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Map Layers

SnowView provides a variety of map layers regarding snow and other hydroclimate information relavent to Water Supply. The layers are organized into five groups described below, and are selectable using the layer picker. Note that when displaying maps as Dual Panel or Swipe View, different layers can be displayed on each side of the screen.

SnowView map layers and layer picker.

Basemaps

These layers appear underneath other map layers and provide geographic context.

  • Imagery: Satellite and aerial imagery for viewing land cover and landscape features.
  • Topographic: Topographic maps showing contours, place names, and terrain features.
  • Streets: A road map with towns, cities, and other reference features.
  • Terrain: A terrain-focused reference map showing landforms and geographic features.

Dynamic Maps

These layers display snow conditions and cumulative precipitation since the beginning of the water year (since October 1st) for the selected map date. These layers include the UA SWANN snow product (showing both its quantity and comparison with normal condiditions), while other snow, precipitation, and satellite layers provide context. Use the date picker to display data for different dates, display different products on different sides of the screen (if using Swipe View or Dual Panel), and adjust the opacity of the layers in order to see the basemap underneath. Availability of the dynamic maps varies by product and data, but all products are generally available for current years.

  • UA SWANN SWE: Snow Water Equivalent (SWE) based on the UA SWANN product, showing the amount of water stored in the snowpack. (Oct-1981 to present)
  • UA SWANN SWE Anomaly: The difference between SWE on the selected date and the historical average for that time of year. (Oct-1981 to present)
  • UA SWANN SWE Percentile: Ranks SWE on the selected date relative to historical conditions for that time of year. Low percentiles indicate relatively little snow water; high percentiles indicate relatively abundant snow water. (Oct-1981 to present)
  • SNODAS SWE: Snow water equivalent from NOAA's Snow Data Assimilation System, providing another estimate for comparison with UA SWANN. (Sep-2003 to present)
  • IMS Cover: Snow and ice cover from the Interactive Multisensor Snow and Ice Mapping System. This shows snow cover rather than snow water equivalent. (Dec-2014 to present)
  • Accumulated Water Year PRISM Precip: Total PRISM precipitation from October 1 through the selected date. (Oct-1981 to present)
  • Accumulated Water Year PRISM Precip (Departure): The difference between accumulated water year precipitation and its historical average through the same date. (Oct-1981 to present)
  • Accumulated Water Year PRISM Precip (Percentage): Accumulated water year precipitation expressed as a percentage of its historical average through the same date. A value of 100% represents average precipitation. (Oct-1981 to present)
  • VIIRS True Color: Satellite imagery with natural-looking colors for viewing snow, clouds, and land cover. (Jan-2018 to present)
  • VIIRS False Color (Green Veg, Blue Snow): Satellite imagery using a band combination that highlights vegetation in green and snow in blue. (Jan-2018 to present)

Outlooks from NWS

These layers show forecasts and outlooks from the National Weather Service (NWS). Quantitative precipitation forecasts (QPF) show forecast precipitation amounts; climate outlooks show probabilities of conditions relative to normal. Note that these layers display on top of the dynamic map layers, and they are valid for the current time only, so adjusting the date picker has no effect on them. The legend shows the valid period reported by NWS.

  • No Outlooks: Hides the NWS outlook layer.
  • QPF (Next 24 Hours): Forecast total precipitation for the next 24 hours.
  • QPF (Next 2 Days): Forecast total precipitation over the next two days.
  • QPF (Next 3 Days): Forecast total precipitation over the next three days.
  • QPF (Next 5 Days): Forecast total precipitation over the next five days.
  • QPF (Next 7 Days): Forecast total precipitation over the next seven days.
  • Precip. Outlook (6-10 Day): Probabilities of above-, near-, or below-normal precipitation during days 6-10 of the forecast.
  • Precip. Outlook (8-14 Day): Probabilities of above-, near-, or below-normal precipitation during days 8-14 of the forecast.
  • Precip. Outlook (Month): Probabilities of above-, near-, or below-normal precipitation for the valid month shown in the layer picker and legend.
  • Temp. Outlook (6-10 Day): Probabilities of above-, near-, or below-normal temperatures during days 6-10 of the forecast.
  • Temp. Outlook (8-14 Day): Probabilities of above-, near-, or below-normal temperatures during days 8-14 of the forecast.
  • Temp. Outlook (Month): Probabilities of above-, near-, or below-normal temperatures for the valid month shown in the layer picker and legend.
  • Seasonal Drought Outlook: Expected drought development, persistence, improvement, or removal during the seasonal outlook period.

Recent Precipitation from NWS

These layers show recent observed precipitation estimates from NWS. Like the Outlook layers, they display on top of the dynamic map layers, and they are valid for the current time only. The legend shows the valid period reported by NWS.

  • No Recent Precipitation: Hides the recent precipitation layer.
  • Since 12 UTC Observed: Precipitation accumulated since the latest 12 UTC cutoff.
  • Last 1 Day (Ending at 12 UTC) Observed: The daily analysis total for the 24 hours ending at 12 UTC on the analysis date.
  • Last 2 Days Observed: Total precipitation for the latest two daily analysis periods.
  • Last 3 Days Observed: Total precipitation for the latest three daily analysis periods.
  • Last 5 Days Observed: Total precipitation for the latest five daily analysis periods.
  • Last 7 Days Observed: Total precipitation for the latest seven daily analysis periods.
  • Last 10 Days Observed: Total precipitation for the latest ten daily analysis periods.
  • Last 14 Days Observed: Total precipitation for the latest fourteen daily analysis periods.
  • Last 30 Days Observed: Total precipitation for the latest thirty daily analysis periods.
  • Month to Date Observed: Precipitation accumulated for the current month through the latest daily analysis.

Vector Data

These layers add reference features and locations that you can explore on the map.

  • Roads and Borders: Road and boundary lines to help locate places beneath snow and precipitation layers.
  • Watersheds: Basin boundaries. Click a watershed to open its dashboard, comparison tools, forecasts, and timeseries download.
  • SNOTELs: Snow monitoring station locations, including supported automated cooperator snow sensors. Click a station to explore its available snow and precipitation records.
  • Stream Gauges: Stream monitoring locations. Click a gauge to explore its available streamflow records.