POP and QPF for Jan 16, 2004
1.8
AMW METAR POP wFSL
AMW METAR POP woFSL
AMW OB
AMW RWIS POP wFSL
1.6
AMW RWIS POP woFSL
AMW METAR QPF wFSL
AMW METAR QPF woFSL
1.4
AMW RWIS QPF wFSL
AMW RWIS QPF woFSL
1.2
1
0.8
break in the forecasted precip
0.6
0.4
POP Threshold
0.2
QPF Threshold
0
18 20 22
0
2
4
6
8
10 12 14 16 18 20 22
0
2
4
6
8
10 12 14 16 18
METAR/RWIS wFSL Start
METAR/RWIS w/woFSL End
Jan 17, 2004
Jan 18, 2004
METAR/RWIS woFSL Start
Fig. 10.8. Same as Fig. 10.4 except the 18 UTC 16 January 2004 run and
for probability of precipitation (%) and quantitative precipitation forecast
(mm/hr). The blue arrow indicates the forecasted start with FSL time at
the METAR and RWIS sites, the green arrow indicates the forecasted start
without FSL time at the METAR and RWIS sites, and the orange arrow
indicates the stop time with and without FSL at the METAR and RWIS
sites.
For this event the LEDWI data was unavailable. However, the hourly observations for the
ASOS tipping bucket gauge indicated a total of 0.45 inches of precipitation. The 12 UTC
RWFS run had comparable total QPF forecasts, including 0.39 inches with the FSL
models and 0.41 without the FSL models. However, had the predicted end time of the
event been closer to reality, the RWFS would have under-forecast the total precipitation.
The road temperature forecasts were within about 1C before and during the precipitation
(Fig. 10.9). After the precipitation ended, forecasts were too warm by as many as 5C
during the daylight hours of the next day. This is likely due to the fact that the cloud
cover forecasts (Fig. 10.10) moved out the clouds too quickly which resulted in a forecast
of greater insolation (solar radiation) for the road.
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