World Meteorological Organization Symposium on Nowcasting - WMO

132
P2.27
Comparison of nowcasting methods in the context of high-impact weather events for
the Canadian Airport Nowcasting project
Monika Bailey, George Isaac, Norbert Driedger, Janti Reid
Environment Canada
The focus of this study is the improvement of forecasts of high-impact weather events at
Pearson International airport for the Canadian Airport Nowcasting Project (CAN-Now). A
comparison is presented of short-term point forecasts in which observations are blended with
NWP model data (the Canadian GEM Regional and GEM-LAM models) to correct the model
for local effects. Data collection for CAN-Now began in February 2007 and a two year archive
is now available for such studies. The study is organized as follows. (1) Definition of
significant aviation related weather scenarios in terms of observables such as winds,
temperature, relative humidity, occurrence of precipitation, ceiling and visibility. (2) Extraction
of hourly surface observations from the Environment Canada archives and identification of
the start and end times of significant events. (3) Extraction of high time-resolution data from
the archive of on-site instrument data for these times. (4) Verification, separately for each
scenario, of forecasts of temperature, relative humidity, winds and precipitation occurrence.
The forecasting performances of the models, of the blended models, extrapolated
observations and of persistence are compared and ranked for forecast lead times out to 6
hours. Results show that, in general, methods that blend model and observations perform
better than the raw model at all times and on average perform better than purely
observational methods after one hour. In each case the optimum method depends on the
event type, the forecast variable and the forecast lead time. The implications of these results
for forecasting derived variables such as visibility and ceiling will be discussed.
<strong>World</strong> <strong>Meteorological</strong> <strong>Organization</strong>
<strong>Symposium</strong> on Nowcasting and Very Short Term Forecasting
Tuesday, 1 September 2009
07:00 Breakfast (Sea to Sky Ballroom B)
07:30 Registration
SESSION 3: NWP, Ensembles and Assimilation (Sea to Sky Ballroom C)
Chair: Linus Yeung and Matthias Steiner
08:15 3.1 Integrated assimilation of radar, satellite, and METAR cloud data for
initial hydrometeor/divergence fields to improve hourly updated short-
range forecasts from the RUC, Rapid Refresh, and HRRR,
Stan Benjamin, Ming Hu, Steve Weygandt, Dezso Devenyi
08:45 3.2 Data assimilation for a 1.5 km grid length version of the unified model, for
short range forecasting of convective precipitation
Susan Ballard, Zhihong Li, David Simonin, Mark Dixon, Helen Buttery,
Graeme Kelly, Catherine Gaffard, Owen Cox and Humphrey W Lean
09:00 3.3 Data Assimilation Issues Related to Very Short-Range Forecasts of
Precipitation with the Operational Convection-Permitting Model
COSMO-DE
Klaus Stephan and Christoph Schraff
09:15 3.4 Numerical weather prediction and machine learning in operational
short-term wind power forecasting
Eric Grimit, Scott Otterson, Kristin Larson, and Cameron Potter
09:30 3.5 A real-time radar wind data QC and analysis system for nowcast
application
Qin Xu, Kang Nai, Li Wei, Pengfei Zhang, Qingyun Zhao and P. R. Harasti
09:45 3.6 Data Assimilation of Hydrometeor Types Estimated from the Polarimetric
Radar Observation
Kosei Yamaguchi, Eiichi NAKAKITA,Yasuhiko SUMIDA
10:00 – 10:30 Coffee, Poster 1 and Exhibit Viewing (Grand Foyer)
Tuesday 1 September
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