1. 1 Appendix

2. 2 For the Encore: NYC Blizzard (Dec 25-27, 2010)

3. 3 Radar/HPC Surface Analysis December 25-28, 2010

4. 4 H 1036 1024 1008 1020 1024 1036 1032 1028 1016 1012 1016 1032 1028 1016 L L 1200 UTC 25 December 2010 H H 1016 1036 1012 L 1008 1012 1032 1028 1024 1020 1016 10121008 1032 102 4 1016 L 1012 0000 UTC 26 December 2010 H 1032 1028 1024 1020 1016 1004 1016 1000 1008 1028 1020 1024 1028 1020 1012 1004 1012 1008 996 L 1200 UTC 26 December 2010 H 1020 1000 996 1004 1008 1012 1016 1020 L 1028 1024 992 972 988 100010041008 1012 1016 996 1024 L 1016 1012 1008 1012 992 L 0000 UTC 27 December 2010 NYC Blizzard Dec 25 – 27, 2010

5. 5 Snowfall Totals

6. Guidance from 12Z December 22 - Wednesday Forecast uncertainty led to inaction that increased the overall impact of the storm Observed – Blue ECMWF – Red GFS - Green

7. 7 Guidance from 12Z December 24 - Friday Observed – Blue 12Z ECMWF – Red 12Z GFS – Green 00Z ECMWF - Brown

8. Surface Analysis Seven day forecast Valid 12Z December 27, 2010

9. Surface Analysis Six day forecast Valid 12Z December 27, 2010

10. Surface Analysis Five day forecast Valid 12Z December 27, 2010

11. Surface Analysis Four day forecast Valid 12Z December 27, 2010

12. Surface Analysis Valid 12Z December 27, 2010 Forecast Issued 24 December 2010 Three day forecast

13. Surface Analysis Two day forecast Valid 12Z December 27, 2010

14. Surface Analysis One day forecast Valid 12Z December 27, 2010

15. 15 3 days prior SREF/GEFS Forecasts for Dec 26, 2010: NYC Blizzard 2 days prior 1 day prior

16. Favorable Jet-Streak Circulation Pattern Radar Simulation of Snow Bands* 16 Short Term Forecasts Point to Potential Heavy Snowfall in NYC and Surrounding Areas * 4km NMMB will be operational for next winter

17. Model Forecasts: 250 MB Coupled Jets (00Z Mon Dec 28 2010) GFS 24 Hour Forecast *

18. HPC SFC MapObserved Radar NAM 4km Reflectivity 18 Z Dec 26 00 Z Dec 27 06 Z Dec 27 * * * * * * 18hr fcst 24hr fcst 30hr fcst

19. Model Forecast: Simulated Reflectivity 33 hour Reflectivity Loop (03 UTC 26 Dec to 12 UTC 27 Dec) NAM (run on 00Z Dec 26) Simulated Reflectivity experimental 4 km NMMB model (to become operational this summer) *

20. December 26-27, 2010 20 Potential for major east coast storm highlighted 5 days in advance Low confidence about model predictions – especially track forecasts – until late December 24 Blizzard warning issued for NYC at 4PM Saturday, December 25 (14 hours prior to onset) By December 24-25, special effort made to reach out to Emergency managers and airline industry prior to onset of heavy snow in Northeast corridor/NYC Airline industry takes action Snow emergency not declared in NYC NYC/NJ/West CT gets buried by 2+ feet of snow with 50+ mph winds

21. Airlines/airports are prepared for crippling event –Cancel thousands of flights –Attempt to mitigate impact on national and international flight operations –Fully recover in 3-4 days NYC does not declare snow emergency despite blizzard warning – results in major gridlock within city Impacts: Forecast for 26-27 December 2010 21

22. New York City Report: Preliminary Review of the City’s Response to the December 2010 Blizzard - Report and Recommendations 22 From Introduction – “On December 26, 2010, a blizzard struck New York City and surrounding areas. Though earlier forecasts had called for only a light to moderate snow falls, the National Weather Service issued a blizzard warning at 3:55 PM on December 25th. At that time, between 11 and 16 inches of snow were predicted, along with high winds and low visibility. Even this forecast underestimated the storm’s ferocity. ” Third of six key problems – “Insufficient and delayed deployment of City assets. The weather forecast for the storm got significantly worse rather quickly, culminating in a blizzard warning issued at 3:55pm on Christmas Day. Due to the late change in the forecast, as well as the fact that DSNY has adeptly handled large snowfalls so many times previously without assistance, agencies that are not typically involved in snow removal—such as the Taxi and Limousine Commission --were not mobilized expeditiously.”