Winter-Weather Forecast Research

Transcription

1 Winter-Weather Forecast Research Dr. Jennifer Bewley 23 April 2014 AvMet Applications, Inc Alexander Bell Dr., Ste. 130 Reston, 1 VA 20191

2 Number of Hours with Wintry Precipitation November 2013 March 2014 The number of hours with wintry precipitation (snow, sleet, freezing rain, ice pellets) occurring during 6 AM 11 PM local shown in chart below Compares winter with last winter and the 30-year mean ( ) Results for MEM calculated for full 24 hours to account for overnight operations All 20 of the 30 US Core airports + top 4 Canada airports analyzed, except BOS and SLC, experienced more periods of wintry precipitation than last year All except SEA, SLC, and MSP experienced more periods of wintry precipitation than the 30-year average 2

3 Total Snow Accumulation Comparison All 20 of the 30 US Core airports analyzed, except SLC and DEN, BOS, had higher snow accumulations than last year DTW, ORD, EWR, PHL, MSP, and BOS all had 55+ inches of snow from 01Nov 2013 to 31 Mar 2014 Considering only Dec Feb period, the following airports have surpassed 30-year ( ) average snowfall totals during (percent increase compared to climatology included): - ATL (+138%) - CLT (+158%) - DTW (+141%) - JFK (+132%) - ORD (+137%) - BOS (+72%) - DCA (+42%) - EWR (+167%) - LGA (+140%) - PHL (+218%) - BWI (+51%) - DFW (+71%) - IAD (+79%) - MSP (+79%) 3

4 Number of Hours with Dangerous Wind Chill Factors The wind chill temperature represents the perceived decrease in air temperature felt by the body on exposed skin due to the flow of air (wind) Although warning criteria varies by state, a wind chill < -15 F (-26 C) is likely to result in a Wind Chill Advisory and < -30 F (-34 C) is likely to result in a Wind Chill Warning (wind chill is life threatening) Strong winds and cold temperatures associated with the Polar Vortex event resulted in multiple Midwest airports experiencing several hours of life threatening wind chill factors, limiting the amount of time people could safely work outside 4

5 Winter Weather Research Many challenges exist in identifying requirements for winter weather impact management The climatology of winter weather events for different regions of the NAS varies in frequency, extent, type, and intensity Operations and procedures for winter weather events vary widely across the core airports, as do the impacts Research approach includes Airline and Airport stakeholders, in addition to FAA In the US, FAA decisions typically center around expected airport arrival and departure rates, and any Traffic Management Initiatives necessary to ensure these are met These decisions are significantly impacted by other stakeholders: Airlines Airport Cancellation strategy for winter weather (especially significant with Tarmac Rule and Part 117 restrictions) may significantly change demand Ability to deice departures Ability to clear runways and taxiways Decisions made by other stakeholders can occur hours ahead of time and have direct influence on how efficient the airport operation will be during the event Deicing Operations Runway Conditions Braking Action Runway and Taxiway Treatment / Clearing 5

6 Winter Weather Planning/Decision Risks Precise thresholds necessitate accurate, high resolution forecasts that are updated frequently Though there are many risks associated with bad forecasts, there are also risks with using several differing forecasts These risks can be mitigated by filling gaps with forecast products that perform well, provide sufficient decision support and are available to all stakeholders Example Risks for Airport Operations Pre-treatment efforts unnecessary, ineffective (washed off by rain), or absent Over staffing for an event significant financial implications for airports Under staffing for an event inefficient surface treatment, may hinder operations Loss of ability to operate the airport effectively lost revenue, with potential additional impact of IROPS 6

7 Winter Weather Gap Analysis Overview Goal: Collect and evaluate stakeholder utilized weather forecast products, identify weather forecast gaps critical to key decisions, and identify potential applicable forecast information for a performance assessment Research collected operations / procedures documentation and perform stakeholder interviews Isolate key decision points, thresholds and relevant forecasts and observational data Map operational airport and aviation decisions to execution periods, frequency of iteration/monitoring, and winter weather forecast support to establish a current operating picture Combine, organize, and visualize winterweather constraint decision map to support and focus winter weather forecast gap analysis Compare current user needs to current forecast capabilities to identify gaps or potential shortfalls Identify potential applicable forecast products to fill gaps or potential shortfalls Documentation Key Decisions Decision Trees User Needs Interviews Gaps or Potential Shortfalls Current Forecast / Obs Capabilities 7

8 Critical Decision Tree for Winter Operations Action Category Stakeholder Time Frame Time Frame Stakeholder Category Action LEGEND Precipitation Type Precipitation Rate Total Accumulation Ambient Temperature Transition Timing Precipitation Timing Wind (Direction/Speed) Ceiling and Visibility Critical decisions for winter weather events that rely on forecast information 8

