Friday, March 29, 2013

The Big Diurnal

Courtesy of NWS Alaska Region
So you probably have read of the big temperature swing on Thursday at Fairbanks, with a low of 24 below and a high of 31 above, for a daily temperature range of 55 degrees, the largest calendar day  temperature range in the Weather Bureau/NWS era (since Dec 1929). Slightly larger ranges were observed at other locations in the area, including 57ºF at Eielson and North Pole and 59ºF at Goldstream Creek and Woodsmoke. Meanwhile, 25 degree range here at Keystone Ridge.

On the NWS Facebook page, there are, unsurprisingly. claims of 110 and 120ºF one day temperature ranges. Considering that the US record is evidently 103 degrees at Loma Montana, that would be something. My response is: what day? My guess is that people are either telescoping changes that occurred over a few days or a simply exaggerating, which, believe or not, does happen with weather. 

So what is the Alaska record for one day temperature change? That's a good question. I'm sure it's over 70 degrees, and will update when I find some examples. If you know of any documented 70+ degrees ranges in one day, let us know.

4 comments:

  1. Brian BrettschneiderMarch 29, 2013 at 8:34 PM

    For Anchorage, the highest diurnal range on record is 52 degrees. Interestingly, it has happened three times – on consecutive days no less. March 17, 18, and 19, 1922. The temperatures were: (38,-14), (40,-12), and (42,-10) respectively.

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    1. Thanks Brian. There are a couple of days in the pre WB/NWS era at Fairbanks with greater than 60 degree range, but the data is, to my mind, suspect.

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  2. Rick,

    This is a fun question. Here's one that seems quite likely to be real, though I'll be interested to hear your opinion: Glenallen on Jan 23, 1999. The max/min reports from GHCN data are as follows beginning on Jan 21: -31/-53, -35/-53, 29/-47, 30/13, 21/-6. So on the 23rd the reported range was 76 F.

    On the same day and not too far away, Slana reported a range of 75 F (33/-42) so this adds credibility.

    Richard

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    1. Thanks Richard. Here's the hourly data from Gulkana for Jan 23-24, 1999 (note this is pre-ASOS, no obs 0630-1459 UTC):

      PAGK 23/1748 1005.3 29.54 28 21 74 170 23 32 20.0 SCT045 BKN070 25 28
      PAGK 23/1650 1006.2 29.56 28 19 69 170 25 34 7.0 FEW035 BKN055
      PAGK 23/1550 1007.1 29.58 27 18 68 160 19 30 7.0 FEW041 SCT100
      PAGK 23/1459 1008.4 29.60 27 16 63 160 23 31 7.0 FEW044 SCT100
      PAGK 23/0630 1022.1 29.93 3 -4 71 170 12 7.0 OVC140
      PAGK 23/0550 1024.3 29.97 -9 -15 76 170 9 7.0 OVC140 -24 -8
      PAGK 23/0448 1026.8 30.02 -18 -24 75 0 0 7.0 OVC140
      PAGK 23/0350 1029.2 30.09 -20 -27 68 3 7.0 OVC140
      PAGK 23/0248 1031.2 30.14 -24 -29 75 0 0 7.0 FEW070 OVC140
      PAGK 23/0147 30.18 -24 -29 75 0 0 30.0 FEW070 OVC140
      PAGK 23/0048 1033.7 30.22 -22 -29 68 0 0 40.0 SCT100 OVC140
      PAGK 22/2350 1035.6 30.27 -24 -29 75 0 0 40.0 SCT100 OVC140 -43 -24
      PAGK 22/2250 1036.5 30.29 -26 -31 75 0 0 60.0 SCT100 OVC140
      PAGK 22/2150 1038.1 30.33 -29 -35 74 0 0 60.0 SCT100 OVC140
      PAGK 22/2050 1039.1 30.36 -29 0 0 60.0 FEW130 OVC160
      PAGK 22/1950 1039.6 30.37 -33 0 0 60.0 BKN160 OVC200
      PAGK 22/1850 1039.9 30.37 -35 0 0 60.0 FEW150 OVC200
      PAGK 22/1750 1040.6 30.38 -44 0 0 60.0 FEW150 FEW200 -43 -39
      PAGK 22/1654 1040.8 30.39 -42 0 0 7.0 FEW180

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