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Thursday January 31, 2019

Assignment: Predict the 24 hr minimum temperature (deg F) for Rockford, IL (KRFD)

After historic low temperatures on Wednesday morning, it's possible that some locations will be even colder on Thursday morning. For example, the National Weather Service discussion from Chicago says this: "With the teens below zero starting point, see no reason why favored outlying locations in northern Illinois won`t reach or exceed the state low temperature record (-36F in Congerville on 1/5/1999) . . If RFD [Rockford, Illinois] does not set new all time record cold temperature Wednesday morning, it appears likely to shatter the record Thursday morning (our official forecast is now -32)." So let's forecast Thursday's low temperature in Rockford and see if they manage to break the all-time low temperature record for the state.

Question: There's one very important weather variable in the forecast for Thursday morning in Rockford that is predicted to change significantly from Wednesday morning, and that factor is mostly responsible for the chance of Thursday morning's temperatures being even lower. What is it?

Forecasts for Rockford, IL (KRFD)
Forecaster Tmin, deg F (error) Comment Day Score
GFS-MOS-18-DAY01 -29 (2) 2.7
GFS-MOS-12-DAY01 -29 (2) 2.7
GFS-MOS-06-DAY01 -27 (4) 2.5
GFS-MOS-18-DAY02 -27 (4) 2.5
GFS-MOS-06-DAY02 -27 (4) 2.5
GFS-MOS-00-DAY01 -26 (5) 2.4
GFS-MOS-12-DAY02 -26 (5) 2.4
PERSISTENCE -25 (6) 2.3
GFS-MOS-00-DAY00 -24 (7) 2.2
NAM-MOS-12-DAY01 -22 (9) 2.0
NAM-MOS-00-DAY00 -21 (10) 1.9
NAM-MOS-00-DAY01 -20 (11) 1.8
NAM-MOS-12-DAY02 -20 (11) 1.8
CLIMATE 14.2 (45.2) NCDC Climate Normals, 1981-2010 0