  Despite marked progress over the past several decades, convective storm
nowcasting remains a challenge because most nowcasting systems are based on
linear extrapolation of radar reflectivity without much consideration for other
meteorological fields. The variational Doppler radar analysis system (VDRAS) is
an advanced convective-scale analysis system capable of providing analysis of
3-D wind, temperature, and humidity by assimilating Doppler radar observations.
Although potentially useful, it is still an open question as to how to use
these fields to improve nowcasting. In this study, we present results from our
first attempt at developing a Support Vector Machine (SVM) Box-based nOWcasting
(SBOW) method under the machine learning framework using VDRAS analysis data.
The key design points of SBOW are as follows: 1) The study domain is divided
into many position-fixed small boxes and the nowcasting problem is transformed
into one question, i.e., will a radar echo > 35 dBZ appear in a box in 30
minutes? 2) Box-based temporal and spatial features, which include time trends
and surrounding environmental information, are elaborately constructed, and 3)
The box-based constructed features are used to first train the SVM classifier,
and then the trained classifier is used to make predictions. Compared with
complicated and expensive expert systems, the above design of SBOW allows the
system to be small, compact, straightforward, and easy to maintain and expand
at low cost. The experimental results show that, although no complicated
tracking algorithm is used, SBOW can predict the storm movement trend and storm
growth with reasonable skill.
