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Joseph P. Villani NOAA/NWS Albany, NY Michael L. Jurewicz, Sr. NOAA/NWS Binghamton, NY

Forecasting the Inland Extent of Lake-Effect Snow (LES) Bands: Application and Verification for Winter 2010-2011. Joseph P. Villani NOAA/NWS Albany, NY Michael L. Jurewicz, Sr. NOAA/NWS Binghamton, NY Jason Krekeler NOAA/NWS State College, PA. Outline. Introduction Forecast Application

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Joseph P. Villani NOAA/NWS Albany, NY Michael L. Jurewicz, Sr. NOAA/NWS Binghamton, NY

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  1. Forecasting the Inland Extent of Lake-Effect Snow (LES) Bands: Application and Verification for Winter 2010-2011 Joseph P. Villani NOAA/NWS Albany, NY Michael L. Jurewicz, Sr. NOAA/NWS Binghamton, NY Jason Krekeler NOAA/NWS State College, PA

  2. Outline • Introduction • Forecast Application • Verification of App. • A few case studies • Composite Plots • Future Work

  3. Introduction • Determine atmospheric parameters which commonly have the greatest influence on a LES band’s inland extent • Examined over 20 LES events across the Eastern Great Lakes (Erie/Ontario) during 2006-2009 winter seasons • For each event, parameters evaluated at 6-hour intervals (00, 06, 12, and 18 UTC), using mainly 0-hr NAM12 model soundings

  4. Introduction • Wind regimes stratified by mean flows: • 250-290° for single bands • 300-320° for multi bands • LES bands’ inland extent (miles) calculated from radar mosaics, distance measuring tool • Data points: • Locations inside and north/south band

  5. Parameters

  6. Strategy to Determine Best Parameters • Used statistical correlations in Excel spreadsheet to determine most influential factors driving inland extent of LES bands • Values for the best correlated parameters statistically significant to the 99.95% level with N > 500

  7. Statistical Correlations • Best correlators to inland extent (all points together): ALY events • 850 hPa Lake-air ∆T (-0.63) • Multi-lake connection present (0.59) • Capping inversion height (0.53) • 0-1 km bulk shear (0.44)

  8. Results from Correlations • Environments that promote greater inland extent (IE): • Multi-Lake Connection (from upstream lakes) • Conditional instability class • Strong 0-1 km shear, weaker shear in1-3 km layer • High capping inversion height

  9. Favorable Environment far-reaching IE • MLC present (not shown) • Strong 0-1 km shear; little shear in 1-3 km layer • High capping inversion height over 3 km 0°C Inversion 1-3 km 0-1 km

  10. AWIPS Forecast Application • Equation developed to determine inland extent of lake effect snow bands based on most strongly correlated parameters • Forecast application based on equation created for use in NWS AWIPS software • Application integrated on experimental basis at Albany and Binghamton NWS offices

  11. Example of Forecast Application

  12. Multi-Lake Connection (MLC) • Use pattern recognition for favorable surface, 850/700 hPa low center tracks in forecasting MLC • 850 hPa low center tracks

  13. Verification of Application • 10 event times verified via radar with >15 dBZ • Avg error = 10 miles • Excluding two narrow/multi-band/NW flow events • Avg error = 4 miles • Avg bias = (-7) miles(under-forecasting IE) • Avg bias = (1) miles (excluding the two outliers) • Avg bias = (-35) miles (for 2 outliers) • Need more events to support verification

  14. Example of single-band event • 27 November 2010 • Single band event – extensive IE • MLC Present • IE forecast from application: • 1100 UTC = 94 miles • Verification = 92 miles • 1600 UTC = 90 miles • Verification = 100 miles

  15. 27 November 2010 – 1600 UTC • MLC present from Georgian Bay • Well-developed single band depicted by satellite

  16. 27 November 2010 – 1200 UTC • MLC present • Strong 0-1 km shear; little shear in 1-3 km layer • High capping inversion height over 3 km 0°C Inversion 1-3 km 0-1 km

  17. 27 November 2010 – 1100 UTC • IE Forecast from application = 94 miles • Actual IE = 92 miles • Good performance of app.

  18. Example of single-band event • 02 December 2010 • Single band event – IE not extensive • No MLC Present • IE forecast from application: • 1400 UTC = 46 miles • Verification = 45 miles • 1500 UTC = 43 miles • Verification = 37 miles

  19. 02 December 2010 – 1400 UTC • No MLC present (not shown) • Modest 0-1 km shear; greater shear in 1-3 km layer • Lower capping inversion height 0°C 1-3 km Inversion 0-1 km

  20. 02 December 2010 – 1400 UTC • IE Forecast from application = 46 miles • Actual IE = 45 miles • Good performance of app.

  21. Example of multi band event • 08 December 2010 • Multi band event – IE extensive • MLC Present • IE forecast from application: • 2100 UTC = 67 miles • Verification = 120 miles

  22. 08 December 2010 – 2100 UTC • IE Forecast from application = 67 miles • Actual IE = 120 miles • Poor performance of app.

  23. Example of single-band event • 16 January 2011 • Single band event – IE extensive • MLC Present • IE forecast from application: • 0200 UTC = 92 miles • Verification = 87 miles • 0600 UTC = 103 miles • Verification = 104 miles

  24. 16 January 2011 – 0200 UTC • IE Forecast from application = 92 miles • Actual IE = 87 miles • Good performance of app.

  25. Composite Plots using NARR • Composite maps of surface pressure and 500/700/850 hPa mean geopotential height plotted for far-reaching IE of LES bands • Plus favorable environments with: • Multi-Lake Connection (from upstream lakes) • Conditional instability class • Strong 0-1 km shear, weaker shear in1-3 km layer • High capping inversion height

  26. Mean Sea-Level Pressure Composite 850 hPa Mean Height Composite

  27. 700 hPa Mean Height Composite 500 hPa Mean Height Composite

  28. Composite Plots using NARR • Plots obtained from NOAA’s Earth System Research Laboratory (ESRL) using North American Regional Reanalysis (NARR) • Favorable positions for low centers generally in South-Central Quebec for far-reaching IE of LES bands into Albany forecast area

  29. Conclusions • In general, application represented IE well for well-developed single bands in W to WSW flow. • Application under-forecasted IE (significantly at times) for narrow multi-bands in NW flow • Additional changes may be needed for multi-band events

  30. Ongoing/Future Work • Solidify operational functionality of application through additional real-time events • Develop graphical representation of the inland extent of snow bands, compare to models

  31. Acknowledgements • Jason Krekeler • NOAA/NWS State College, PA/State University of NY at Albany • Vasil Koleci • NOAA/NWS Albany, NY • Hannah Attard • State University of NY at Albany

  32. References • Niziol, Thomas, 1987: Operational Forecasting of Lake Effect Snowfall in Western and Central New York. Weather and Forecasting. • Niziol, et al., 1995: Winter Weather Forecasting throughout the Eastern United States – Part IV: Lake Effect Snow. Weather and Forecasting.

  33. Questions? Joe.Villani@noaa.gov Michael.Jurewicz@noaa.gov Jason.Krekeler@noaa.gov www.weather.gov/aly www.weather.gov/bgm www.weather.gov/ctp

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