1. Warn on Forecast Briefing September 2014 Warn on Forecast Brief for NCEP planning NSSL and GSD September 2014

2. Warn on Forecast Briefing September 2014 Warn on Forecast Vision (~2020+) Short-term NWP forecasts at 0.5-1.0 km resolution Using improved models for convective-scale NWP Incorporation of high-resolution satellite and radar data Sub-hourly update cycle with 2-3 hour forecasts Providing uncertainty estimates via an ensemble system New paradigm for severe weather warnings Blend WoF output with observed/historical radar data Blending using the Multi-Year Reanalysis Of Remotely-Sensed Storms (MYRORSS) Similar approach is used by NHC Extending lead times (1 hour for tornadoes, 2-3 hours wind, QPF, hail) Probabilistic warnings visualized using) Probabilistic Hazard Information tools (PHI) Forecasting A Continuum of Threats tools (FACETS) Leveraging societal knowledge and its technology Improving warning effectiveness via social science research Communicating threat information via new media

3. Warn on Forecast Briefing September 2014 Assimilation relative value of hybrid versus pure ensemble approaches as well as multi-resolution approaches ensemble ICs and mechanisms for maintaining optimal forecast spread (uncertainty) dealing with model biases use of dual-polarization data Observations data quality control for dBZ, Vr, and dual-polarization variables optimal combinations of surface, radar and satellite appropriate superobbing for dense observational data Models Reducing model errors in PBL, radiation, and land surface appropriate microphysics relative to observations (e.g., single-pol versus dual-pol radar data) Verification quantitative ensemble object based verification best methods to quantify model skill for these types of high-impact & rare events? value of high-resolution WoF system for non-severe convective weather Predictability what is the practical predictability for different environments and weather threats? how long does high-resolution satellite/radar data assimilation positively impact forecasts? hail and lightning? Current Research Issues

4. Warn on Forecast Briefing September 2014 Operational Implementation? Background: Hourly-updated ~60 member 3 km convective-permitting model Warn on Forecast system: 0.5-1 km resolution with ~60 members Regional grid (1500-2000 km size grid, possibly moving) 5-15 min cycling with 1-3 hour forecasts generated 4-6x per hour 15 min latency (e.g., forecast is available T+15 minutes). Inputs: sub-hourly radar, satellite (GOES-R?), mesonet obs. Outputs: rotation tracks and intensities, QPF, severe wind probabilities, hail, etc. Operational Use? WoF system is an ON-DEMAND service, much like HWRF is today. NOAA Storm Prediction Center would control placement and activation of WoF system (that would be run at NCEP) Output would be made available to SPC and WFOs through products WFOs might “blend” products locally for their needs with other observations(?) FACETS and PHI tools would consolidate model output and observations for forecasters into probabilistic threat information Operational Warn on Forecast?

5. Warn on Forecast Briefing September 2014 Research and development of a Warn on Forecast system is on track for end-of-decade specification for NCEP NSSL and GSD are working closely together to develop the high- resolution and high-frequency NWP system to provide probabilistic hazardous weather information for watches and warnings in 2020s. Given current state of NWP science for convective scale: high-resolution & high-frequency will likely regional grid initially (~40K cores?) system runs on-demand at NCEP? (like HWRF does?) SPC: logical center to decide on location for WoF on high-impact days. SPC and WFO’s can collaborate as to configuration (similar to how the convective outlooks and watches are already done) unclear yet whether sub-hourly 0.5-1 km forecasts will be useful for non-severe convective weather situations. Summary