Current Theme: Waterworks
	Snowpack report - Niwot Ridge - March, 2005 Mark Losleben - CU INSTAAR Research Staff

The following snowpack conditions on Niwot Ridge have been reported by Mark Losleben for March 2005. Select here for more information about these snowpack reports

Greetings!

Tomorrow is April 1, the traditional 'state of the snowpack' date for the western US. As such, conditions right now carry extra importance, because these are the values water managers and planners tend to rely upon more than at any other time of the year.

The general snowpack pattern begun at the start of this season has pretty much remained constant this season at all spatial scales; Niwot (C1), the Front Range, the state of Colorado, and the western US.

Today, March 31, 2005, the hand measurement at C1 (special thanks to Kurt Chowanski for making this possible today!) shows 11.625" of water in the 40" snowpack at C1. This is 90% of the manual record average and close to the earlier season values (90%, 98%, 92% at the end of December, January, and February, respectively). In comparison, there was almost 5" less water in last years snowpack at this time.

According to the Snotel NRCS database, Niwot has 12.4" SWE (89% of average), and the cumulative winter precipitation is 14.3" (99% of average) at C1. As in past months, this shows the Snowpack Index to be a bit less than one, meaning a little less than usual of the precipitation is stored in the form of snow for later spring and summer water availability.

Our South Platte basin snowpack is 85% of average (83% for winter precipitation) which just barely puts it in last place of the states basins. The Laramie/N. Platte and Yampa/White basins are essentially the same, with 86% and 87% of average, respectively. Given the steady pattern this year, it is unlikely that the S. Platte reaches average conditions by the time of historical peak in latter April, because it would need to receive 262% of average snowfall to do so. The highest snowpack honors again go to the southern basins, San Miguel/San Juan/ Dolores/Animas is147% of average (133% winter precipitation), and the Upper Rio Grande and Gunnison close have 142% and 137%, respectively. The Snowpack Index (SI) is greater than one in all of these basins. Colorado as a whole is 110% of average snowpack and an SI>1 (winter precipitation is 102%)

Snowpack in the western US retain the season pattern as well. Washington and Oregon suffer with 31% and 37% of average (67% and 61% winter precipitation), and areas below 40 degrees north latitude continue to be above average, with some locations at historical highs (SW Utah). Arizona, New Mexico, the Great Basin sites in California, and Utah are at 161%, 142%, 139%, 137%, respectively, and all have SI's greater than, one (Utah SI=1).

The downstream storage on the Colorado River should benefit somewhat from this seasons snowpack as the basin is at 120% of average (SI=1). The Columbia River basin, however is at 49% of average.

So, this season may prove that there is more than El Nino or La Nina controlling the western US snowfall. The ENSO index has never been strongly off neutral, but this is a very strong El Nino winter precipitation signal. This may provide a valuable data point for the climate community to evaluate for controls on western US winter weather!

Until next month, Mark Losleben

                      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

     Average   5.409    7.819    10.242   12.908   13.266