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I I I I I I I I I I I I I I I I I I I After some trials with various schemes, it was decided to use the relatively simple approach of using the interval midpoints for the "5 to 10" and "10 to 15" dBZ intervals, subtracting 0.5 dBZ from the midpoint of the "15 to 20" dBZ interval, and subtracting 1.0 dBZ for all greater intervals. This approach to selecting the dBZ value expected to be most representative of each Level III interval resulted in reasonably good agreement between Level II and Level III SAA runs. Further improvement may be possible, especially at far ranges, but this current approach provides reasonable SWE accumulations with Level III reflectivity data. Examples of storm total SAA SWE accumulations are shown for five Minnesota storms in figures 2 through 6. These storms were the greatest precipitation producers of the available data set. Four of the storms had dry snowfall, and the figures cover the same or similar time intervals as noted in table 1 for storms 1,4, 5, and 9. One storm not in table 1 (97022818 start) had an above-freezing layer aloft which produced obvious "bright band" effects at mid ranges; that is, reflectivities were greater than expected from dry snow because the snow particles were melting. This storm was included in the comparisons because it had sharp gradients in precipitation estimates, which might be especially challenging to deal with using Level III data. Visual examination of the five sets of Plan-Position Indicator (PPI) type plots for Level II and III input data reveals minor differences and generally quite reasonable agreement. This encouraging result indicates that Level III reflectivity data can be used with the SAA to produce reasonably accurate SWE estimates, at least for storm totals in Minnesota. Further testing at other locations would be desirable, but use of Level III data with the SAA is probably an acceptable approach within the GCIP LSA-NC. This finding opens the interesting possibility that Level III reflectivity data, obtained from a NIDS vendor, could be used with the SAA to provide near real-time SWE (and snow depth) estimates almost anywhere. The current SAA can only be used in real-time at NWS Weather Forecast Offices which have a WSR-88D radar as well as special processing and display computers. The latter, known as the Warning Decision Support System (WDSS), are currently available only at perhaps 20 or so Forecast Offices. Table 2 further illustrates the degree of agreement between Level II and III data runs. Results are given for the same storm periods offigures 2 through 6 for 5 different sets of range intervals. One interval is for the entire area of radar coverage, ignoring. the 3 km nearest the radar. The other intervals are from 4 through 75 km, 76 through 150 km, 151 through 230 km and 4 through 150 km, respectively. 10