1. Workshop on Use of NWP in Support of Nowcasting Initiated by Tom Keenan Proposal by Jenny Sun, Jeanette Onclee, and Tom Keenan Organizing committee: Jeanette Onvlee (WG-MWFR) Jenny Sun (WGNR) Dale Barker (WG-MWFR) Paul Joe/Peter li (WG-WGNR) (?)

2. Objectives Nowcasting tools: –Purely observation-based (e.g. radar extrapolation) –NWP used indirectly as input in dedicated nowcasting applications Workshop aims: –Strengthen interaction between NWP and NWC communities –Confront present and future prospects of NWP for NWC with challenges of NWC, come up with recommendations on way forward (how to optimize NWP in support of NWC, and how/when to best use it (or not))

3. Scientific questions use and potential of existing techniques and observation types for nowcasting major physical processes that influence the forecast accuracy for the very short term requirements from nowcasting for mesoscale NWP systems, in terms of products, quality, timeliness, etc., from the perspective of several typical nowcasting applications conversely, requirements from mesoscale models on observations, and typical problems and limitations experienced by them on this account experiences to date in, and plans for, application of mesoscale NWP for nowcasting in rapid update cycling systems: experiences so far, challenges, (comparison of) potential of various assimilation techniques challenges for NWP posed by the nowcasting applications, i.e, different operational setups for nowcasting and longer range, how to handle issues related to specific location and phenomenon data types that have the most impact for nowcasting purpose from both the typical nowcasting and NWP approaches identification of topics where stronger interactions between the nowcasting and NWP communities should be fostered ways to assess and evaluate the potential of mesoscale NWP models for nowcasting purposes discussion on possible follow-up actions and experiments

4. Current status Workshop will be held in Boulder, on 27-29 June 2010 in conjunction with WRF Users Workshop - Local sponsorship approved ~30 participants (invitation only) - A preliminary list of invitees made - Balance between NWP and NWC - Broad representation of regions - Balance between research and operation JSC support already given in principle, invitation awaiting their final approval

5. Proposed setup of workshop First two days: Presentations –Challenges of typical NWC applications, and user needs –Present use of NWP either directly or indirectly in support of NWC: capabilities and limitations. –Future prospects and their expected impact: > New types of observations; > Advances in data assimilation for the convective-scale > Innovations in mesoscale analysis and model treatment of e.g. severe convection, and fog; > Blending techniques; > Inclusion of uncertainty information in NWC; > Developments in spatialization / downscaling techniques; > Etc.

6. Proposed setup of workshop Third day: working group discussions Working groups to explore the way forward on several topics, e.g.: –How to optimize and improve NWP for high accuracy/detail in the 0-6h range? –Which nowcasting needs could be better met in the future through dedicated changes in either the quality or use of NWP models? –When to use NWP directly, when better indirect? –Define/organize experimentation aimed at performance assessment and intercomparison of alternative nowcasting methods, including NWP-based ones. Plenary wrapup meeting to consider and finalize WG