Geoscience Reference
In-Depth Information
there functioning radars or other data sources? Is there the capacity to design or even adopt
a radar processing system? Is there the knowledge and capacity to interpret the data
products to make effective warning decisions and issue warnings? And is there a way to
reach the end-user in a timely fashion? It should not be forgotten that the end-user must be
educated on the meaning of the warning and on how to react appropriately. Is there
sufficient budget to develop a warning system? What is risk is acceptable? What level is the
moral outrage?
An often overlooked design issue is the organization of the weather service. Warnings are
provided for small areas (scale of the weather feature) in order to mitigate the "cry wolf"
syndrome to be effective (Barnes et al, 2007; Hammer and Schmidlin, 2002). The critical issue
is the capacity to provide the attention to the detail given the totality of the forecast
responsibilities. The system design will be quite different if there are many forecast offices
and few radars (one to one) compared to few offices and many radars (one office to ten
radars as in Canada).
Of course, an overarching issue is the climatology of severe weather which ultimately is the
core issue. For many countries, convective weather may occur year round and some only for
the summer season. In the latter case, a design question is to determine the use case for the
shoulder season where severe weather may occur unexpectedly and the warning service is
seasonal.
Severe weather forecasting requires a unique forecasting skill set. In synoptic forecasting
(for 12 hours and beyond), the forecaster compares current observations to numerical
weather prediction models to evaluate the appropriateness of the model or to develop a
conceptual model of the weather for the creation of the public forecast product (Doswell
2004). The product is usually produced on a fixed schedule. In severe weather forecasting,
the observations need to be timely; there is urgency in the interpretation and the generation
of the warning product. It is a "short fused" situation. These require different personality
types and this also drives the design considerations. In order to mitigate the "cry wolf"
situation while maintaining high probability of detection, a dedicated and separate warning
forecaster function is required to be able to address the immediacy issues of the warning
service. These are just some of the design considerations for a radar processing and
visualization system and the forecast process for the provision of severe weather warnings.
Forecast process refers to all components of the transformation of the data or observations
into information used for decision- making and warning service production. It includes both
the human and their tools and is often referred to as the man-machine mix. Given all the
degrees of freedom in the chain, there are different models of the forecast process.
In the next section, a global survey (necessarily incomplete) is presented that will briefly
examine the operational or near-operational systems that have been developed. Many have
commonalities and only the underlying unique aspects will be highlighted.
5. Components of a basic system
In this section, the basic components or issues of severe weather radar
processing/visualization are briefly discussed and a block diagram is provide in Fig. 5. The
benefits of different radar types are discussed elsewhere (WMO, 2008).
