Saturday, March 19, 2016

Brooks Range Wind Chill

Extreme wind chills are showing up today in the Brooks Range, as a 1052mb anticyclone north of Alaska has created a very strong pressure gradient that is transporting cold air south across the northern and western parts of the state.  Anaktuvuk Pass (2100' elevation) has been hovering at or below -20°F with sustained winds close to 30mph, resulting in wind chill in the -50's.  Of course the notorious Howard Pass RAWS (2062'), 130 miles to the west, is faring much worse, with sustained winds reported as high as 83mph this morning combined with a temperature of -29°F, leading to a wind chill of -80°F.



We've discussed the extreme environment of Howard Pass many times before on this blog (just enter "Howard Pass" in the search box).  Today's highest reported wind gust of 88mph is not even the highest reported this winter: 93mph winds were measured on January 16.  However, today's wind chill of -80°F appears to be the lowest of the winter so far; -70°F was recorded on January 19 and -76°F on December 4.  [Correction March 21: the hourly data from December 4 show a wind chill of -82°F.]  It's nice that the anemometer has survived the extreme conditions (so far) this season - it was destroyed in the past two winters.

The chart below gives a sense of how frequently these extreme conditions are observed at Howard Pass; I've calculated a daily wind chill value based on the mean daily wind speed and mean daily temperature.  Daily minimum wind chill values would often be lower, because temperature tends to decrease as wind speed increases in these northerly wind events at Howard Pass (indeed that is why the wind chill gets so low).  The chart shows that wind chill values of -60°F are hardly unusual at Howard Pass, even in a very mild winter such as this one.  If the NPS keeps maintaining the station, it's only a matter of time before the U.S. national wind chill record is broken again.


10 comments:

  1. Interesting...I was just looking at the Howard Pass WX...-29F/Gust 88 seems the lowest chill.

    The anemometer discussion a year ago focused on whether or not the unit's design led to head separation under extreme upward load (the rotation base was left on the mast; the spinner had departed). The company offered a better fastening mechanism so perhaps they decided to upgrade. Good to see it still whirling away.

    Gary

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    1. The anemometer reported a gust of 106 last eve @ -26F. Bet there's not much snow left and rocks are rolling uphill! See the link above for Brian's pics of the site.

      Gary

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    2. I was going to point that out myself, Gary - thanks. Assuming the measurements are accurate, the conditions are mind-boggling. It does appear the NPS went for a more industrial-strength anemometer this time around.

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    3. This is the unit Ken Hill and I discussed back in 12/14. Not sure what they ended up installing. Unlike the original Model 5103 it employs ceramic bearings and four retaining screws to prevent vertical separation of the components. The original unit used a plastic catch perhaps subject to deformation and loss of fastening.

      http://www.youngusa.com/products/7/68.html

      Gary

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  2. Yes - that's the sensor we switched to at Howard Pass (and Kaluich). They seem to be working well this year!
    http://www.campbellsci.com/p05103-45-alpine-wind

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    1. Hi Ken...many thanks to you folks and the NPS for supporting this important project. I hope the setup endures as that location is quite unique.

      How early man survived in that Howard Pass, Feniak, and Desperation Lake zone of the Noatak is amazing. Maybe the wind is generally less to the west of Howard Pass.

      Gary

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  3. Hey Richard,
    I was hoping you could help me find some weather information at the time and pace this video was taken. It was around the same time the storm you spoke of moved in. My GPS messenger checked in with the following information:

    Latitude:66.11875
    Longitude:-150.16632
    GPS location Date/Time:03/20/2016 01:48:50 AKDT

    I was experiencing some high winds and snow in this spot, but was unable to find weather data from surrounding stations that could support my observations.

    Any information you could provide would be appreciated.

    Thank you.

    See link below.

    https://www.youtube.com/watch?v=WRgPVvA21pw

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  4. This video is from earlier in the day near the gps messenger check-in listed below. Wind speeds were significant there as well.

    https://www.youtube.com/watch?v=cQB3WU5EwR0

    Latitude:66.25790
    Longitude:-150.32816
    GPS location Date/Time:03/19/2016 18:15:40 AKDT

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    1. Kyle, thanks for posting the impressive videos. Glad you made it out OK.

      The closest weather station to your location was the Seven Mile RAWS, located very close to Five Mile airport just above the Yukon River. You were about 15 miles up the road in the nighttime video.

      You can view the Seven Mile RAWS data here:

      http://www.raws.dri.edu/cgi-bin/rawMAIN.pl?akASEV

      At the RAWS site winds were sustained at 25mph, gusting 45mph, in the late evening. It looks like the site is sheltered from northeasterly winds, however, so it's no surprise that winds were higher in more exposed areas.

      Unfortunately that's all I can point to in terms of "official" weather data. The observing network is pretty sparse compared to the vast expanse of Alaska's wilderness.

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    ReplyDelete