1. Surface Transportation Weather Research Center University of North Dakota Pavement Precipitation Accumulation Precipitation Data Sources Presenter: Mark Askelson University of North Dakota Department of Atmospheric Sciences/RWIC/STWRC

2. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 2 Precipitation Data Sources Primary sources Surface observations Radar Satellite Analyses/models

3. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 3 Precipitation Data Sources Surface Gauges Strengths Accuracy (but wind contamination) Weaknesslimited capacity for indicating snowfall in real time ASOS: Automated Surface Observing System Tipping bucket gaugesnot presently useful for measuring snowfall. Visibility snowfall rate (significant variability) Manual intervention stations Useful information, but not enough of them.

4. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 4 Precipitation Data Sources North Dakota ASOS/AWOS stations. Manual intervention stations circled. Not shown (KRDRGF AFB, a manual intervention station). Only some of these provide real time snowfall amounts. ND ASOS/AWOS stations (from http://www.faa.gov/asos/m ap/nd.cfm). http://www.faa.gov/asos/m ap/nd.cfm

5. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 5 Precipitation Data Sources South Dakota ASOS/AWOS stations. Manual intervention stations circled. Not shown (KRCAEllsworth AFB, a manual intervention station). Only some of these provide real time snowfall amounts. SD ASOS/AWOS stations (from http://www.faa.gov/asos/m ap/nd.cfm). http://www.faa.gov/asos/m ap/nd.cfm

6. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 6 Precipitation Data Sources AWOS: Automated Weather Observing System AWOSIII-P has a precipitation identification sensor, but does not record amounts. RWIS: Road Weather Information System DOT 14 in North Dakota; 35 in South Dakota Indicate precipitation occurrence

7. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 7 Precipitation Data Sources RAWS: Remote Automated Weather Stations United States Forest Service 9 in North Dakota; 5 in South Dakota Uncertain regarding utility for snowfall estimation Citizen Weather Observer Program (CWOP) Forecast Systems Laboratory Private weather stations PRIMENet EPA and NPS 1 station in North Dakota Uncertain snowfall measurement potential

8. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 8 Precipitation Data Sources High Plains Regional Climate Center Automated Weather Data Network (HPRCC-AWDN) NDAWN: North Dakota Agricultural Weather Network NDSU 55 in North Dakota Tipping bucket rain gauge South Dakota 11 in South Dakota Tipping bucket rain gauges

9. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 9 Precipitation Data Sources South Dakota Television Stations KOTA-TV WeatherNet KELO WeatherNet KMEG Weather Net Uncertain snowfall measurement utility

10. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 10 Precipitation Data Sources Non real-time networks NWS Cooperative Observer Program NOAA/NWS 15 Minute Cooperative Observer Program 55 in North Dakota; 40 in South Dakota Weighing rain gauges. North Dakota Atmospheric Resource Board Cooperative Observer Network Principally concerned with rainfall. Operates from April to September.

11. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 11 Precipitation Data Sources Cost of setting up surface gauges for South Dakota 75,885 square miles Yankee Sensor Estimated ~$10,000 each (for sensor alone) Minimizes wind contamination of amounts Estimates 1 gauge/900 mi 2 : ~$850,000 1 gauge/400 mi 2 : $1.9 million 1 gauge/100 mi 2 : $7.6 million Infrastructure and maintenance?

12. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 12 Precipitation Data Sources Radar Strengths Good spatial and temporal coverage Park River Basin example courtesy of Scott Kroeber RADAR Estimated Precipitation (2 km resolution) NDAWN Interpolated COOP InterpolatedNDARB Interpolated

13. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 13 Precipitation Data Sources Weaknesses Accuracy 40-50% error common for storm total accumulation Can reach 100% for < 1 snowfalls. Overshooting 0.5˚ beam reaches 5.0 km at ~225 km range.

14. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 14 Precipitation Data Sources Ground Clutter and Anomalous Propagation Ground Clutter: Commonly observed return owing to radar beam bouncing off buildings, towers, etc. Anomalous Propagation: Radar beam bends downward towards the Earth more than normal…produces anomalous returns to the radar.

15. Surface Transportation Weather Research Center University of North Dakota STWRC--Precipitation Data Sources 15 Precipitation Data Sources Satellite StrengthsExpands coverage area. Weaknesses Been applied more to rain than snow. Probably more effective for heavy snow (identify cloud patterns) May not resolve light snow (clouds cannot be discriminated from snow on the ground).