9 Winter Weather Forecast Products used by Stakeholders 48 Hours 24 Hours 12 Hours 6 Hours Time Of Event Airport Operations Contract Weather Support NWS WFO Airlines Contract Weather Support FAA Mass Media Airline Forecasts TAF NWS WFO Airline Forecasts TAF WPC Winter AWWD CIWS NWS WFO CWSU Mass Media TAF CIWS 48 Hours 24 Hours 12 Hours 6 Hours Time Of Event Winter weather products utilized per stakeholder for each winter weather planning period Chart displays availability of winter weather forecast products and scheduled update timing (dots) Information can be lacking from 6 hours prior to the event through the duration of the event Product Available Information may be old Not a 24 hour operation Updated every 5 mins 9

10 Winter Weather Forecast Products used by Stakeholders 48 Hours 24 Hours 12 Hours 6 Hours Time Of Event Airport Operations Contract Weather Support NWS WFO Airline Forecasts Airlines Contract Weather Support FAA Mass Media TAF NWS WFO Airline Forecasts TAF WPC Winter AWWD CIWS NWS WFO CWSU Mass Media TAF CIWS Airport Operations Contract Weather Support NWS WFO Mass Media Airline Forecasts 48 Hours 24 Hours 12 Hours 6 Hours Time Of Event TAF 48 Hours 24 Hours 12 Hours 6 Hours Time Of Event Winter weather products utilized per stakeholder for each winter weather planning period Chart displays availability of winter weather forecast products and scheduled update timing (dots) 48 Hours 24 Hours 12 Hours 6 Hours Time Of Event Information can be lacking from 6 hours prior to the event through the duration of the event Product Available Information may be old Not a 24 hour operation Updated every 5 mins 10

11 Winter Weather Forecast Products Potential Deficiencies Qualitative Forecasts Forecasts output not matched to stakeholder decision making needs More detail than +/- (e.g., TAF), or phrases such as light (e.g., mass media), is required Forecast Exclusivity Effective decision making may require forecasts to be shared among stakeholders Uncoordinated decisions lead to confusion in planning and execution of plans Forecast Issue Times Rapidly changing conditions require up-to-date forecasts to make the best decisions Stale forecasts can lead to under/over staffing and unnecessary treatment of pavement Geographic Resolution Some forecasts (e.g., mass media, NWS WFO) are designed to be applicable to a wide area Differences in elevation, temperature profiles, and other factors can cause a drastic difference in the type and amount of precipitation that falls in an area Forecast Subjectivity Weather forecasts may not be objective (e.g., mass media sensationalizing a winter weather event for ratings) 11

12 Winter Weather Thresholds Operationally-relevant thresholds for each winter weather element were identified based on stakeholder interviews and documentation (e.g., Snow and Ice Control Plan) Thresholds varied among each stakeholder group. Regional examples shown below For example, the threshold for total accumulation to determine an airport recall level varied significantly throughout the NAS. Airports in the SE tend to have lower thresholds for recall levels than northern airports. These thresholds can be used to support a forecast performance assessment of available winter weather forecast products 12

13 Examples of Available Winter Weather Forecast Products Hours Prior to Event 2-8 Hours Prior to Event Winter Weather Event Post Event Recovery Potential Gaps Airport Ops Airlines FAA SREF Probabilistic forecasts, 6 hour update frequency, 4 hours to create 84 hour forecast at 3 hour resolution. Covers all applicable winter weather elements Dependent on length of recovery HRRR Deterministic forecasts, updated hourly, 3 hours to run 24 hour forecast at hourly resolution. Covers all applicable winter weather elements. Dependent on length of recovery CIWS WSDMM RADAR based forecasting product. Near real time creation of 2 hour forecast at 5 minute intervals. Covers precipitation timing, transition timing, and precipitation type. Provides real time weather information from a network of observation stations and NEXRAD radar. Uses algorithms to display forecast information on all applicable elements. 13

14 Conclusions and Future Work This past winter season was more severe than average for many of the North American airports Risks of not getting winter weather decisions right include: Excess staff on call and associated costs Ineffective or wasted pavement treatments (e.g., if washed away by rain prior to snow/ice) Loss of ability to operate the airport effectively if a surprise event occurs, or a small impact event becomes a large impact event Some deficiencies have been identified in winter weather forecasts which may impair an efficient winter operation There are potential forecast products that may address these deficiencies Next steps in our research will be to perform a forecast performance assessment The end goal of research is to identify forecast capabilities that better address airport and other stakeholder needs 14