Niwot Ridge LTER Snow Report for March 2004
Greetings!

This report of March snowpack conditions at C1 (Niwot), and 
general comments on the western US, comes during what appears to be
the start of summer.  Virtually all areas have suffered severe
declines in snowpack, and here we have lost virtually all
snowpack at elevations below 9,000.

The manual measurements of snowpack at the Niwot, C1 site 
on 31 March 2004 show it to be 21 inches deep, contain 7.875"
of water (SWE), which is 60% of average, and have a density of 39%. 
This is the second lowest SWE in 23 years (2002 had 7.563"),
and is a decline from 75% of average last month. 

The NRCS Snotel reports Niwot to have 6.9" SWE, for 56% of average 
compared to 72% of average last month, and the South Platte basin 
to have 61% SWE and 67% of cummulative winter precipitation.  Last
month those values were 68%/70% respectively.
In Colorado, the Upper Rio Grande still has the highest snowpack,
on a percentage basis, with 83%/93% (SWE/cummulative winter precipitation),
but this is a decline from 108%/103% last month.  The S. Platte
still takes the lowest basin award (61%/67%).
In the western US, all states snowpack declined, but the most in
Arizona and New Mexico (currently at 8% and 46% of average SWE,
respectively).  The least decline was in the Pacific Northwest,
particularly the Oregon Cascades which are at near normal levels.
This is also the first time this season that the Snowpack Index was
below one in every state except Oregon.  (This means less moisture
is stored for release from snowpacks thoughout the summer, than on
average). 

More perspective at our local site: the C1 snowpack 
at this time of year, is very close to that in 2002, and not far
from what it would have been last year had not the "mega" snow
storm occurred.  We recieved 2.00" SWE this March, 10.19" last
year (and about 9" of that was in the "mega" storm).  Prior 
March total SWE's were 2.63", 3.74", 3.11", and 1.95"
for the years 2002 through 1999, respectively.
Without a major turnaround in relative conditions, the
peak snowpack will have occurred 10 days earlier this year, than the 
previous record in 2002.  This is 1.96 standard deviations earlier
than the 23 year mean peak date. 
Interestingly though, there is absolutely no statstically 
significant trend in peak snowpack amount,
date of peak, date of melt-out, rate of melt-out,
or the number of days from peak accummulation to 
melt-out over the past 23 years.
So, there are also several other reasons to hope that the snow accummulation
season is not over yet.  Klaus Wolter has found that a wet 
April tends to follow a dry March (but not always!).  
Also, 50% of the time the C1 snowpack SWE is higher at the
end of April compared to March (n=23), and the 
medium range forecasts are predicting mostly wet conditions for 
Colorado starting tomorrow, continuing for at least a week.

So, while it is dry right now, the fire season has already started, and 
it appears there will be insufficient stream flows to fill reservoirs 
right now, there is hope! 
With weather, each day can bring surprises, and especially here in the spring!

Until next month,
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 Average 5.432 7.824 10.274 12.964 13.409

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