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Snowpack report - Niwot Ridge - May, 2003
Mark Losleben - CU INSTAAR Research Staff

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

Spring Greetings!

The signs of spring are clear and unmistakable at C1, Niwot Ridge, now. The snowpack is dense, the storms are often quick and intense, the ground is bare one day, covered with a foot of snow the next and bare again two days later, and the hummingbirds returned (May 12th at C1).

The snowpack at C1 on 15 May 2003 contained 11.44 inches of snow water equivalent (SWE), was 30 inches deep, and had an average density of about 38%. (In contrast with winter densities more in the range of 20-25%). This May 15th ranks as one of the top 5 or 6 years in the past 20 by my hand measurements. (Many years there is no snow at C1 on this date - see record at the end of this message).

The snowpack was bolstered by an event on May 9-10 which was characterised by a nice low to our south and high to the north at 850 mb, resulting in a strong upslope circulation that dropped 1.62" SWE at C1. This raised the snowpack from about 110% to 142%. This illustrates another sign of spring, the rapidly changing snowpack numbers, pointing to cautious interpretation of the percentages at this time of year (just like in the fall when relatively small changes in absolute change yield large precentage changes). For example, on May 12th, C1 SWE was 12.6" and on May 15th it was 11.0" (138% of average), according to Snotel.

For the statewide perspective, the NRCS Snotel reports the South Platte basin with 124% of average SWE and 108% of average winter cummulative precipitation (PPT), which is tops in the state. The Upper Colorado is close with 122% and 103% (SWE and PPT, respectively).

The lowest basins continue to be in southwestern Colorado, the Upper Rio Grande (42% SWE and 82% PPT), and the San Juan, Animas, Dolores, San Miguel group (46% SWE and 76% PPT). This has been the case all season, and as Martin Hoerling pointed out, may be particularly worrisome for this region because there was hope forit to recieve much more moisture this season, given the El Nino conditions. With the suggestion of the return of La Nina next winter, there is much less cause for optimism that this area will catch up on their moisture deficit anytime soon.

The Laramie/N. Platte, and Yampa/White basins are healthy with above 100% snowpacks and SWE/PPT ratios greater than 1 (more of the winter precipitation is sequestered in the snowpack than average), but the Arkansas and Gunnison basin SWE's are less than average (89% and 73%, respectively) and their SWE/PPT ratios are less than one (less of their winter water has remained in the snowpack).

In the western US, storms in the past few weeks have bolstered the percentages, in general (but as noted above, at this time of year, they should not be taken too seriously). Only Alaska, Utah, NM, and Arizona snowpacks missed out. Snowpack in these states continue to be less to much less than average and with SWE/PPT ratios of less than one. Idaho, Montana, California, and Nevada have snowpacks greater than 100% and ratios greater than one. Oregon snowpack is mixed ranging from 0 to 132%, but ratios generally less than one. Wyoming is also a bit mixed, but generally average, and ratios greater than one.

So, this 2002-2003 winter snowpack season has turned out to be pretty good overall, especially for Colorado to fill reservoirs that supply much of its population centers (with the exception of the SW region). However, it in no way has ended the drought much of the west is suffering though. A few more wet winters are most likely needed before the drought could be declared over. There is hope for a shorter and possibly less explosive fire season this summer, though.

The hand mesurement records at C1 follow, and there will be one more mailing this season reporting meltout date at C1.

Cheers! Mark

                      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)

     Average   5.554    7.967    10.389   13.197    13.409

Contact Mark Losleben with comments or questions
Snowpack report for April, 2003
Snowpack report for June, 2003
General information about Niwot Ridge (C1) Snowpack reports

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