Click to Enlarge
Tony Bergantino
Assistant State Climatologist, Wyoming
Butte, Montana, 29 December 2001 - The week after Christmas in Butte, a light snow fell continuously the day of the 28th of December, and into the early morning of the 29th. According to the measurements at the airport (outfitted with ASOS in 2000), I had the dubious honor of helping to shovel several 'traces of snow.' I had arrived in Butte the previous Friday, the 21st, in a minor snowfall. After this snowfall, the total precipitation for December was .08" This morning, with a new thick blanket of snow, the total still stands at .08" Not one to believe that 3.25" of snow, even at a 20:1 Snow Water Ratio, could produce only a trace, I made my own measurements, measuring the depth of the snowfall in several locations, and collecting relative samples.
The snow, when melted, gave a hefty 0.23" water equivalent, roughly a 14:1 ratio. Yet, incredibly, the airport reports a trace. If one looks at the plots from the NWS (See Graphic Below) he will see that there are 22 hourly recordings of a 'trace' starting at 0400 on the 28th and ending at 0300 on the 29th.
Click to Enlarge
 22 Dec 2001 |
 28 Dec 2001 (0900) |
 29 Dec 2001 (1100) |
| Click Images to Enlarge | ||
Where lies the difference? Did the airport recieve less snowfall? No, the snowfall reported there was roughly the same as I measured manually. The problem is that the 24-hour total (if even reported, See Metar Table Below) and the 3- and 6-hour must be calculated by adding the hourly obs, not by actual collection. Six traces is still a trace, and apparently 24 traces still are also just a trace. Yet, if each of those traces were even .001" a daily total of .02"+ should result.
 22 Dec 2001 |
 29 Dec 2001 (1300) |
| Click Images to Enlarge | |
No wonder Butte is approximately 83% of normal for annual precipitation. How are we as climatologists supposed to do our job when our data is only as good as this? Has it been drier lately? Quite probably, but not to the extent that numbers such as this would lead us to believe. How can a longterm climate record be established when the data are this inaccurate and included with values taken previously by other instruments?
Is the Historical Climate Network necessary? Absolutely, but with the strong caveat of attention to the measurements that come from it. In addition, the individuals running the stations have to be trained and responsible. Not individuals who simply accept and report any number that comes from the instrument array. In the case of the missing .23" in Butte, all that would have been necessary to catch the misreport would be common sense. Afterall, a greater-than 360:1 snow to water ratio should raise even the most heavy of eyebrows.
3-hr
6hr 6hr 24h 24h 1-hr 6-hr 24hr
tmp dew rh wind wnd barom uncor vis max min max min pcpn pcpn pcpn alt
date/time F F % mph chl in press mi weather clouds F F F F in in in settg
