Weather Products for Decision Support Tools Joe Sherry April 10, 2001

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1 Weather Products for Decision Support Tools Joe Sherry

2 National Convective Weather Forecast (NCWF) Computer generated graphical forecast extending 0-1 hours, updated every 5 minutes Conservative forecast useful for rerouting (bias of ~1) Deterministic forecast (doesn t use probabilities) Better at forecasting lines than air mass storms TFM decision support more interested in lines Current operational forecast is an extrapolation only Lacks initiation, growth and decay algorithms Ongoing R&D will lead to better/longer forecasts (2-3 hrs) Limited vertical storm definition Better vertical definition may increase available capacity

3 2000Z Storm in Steady State Forecast Accuracy Acceptable

4 Collaborative Convective Forecast Product (CCFP) Human generated, collaborative, graphical forecast extending 0-6 hours, updated several times a day Non-conservative forecast less useful for rerouting (bias >1) Over forecasts, reducing capacity more than necessary Probabilistic forecast (e.g., 40% chance of 60% coverage) May be better at forecasting air mass storms Helped by over forecasting and human generation TFM decision support more interested in lines Limited vertical storm definition Better vertical definition may increase capacity

5 CCFP

6 Convective Weather R&D FAA NWS AWR funding NCWF, CCFP, TCWF Funding THOR CWSU meteorologists supporting CCFP AWC Distributing NCWF and supporting CCFP Airlines FSL Meteorologists supporting CCFP Inter-comparison exercise project is evaluating forecasts NCAR NCWF and Auto-Nowcaster MIT/LL TCWF

7 NCAR s Auto-Nowcaster (AN) Augments extrapolation forecast with initiation, growth and decay Based on storm, boundary-layer and cloud characteristics Derives thunderstorm likelihood fields (polygons) that are weighted, combined and compared to thresholds Linked to individual NEXRADs and requires mosaic for a national product Improves accuracy over extrapolation alone Needs improved growth and decay algorithms, greater spatial coverage, longer time periods (0-3 hrs) Needs vertical storm definition

8 Other Research Thunderstorm Operational Research (THOR) project Focussing on 0-2 hour convective weather forecast Plans to establish two regional test and evaluation sites Goal is to develop a seamless national product Working closely with weather research and aviation communities MIT/LL is developing a regional convective weather forecast by leveraging their terminal area work

9 CAASD s NCWF Weather Assessment 1-Hour NCWF Assessment (Polygon Comparison Methodology) POD FAR BIAS May-99 Jun-99 Jul-99 Aug-99 Sep-99 Oct-99 Nov-99 Dec-99 Jan-00 Feb-00 Mar-00 Apr-00 May-00 Jun-00 Jul-00 Aug-00 Sep-00 Apr-99 Statistical Results

10 CAASD s NCWF Weather Assessment (continued) Northern Extent of Missed 1-hr Forecasts, Where Extrapolation Possible Frequency Northern extent of 92% of missed forecasts <30 nmi, 96% <40nmi. Southern extent is 94% and 98%, respectively. Improvement detected between 1999 and Currently, applicable to mature lines only Missed Forecast (nmi) Apr-1999 May-1999 Jun-1999 Jul-1999 Aug-1999 Sep-1999 Oct-1999 Nov-1999 Dec-1999 Jan-2000 Feb-2000 Mar-2000 Apr-2000 May-2000 Jun-2000 Jul-2000

11 Conclusion Convective weather research is proceeding in a positive direction Accurate 2-hour forecasts of convective lines are anticipated in the near term (accurate 3-hour forecast may be possible)