Of hot and cold and 250

The top panel of the figure above shows the past 7 days of temperature measurements taken on the roof of our building here at the university. It reads right-to-left, with newest measurements on the right (and obviously, oldest on the left). One neat automatic calculation is the 24-hr comparison: on the right-side of the top panel, it shows how much warmer or colder we are than the same time 24 hrs ago: dT(24h)= xx. Yesterday was really warm, the warmest we've been in at least a month. The max temp was somewhere near 23C, or about 73F. We were really dry during the day (with RH less than 20%), and because we were also cloud-free, the temp plumetted after dark, reaching a low of around 3C (37F), one of the coldest we've been in the past month. The diurnal range was impressive: 20C, or 36F, in one day. (It's like having a high of 80 and a low of 44). We reached saturation rather quickly this morning which resulted in a thick layer of fog that burned off around 10 a.m.

The dT(24h) is around -11C, which is a little puzzling considering I'm not sure we've had a change of airmass. I note the mixing ratio, measured by the black line in the middle panel, scaled by 10 [so the most recent mixing ratio was ~ 6 g/kg], barely changed. I guess it's possible that around 6 pm on the 16th the airmass changed: the mixing ratio did bump up from 4 to 6 g/kg, the pressure started rising, and of course the temp dropped quickly.

Fellow meteo readers, what do YOU think? (if you're reading on Facebook and can't view the figures, surf to http://bradbarrett.blogspot.com/2008/06/of-hot-and-cold-and-250.html ) Below, I've included the plot of wind speed (top 2 panels), direction (middle panel), and direction standard deviation. Because of our location in the central valley, our winds are normally either northerly or southerly (rarely easterly, which would imply a strong downslope component).

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This post is my two hundred and fiftieth post! Thanks, loyal reader, for hanging with me through them all! Here's to much more!