Snowfall Analysis at FGF using Snoopy and ArcGIS

1. Snowfall Analysis at FGFusing Snoopy and ArcGIS Mike Lukes NWS Service Hydrologist WFO Eastern North Dakota Grand Forks, ND

2. 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.

3. SNOOPYAWIPS IHFS database “snooper” • Developed by Mike Callahan, SH @ 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.

5. 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.

6. 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; 2-day Snowfall SQL Querry

7. GNU gFTP clientxfer 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.

9. Snow Amounts in ArcGISplotted 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.

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

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

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