouds, and when discharged, the flow of electricity is via the easiest path to ‘ground’. The easiest path is the most ‘conductive’ path, which may be via trees, buildings, metal objects and even people. That’s why it’s really dangerous to be caught out in a lightning storm.

Reducing the risk of being struck by lightning is about reducing the chance of you being part of that ‘conductive’ pathway. In an urban context, the rule is When Thunder Roars, Go Indoors.

But on a bushwalk, there’s not always that option. So if you are caught out on a bushwalk, it’s a matter of reducing the risk of being struck. Here are some tips:

• Follow the 30/30 rule: count the seconds between lightning flash and thunder being heard. If it is less than 30 seconds, you should already have taken shelter as lightning can strike up to 10km away from the source. Take immediate action if it’s less than 30 seconds and you have not yet taken shelter. Wait for 30 minutes after the last thunder roll you heard.
• The best shelter is a building with plumbing and/or electric outlets as these will dissipate any lightning strikes through the circuits instead of you. If possible, retreat to a nearby building. Open picnic shelters are not appropriate shelter. If you are near your car, get in, wind up the windows and do not touch anything metal. If none of these are options, select a place to shelter based on the least risky option relative to where you are located:

https://www.climbing.com/skills/learn-this-laws-of-lightning/

According to Climbing.com, in general:
The spots most likely to be struck are based on three factors (in order of importance):

Rock shelters and cave entrances are also dangerous because lightning will travel along any surface to reach electrical ground. If any part of your body touches any part of these surfaces, the lightning will travel through your body. If you must shelter, sit on any kind of object that is electrically insulated like dry sleeping mats, sleeping bag, and packs.

Follow this table of things to do and not to do:

IMPORTANT
If you cannot find shelter, minimise the chance of being struck by lighting by making yourself as small and round as possible: Crouch down on balls of your feet with head tucked in to reduce exposure and encourage lightning strike to travel down your back rather than through vital organs.

If you get struck: Lightning First Aid
The Centre for Disease Control and Prevention in the USA, recommends the following actions to be taken if someone is struck by lighting (note: we could not find guidelines from Australian government).

People struck by lightning are likely to suffer cardiac arrest and burn injuries, and giving first aid treatment while waiting for professional medical attention can significantly improve the chance of survival. People struck by lightning DO NOT carry a charge: you can’t get electrocuted touching someone after they have been struck.

1. Follow DRSABCD: Safety is the first priority. You must be aware of continuing lightning danger to both victim/s and others in the group. You may have to move the victim/s to a safer location. As soon as you are out of immediate danger (‘D’ in DRSABCD), check for a response from the victim/s (‘R’ in DRSABCD), and call for help (‘S’ in DRSABCD). It is safe to use a mobile phone during a storm. If you have reception, call 000 or 112, or trigger a PLB. Be aware that in the case of multiple victims you must triage and prioritise care.
2. Work through ‘ABCD’ in DRSABCD. People struck by lightning may suffer cardiac arrest, so immediate and aggressive resuscitation greatly improves survival.
3. Lightning may also result in other injuries including trauma, burns and shock, which should be treated with first aid until professional medical help arrives. Check for burns around jewellery, buckles, fingers and toes.

Definition
Rain is precipitation that forms out of condensed atmospheric water vapour, and falls to the ground when it gets too heavy.

Enjoying walking in the rain
Rain is not a showstopper when it comes to bushwalking. In fact, it can be quite fun to experience different walking conditions and see the bush differently, as long as you are prepared with good rain gear and warm layers.

Ideally, layer up with wet-weather clothing before the rain sets in. It’s much easier to put on gear before it’s really raining! Stay positive, keeping up group moral can make all the difference in rainy conditions.

Here are some of the issues that come up when walking in the rain, why they are important, and how to reduce associated risks.

‘Go’ or ‘No go’ decisions
Bushwalking in heavy rain carries additional risks of slip and fall injuries, as well as additional concerns of flash flooding and rising water levels that can make some tracks impassable and dangerous. If heavy rain is forecast (>10mm/hour), seriously consider postponing the walk.

Rainfall intensity is classified according to precipitationGlossary of Meteorology (June 2000). “Rain”. American Meteorological Society; Met Office (August 2007). “Fact Sheet No. 3: Water in the Atmosphere” (PDF). Crown Copyright.

Before heading out, check weather forecasts including rainfall and storm predictions and weather warnings. Also, check in with another bushwalker that is familiar with that region. It pays to understand the typical weather patterns in that area from someone who has walked there before. For instance, in some regions, storms are more likely in the afternoon, and bushwalkers select early morning starts and finishes in these regions. Plan ahead and know the logical exit points along the track in case the group needs to exit early.