-------------- --- --- --- -------- --- ----- ------ ----- ---------- -------------------- --- --- --- --- ---- ---- ---- -----
29 10:53am MST 21 18 88 CALM 30.23 24.517 10.00 OVC044 22 14 30.06
29 09:53am MST 20 17 88 CALM 30.22 24.509 10.00 OVC044 30.05
29 08:53am MST 19 16 88 CALM 30.22 24.492 10.00 OVC046 30.03
29 07:53am MST 18 15 88 CALM 30.19 24.475 10.00 OVC050 30.01
29 06:53am MST 18 15 88 CALM 30.18 24.466 10.00 OVC050 30.00
29 05:53am MST 16 15 96 S 5 30.18 24.458 5.00 BR OVC050 29.99
29 04:53am MST 14 12 92 CALM 30.18 24.466 10.00 OVC055 21 10 T 30.00
29 03:53am MST 11 9 92 CALM 30.20 24.475 10.00 OVC055 30.01
29 02:53am MST 15 14 95 CALM 30.19 24.475 6.00 BR OVC060 T 30.01
29 01:53am MST 19 17 92 CALM 30.16 24.466 4.00 -SN BR SCT023 BKN034 OVC060 T T 30.00
29 01:33am MST 19 18 93 S 3 24.458 3.00 -SN BR FEW019 OVC038 T 29.99
29 12:53am MST 20 18 92 CALM 30.15 24.458 2.50 -SN BR FEW019 OVC032 T 29.99
29 12:27am MST 19 18 93 CALM 24.458 1.50 -SN BR SCT009 BKN023 OVC031 T 29.99
29 12:11am MST 19 18 93 CALM 24.458 1.25 -SN BR BKN009 OVC023 T 29.99
28 11:53pm MST 21 19 92 CALM 30.14 24.458 1.50 -SN BR BKN013 BKN040 OVC050 24 10 T 29.99
28 10:53pm MST 20 18 92 CALM 30.14 24.441 8.00 BKN055 OVC080 23 19 T T 29.97
28 09:53pm MST 20 18 92 CALM 30.14 24.441 7.00 BKN060 OVC080 T 29.97
28 09:30pm MST 19 18 93 SE 3 24.441 5.00 -SN BR BKN049 BKN060 OVC080 T 29.97
28 09:22pm MST 19 18 93 S 3 24.449 2.50 -SN BR BKN045 OVC060 T 29.98
28 08:53pm MST 19 17 92 CALM 30.16 24.449 5.00 -SN BR BKN034 BKN049 OVC070 T 29.98
28 08:36pm MST 19 18 93 CALM 24.449 1.50 -SN BR BKN019 OVC036 T 29.98
28 08:26pm MST 19 18 93 CALM 24.449 2.50 -SN BR BKN018 BKN034 OVC055 T 29.98
28 07:53pm MST 20 17 88 S 7 30.16 24.449 4.00 -SN BR FEW036 SCT060 OVC075 T T 29.98
28 06:53pm MST 20 18 92 CALM 30.17 24.458 3.00 -SN BR FEW008 BKN046 OVC060 T 29.99
28 06:39pm MST 21 18 86 CALM 24.458 5.00 -SN BR FEW008 OVC038 T 29.99
28 05:53pm MST 20 18 92 CALM 30.16 24.449 5.00 BR OVC040 T 29.98
28 05:17pm MST 21 19 93 CALM 24.449 4.00 -SN BR FEW032 OVC050 T 29.98
28 04:53pm MST 23 21 92 CALM 30.15 24.449 2.50 -SN BR BKN034 OVC048 24 20 T T 29.98
28 04:42pm MST 23 19 86 CALM 24.449 2.50 -SN BR OVC037 T 29.98
28 03:53pm MST 24 20 84 CALM 30.14 24.449 10.00 BKN036 OVC046 29.98
28 02:53pm MST 23 20 88 CALM 30.15 24.441 10.00 OVC038 T 29.97
28 01:53pm MST 23 19 85 CALM 30.15 24.432 5.00 BR SCT022 BKN042 BKN090 T T 29.96
28 12:53pm MST 24 19 81 N 3 30.16 24.441 3.00 -SN FEW023 BKN028 OVC037 T 29.97
28 12:39pm MST 23 19 86 CALM 24.441 2.50 -SN BR BKN030 OVC040 T 29.97
28 12:27pm MST 23 19 86 CALM 24.441 2.00 -SN BR BKN028 OVC035 T 29.97
28 12:04pm MST 21 19 93 CALM 24.449 1.00 -SN BR VV019 T 29.98
28 11:56am MST 21 19 93 CALM 24.449 0.75 -SN BR VV014 T 29.98
28 11:53am MST 22 19 88 CALM 30.19 24.449 1.00 -SN BR VV015 T 29.98
28 11:33am MST 21 18 86 CALM 24.449 1.75 -SN BR OVC019 T 29.98
28 11:19am MST 21 18 86 CALM 24.449 2.50 -SN BR OVC025 T 29.98
28 11:11am MST 21 18 86 CALM 24.449 3.00 -SN BR BKN027 BKN035 OVC050 T 29.98
