Can you really get Frostbite within 30 minutes at -35 'C
Just got this Weather advisory, and it appears over-dramatic, so would like some feedback if it's actually possible to get frostbite within 30 minutes if it's only around -30-35 Celsius (that's not really that cold, just 5-10 degrees less than normal temperature).
WIND CHILL ADVISORY REMAINS IN EFFECT UNTIL NOON MST TUESDAY... * WHAT... VERY COLD WIND CHILLS EXPECTED. THE COLD WIND CHILLS WILL CAUSE FROSTBITE IN AS LITTLE AS 30 MINUTES TO EXPOSED SKIN. EXPECT WIND CHILLS TO RANGE FROM 20 BELOW ZERO TO 30 BELOW ZERO. * WHERE... PORTIONS OF CENTRAL AND NORTH CENTRAL MONTANA. * WHEN... UNTIL NOON MST TUESDAY. * ADDITIONAL DETAILS... THE COLDEST WIND CHILLS ARE EXPECTED LATE THIS EVENING THROUGH MID-MORNING TUESDAY. PRECAUTIONARY/PREPAREDNESS ACTIONS... A WIND CHILL ADVISORY MEANS THAT COLD AIR AND THE WIND WILL COMBINE TO CREATE LOW WIND CHILLS. FROST BITE AND HYPOTHERMIA CAN OCCUR IF PRECAUTIONS ARE NOT TAKEN. MAKE SURE YOU WEAR A HAT AND GLOVES
- I find it simply hard to believe that if I never got frostbite at -25 Celsius, that 5-10 degrees more would be enough to cause it
- Is -25 some kind of biological threshold or something ?
- For longer walks(>1 hour), I usually start using gloves&hat below -12-15 and a lambskin fur coat (below -18 C), though front half of face is obviously uncovered. But that's the part of body which is 'trained' for cold the most, no ?
- Doesn't the face's frostbite threshold move further, because that part of skin is frequently exposed to cold ? Or it doesn't really work that way ?
- Perhaps there's a difference between "1. Real -35 C" and "2. Windchill -35 C" that's making this confusing?
- Not sure if important to this, but there's a larger river right next to our village (hence the "lake effect")
Around 3am tonight (at least according to weather.com interpolations) the windchill should be around -30 F, which is about -35 C. I'm gonna stay up and walk my Husky (who, btw, isn't really bothered by these temperatures) then to see for myself.
I would appreciate your input to either of the questions, thanks!
EDIT1: It's 3.30 am, but the -30F is now moved to 9am, so no luck...
EDIT2:
These are my [non-scientific] observational findings/opinions from the experiment of spending 45 minutes at -33 C (-27 F) Windchill at 9.30am yesterday:
- The thermal face-slap when walking out of building was strong, but definitely far from the worst ones in past (like that blizzard), which to me confirms you also really need a proper base air temperature (air was only -15F (-26 C) after all). It did provide a proper "lung bite" though as breathing was a notch more painful
- My current gloves/hat combo cost $15 at a local HW store, so it should be obvious how well it [does not] protect against cold compared to the pro gear
- The gloves are, however, very good at gauging the temperature, as the time when my hands get cold inside is , empirically, linear to the temperature
- At -33 C, my hands got really cold inside under 5 minutes
- After 15 minutes I did a bit of exposure - 12 minutes of no gloves and taking picture of the very interesting [NatGeo-worthy] river fog phenomenon. It was pretty painful the whole time
- fingers got totally white within few minutes
- After 12 minutes I put on gloves and walked for another 20 minutes
- I also noticed there's a surprisingly huge difference in perceived cold between walking right on the river bank and walking, say, 10 minutes away from it, between the houses. That [very] local river humidity in the air, that beautifully frosts all the twigs and branches on the trees by the river, makes quite a strong difference at -33 C, though. Much, much stronger than under -25 C
- When I got back home after 45 minutes, it took about another 15 very painful minutes for my fingers to regain the full dexterity so I could work on computer. Right hand took slightly longer as I got carpal tunnel there (it's also much more sensitive to cold than the left hand)
- Face was alright (other than the slight pain) - I was periodically touching it with gloves to check (as per the recommendations I received here below) - like I said, I don't really care if I freeze to death, but sure as hell don't want to walk around face-disfigured (with stage-3 necro chunks of skin)
So, it turns out after all, that those 5-10 degrees more [base point being at -25 C], are indeed just that : few degrees more and not really a big deal for a short exposure. Of course, on a mountain or on a multi-day tent hike, it'd be a whole different story...
