Warren Eckels
WGN weather tends to extremes
It seems to me that WGN's forecasts tend to be hotter in the summer than others. When everybody else said 94-96, they said 100. When other forecasts rose to 98, theirs rise to 101. When everybody caught up to them at 100, they jumped to 103. Unfortunately, this temperatures during this summer's heatwaves have tended to exceed forecast values, making WGN the best guess.
My guess is to go with the GFS (best record this year IMO) for the 850 mb temperature and simply advect dewpoints from the SSW. This would bring T850 of 25.0-25.5 C and dewpoints of 21.5 C. I added a conservative 14.8 C to T850, and got about 40 C or 104 F.
Now, the National Weather Service forecast calls for a T8 of 27-28 C, which is near the 1995 level. I hope they're wrong, since those seem to coincide with 41-43C (106-109 F) on the ground.
Update: The highest hourly reading at O'Hare (official reading, on NW side of city) was 102 F, at Midway (SW side) it hit 104 F. Dewpoints fell into the 60s over metro Chicago as temperatures soared, which kept the heat index under 110. Official high temperatures may be a bit higher when the NWS releases its 6-hour temperature data.
It seems to me that WGN's forecasts tend to be hotter in the summer than others. When everybody else said 94-96, they said 100. When other forecasts rose to 98, theirs rise to 101. When everybody caught up to them at 100, they jumped to 103. Unfortunately, this temperatures during this summer's heatwaves have tended to exceed forecast values, making WGN the best guess.
My guess is to go with the GFS (best record this year IMO) for the 850 mb temperature and simply advect dewpoints from the SSW. This would bring T850 of 25.0-25.5 C and dewpoints of 21.5 C. I added a conservative 14.8 C to T850, and got about 40 C or 104 F.
Now, the National Weather Service forecast calls for a T8 of 27-28 C, which is near the 1995 level. I hope they're wrong, since those seem to coincide with 41-43C (106-109 F) on the ground.
Update: The highest hourly reading at O'Hare (official reading, on NW side of city) was 102 F, at Midway (SW side) it hit 104 F. Dewpoints fell into the 60s over metro Chicago as temperatures soared, which kept the heat index under 110. Official high temperatures may be a bit higher when the NWS releases its 6-hour temperature data.
