Weather Products for Decision Support Tools Joe Sherry
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
2000Z Storm in Steady State Forecast Accuracy Acceptable
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
CCFP
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
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
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
1.2 1 0.8 0.6 0.4 0.2 0 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
CAASD s NCWF Weather Assessment (continued) Northern Extent of Missed 1-hr Forecasts, Where Extrapolation Possible Frequency 30000 25000 20000 15000 10000 5000 0 Northern extent of 92% of missed forecasts <30 nmi, 96% <40nmi. Southern extent is 94% and 98%, respectively. Improvement detected between 1999 and 2000. Currently, applicable to mature lines only. 0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 100-109 110-119 Missed Forecast (nmi) 120-129 130-139 140-149 150-159 160-169 170-179 180-189 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
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)