How to determine wind speeds for windchill effect?

[uphillklimber]

We just had a blustery weekend in BSP. Temps to -14 with 14 mph winds, windchill of about -37. Frostbite can occur in 15 minutes. Fortunately, the worst winds were at our back. On the way out, it was much warmer and slower winds.

BSP requires we have a thermometer and windchill chart. Easily done with a $3.00 LL Bean thermometer, with chart on back. Fat lot of good it does if I can not estimate the wind speed . I am not about to carry a wind speed whirlygig thingy with me for just that one purpose. (Unless I can find a superlightweight inexpensive small one).

Seems to me that I have, way in the past, seen some such guide for estimating within 5 mph the speed of the wind. The one I remember seeing went along the lines of: If the leaves are shaking it is less then 5 mph. If they are straight out it is 5-10 mph, etc...... Flags straight out mean 20 mph or more. I am just throwing numbers out here. I do not remember what they are, honestly. Also, how would any of those references have helped me this weekend in the backcountry?

Anyways, how do you determine wind speed out in the field?

 

[David Metsky]

Here's the first one I could find online: http://spruce.flint.umich.edu/~jalarie/jaa_tg.htm

-dave-

 

[uphillklimber]

Many thanks

 

[Waumbek]

The Beaufort scale scale has been around for a long time (1806), and I like it better than most others because, in the higher wind speed categories, it is the least "urban," it makes the fewest references to things like flags and smokestacks that you won't be seeing in the backcountry and the most references to trees, which you will be seeing. The hyperlinked scale can be printed out for easy reference.

 

[jbrown]

I am not about to carry a wind speed whirlygig thingy with me for just that one purpose. (Unless I can find a superlightweight inexpensive small one).

It's not what I would call inexpensive, but Kestrel makes good stuff. The 2000 calculates windchill so you won't have to, the 1000 does not.

 

[Kevin Rooney]

Here's what I call the Rooney Scale - if it's breezy but you can walk steadily most the time, it's < 30mph. If you're being to get rocked regularly, it's probably 35mph and greater. It's very difficult/impossible to stand up/hike with a pack in winds of greater than 50-60mph, so it's time to head for the trees.

If the wind's in the 35 mph range or greater, the risk of frostbite increases substantially. Not only is the windchill increased, but the ability to check each other's face visually is compromised. It's very tough to determine frostbite on your own face as it occurs, but obvious for others. Any time the wind's above 35mph and it's cold, my caution level increases substantially.

With all due respect - in conditions where frostbite is a factor, any device beyond a thermometer may be more trouble than it's worth, and fiddling with it, and holding the group up which someone determines the exact wind speed, etc, should be regarded with caution. It may contribute more to causing frostbite than preventing it.

 

[uphillklimber]

With all due respect - in conditions where frostbite is a factor, any device beyond a thermometer may be more trouble than it's worth, and fiddling with it, and holding the group up which someone determines the exact wind speed, etc, should be regarded with caution. It may contribute more to causing frostbite than preventing it.


I absolutely agree. To be effective, I feel a device has to be efficient. I can see my self being pushed over the edge of a cliff trying to work out the exact windspeed and windchill. Or if I'm waiting for you while I am freezing my tail off......

Kinda reminds me of that time when Mom cooked up an awesome roast, and Dad just had to try out his new knife sharpener. We had just been playing ball and were famished and the roast was to die for. There was a sharp knife 4 feet away, but nooooo. Dad just had to try to sharpen the knife and test it out on that now luke warm roast. I think it became readily apparent that we all knew exactly where that sharp knife was.......

 

[Pete_Hickey]

With all due respect - in conditions where frostbite is a factor, any device beyond a thermometer may be more trouble than it's worth,

I'll go one step further. I don't even think a thermometer is necessary. To me, at least, it's kind of obvious by feel, what the probability of frostbite is. Either extreme cold (say less than -30F) (easy to tell by breathing and/or listening to trees), or the wind, which is easy to tell by....by.....Welkl, heck. Even a little kid can say it's a windy day.

If you don'T have experience to know by feel, maybe you should just ASSUME that you should take precautions.

 

[whcobbs]

snowman Beaufort

Seems to me that I have, way in the past, seen some such guide for estimating within 5 mph the speed of the wind.
Anyways, how do you determine wind speed out in the field?

