Influence of winter season climate variability on snow-precipitation ratio in the western United States

2015 ◽  
Vol 36 (9) ◽  
pp. 3175-3190 ◽  
Author(s):  
Mohammad Safeeq ◽  
Shraddhanand Shukla ◽  
Ivan Arismendi ◽  
Gordon E. Grant ◽  
Sarah L. Lewis ◽  
...  
Keyword(s):  
United States ◽  
Climate Variability ◽  
Winter Season ◽  
Western United States ◽  
Precipitation Ratio ◽  
Snow Precipitation

scholarly journals Verification of Surface Temperature Forecasts from the National Digital Forecast Database over the Western United States

2006 ◽  
Vol 21 (5) ◽  
pp. 869-892 ◽  
Author(s):  
David T. Myrick ◽  
John D. Horel
Keyword(s):  
United States ◽  
Surface Temperature ◽  
Winter Season ◽  
Forecast Accuracy ◽  
Horizontal Resolution ◽  
Western United States ◽  
Lead Times ◽  
Advanced Regional Prediction System ◽  
Regional Prediction ◽  
Mean Square Errors

Abstract Experimental gridded forecasts of surface temperature issued by National Weather Service offices in the western United States during the 2003/04 winter season (18 November 2003–29 February 2004) are evaluated relative to surface observations and gridded analyses. The 5-km horizontal resolution gridded forecasts issued at 0000 UTC for forecast lead times at 12-h intervals from 12 to 168 h were obtained from the National Digital Forecast Database (NDFD). Forecast accuracy and skill are determined relative to observations at over 3000 locations archived by MesoWest. Forecast quality is also determined relative to Rapid Update Cycle (RUC) analyses at 20-km resolution that are interpolated to the 5-km NDFD grid as well as objective analyses obtained from the Advanced Regional Prediction System Data Assimilation System that rely upon the MesoWest observations and RUC analyses. For the West as a whole, the experimental temperature forecasts issued at 0000 UTC during the 2003/04 winter season exhibit skill at lead times of 12, 24, 36, and 48 h on the basis of several verification approaches. Subgrid-scale temperature variations and observational and analysis errors undoubtedly contribute some uncertainty regarding these results. Even though the “true” values appropriate to evaluate the forecast values on the NDFD grid are unknown, it is estimated that the root-mean-square errors of the NDFD temperature forecasts are on the order of 3°C at lead times shorter than 48 h and greater than 4°C at lead times longer than 120 h. However, such estimates are derived from only a small fraction of the NDFD grid boxes. Incremental improvements in forecast accuracy as a result of forecaster adjustments to the 0000 UTC temperature grids from 144- to 24-h lead times are estimated to be on the order of 13%.

scholarly journals Spatiotemporal Characteristics of Snowpack Density in the Mountainous Regions of the Western United States

2008 ◽  
Vol 9 (6) ◽  
pp. 1416-1426 ◽  
Author(s):  
Naoki Mizukami ◽  
Sanja Perica
Keyword(s):  
United States ◽  
Snow Depth ◽  
Snow Water Equivalent ◽  
Winter Season ◽  
Western United States ◽  
Densification Rate ◽  
Snow Density ◽  
Mountainous Regions ◽  
Spatiotemporal Characteristics ◽  
Snow Water

Abstract Snow density is calculated as a ratio of snow water equivalent to snow depth. Until the late 1990s, there were no continuous simultaneous measurements of snow water equivalent and snow depth covering large areas. Because of that, spatiotemporal characteristics of snowpack density could not be well described. Since then, the Natural Resources Conservation Service (NRCS) has been collecting both types of data daily throughout the winter season at snowpack telemetry (SNOTEL) sites located in the mountainous areas of the western United States. This new dataset provided an opportunity to examine the spatiotemporal characteristics of snowpack density. The analysis of approximately seven years of data showed that at a given location and throughout the winter season, year-to-year snowpack density changes are significantly smaller than corresponding snow depth and snow water equivalent changes. As a result, reliable climatological estimates of snow density could be obtained from relatively short records. Snow density magnitudes and densification rates (i.e., rates at which snow densities change in time) were found to be location dependent. During early and midwinter, the densification rate is correlated with density. Starting in early or mid-March, however, snowpack density increases by approximately 2.0 kg m−3 day−1 regardless of location. Cluster analysis was used to obtain qualitative information on spatial patterns of snowpack density and densification rates. Four clusters were identified, each with a distinct density magnitude and densification rate. The most significant physiographic factor that discriminates between clusters was proximity to a large water body. Within individual mountain ranges, snowpack density characteristics were primarily dependent on elevation.

scholarly journals Climatology of Orographic Precipitation Gradients in the Contiguous Western United States

2020 ◽  
Vol 21 (8) ◽  
pp. 1723-1740
Author(s):  
Lucas Bohne ◽  
Courtenay Strong ◽  
W. James Steenburgh
Keyword(s):  
United States ◽  
Function Analysis ◽  
Precipitation Amount ◽  
Winter Season ◽  
Western United States ◽  
Orographic Precipitation ◽  
Spatial And Temporal Patterns ◽  
Case Examples ◽  
Modes Of Variability ◽  
States Experience

AbstractOrographic precipitation gradients (OPG) relating to the increase or decrease in precipitation amount with elevation are not well studied or analyzed except for case examples. A quality controlled daily OPG dataset for the western United States that is based on a linear regression framework of gauge precipitation observations and elevation for a 39-yr time period was created and analyzed to identify spatial and temporal patterns and variability in OPG and some of the drivers of variability on seasonal, annual, interannual, and climatological time scales. Most locations in the western United States experience positive OPG during most of the year, exhibiting an annual cycle with the highest magnitude of OPG in the winter season and lowest magnitude of OPG in the summer season. Coastal locations tend to have OPG with higher magnitude and larger variability in OPG than do interior locations during cool seasons. Empirical orthogonal function analysis identifies two principal components that account for 33% of the variability in a subset of the OPG dataset, and these modes of variability are related to precipitation amount and atmospheric circulation over the Pacific Ocean. Comparison of daily OPG with similarly calculated 3-day and monthly OPG identifies that OPG magnitudes are sensitive to the choice of length of the precipitation accumulation period.

HIBERNATION PECULIARITIES OF PLATYSAMIA GLOVERI STR. (SATURNIIDAE, LEPIDOPTERA)

1940 ◽  
Vol 72 (5) ◽  
pp. 89-90
Author(s):  
James B. Duncan
Keyword(s):  
United States ◽  
Winter Season ◽  
Rocky Mountain ◽  
Mountain Region ◽  
Western United States ◽  
Rocky Mountain Region ◽  
Varying Length

Recent observations of Platysamia gloveri Str. have brought out some interesting facts on the varying length of hibernation periods. The gloveri moth is restricted almost entirely to the Rocky Mountain Region of the western United States. This implies in general, therefore, the ability to withstand subzero weather throughout the lengthy winter season.

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