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Central Region Snowfall Analysis

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Central Region Snowfall Analysis. Brian P. Walawender NWS Central Region Headquarters Matt W. Davis NWS WFO La Crosse, WI 5/26/2011. History. In the early 2000’s, NWS offices began creating precipitation analysis graphics for display on their web pages. - PowerPoint PPT Presentation

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Central Region Snowfall AnalysisBrian P. WalawenderNWS Central Region HeadquartersMatt W. DavisNWS WFO La Crosse, WI5/26/2011

1HistoryIn the early 2000s, NWS offices began creating precipitation analysis graphics for display on their web pages.Two primary software packages were utilized for the creation of the graphicsArcMapGFE Both software packages interpolated the random points into a graphical analysis

2 Weaknesses of Previous MethodsManually created, via a multistep process, on a non routine basisTypically restricted to the local forecast area, requiring the user to view several graphics to see the big pictureColor and contour intervals typically varied from office to office, leading to confusion when viewing graphics from multiple offices.No ability to zoom the graphics or add/remove layers3 Central Region PrototypeCollaborative effort between NWS Central Region Headquarters and WFO La Crosse, WI.Key RequirementsUse commonly available to Open Source GIS toolsAutomatedOutput can be zoomed and pannedConsistent colors and contour intervals4 Open Source Tools UtilizedPostgresql/PostGIS database allows for the storing of a geometry object (latitude and longitude in our case) with any database entryGDAL - Geospatial Data Abstraction LibraryUsed perform the interpolation of the raw data into the output analysis graphicUsed perform the contour analysis from the output imageUsed to create the multiday analysis products

5 Open Source Tools Utilized Mapserver web mapping server used to serve out the raster and shapefile output productsOpenLayers web mapping APISimilar to Google MapsAllows for adding interactive maps to web pages 6 DataflowInput data of consists of:NWS Cooperative Observer ReportsCommunity Collaborative Rain, Hail and Snow Network (CoCoRaHS) reportsTypical Analysis will consist of about 7500 observationsNWS Local Storm Reports (LSR) were purposely left out because of time range concernsLSR reports currently contain no start, stop or duration information (yet)7 DataflowReports are received via LDM from MADIS and NOAAportReports are decoded and databased in realtime Database can hold several months of data8 Data AnalysisThe scattered point to grid analysis is done via an inverse distance weighted interpolation scheme.Grid box is a moving1.8 degs, requiring three observations. Inverse power is 6, and output is smooth very slightly at 0.2.Output is a georeferenced tagged image file format (GeoTIFF)2000 x 2000 GeoTIFF covering CONUS.9 Data AnalysisTo increase the display performance, the large GeoTIFF is converted into polygon shapefile via GDALThe conversion into the polygon shapefile bins the analysis into the standard contour intervals The analysis is run every 30 minutes from 12 UTC until 20 UTC to continuously update the analysis10 Multiday ProductsMultiday products pose a challenge since there is dilemma on whether or not to include stations that do not report each day of the reporting periodExample a station reports three days over a four day period do you use it in a four day analysisTo avoid this concern, the multiday products are created by summing the output analysis for each day in the period, instead of the raw data.11 Quality ControlAn internal web interface allows offices to quality control the analysisThe interface allows the forecaster to flag stations with questionable data, causing them to be removed from the analysisThe analysis is automatically run twice per hour, including new observations, and removing those which were quality controlled.

12 Web DisplayThe final analysis products are displayed on the web page via an interactive mapThe interactive map can be panned and zoomedThe interactive map has multiple layers that can be toggled on and offThe map includes output for the last 24, 48 and 72 hours13 Web DisplayThe snowfall analysis can be viewed at:http://www.srh.noaa.gov/ridge2/snow/index.phpNote this URL may change for the 2011/2012 snow seasonFuture enhancements will included increased resolution, and more observations (Snotel, etc.)14 Customer ResponseCustomer Survey ran from Jan 10th until April 30th, 2011300 responses180 users rated the technical quality of the product as a nine or higher (out of ten)207 users rated the ease of use as a nine or higher15 Examples16

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AuthorsMatt W. DavisLa Crosse, WI Weather Forecast OfficeN2788 County Road FALaCrosse, WI 54601Matt.W.Davis@noaa.govBrian P. WalawenderCentral Region Headquarters Regional Office7220 NW 101st TerraceKansas City, MO 64153Brian.Walawender@noaa.gov

19 QUESTIONS?20

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