World Meteorological Organization Symposium on Nowcasting - WMO

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implementation of the methods and approaches suitable for forecasting and verification of the
RCM performance for fine-scales at road stations/ stretches. The applicability of results
related to the improved quality of detailed forecasts at road stretches will: (1) Facilitate the
use of data from the road stretch forecasting to automatic adjustment of control of the dosage
spread by salting spreaders, i.e. for optimization of the amount of salt spreaded over the road
surface to prevent the icing/freezing as well as better timing of schedule for such operations
by the road authorities; (2) Lead to improvement of the overall safety of the road traffic in
winter weather; (3) Contribute to further development and improvement of the visualization
tools for the road stretches forecasting; (4) and Reduce the environmental impact in the road
surroundings due to an optimized spreading of the salt.
P1.11
Influences of different soil moisture conditions upon South Atlantic convergence zone
associated precipitation forecasting performed by a regional model
Ana Carolina Nóbile Tomaziello, Adilson Wagner Gandu
Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric
Sciences, University of São Paulo, Rua do Matão, 1226 - Cidade Universitária, ZIP Code:
05508-090 - São Paulo - SP - Brazil
Brazil south and southeast regions suffer periods of intense rainfall, generally associated to
South Atlantic Convergence Zone (SACZ) during austral summer, which causes serious
problems to the inhabitants. The objective of this work was to study the influence of soil
moisture initial conditions in SACZ position and associated rainfall intensity. This study was
carried out through simulations with model BRAMS (Regional Atmospheric Modeling System
with Brazilian Developments) during a SACZ episode. In order to evaluate the model
performance a statistical analysis was performed. The model positioned SACZ
southwestward of observations and tended to overestimate precipitation. Comparing
simulations with horizontally homogeneous and heterogeneous initial soil moisture, we
concluded that the first simulation showed higher accuracy on ocean than the latter. For
Amazon region, the best model performance was to heterogeneous soil moisture. Without
surface-atmosphere interaction the system was not well marked, so this interaction plays an
important role in SACZ formation. The best model performance is provide
occurrence/nonoccurrence of rain than predict and locate more intense rainfall nuclei. We
pretend, in future stages, to verify the role that sea surface temperature in South Atlantic
plays in SACZ and analyze differences between simulated SACZ during El Niño and La Niña
periods.
the forecaster is therefore to reduce the FAR to a reasonable value, without a significant
change in the POD. Usually such systems are designed for an availability of all input data as
well as failure proof computer hard- and software. The real world includes all kind of possible
failure and the forecaster has to cope with them, particularly when issuing weather warning.
The change in the forecaster role often generates some fears to loose the control in the
forecasting process. Adequate training and coaching in difficult situations should help to
mitigate such a fear.The presentation will show some concrete examples with existing
operational systems, as well as some work in progress and outlook on that topic at
MeteoSwiss.
2.7
Experiences from Nowcasting Convective Storms for the Beijing Olympics: Future
Nowcasting Implications
James W. Wilson [1] Yerong Feng [2] and Rita D. Roberts [1]
[1] National Center for Atmospheric Research, P.O. Box 3000, Boulder CO 80307 USA, [2]
Guangdong Provincial <strong>Meteorological</strong> Bureau/Chinese Academy of <strong>Meteorological</strong> Sciences
A Forecast Demonstration Project (B08FDP) took place during the summer of 2008 that
included the period of the summer Olympic Games in Beijing China. This demonstration was
sanctioned by the <strong>World</strong> <strong>Meteorological</strong> <strong>Organization</strong> <strong>World</strong> Weather Research Program. The
focus was on forecasting convective storms for the nowcasting time period (0-6 hours). The
demonstration included state-of-the-art forecast systems from Beijing, Hong Kong, Australia,
Canada and the United States.The metropolitan area of Beijing is on a flat plain located at the
foot of a mountain range, Yan Shan Mountain, that extends west and north of the city. Beijing
is at an altitude of only 30 m and is open to the south and east to the influx of very warm
moist air. Significant forecast challenges present themselves in the vicinity of Beijing in
response to this very humid air impinging on the nearby mountains. Thunderstorms frequently
initiate over the mountains and move towards Beijing. Sometimes these storms dissipate on
reaching the foothills and other times grow and organizing into major squall lines. A variety of
boundary layer convergence lines frequent the plains and play a significant role in storm
initiation and evolution.Initiation and dissipation in close proximity to Beijing meant that radar
echo extrapolation techniques were often unreliable. Very short period numerical model
forecasts were not well suited to predicting the convective storms since they were strongly
influenced by local terrain. However, at the same time, the human forecaster who had a good
understanding of local influences and experiences with high resolution data sets showed skill
in nowcasting these events. This includes past experiences in studying the movement of
convective storms from the mountains to the plains and the initiation of storms by localized
boundary layer convergence lines. Examples of thunderstorm initiation and evolution will be
shown for a variety of forecasting challenges that occurred during the B08FDP. Based on
B08FDP experience implications for development of future nowcasting systems will be
presented.
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