28 11:01am MST 19 18 93 CALM 24.449 4.00 BR OVC034 T 29.98
28 10:53am MST 21 18 88 CALM 30.21 24.449 2.50 -SN BR BKN034 OVC050 21 16 T T 29.98
28 10:46am MST 21 18 86 CALM 24.449 2.00 -SN BR BKN033 OVC050 T 29.98
28 10:07am MST 19 18 93 N 3 24.432 1.00 -SN BR SCT013 BKN023 OVC029 T 29.96
28 10:00am MST 19 18 93 NE 5 24.432 0.75 -SN BR BKN011 BKN023 OVC029 T 29.96
28 09:53am MST 19 17 92 N 5 30.19 24.424 0.75 -SN BR BKN009 BKN023 OVC029 T 29.95
28 09:33am MST 19 18 93 N 6 24.416 0.75 -SN BR BKN007 OVC023 T 29.94
28 09:25am MST 19 18 93 N 3 24.416 0.75 -SN BR FEW001 BKN005 OVC020 T 29.94
28 08:53am MST 19 17 92 CALM 30.14 24.399 0.50 SN FZFG BKN003 BKN007 OVC026 T 29.92
28 08:29am MST 18 18 100 CALM 24.382 0.50 SN FZFG BKN009 OVC026 T 29.90
28 07:53am MST 18 16 92 CALM 30.11 24.373 1.25 -SN BR BKN009 OVC020 T T 29.89
28 07:43am MST 18 16 93 CALM 24.365 1.50 -SN BR SCT009 OVC020 T 29.88
28 07:39am MST 18 16 93 CALM 24.365 2.00 -SN BR FEW011 OVC020 T 29.88
28 06:53am MST 17 15 92 CALM 30.09 24.348 1.25 -SN BR FEW006 SCT015 OVC022 T 29.86
28 06:42am MST 18 16 93 CALM 24.339 1.00 -SN BR SCT004 BKN015 OVC022 T 29.85
28 06:12am MST 18 16 93 CALM 24.322 0.50 SN FZFG VV004 T 29.83
28 05:53am MST 17 15 92 SE 3 30.04 24.322 0.75 -SN BR VV006 T 29.83
28 05:42am MST 18 14 86 S 3 24.314 0.75 -SN BR VV006 T 29.82
28 05:16am MST 18 14 86 CALM 24.314 1.00 -SN BR VV008 T 29.82
28 05:01am MST 18 12 79 CALM 24.314 1.50 -SN BR OVC012 T 29.82
28 04:53am MST 17 13 83 CALM 29.99 24.314 1.50 -SN BR BKN016 OVC032 17 4 T T 29.82
28 04:44am MST 18 12 79 CALM 24.305 1.75 -SN BR BKN018 BKN032 OVC044 T 29.81
28 04:38am MST 18 12 79 SE 3 24.305 2.00 -SN SCT020 BKN032 OVC044 T 29.81
28 03:53am MST 17 10 73 SE 5 29.98 24.314 10.00 OVC042 29.82
28 02:53am MST 14 8 77 SE 3 29.99 24.322 10.00 BKN042 OVC085 29.83
28 02:15am MST 14 9 79 CALM 24.322 10.00 BKN030 BKN036 OVC085 29.83
28 02:05am MST 12 9 85 E 5 24.322 10.00 BKN028 BKN060 OVC090 29.83
28 01:53am MST 12 7 80 SW 3 30.02 24.331 10.00 FEW028 OVC090 29.84
28 12:53am MST 11 6 80 CALM 30.03 24.322 10.00 SCT055 BKN075 OVC090 29.83
27 11:53pm MST 10 5 80 CALM 30.08 24.348 10.00 OVC070 26 -8 29.86
27 10:53pm MST 4 -1 80 E 5 30.16 24.365 10.00 BKN070 20 2 29.88
27 09:53pm MST 4 0 83 CALM 30.19 24.365 10.00 CLR 29.88
27 08:53pm MST 7 2 79 CALM 30.21 24.373 10.00 CLR 29.89
27 07:53pm MST 7 2 79 CALM 30.24 24.382 10.00 CLR 29.90
27 06:53pm MST 6 1 79 SE 6 30.24 24.399 10.00 CLR 29.92
27 05:53pm MST 10 3 73 S 5 30.24 24.407 10.00 CLR 29.93
27 04:53pm MST 20 7 57 SE 3 30.20 24.416 10.00 CLR 26 9 29.94
27 03:53pm MST 23 8 52 S 3 30.22 24.441 10.00 CLR 29.97
27 02:53pm MST 26 7 44 CALM 30.22 24.458 10.00 CLR 29.99
27 01:53pm MST 24 7 47 CALM 30.24 24.466 10.00 CLR 30.00
27 12:53pm MST 20 6 54 CALM 30.29 24.483 10.00 CLR 30.02
27 11:53am MST 15 5 64 CALM 30.34 24.517 10.00 CLR 30.06
The Wyoming State Climatologist Office is funded by the
Wyoming Water Development Commission
WEBMASTER: stateclim@wrds.uwyo.edu
Last reviewed or update: 29 December, 2001