Niwot Ridge LTER Snow Report for December 2004

Positive snow pack conditions continue to favor the lower western US, and Colorado as of today.   
The pattern reported at the start of this month continues in bothe western US and Colorado (dry 
north, wet south-western states), and promises to continue into early 2005 (NOAA CPC Dec 6 
report on ENSO conditions).

Here on Niwot Ridge, the snow pack is almost average.  The hand measurement shows 4.875" of water 
(90% of past 23 year average).  The Snotel network shows 5.1", or 98% of average, and cumulative 
winter precipitation of 119% of average.  Either way, this years snow pack is much better than last, 
which was 51% of average at this time.

The State of Colorado is also in good shape, loosely mimicking the western US as a whole, in 
that the south is generally wetter than the north.  The similarity ends there, though, because 
even the northern Colorado basins are not much below average.  The state shows 96% SWE and 97% 
PPT (snow water equivalent (SWE)/cumulative winter precipitation (PPT)).
The South Platte basin shows 92%/94% of average SWE/PPT, respectively.
The Gunnison basin is still tops with 120% / 113%, SWE/PPT, respectively.  The Yampa/White is 
still in last place with 87% and 93% of average values, respectively.
The southern basins of the Rio Grande, and the San Juan/Dolores/San Miguel/Animas are doing 
very well with 116%/116% and 109%/107%, for SWE/winter precipitation, respectively.
Also noteworthy, most of Colorado basins are showing Snowpack Indicies (SI) of near one, 
meaning the winter weather is also about normal, so far.

The western US snow pack pattern is also little changed from  the start of this month, but is 
much more extreme compared to Colorado.  Washington has only 39% of average snow pack (73% of 
PPT, however), and Oregon has 48%/67%, respectively.
Utah still is tops with 137% SWE and 152% PPT.  The California Great Basin sites show 123%/97%, 
and Arizona shows131%/140%, SWE/PPT, respectively.
Colorado, Nevada, New Mexico are about average, and Idaho, Montana and Wyoming are lagging with 
72%, 69%, and 81% of average SWE, respectively.
Low or high snow pack, however, most all states show SI's of less than one (weather conditions less 
conducive to snow pack development given the amount of winter precipitation received), with the 
exception of the California Great Basin sites, and Colorado.
Looking "upstream" for clues for the rest of winter we find no strong indicators.  The NOAA CPC 
predicts continued weak El Nino conditions in the Pacific into early 2005, and although the PDO 
may be shifting (negative index values the past two months), it is too early to say for sure.  
So, weather-watching may continue to be interesting this month!

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 3.69 (14th) 04/2005 4.875 Average 5.409 7.824 10.274 12.964 13.266

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