A Thunderstorm Nowcasting System for the Beijing 2008 Olympics: A U.S./China Collaboration by James Wilson 1 and Mingxuan Chen 2 1. National Center for Atmospheric Research, Boulder, CO Institute of Urban Meteorology, CMA, Beijing

OUTLINE Olympics 2008 support and B08FDP Beijing Auto-Nowcast system Climatology Important local considerations Plan

Convective storms frequent Beijing area For supporting 2008 Olympics, BMB and NCAR are conducting a joint project on convective storm nowcasting that is implementation and further development of ANC at BMB

Beijing 2008 Forecast Demonstration Project ( B08FDP, ) sanctioned by the WMO World Weather Research Program Beijing 2008 Forecast Demonstration Project ( B08FDP, ) sanctioned by the WMO World Weather Research Program Objective - Test state-of-the-art very short period forecasting systems Objective - Test state-of-the-art very short period forecasting systems Participants: China/U.S. – Beijing Auto-Nowcast China - GRAPES Hong Kong – SWIRLS Canada – CARDS Canada/U.S. – MAPLE U.S. – Niwot U.S./Australia – RTFV Australia – STEPS, TIFS

600 km 200 km B08FDP Forecast and Verification Domain ~ 4 radars (S-band & C-band) ~ 100 surface stations (AWS) ~ 3 profilers ~ 14 GPS/Met Satellite (FY-2C & MTSAT) ~ 3 radiosondes (4 times/day in Aug) Meso-NWP

OUTLINE Olympics 2008 and B08FDP Beijing Auto-Nowcast system Climatology Important local considerations Plan

Data Sets Radar Satellite Mesonet Profiler Sounding Numerical Model Lightning Analysis Algorithms Predictor Fields Forecaster Input Fuzzy Logic Algorithm - Membership functions - weights - Combined likelihood field Final Prediction Beijing Auto-Nowcast System

Produces 0-1 hr time and place specific forecast Expert system utilizes fuzzy logic Ingest multiple data sets Ingest Meso-NWP outputs Beijing Auto-Nowcast System 4-D Variational Doppler Radar Analysis System (VDRAS) Extrapolates radar echoes Forecast storm initiation, growth and dissipation Algorithms derive forecast parameters based on the characteristics of the boundary- layer, storms, and clouds

Example of Auto-Nowcast 60-min Initiation Forecast 1 hour forecastVerification Initiation nowcasts Extrapolation nowcasts

OUTLINE Olympics 2008 and B08FDP Beijing Auto-Nowcast system Climatology Important local considerations Plan

Distribution of storm initiation or appearance location over Beijing area Based on 2003~2005 data from Beijing C- band radar (77 cases and > 30 dBZ) Conclusion: Most (77%) of those come from a westerly direction 6 ％ of total 17 ％ of total 4 cases north 77 ％ of total 2 cases south 28 cases northwest 9 cases northeast 20 cases southwest 3 cases southeast 11 cases west

28(10) 20(7) 11(4) 9(7) 4(2) 3(2) 2(1) 2(2) 0 Origin of storms (>30 dBZ) that arrive in or initiate in Beijing area Based on 2003~2005 data from Beijing C-band radar (79 cases and > 30 dBZ) inside bracket number storms initiatiated in Beijing Conclusions: 57% move in and 43% initiate 28% of those that move in enhance

OUTLINE Olympics 2008 and B08FDP Beijing Auto-Nowcast system Climatology Important local considerations Plan

Important local considerations for the Beijing Auto-nowcast system Terrain and southeast winds Convection initiation along convergence lines Sea breeze influences Dissipation or enhancement as storms move from mountains to plains Dissipation of storms when convergence line moves away

Example 1: Terrain influence with southeast low-level flow

Example 2: Squall line dissipation moving from mountain to plains Click to start or pause animation

Example 3: Squall line enhancement moving from mountain to plains Click to start or pause animation

Example 5: Boundary running away from storm and dissipating Click to start or pause animation

Example 6: Initiation and enhancement of storms when boundaries interact and storms move from mountains to plain/urban areas

Click to start or pause animation

OUTLINE Olympics 2008 and B08FDP Beijing Auto-Nowcast system Climatology Important local considerations Plan

Ingesting of new local data (Zhangbei C-band radar, AWS surrounding Beijing, FY-2C, profiler, etc.) Further development and improvement of the nowcast system Rerun some 2006 cases Tune parameters and memberships Add some new algorithms Radar climatology study Trial demonstration summer 2007 Formal FDP in 2008 Plan

Thank you for your attention!

Example 4: Storm initiation by convergence lines, rolls also play role Click to start or pause animation

Example 6: Initiation and enhancement of storms when boundaries interact and storms move from mountains to plain/urban areas

Three S-band Radar Mosaic (Beijing, Tianjin and Shijiazhuang) 06/27/ UTC

Diurnal Cycle based on Tianjin radar Minimum over Beijing 1-2 a.m. local Echo Frequency >35 dBZ Maximum 6-7 p.m. local

30min fcst (08/01/ UTC) 60min fcst (08/01/ UTC) Ref (08/01/ UTC) growth steady decay initiation

Cold vortex Trough Subtropical high Jun AugJul The monthly number of related synoptic system with storms

The percent of related steering wind with storms 500 mb850 mb700 mbNo data

Frequency distribution of convective weather phenomena in Beijing area Based on surface observations in 5-9 month of 12 years ( ) Total Thunderstorm Rainstorm hailstormGale

Cold vortex Trough Subtropical high The percent of related synoptic system with storms