A powerful jet stream approached NM from the Pacific Northwest on February 23, 2016 and carved out a large scale upper level trough over the southern Rockies. Meanwhile, a strong area of surface high pressure raced southward down the front range of the Rockies and provided an influx of moist, cold air into eastern NM. Winter storm warnings were issued for several counties in northeastern NM with winter weather advisories in a few surrounding zones. Forecasters were eagerly anticipating how the event would unfold on the merged SFR product given the recent stretch of very dry and exceptionally warm weather. Figure 1 below is a Graphical Briefing issued prior to the event with expected snowfall totals.
Rain and high terrain snow developed from north to south late on the 22nd before transitioning to all snow early on the 23rd. Forecast models from the 21st indicated that an area of heavy snow would impact northeastern NM on the 23rd. Figure 2 shows a well-defined axis of higher snowfall rates stretching from Trinidad, CO to Capulin, NM and Tucumcari, NM in the stand-alone SFR product from 0912 UTC 23 February 2016. Sampling this area showed peak liquid equivalent values near 0.07″/hr. The 0900 UTC observation at Trinidad showed the visibility had fallen to 1/2 mile within the snow band while the observation at Raton, NM showed no snowfall where the SFR product had near zero values. Farther south near Tucumcari the observation showed unknown precipitation falling at a temperature of 36° south of the main snow band.
The following merged SFR image at 0940 UTC showed the area of higher snowfall rates persisting (Figure 3 (left)). A merged SFR product from 0950 UTC is shown to note the extent of the radar void area (Figure 3 (right)). The following stand alone SFR product at 1245 UTC indicated the higher rates had shifted farther south but were still impacting at least portions of this same area (Figure 4). In this example the observation at Las Vegas, NM was indicating snowfall with visibilities down to 1 1/4 miles while Tucumcari showed very light snow with no values on the SFR product.
Based on the peak values depicted in the SFR product and the persistence of the snow band in the area forecasters were anticipating snowfall reports in the 2 to 6 inch range. The Snow-Cloud RGB product later in the day in Figure 5 verified this area of snowfall very well (red shades). Spotters reports are overlaid on the RGB imagery. Feedback from forecasters during this event supported accurate observations of the SFR product during the transition from rain to snow as well.