Matthew A. Dux* Philip N. Schumacher* Ray Wolf+ * National Weather Service – Sioux Falls, SD + National Weather Service – Quad Cities, IA/IL October 21, 2015, National Weather Association

October 21, 2015, National Weather Association #nwas15 Meteorological Challenges: - High Snowfall Gradients -Significant Snowfall Rates -Rapid and Unpredictable Development -Model Ingredient Variance

October 21, 2015, National Weather Association #nwas15 Impact/Messaging Challenges -Short “Lead Time” to Warning -Less Planning Time by Partners -Can Produce Significant Impacts -Difficult to Message Uncertainty -Changing Forecast  Public Confusion Many of these events are considered “surprises” by the public.

October 21, 2015, National Weather Association #nwas15 Prediction and Forecast of Heavy Mesoscale Banded Snow Can Be Similar to That of Summer-Time Convection Similarities: -Conceptually Modeled Days in Advance -Highly Depend on Mesoscale Details -Rapidly Evolve as Event Approaches -Share a Localized High-Impact Potential Why Not Model the Forecast and Messaging Process in Similar Fashions?

October 21, 2015, National Weather Association #nwas15 12 to 24+ Hours Ahead -Focus on Potential -Highlight Broad Area -May Already Have Ongoing Watch 6 to 12 Hours Ahead -Address a Headline? -Narrow Down Corridor of Potential -Address Potential Impacts 0 to 6 Hours Ahead -Similar to SPC Meso Discussion -Certainty Increased -Warnings May Be Needed -Message Focuses on Certainty Event Ongoing -Focus on Current Information -Allow Forecast to Evolve -Stress Impacts 12 to 24+ Hours Ahead 6 to 12 Hours Ahead 0 to 6 Hours Ahead Event Ongoing Increased Accuracy & Certainty

October 21, 2015, National Weather Association #nwas15 Typical Mid-Winter Snow Event for Northern Plains Expectations of Widespread Light Snow 3” or Less Arrival of Snow Late Afternoon/Evening Models Showing Signs of Banded Precipitation Timeline: 36 Hours in Advance

October 21, 2015, National Weather Association #nwas15 Timeline: 12 to 24 Hours Prior Forecast Awareness -Be Aware of Model Trends -Address Concerns in the AFD -WWA in Effect? Event Messaging -Focus on Potential -Highlight Broad Area -Address Uncertainty

October 21, 2015, National Weather Association #nwas15 Timeline: 6 to 12 Hours Prior Forecast Awareness -In Depth Examination of Environment -Use Probabilities to Inspect Heavy Snow Potential -Change in Headlines Needed? -Adjust Staffing? Event Messaging -Narrow Down Risk of Heavy Snow Area -Begin to Stress Potential Impacts -Address Uncertainty

October 21, 2015, National Weather Association #nwas15 Timeline: 0 to 6 Hours Prior Forecast Awareness -Heavy Focus on Observations -Begin Mesoscale Interrogation -Write a Mesoscale Discussion in AFD -Headline/Staffing Changes? Event Messaging -Narrow Risk of Heavy Snow Area -Begin to Stress Potential Impacts -Change Tone of Message

October 21, 2015, National Weather Association #nwas15 Timeline: Event Ongoing Forecast Awareness -Focusing on Incoming Information -Gather Reports -Continual Weather Watch and Forecast Adjustments -Warning Already Issued -Staffing Adjusted Strong Emphasis on Social Media and Communications Event Ongoing -Focus on Current Information -Allow Forecast to Evolve -Stress Impacts

October 21, 2015, National Weather Association #nwas15 Timeline: Event Ongoing What Types of Messages: -Live Traffic Cameras -30 Second Human Video Updates -Animated Radar GIFS to Show Motion -Showing Impacts/Snow Data Event Ongoing -Focus on Current Information -Allow Forecast to Evolve -Stress Impacts Event Messaging -Heavy Focus on Impacts -Continual Flow of Information -Express Certainty in the Message -Provide Outlooks into the Night

October 21, 2015, National Weather Association #nwas15 NWS Sioux Falls Will be Participating: Experimental Probabilistic Snowfall Forecast Products With Goals: 1.) Better defining categorical term usage for “Low, Moderate, High” based on forecast probabilities. 2.) Targeting Communication Based on NWS Partners

October 21, 2015, National Weather Association #nwas15 How Do We Advertise the Worst Case Snow Scenario? Can We? How Do You Message Extreme Events Without Leading to “Forecast Hype”? Does “One-Size-Fits-All” Messaging Work? Does Message Need to Vary by User (Public/Schools/Emergency Management/DOT)? Let’s Keep the Conversation Going!