Sunday, August 1, 2010
Inversions and Diurnal Ranges
With growing early morning inversions, diurnal ranges in the nighttime cool spots are growing too. Amongst the cooperative observations, Clear Sky Lodge, on the Parks Highway south of Anderson had a 40F spread on Saturday, 42F to 82F, and Chena Hot Springs made 81F Saturday, then back to 43F this morning. Goldstream Creek still looks like it's running a bit too warm for max temps, but for what it's worth, 86F Saturday, down to 43F this morning. Some RAWS have even bigger spreads, but these are artifacts of the too warm temps that RAWS run on brite sunny summer days.
In contrast, higher elevation ridge and slope sites are running diurnals of 20F or less. Here on Keystone Ridge, 78F Saturday, down to 58F this morning. The Nenana Hills RWIS at 1400' MSL had 78F Sat, 62F this morning, and the Cleary Summit RWIS, at 2200', had 75F Sat, 62F this morning. Note though that on RWIS platforms the thermometer is 10-15' above the ground.
Above is a plot of temperatures from Keystone Ridge and Goldstream Valley Bottom over the past day, illustrating the difference. Note that later times are too the left.