Extended Abstract (324K)9A.6
The sensitivity of object-based nowcasts to object threshold selection
Neil I. Fox, University of Missouri - Columbia, Columbia, MO; and S. A. Lack, G. L. Limpert, J. Miranda, N. Miller, A. Schnetzler, A. Koleiny, and W. T. Gilmore
Nowcasts that involve the identification and tracking of �objects� may be sensitive to the choice of threshold used to delineate an object. This paper explores the variability in forecast by looking at a number of cases using two nowcast schemes. These are the K-means cluster method used in the WDSS � II (Lakshmanan et al. 2003) and the Spectral Prognosis scheme (Seed 2003). A number of cases are examined representing a range of storm types.
It is found that the choice of reflectivity threshold used to define a cell can significantly impact the quality of a forecast, and that adapting the threshold value to the meteorological situation or storm-type can have benefits. Alternatively using a range of different threshold values to nowcast the same storm can efficiently generate an ensemble of nowcasts which can produce a robust product that captures some measure of the uncertainty in the storm track.
Session 9A, Forecast Verification
Thursday, 28 June 2007, 10:30 AM-12:00 PM, Summit A
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