How to minimise the risks of getting caught out in heavy rain
Weather systems can change quickly, and it is possible to get caught out in heavy rain. Although weather forecasts are getting far more reliable, they still can be wrong. Local weather patterns can come into play, as well as unexpected changes. That’s why it’s always a good idea to carry wet-weather gear on a bushwalk and have a plan in place for an early exit.

The outcome of heavy rain is quite different depending on catchment size. Heavy rainfall sees dramatic increase water flow in watercourses, and the rate of change relates to the river catchment size and is exaggerated in narrow valleys and canyon systems. Watercourses with large catchments, those that are fed by many water sources or have high runoff from land contours, expand rapidly with rainfall. Narrow valleys fill up even with a small amount of rain as there is a limit to where the water can go and how quickly it can move through the system. Depending on the size of the river catchment area, a watercourse can collect rainfall from a wide area and change in volume dramatically over a relatively short time period.

Heavy rain can cause rapid changes in river levels and flash flooding in canyons and gorges. When walking in these areas, plan your bushwalk route with alternate exists in mind in case water levels rise and rivers are not safe to cross. If you are in a canyon or gorge system in heavy rain conditions, exit immediately.

In general, if you are caught out in heavy rain, seek shelter. Heavy rainfall is often short, and you can avoid getting really soaked by finding a cave or thick stand of trees to shelter under to wait out the worst of it.

On the track, keep an eye out for conditions that suggest the onset of severe weather patterns. Look at the horizon regularly (every 15 minutes) for cumulus clouds (clouds that typically indicate stormy weather) and rain lines: streaky cloud formations indicating rain.

Definition
Exactly how hot it feels on a bushwalk is the combined measure of temperature, humidity, cloud cover (solar radiation), sun angle and wind speed. The WetBulb Globe Temperature (WBGT) takes this into account and gives a sense of the ‘feels like’ temperature and is the best way to gauge exactly how hot the conditions will feel.

Enjoying walking in hot weather
Hot weather can be great fun to go walking in, particularly if there is a nice shady swim spot to stop at along the way. Choosing an appropriate walk is key here: avoid open exposed ridgelines, and select walks that follow shady waterways or valleys. Remain vigilant of the increased risk of bushfires in hot conditions.

Here are some of the issues that come up when walking in the hot conditions, why they are important, and how to reduce associated risks.

Water requirements increase dramatically as temperature and workload goes up. So selecting to walk in cooler conditions means less water loss via sweat and makes for a more enjoyable trip.

Wear light and loose clothing, nothing that sticks or irritates the skin. Select quick dry materials that still insulate when wet. Use sun protection and stop to reapply sunscreen during the walk.

Last, and most importantly, slow down! Going as fast as possible not only exhausts the group, but it means they have less energy and incentive to enjoy their beautiful natural surroundings. People go to natural places for different reasons, but often it’s for many more reasons that getting from A to B: the journey is every bit as enjoyable as the endpoint, and slowing down allows more time to get to know the people in the group and relax.

‘Go’ or ‘No go’ decisions
Bushwalkers can cope with a surprisingly broad range of temperatures through specific gear (e.g. warm clothing) and behaviours (e.g. avoid walking at the hottest time of the day). But there’s a limit to what the human body can cope with.

As temperatures increase, the amount of water that we need to consume goes up exponentially.

If the Wet-bulb-globe-temperature (the feels like temperature) is greater than 32℃, physical activity should be kept to a minimum. That means, choosing an alternate route (one that goes through less exposed country e.g. gullies, forests) or going back another day. With hot temperatures comes the risk of bushfires, and the potential for TOBANs.

If high temperatures are forecast, do not set out – your body simply cannot cope with these conditions. Furthermore, consider cancelling is TOBAN or when Severe. Always cancel if Extreme or Catastrophic.

Before heading out, check weather reports for predicted conditions including temperature predictions and weather warnings. Also, check in with another bushwalker that is familiar with that region. It pays to understand the typical weather patterns in that area from someone who has walked there before. For instance, some ridges are particularly exposed and heat up quickly.

How to minimise the risks if caught out in hot conditions
Sometimes, the conditions are hotter than expected out on the track, which can make for really tough walking. If the temperature starts rising too high for the group’s comfort, consider changing the route or exiting early.

In hot weather, stop regularly and rest in a sheltered and shady area. Regularly check in with your group to see how everyone is feeling. Take a slow pace, and avoid walking during the heat of the day.

Definition
Just as with hot weather, how cold it feels is not just a function of temperature, but also wind chill and how fast water evaporates from your skin. Cold weather also increases the chance of snow and ice.

When the atmospheric temperature is at, or below, zero degrees, ice crystals form. When these then aggregate together, they create snowflakes and fall to the ground because they are too heavy. If the ground temperature is cold enough, snow accumulates on the ground.

The main risks associated with heavy snowfall are exposure to cold and wet conditions, intended routes impassable, as well as increased risks of falls and injuries due to slippery conditions.

