Thursday, January 27, 2011

Suprisingly Mild This Morning

East winds set up during the early nighttime hours across much of southeastern Arizona, leading to low temperatures this morning that were 10 to 15F warmer than yesterday morning. Mike Leuthold noted yesterday afternoon that the WRF forecast was predicting morning temperatures considerably warmer than the NWS forecast was indicating. He sent the plot above that shows WRF surface observations for 7 am this morning (27 January 2011). It looks like the WRF was just a bit too warm but quite close, and captured the 24-hour change very nicely. Some observations this morning: here at house at 7am 45F with a nighttime low of 34F (versus 22F yesterday); TUS at 7am was also 45F with a nighttime low of 43F. Douglas changes were quite interesting: 29F at 7am today versus 16F yesterday morning at 7 am! However a few spots were about the same as yesterday, or even a bit cooler, as per the RAWS observations at: Mt. Hopkins, Rincon, Empire. This warming event indicates, again, the difficulty of low temperature forecasting across southeast Arizona, especially when there's a large-scale pressure gradient favoring easterly winds during the night.

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