Road temperature forecasts for this event (Fig. 10.61) were within about 1 to 1.5C for
both the RWIS site and Segment 3 prior to and during the first snow event. Between the
two events the road temperature forecast were about 2C too low, probably due to the
overestimate of cloud cover during this period. Recall that the observations indicated
clear skies, while the forecasts predicted broken skies. For the second event the road
temperatures were again within 1 to 2C.
A comparison of errors and biases between Ames and the entire forecast domain (Figs.
10.62 and 10.63) shows that for this event, the errors at Ames were fairly typical. Cloud
cover forecasts were error prone across the domain in the 0-9 and 27-42 hr ranges,
especially at Ames. Air temperatures were a bit too warm across the domain just before
the snow began, and more so at Ames
Road Temperature Comparison for Mar 15, 2004
20
AMW RWIS OB
AMW RWIS wFSL
AMW RWIS woFSL
AMW OB
SEG 3 wFSL
AMW OB
SEG3 woFSL
15
10
5
0
-5
6 8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 16 18 20 22 0 2 4 6
Mar 17, 2004
Mar 15, 2004
Mar 16, 2004
Fig. 10.61. Road Temperature (C) time-series plot comparing the Ames
RWIS observations to the RWFS forecasts (both with and without the FSL
supplemental models) for the RWIS site and segment 3. The vertical lines
represent the time period that the Ames METAR was reporting falling
90
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