Snowfall Analysis at FGF using Snoopy and ArcGIS Mike Lukes NWS Service Hydrologist WFO Eastern North Dakota Grand Forks, ND

Snowfall Reports to Graphic Analysis  Collect 1, 2, or 3-Day Snowfall Amounts from the Hydro DataBase (IHFS).  Transfer Snowfall Data from AWIPS to PC-based ArcGIS host.  Use ArcMap and Spatial Analyst to make a raster Snowfall analysis graphic.

SNOOPY AWIPS IHFS database “snooper”  Developed by Mike Callahan, WFO Louisville, Ky. (Available from LAD).  Graphical Interface to IHFS database.  Interactively runs SQL queries, saves results in electronic files.  Use INFORMIX flavor of SQL.  Plan to use Mike’s Pref – preformater utility - in the near future.

SQL Queries  1, 2, 3, 4-day Snowfall Analysis  2-day Snow Depth Analysis  Snow Water Analysis  Other uses include AWOS 00z/12z precip amounts.

2-day Snowfall SQL Querry select * from snow s where s.obstime = (select max(obstime) from snow where lid = s.lid and s.pe=‘SF’ and date(obstime) = today) and s.value>0 order by 1 into tem tsf1; select * from snow s where s.obstime = (select max(obstime) from snow where lid = s.lid and s.pe=‘SF’ and date(obstime) = today-1) and s.value>0 order by 1 into tem tsf1; select lid, value, obstime from tsf1 union select lid, value, obstime from tsf2 order by 1 into temp tsft; select lid, count, (*) num, sum(value) tot from tsft group by lid order by tot desc into tsff; select t.lid nwsli, round(t.tot,1) tot, round(l.lat,3) lat, round(l.lon,3)*-1 lon, t.Num num from tsff t, location l where t.lid=l.lid order by 2 desc;

GNU gFTP client xfer Snow Analysis File to PC  FGF uses the Linux gFTP utility to xfer the Snow Analysis SQL results file to samba mapped network drive  Results file is accessible to ArcGIS on a local LAN PC.  NWS CRH has a number of “floating licenses” for ArcGIS and Spatial Analyst which the region’s WFOs can use locally.  Pref may be able to bypass gFTP step.

Snow Amounts in ArcGIS plotted on FGF HSA County Background  Results file contains NWSLI, Snowfall Amount, Lat, Lon, and # of daily obs.  Snow Amounts are plotted (add XY data from tools menu) on HSA county background.  NWSLIs can be also plotted for geographical orientation.

Spatial Analyst Snow Analysis  Interpolated to Raster using: Inverse Distance Weighting Inverse Distance Weighting Spline…??? Spline…??? Kriging…??? Kriging…??? ArcUser Magazine Jul-Sep 04 “Interpolating Surfaces in ArcGIS Spatial Analyst”ArcUser Magazine Jul-Sep 04 “Interpolating Surfaces in ArcGIS Spatial Analyst”  To do: Compare spline and kriging to IDW for a better analysis.

Contouring and Time Stamping  Spatial Analyst – Surface Analysis – Contour function. Specify contour intervals. Specify contour intervals.  Day/Time Stamp VB add-on. DateElement icon put on toolbar. DateElement icon put on toolbar. Available from ESRI web page. Available from ESRI web page.

Improvements notes, ideas and limitations  Use Pref for SQL query and file xfer (RRM?) (RRM?)  Snow Obs from buffer counties Improve boundary conditions for better analysis near borders Improve boundary conditions for better analysis near borders  Can serve as 1 st guess for subjective analysis  Compare to sat pix  IDW not good fit to natural snowfall patterns Kriging? Kriging?  Easier process to send to graphic to web