What is needed is a validated version of the Beaufort Scale for snow conditions above treeline. I searched a year ago, including an entire book on the Beaufort Scale, and was unable to find such an item. Perhaps others can suggest observations that might make a start, e.g. spindrift conditions, existence of ridge/summit snow clouds, distance dropped snow travels free, etc.

Walt

 

[DougPaul]

With all due respect - in conditions where frostbite is a factor, any device beyond a thermometer may be more trouble than it's worth, and fiddling with it, and holding the group up which someone determines the exact wind speed, etc, should be regarded with caution. It may contribute more to causing frostbite than preventing it.

Agreed--in high frostbite risk conditions, you shouldn't be fooling around with a thermometer and chart. The windchill charts are just an approximation anyway. And they don't take into account the status of the potential victim. (I simply use the charts to guess the general level of seriousness ahead of time and go by feel out on the mountain. I don't carry the charts with me. I carry a themometer, but rarely bother to look at it.)

For a hiker who is moderately warm and generally ok:
* 20F, no problem except perhaps in high winds
* 10F, be careful in moderate and higher winds
* 0F, be careful in low and higher winds.
* -10F and below, the wind-induced cooling from just walking (or gentle breezes) will be serious. Be careful.

When the risk is high use a facemask and goggles (no gaps!). Mittens are warmer than gloves. (Make sure you have a good wind seal at the wrists.) Any exposed skin anywhere is at risk.

You can feel the effects on your skin: if you can feel your face (don't forget your ears), it is ok. (Flesh goes numb before it freezes.) As it gets colder, I feel a burning-like sensation on my face (my skin will be rather red at this point. At some point the cold feels penetrating and then my skin will go numb. (Numb skin is not necessarily frozen--but if you never let it get numb, then it never gets cold enough to freeze.)

My approach is to stay above the numb point. Make sure you can feel your entire face and ears (and any other exposed skin--wrists are a problem area). One trick is to rub your face gently with the back of your mitten/glove and make sure that you can feel it. Checking each other's faces every few minutes or so is also helpful--the flesh will turn white when it freezes. If you get superficial frostbite (just the surface of the skin) or a spot on your face gets unduly cold, just hold your glove/mitten against it--blocking the wind will allow warm blood from within to heat the area.

For toes and fingers, wiggle them inside your boots/gloves/mittens. Make sure you can feel them. Otherwise, rewarm. Feet and hands are warmed by excess body heat--make sure that your body is warm enough to heat your feet and hands. This is why insulating your head and body are essential for warming your feet/hands, even if only your feet/hands feel cold. (Old saying--if your feet are cold, put on a hat.) It can take 20 min or so for body heat to work its way out to your hands and feet.

Keep moving: wiggling fingers and toes and shuffling around when standing to promote circulation to the hands and feet.

Dehydration is a significant factor in many cases of frostbite.

If a foot gets seriously frozen out in the woods you can walk out on it, but if you thaw it you become a litter case. Seriously frozen flesh must be very carefully (both mechanically and thermally) protected after thawing. One of the worst things you can do is refreeze after thawing. (It is safe the rewarm superficial--see above.)

Doug

 

[Kevin Rooney]

I tend to agree with Pete in that if you spend alot time in cold weather, you just know when it getting cold enough to be careful - a therometer simply confirms it.

I'd add another variable to the cold/wind speed equation in terms of windchill and comfort levels, and that's relative humidity. Most of the time in the Northeast the relative humidity is fairly high. Now that I'm in the Sierra in an incredibly dry climate I can tell you that when the sun goes it gets COLD in a hurry. I rarely use my down jacket in the East, but use it all the time in the West.

As for wind chill charts - IMHO the old windchill chart understated the effect of wind, and the new one overstates it - the "real" values are somewhere in between. And, whether someone gets frostbitten or not varies between individuals, and the amount of rest and hydration they've had, among other variables.

 

[David Metsky]

And, whether someone gets frostbitten or not varies between individuals, and the amount of rest and hydration they've had, among other variables.

Such as how much fur they have...

-dave-

 

[Kevin Rooney]

Such as how much fur they have...

-dave-

Good point, Dave! And whether they have not one fur coat but two. I think that's a large part of what makes some dogs like Newfies, Huskies, Samoyed's, etc, so well-suited for subzero conditions.

