The blowing snow algorithm did not exist when this case took place, but post-analysis
runs indicate that low-level (1 out of 3) blowing snow alerts would have been given for
the Ames area (indicated for I-35 N (closest road to US-69 N), US-30 and US-65 N) from
the start of the run (18 UTC on 9 February) to 22 UTC on the 10 February. The alerts
were based on snow which fell 13 hours before the RWFS initialization time, adequate
winds (4-7 ms-1; see Fig. 10.33), temperatures which did not exceed freezing
(Fig. 10.32) and a lack of observed or forecast liquid precipitation (Fig. 10.31). The low
level of the alert was based on relatively meager wind speeds near Ames.
A comparison between forecast errors at Ames and for all of Iowa for the 18 UTC, 9
February RWFS run reveal that errors were relatively large at Ames (Fig. 20.34). This
was especially true for temperature and dewpoint early in the run, though unusually large
errors were present throughout the domain at times near +12 hrs (6 UTC, 10 Feb). Bias
plots (Fig. 10.35) show that this was primarily due to significantly cold forecasts, like
those found in the Ames time series analysis (e.g. Fig. 10.28). Wind speed forecasts were
reasonable across the domain, while cloud cover forecasts were underdone early and
overdone late in the run.
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