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Danger Degree Project. Assessing the Threat of Winter Events. Amanda Graning General Forecaster NWS WFO Duluth, Minnesota. Winter Storm Conference November 9 th , 2009. Danger Degree Project. Weather Forecasting Office Duluth, MN. Motivation.
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Danger Degree Project Assessing the Threat of Winter Events Amanda GraningGeneral Forecaster NWS WFO Duluth, Minnesota Winter Storm Conference November 9th, 2009
Danger Degree Project Weather Forecasting Office Duluth, MN Motivation There are situations where the physical science can be perfect, but its utility is greatly reduced where there is not adequate attention to the societal aspects Goal An effort to create a historical reference for use in assessing the threat of snowfall cases that may or may not fall into the National Weather Service (NWS) defined criteria for winter weather advisories or warnings
Danger Degree Project Weather Forecasting Office Duluth, MN • In order to classify winter events we will develop a "checklist" of factors that are given values. • These values are added up to result in a quantitative "score" or Danger Degree(like a threat level) of that storm. • Theory: higher the score the greater the Danger
High Impact Events • 2009 April – North Shore Ice Storm • National Disaster • 2008 April 6-7th Blizzard • 2007 March 2nd – Blizzard • 2005 Extreme Cold • Temperatures -30 F to -54 F • 119 hours below zero • 2001 April - Ice Storm • with 80% of Duluth without power
The Checklist • WFO Duluth, MN • Specific Location • Duluth, MN • International Falls, MN • Event Criteria • Snowfall of >2” • Looked at Daily Climate Report (LCDs) • Weather & Societal Factors • METARs • Sum Each Section
2006 October 11-13th DLH SN began 400 am 3 First >2 of winter 2 Mixed Phases Snow Total = 3.5” 2.3” in 24 hr period. Gusts 30-35 kt for 24 hrs 6 Began: 36 F & Rain SN ended for 4 hrs - then continued. 5 14
Danger Degree Project Duluth, MN 146 Events International Falls, MN 105 Events • 2009: 4 • 2008: 10 • 2007: 8 • 2006: 18 • 2005: 18 • 2004: 8 • 2003: 6 • 2002: 10 • 2001: 11 • 2000: 9 • 1999: 10 • 1998: 16 • 1997: 11 • 2009: 12 • 2008: 10 • 2007: 8 • 2006: 18 • 2005: 18 • 2004: 8 • 2003: 16 • 2002: 3 • 2001: 11 • 2000: 9 • 1999: 10 • 1998: 9 • 1997: 12
Danger Degree Project • Warning Events
Danger Degree Project • Advisory Events
Danger Degree Project • No Headline
Danger Degree Project 91% 60%
Danger Degree Project • Several Warnings with Danger Degree Values < 5 • Low potential Impact • Events with Danger Degree > 14 with No Headline • High Potential Impact • What was the Impact?