 

[uphillklimber]

Lots of good info here. Just some perspective. I work in construction and often work outdoors in the winter without gloves. Not really a lot of fun, most times not even an issue, but never got frostbite. Sure I've had to warm em up and work goes on. While I have mittens (forever it seems) I have not had to use them in the last 10 years or more. They are in my ski bag. My tact is to keep my hands and feet dry, which makes it easier to keep em warm.

Now that just won't work for my wife, who works at a desk in an office. She also has much less, ahem, mass, than I do. If it is cold at all, she has her gloves. If my gloves are on, she is looking for her mittens and putting them on.

Different strokes for different folks. What do I do? I find her the nicest pair of goretex mittens I can find, at, of course, the right price. I wouldn't try to dictate to her that she ought to know better than to do that in this weather. Although I will occasionally ask her where her mittens are if she says her hands are cold.

All that being said, I have a lot of respect for a thermometer and a windchill chart and relaitive humidity and personal resistance to weather. So many variables. All the weather guages in the world basically give a "barometer" of what you need to survive, endure and thrive at different climates.

This past weekend, we started in at 10 below and a stiff wind. Camelbak hoses frozen in the ride in the back of the pickup from the hotel to trail head. All I could say was that it was mother cold out there. We bundled up pretty good, being prepared to come out in a mother cold blizzard. We ended up shedding some clothes.

I just want some way to effectively say how cold it is while we are out there. Bragging rights, you know. Also want to always be gaining in experience as to what gear to wear, have we ever done anything like this before, etc....

 

[grouseking]

I try not to hike when the temperature is to the point where my nose hairs freeze instantly (near zero) but then again I have little or no winter gear. I do keep myself very warm and I sweat ridiculously...but that is what worries me. If I get above the trees and suddenly its -10 with a 30 mph breeze with gusts to 50 I'm in trouble considering my wet skin. For me its very difficult to regulate my body heat on cold days because I sweat so much no matter what the temperature and no matter what I wear. So I tend to stick with warmer hikes below treeline in winter (that is until i get the guts...and the hiking buddy to get out there with me).

grouseking

 

[uphillklimber]

Grouseking, we tend not to hike so much in winter, as we are skiiers. We go skiing almost every weekened. (Not this winter, as conditions ahve been a little rough some weekends.) We'll do mostly day hikes when we do go, or have a base of operations like a cabin. But it sure is nice in winter. With some practice, dressing not to sweat in winter can make it fun. You'd be surprised how little you need to wear for a winter hike. But you gotta have it for when you stop. There are other advantages to winter hiking: No bugs. Rocks and roots get smoothed out by the snow. The air is unbelievably clean.

You live in Chester NH. We live in Barrington NH. Perhaps we could hook up. There are some shorter hikes near here, great for a shakedown on winter gear of a couple hours. Best way to start out. Be close enough that if the gear is wrong, you can just walk to the car inan hour or less. Then build up from there.

 

[Grumpy]

Yet Another Possible Factor . . .

Many years ago I had a frostbite episode while photographing recreational downhill skiers.

Nice, sunny day and quite pleasant, with very little wind. Foolishly, I was not wearing a hat or ear protection. I stayed in one position for quite a long time, looking for “just the right image” to pop into the viewfinder.

The ear on the sunny side of my face/head was OK. The one on the shaded side suffered severe frostbite damage.

G.

 

[daxegraphix]

Wind speed

My favorite is the ax angle test. If the wind can hold my tethered ax at dead level--it's probably above 50 or 60mph.

 

[uphillklimber]

My favorite is the ax angle test. If the wind can hold my tethered ax at dead level--it's probably above 50 or 60mph.

LOL!!!!

 

[Lawn Sale]

Sine you are looking for just an approximation of the wind and do not need something NIST traceable, I'd suggest a Dwyer Wind Meter . I have one I use for reporting the lake winds for sampling, it works great and won't break the bank. I found one on Ebay, that's going cheap. I found mine for $0.25 at a lawn sale (where else!), and so long as you keep it clean it'll function well. It's good from 0 to about 66 mph and does not need batteries.

That being said, I know when I hike how cold I am, which is all I really care about. Yes, I check the weather before heading out and bring the appropriate clothing. Just remember, you can always dress down, but if you don't have it, you can't dress up. When it's below 0°F (not just below freezing), I take extra precautions and hike slower so as not to build up any sweat. Water becomes more of an issue as the nalgene will freeze on your hip, even when insulated, and camping at sub-zero temperatures presents a whole host of new issues from camping above 0°.