Central PA Microclimate Strikes Again!

UPDATE 11/16: I tested my station last night with a thermometer probe inserted into the shelter of the thermometer. Although I was (by far) the lowest minimum in the area this morning, I've confirmed the reading.

ORIGINAL POST 11/15: Last night, calm winds led to a large temperature fall behind my house here in State College, Pa., and by 10:30 p.m., I was 19 F while surrounding stations were 34 (AccuWeather HQ) and 38 (KUNV airport - see map). That turned out to be my overnight low, while nearby stations barely dropped below freezing all night (map).

My reading was questioned on Twitter, but thermometers rarely read too low (usually too high) and mine is located in a field (NOT retention pond) that cool air drains into quickly when the wind stops. It's not unusual for me to run 5-7 degrees colder than AccuWeather HQ, a station which is about 50 feet higher in elevation than mine.

I wrote back to Matt and he confirmed that there was a lot of local variability last night:

So far today, I've topped out at 59 F which makes a night-to-day (diurnal) change of 40 degrees, unusual for this area, but this is the time of year to get them. On Nov. 13, 2010, I recorded a 48-degree diurnal change at my station, which is probably a record for my station. The low that day was 16 but the temperature spiked to 64 in the afternoon!

Here's a map of where the station is -- elevation falls through the yard and into the middle of the field. You can actually see the Davis weather station on my weather cam #5.