Current Theme: Waterworks
	Snowpack report - Niwot Ridge - April, 2003 Mark Losleben - CU INSTAAR Research Staff

The following snowpack conditions on Niwot Ridge have been reported by Mark Losleben for April, 2003. Select here for more information about these snowpack reports

Spring Greetings!

Niwot Ridge and the South Platte basin continue to do well this month, meaning they are still above average. On April 28, 2003, the snowpack at C1 held 14.375 inches of water, or 108% of average, in almost 40 inches of snow. This is very good compared to last year when those numbers were zero! The pack is melting and consolidating now that spring temperatures have arrived, and this is reflected by increasing snowpack densification. Today the density is 36% compared with last months' 27%.

The SnoTel record shows C1 to have 13.9" for 113% of average snow water equivalent (SWE), and the precipitation is 21.5" to date for 100% of average. (Another sign of spring is a larger difference between the Snotel and hand measurements, as the snowpack tends to "bridge" the snowpillow sensors, resulting in lower SWE values).

The South Platte basin continues to lead the state of Colorado with the highest snowpack, by percent, this month, with 113%. The cummulative winter precipitation (ppt) is 111%, so the SWE:precip ratio is about normal. This is also the case for most of the basins in the state that have near average snowpack, which are all of them except those in the southwest (Rio Grande, and San Juan, San Miguel, Dolores, Animas), and the Gunnison. The San Juan basin group has the lowest snowpack of 60% (ppt is 77%) of average, with the Rio Grande at 67% SWE and 86% ppt, and the Gunnison at 75% SWE and 86% ppt. The rest of the state is near average.

In the western US, Alaska and Arizona have very low snowpacks, but the winter precipitation to date is well above average in AK, but slightly below in AZ. Oregon and Utah continue to have half to three quarters of average SWE with slightly higher values of precipitation, and with SWE:PPT ratios still less than one (less than normal amount of water is sequestered in the snowpack than would be expected for the amount of precipitaiton that has fallen this winter). In addition to Colorado, California and Nevada are doing well right now, with average or above SWE and ratios greater than one. Idaho, Montana, and New Mexico are a mixed bag with some basins above and others well below average, and ratios less than one.

So, overall, the western snowpack is less than average, but Colorado is doing well, except in the southwest area and the Gunnison. The S. Platte seems to have benefitted from last months large snowfall by turning the corner from last years dry feedback to what is beginning to appear as a wet feedback mode this year (read as near normal spring and summer precipitation).

So, thus far, this year is a great improvement over last, in that we actually have a streamflow runoff, and a later start to the fire season, but not enough snow to end the drought conditions.

Although the snowpack is diminishing now, I will issue a last report about mid-May.

The full hand-measured record follows.

                     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

     Average   5.554    7.967    10.389   13.197    13.409