Summary of Western US SNOTEL Snowpack Update Report
Based on Mountain Data from NRCS SNOTEL Sites
**Provisional data, subject to revision**
Data based on the first reading of the day (typically 00:00) for Sunday, February 04, 2018
State/River Basin Snow Water Equivalent # of Sites Median Peak Median Peak Date Percent of Median Percent of Median Peak Alaska 28/59 13.9(19) Apr 18 80    48    Arizona 21/23 7.0    Feb 28 14    9    California 32/32 26.1    Apr 01 40    26    Colorado 101/105 17.3    Apr 13 61    34    Idaho North of Salmon River 30/31 28.8(29) Apr 05 115    73    Idaho South of Salmon River 64/65 19.6    Apr 06 86    52    Montana 86/91 19.1(24) Apr 17 130    76    Nevada 29/32 14.7(20) Mar 27 45    28    New Mexico 21/21 8.2    Mar 10 13    9    Oregon 78/81 18.2    Mar 17 52    31    Utah 89/90 16.8(26) Apr 04 54    30    Washington 68/76 34.6(26) Apr 04 109    65    Wyoming 82/85 17.9    Apr 18 111    63    Arkansas River Basin 6/6 11.4    Apr 10 38    21    Colorado River Basin 105/108 17.1    Apr 11 65    37    Columbia River Basin 260/266 24.4    Apr 02 96    58    Missouri River Basin 44/48 16.1(24) Apr 20 124    70    Rio Grande River Basin 28/29 11.2    Mar 24 26    16    The Great Basin 102/105 20.2    Apr 03 49    30

-M  = Missing data.
 *  = Analysis may not provide a valid measure of conditions.
N/A = Not available.

Footnotes for median and average:
(##) = If less than 30 years are available, this value specifies the number of years used for the median and average calculations.
Sites with less than 10 years available do not have medians or averages.

The snow water equivalent percent of median (or average) represents the current snow water
equivalent found at selected SNOTEL sites in or near the basin compared to the median (or average) value
for those sites on this day.

The snow water equivalent percent of median (or average) peak represents the current
snow water equivalent at selected SNOTEL sites in or near the basin compared to the median (or average)
of the maximum seasonal values observed each water year for those sites.


Contact your state water supply staff for assistance.

Medians and averages are calculated for the period 1991-2020.

Provisional data, subject to revision.

* Site -- Either: (a) the current value is missing; (b) the median or average for the day is not available or is zero; or (c) for snow water equivalent, the median or average for the day is less than 10% of the maximum median or average value for the year.

* Basin - More than half of the stations for a basin with normals report missing or invalid data.

The basin index is calculated as the sum of the valid current values divided by the sum of the corresponding medians or averages and the resulting fraction multiplied by 100.