Enjoying walking in cold weather
Cold weather can be great to walk in, especially to keep yourself warm! Carrying appropriate gear is key here: warm layers, rain jacket, gloves, hat and so on.

Here are some of the issues that come up when walking in the cold conditions, why they are important, and how to reduce associated risks.

‘Go’ or ‘No go’ decisions
In NSW, the Snowy Mountains are the most common place for bushwalkers to experience cold conditions. Snow and ice can change the landscape dramatically, and conditions can change extremely quickly at high elevation. At high elevation, wind is another factor that cools the air temperature down.

Wind Chill is not the actual temperature, but rather how wind and cold actually feel on exposed skin. As the wind increases, heat is carried away from the body at an accelerated rate, driving down the body temperature. The graph below shows how wind lowers temperature. For instance, at 40℉ and a wind speed of 20mph, the temperature feels like 30℉.

If cold temperatures are forecast and there’s an increased risk of snow and ice, bushwalkers need to have appropriate gear to cope with these conditions. If you do not have appropriate gear, or experience do not attempt to bushwalk in cold conditions. It is best to not set out if heavy snow and blizzards are forecast.

Before heading out, check weather reports for predicted conditions including cold predictions and weather warnings. Also, check in with another bushwalker that is familiar with that region. It pays to understand the typical weather patterns in that area from someone who has walked there before. For instance, in some alpine regions, snow can block certain tracks.

How to minimise the risks if caught out in cold conditions
Weather systems can change quickly, and it is possible to get caught out in cooler conditions than expected, and also ice and snow. In extremely cold conditions, bushwalkers need to carry extra gear – warm clothes, good wet weather gear – and use additional skill sets (e.g. navigation in the presence of snow and ice).

Frostbite is damage to body tissue caused by extreme cold (see table above). A wind chill of -20° Fahrenheit (F) with light winds will cause frostbite in just 30 minutes. Frostbite causes a loss of feeling and a white or pale appearance in extremities, such as fingers, toes, ear lobes or the tip of the nose. If symptoms are detected, get medical help immediately! If you must wait for help, slowly re-warm affected areas. However, if the person is also showing signs of hypothermia, warm the body core before the extremities.

When out on the track, keep an eye out for changes in weather conditions by looking at the horizon regularly (every 15 minutes) for darker grey cumulus clouds (indicating storm clouds).

If you are caught out in colder conditions than expected, consider change route, shortening the trip. Monitor group for signs of hyperthermia, and frostbite in extreme cold. If you are caught out in heavy snow: seek shelter. Use huts if available or pitch a tent if carrying one. Find rocks, caves or trees to shelter under to wait out the worst. Keep as warm and dry as possible. If caught out by a blizzard in high alpine regions, seek shelter until the heavy snow has passed and visibility and conditions are easy to continue through.

Hailstones are balls or lumps of ice that are a type of solid precipitation and form in strong thunderstorm clouds. Hailstones tend to occur when the majority of the cloud layer is below freezing and has high liquid water content as well as and there being intense updrafts.

Hailstone showers are generally short but can cause substantial damage due to the size of the hailstones. In 1999, hailstones measuring up to 13cm were reported in Sydney’s eastern suburbs!

The main risks associated with hailstones are injuries associated with the falling hail, particularly large hailstones. Although rare, hailstones have been known to cause fatalities. The key thing in a hailstorm is to seek shelter.

‘Go’ or ‘no go’ decisions:

Accurate forecasting of hail storms is challenging because there are several elements required:

• Adequate updraft to keep the hailstone aloft for an appropriate amount of time,
• Sufficient supercooled water near the hailstone to enable growth as it travels through an updraft, and
• A piece of ice, snow or dust for it to grow upon.

There is no clear distinction between storms that do and do not produce hailstones. Nearly all severe thunderstorms probably produce hail aloft, though it may melt before reaching the ground.When the thunderstorm’s updraft can no longer support the weight of the ice, hail falls. The stronger the updraft the larger the hailstone can grow.

Currently, radar techniques are used to estimate the likelihood of hailstorms and these can predict the near future. Longer term forecasts are much harder: the National Severe Storms Laboratory (NSSL) in the USA is developing techniques to use dual-polarised radar data in short-term computer forecast models to improve forecasts of hail and large hail.

Before heading out on a bushwalk, check weather reports for predicted conditions including weather warnings. Plan ahead and know the logical shelter points along the track. Think carefully about exposed ridges above the treeline with little available options for shelter.

If hail is forecast as likely, it is best to postpone your walk.

How to minimise the risks if caught out unexpectedly in hail
The key risks to be aware of in hailstorms are Injury, especially head injuries and slippery/icy conditions

On the track, look at the horizon regularly (every 15 minutes) for cumulus cloud formations indicating storms and possible hail storms.

In general, if you are caught out in a hail storm, seek shelter. Hailstorms are often short, and you can seek shelter in a cave or thick stand of trees for protection.