Moral of the story : Ignore the [triple-facepalm-worthy] bombastic local weather alerts filled with overly dramatic TV tone ("OMG ! SNOWMAGEDDON !") and really - just use common sense. If it's 5-10 degrees more, it really is just 5-10 degrees more, duh !!!
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- I find it simply hard to believe that if I never got frostbite at -25 Celsius, that 5-10 degrees more would be enough to cause it Is -25 some kind of biological threshold or something ?
I haven't found any reference to such a biological threshold and I highly doubt there is. Most thresholds are compromises, because in an advisory, you can't state all influencing external (weather) and personal factors. And even if you did, there still wouldn't be some precise magic boundary temperature. So take it for what it is: A warning, not a word-for-word guideline for your behaviour. In mattnz answer he gives a table that already does differentiate a lot more by giving a boundary temperature based on both wind and exposure time.
- For longer walks(>1 hour), I usually start using gloves&hat below -12-15 and a lambskin fur coat (below -18 C), though front half of face is obviously uncovered. But that's the part of body which is 'trained' for cold the most, no ?
- Doesn't the face's frostbite threshold move further, because that part of skin is frequently exposed to cold ? Or it doesn't really work that way ?
- Perhaps there's a difference between "1. Real -35 C" and "2. Windchill -35 C" that's making this confusing?
Very important: Even reversible stage 1 frost bite makes you more vulnerable for frostbite in the future [1,2]. There seems to be a training effect if you expose your skin to the cold without frostbite though [2]. So yes it is possible that your face is trained to take more cold, while if you kept your hands in gloves all the time, the might take less before getting frostbite. However nose and ears are usually the very first places to get frostbite. It is hard to detect by yourself, as feeling is impaired already before frostbite hits in and you can't inspect visibly (I don't assume you carry a mirror ;) ). Otherwise the best measure is to pinch the nose and see whether it regains colour. If it doesn't, you are at serious risk (if not already in frostbite). Get to a warm place and/or try covering it.
As a non-representational illustration of different training: I wouldn't stay below -25degC in windy conditions without covering my face at all. When skitouring I always cover my face (as in pull down hat and pull up tube scarf) if there is significant wind (and temps usually -20-0degC).
- Not sure if important to this, but there's a larger river right next to our village (hence the "lake effect")
This as well as remarks about coats conflate two different (while linked) issue: In these scenarios your main problem is hypothermia. This is a risk factor for frostbite, but you can contrive frostbite without any hypothermia at all. I think further discussion of hypothermia just distracts from the main issue of your question, especially given your very martial comments about nice ways to die ;)
[1] https://patient.info/doctor/cold-injury#nav-0
[2] https://www.researchgate.net/publication/7401208_Resistance_Index_of_Frostbite_as_a_predictor_of_cold_injury_in_Arctic_operations
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Yes. Refer https://www.almanac.com/windchill-chart-united-states
Frostbite is possible in temperatures as warm as 10F in 30 minutes, and easily within 5 minutes at the temperatures you are quoting. It is not entirely down to wind chill, clearly appropriate clothing makes all the difference, include water proofing. In the very cold temperatures, the snow is dry, but if you fell into a river or lake (and got out) at -35C I doubt you would have more than a few minutes, let alone 30, unless you were able to get dry.
Personal experience - after 4 hours in -5C of exceptionally adverse weather (60-80knot winds, sleety rain and accident requiring removing outer gloves to apply first aid as well as slowing our return to a safe camp), I was as serious risk, I have no doubt I would have lost figures had I ignored the warning signs. I have no reason to doubt the time frames in the above charts.
However, plenty of people love frolicking around in -40C and do it nearly every day in winter with no adverse outcomes. It just goes to show that frostbite (and other related issues) are a product of more than temperature alone.
Side note - Where I live, plenty of international tourists ignore our weather advisories and go home in body bags. Apply your knowledge of local conditions and common sense.
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I find that whenever I have to perform fine manipulation that require removing my gloves, in those temperatures (even up to -20 or -15), I feel my hand cool down really fast to the point of hurting within a minutes (seconds if there is wind and it is really cold).
I don't find it hard to believe that exposed skin can get bad frostbites in 30 minutes. 30 minutes is a long time.
The temperature of your face depends on how much warm blood your body sends there, which depends on how warm you are overall.
If you stay in the wind for a while, monitor the level of feeling in your nose, have someone watch for discoloration if possible, wear a facemask if you need, and remember that when it stops hurting it is already late.
Also remember that the difference between -20 and -35 is the same as between 15 (light jacket on a cool spring day) and 0 (snow, most people wear hats, gloves, and thicker jacket if out for more than 10 minutes)
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