Greetings!

As can easily be the case, April weather changed the spring snowpack 
outlook, not only at Niwot (C1), but also in the South Platte and 
Arkansas basins. Two storm events dropped 7.65 inches of snow water 
equivalent (SWE) at Niwot, giving us a new maximum of 11.6" on April 
26th. The last months maximum was 8.60" on March 16-18, which would have 
been very dismal if it had held.

Measured conditions at Niwot on April 30, 2004 show 10.125" of SWE in a 
31" deep snowpack. This is 76% of average (for the hand measurement record), 
which ranks 17th highest out of the past 23 years. This is low, but the 2002 
snowpack at this time was zero!

The Snotel automated measuring system reports 10.8" SWE, or 89% of average, 
by their records. The hand/Snotel difference commonly occurs in spring, due 
to many factors, some understood, and some not. They include effects of 
snowpack "bridge-ing" of the sensor, and rapidly changing snowpack conditions. 
However, the trend is clear; an increase over last month, and a much healthier 
spring/summer water outlook. The new maximum occurred 40 days later than the 
one in March, and places 2004 as the seventh latest maximum snowpack (16 seasons 
were earlier since 1981), with a SWE that ranks 18th (six seasons had lower SWE's). 
So, although the SWE levels are low, the benefit of later peak accumulation offsets 
this somewhat (later start to the fire season, shorter snowpack-free period in 
the summer).

Statewide, the relative rankings of basins have changed since last month as well, 
according to the NRCS Snotel network. The South Platte, which held a firm grip 
on the lowest snowpack honors is now 4th from the top (77% of average), and 
the Arkansas which was second from the bottom is now second highest (94%), 
right behind the Upper Rio Grande (which has been, and still is, the highest) 
with 95% currently. The lowest is the Yampa/White basin (54%), with the Upper 
Colorado close (58%). So, the two storms that boosted the South Platte and 
the Arkansas, did little for the basins that lag behind the S. Platte (Laramie/N. 
Platte, Gunnison, Upper Colorado, Yampa/White). Colorado as a whole shows 71% 
of average SWE, and has received 87% of average winter precipitation as of 
today.

The western US snowpack is low, 49% to77% of average (Nevada and Oregon, 
respectively). This is the result more of climatic conditions, unkind to 
snowpack development, than to lack of precipitation, which is currently 
81% to 99% of average. This is generally the case in Colorado as well, but 
the S. Platte is close to a normal ratio (77% of average SWE, 79% cumulative 
winter precipitation).

Looking ahead, the S.Platte has melted out earlier than average (about July 2) 
in recent years, including the above average snowpack year of 2003 (melt-out 
in third week of June). The snowpack this year most resembles that of 2001, 
which melted out extremely quickly (gone after the first week in June). ENSO 
conditions continue to remain near neutral, with little change seen in the 
next three to six months (NOAA CPC/NCEP April 8 forecast), so little 
forecasting insight from this quarter, except to go with climatology. 
But here in Colorado, the possibility of a significant May storm is real!

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

     Average   5.432    7.824    10.274   12.964   13.266