Niwot Ridge LTER Snow Report for February 2006
February 28, 2006 Snowpack Report, Niwot (C1), Front Range, Colorado

The spatial pattern of snowpack, above average in the north and below in the south, continues for both for Colorado and the western US. However, warming at the end of this month has had an effect in many areas.

On 28 February 2006, the snowpack at C1 contained 9.5 inches of water (SWE), and was 32.75” deep. This is 93% of average, and exactly the same SWE as at this time last year. This is also about the same depth as at the end of January, however there is more water because the density is greater. The increase in density will continue from now until meltout.

February was an interesting month. Late on the 15th, C1 received 2 ˝” of fresh snow, but the bottom half was red! Dust from the Four Corners area may be the source of this unusual occurrence. Analysis of both the snow chemistry and the atmospheric trajectory of this event are underway by a number of researchers. Following this ‘red snow’ event was some of the coldest temperatures of the season for the Front Range. (It reached -22 F at my house at 8:30 PM on the 17th.) At this time, it seemed like the well-above average snowpack conditions would last for a long time. However, temperatures rose this past week, and snowpack began to suffer.

The Snotel network reports 9.8” SWE at Niwot (C1) for 100% of average, and 12.6” of precipitation, or 116% of average, for the same period. The South Platte basin is showing 107% SWE and 113% cumulative precipitation. Colorado as a whole shows 90% SWE and 97% cumulative precipitation. The highest snowpack in the state is still in the Yampa/White basin at 115% SWE and 118% precipitation, and the lowest is again in the Upper Rio Grande (43% and 63%, respectively). All these percentages reflect decreases in the last month, and a Snowpack Index (SI) of less than one.

The pattern of deepest snowpacks in the northern half of the western US continues, (this is also the pattern for Colorado), however Washington now has top honors with 120% SWE and 105% precipitation. This is the only state with a SI of greater than one, also consistent with the Columbia River basin being the only major western US river basin to also have a SI>1.

The lowest snowpacks are again in the southwest. Arizona shows 6% SWE and 23 % precipitation, which may be why so much red dust was available to cause ‘red’ snow across Colorado and into the Front Range on the 15th.

The basin with the highest snowpack of the major western US river basins is the Columbia (114% SWE and 112% precipitation). The lowest is in the Rio Grande (31% SWE and 51% precipitation), but the lower Colorado has only 11% SWE and 29% precipitation.

So, signs of spring are beginning to show in the snowpacks already. It will be interesting to see if meltout is continuous, or if March, April, and/or May provide some reversals. Such reversals are most possible in states with continental climates, rather than those nearer the Pacific coast.

Cheers!

Mark

Sno Tel Data  Niwot Ridge, C-1
Snow Water Content (inches)
Values are for the end of given month
except as noted for May and June

    Season     Dec      Jan      Feb      Mar      Apr     May            Jun 
      81/82    4.75     10.5     11.75    15.5     14.9    12.0   (17th)
      82/83    3.63              4.75     12.75     17     11.75  (30th)
      83/84    12.6     13.25     15      18.9     20.75   
      84/85    3.75     6.25      8.5     10.25    8.75
      85/86     6.5      7.5      14      15.38    17.5
      86/87    6.25     8.75     11.25    12.75    11.75
      87/88     6.5      9.1     12.4     15.75    14.5
      88/89     5.5      7.6      11      10.25     5.6
      89/90     6.5     9.25     10.75    16.1     16.5
      90/91      3        5       7.1     9.38      10
      91/92    6.65     6.75      8.5     12.25    10.25
      92/93    5.75     6.75     10.75     14      15.875
      93/94    7.125    9.063    12.25    13.25    13.25     2.5  (18th)
      94/95    2.625    3.925     7.0     10.125   16.75    17.0  (22nd) 12.375(13th) 19.75(30th)
      95/96    7.50     12.00    17.5     20.375   18.75     6.125 (15th)
      96/97    8.75     12.625   15.125   14.625   20.375   18.0   (15th)
      97/98    7.0625   10.0     10.125   12.875   17.25    12.875 (15th)
      98/99    3.25     6.625     8.375    9.125   14.125   14.25  (15th)
      99/2000  3.5      7.5      10.625   12.375    7.625   
      00/2001  4.375    5.375     7.125   10.00     9.125
      01/2002  2.625    4.25      6.19     7.563    0.0
      02/2003  4.00     5.25      8.5     16.75    14.375   11.44 (15th)
      03/2004  2.75     4.813     7.75     7.875   10.125    3.69 (14th)
      04/2005  4.875    7.7       9.5     11.625   12.875   12.25 (15th)
      05/2006  5.625    8.375     9.5

     Average   5.418    7.842    10.212   12.908   13.25