Niwot Ridge LTER Snow Report for May 2011
Greetings!

This spring continues to bring above average precipitation and snow to Niwot Ridge. A total of 25.9 inches of new snow fell at C1 in May with 5.49 inches of SWE. The Niwot road is now clear up to C1, and is well covered above C1. There continues to be more snow in the alpine than I have seen in my time here at Niwot. The Gee-Wiz tree measures 7.2 m in height, in 1995 the tree was completely covered with snow; in 1996 maximum snow depth at the tree was 5.3 m, 1984 was 5.2 m, and this year maximum snow depth is 5.5m. At C1, the 2011 peak SWE of 17.0 inches occurred on May 22; this is the 7th highest peak SWE since 1981, and the second latest date for peak SWE.

La Nina conditions are transitioning to ENSO neutral conditions. The ENSO Diagnostic Discussion issued by the NOAA Climate Prediction Center/NCEP predicts above average temperatures in the southwestern US including Colorado, and below average precipitation in the northwestern US.

Hand measurements made at Niwot Ridge C-1 on May 31st, 2011 show 14.125 inches of snow water equivalent (SWE), and a snow depth of 31.8 inches. SNOTEL reported 12.9 inches of SWE for 478% of average. Since 1981, only 14 of the possible 31 years have any snow at the C1 SNOTEL site; SWE for May 31st, 2011 ranks 3rd of those 14.

As of May 31st, 2011, the South Platte River Basin is at 323% of average SWE, and 131% of average precipitation. State wide the South Platte River Basin has the highest percent of average SWE, and Laramie and North Platte River Basins have the highest percent of average precipitation (323%, 149%). The Upper Rio Grande River Basin has the lowest percent of average SWE at 100%, and the lowest percent of average precipitation at 93%.

Across the West, only Arizona and New Mexico have below average SWE, and below average precipitation. New Mexico has the lowest percent of average SWE closely followed by Arizona (9%, 18%); while New Mexico has the lowest percent of average cumulative precipitation at 63%. Utah now has the highest percent of average SWE combined with the highest percent of average cumulative precipitation (449%, 152%). Colorado has 245% of average SWE and 123% of average cumulative precipitation.

Cheers

Kurt

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	(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	10.125	16.75	17	(22nd)	12.375(13th)	19.75(30th)
95/96	7.5	12	17.5	20.375	18.75	6.125	(15th)		
96/97	8.75	12.625	15.125	14.625	20.375	18	(15th)
97/98	7.0625	10	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	9.125		
01/2002	2.625	4.25	6.19	7.563	0		
02/2003	4	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	7.7	9.5	11.625	12.875	12.25	(15th)
05/2006	5.625	8.375	9.5	13.25	6.75	0.875	(15th)
06/2007	9.25	11.5	14.375	15.25	16.75		
07/2008 5.45	7.375	11.0	13.75	14.5
08/2009 3.625	7.25	9.25	10.125	12.75
09/2010 5.375	6.25	8.725	12.375	11.625	0	(31st)
10/2011	5.875	8.375	11.875	16.0	16.75	14.125	(31st)

Average	5.50	7.89	10.35	13.02	13.24