Niwot Ridge LTER Snow Report for Nov 2006
Niwot Ridge LTER Snow Report for November 30th, 2006

This is the first preliminary snow report from Niwot C1 for the 2006-07 winter, and brings a changing of the guard. As many of you know, Mark Losleben is leaving INSTAAR, the Mountain Research Station, and the Niwot LTER program; we will all miss him. I, Kurt Chowanski, am taking over the generation of these snow reports, and hope that you will still find them informative.

It has been a good start to this year’s snowpack at Niwot Ridge C1. Hand measurements made today show 5 inches of snow water equivalent (SWE), with a snow depth of 23.19 inches. SNOTEL is reporting 4.6 inches of SWE for 148% of average.

The South Platte River Basin is at 128% of average SWE, and 130% of average precipitation. State wide the South Platte River Basin has the highest percent of average SWE; the San Miguel, Dolores, and San Juan River Basins have the lowest percent of average SWE (128%, 80% respectively). The Gunnison River Basin has the highest percent of average precipitation, while the Laramie and North Platte River Basins have the lowest percent of average precipitation (150%, 80%).

Across the West, Washington, Oregon, and Colorado are the only states with above average SWE (160%, 128%, and 105%), and above average precipitation (162%, 136%, and 130%). The California Great Basin sites have the lowest percent of average SWE at 28%, and Arizona has the lowest percent of average precipitation at 59%. The Snowpack Index (SI) is less than one throughout the Western United States, meaning that less than average of the precipitation is being sequestered in the snowpack.

The ENSO Diagnostic Discussion issued by the NOAA Climate Prediction Center/NCEP indicates a weak El Nino condition, and forecasts that typical El Nino effects should continue into the spring of 2007. The typical El Nino effects include warmer that average temperatures over the western and northern United States and drier than average conditions in the Ohio River Valley and the Pacific Northwest. At this early stage, the Pacific Northwest snowpack and precipitation is contrary to the typical El Nino effects.

Last year a weak La Nina condition persisted all winter, whereas this year we are starting with a weak El Nino. Last year the Southwest was drier than average and the northwest was wetter; this year at the start we see Washington, Oregon, and Colorado being wetter than average and everywhere else across the West being drier. Last Year’s snowfall at Niwot was characterized by consistent zonal airflow which brought light semi-continuous snowfall; this is very different from this year’s early storms, the most notable of which have been upslope events separated by dry periods. It will be interesting to see the coming winter’s weather pattern.

Happy Holidays 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

(enter historical table here)