Posted 6/11/2019 13:37 (#7553388) Subject: Historic Noctilucent Cloud Outbreak = Early Fall Frost?
North Central Oregon
Not sure how many of you noticed the Noctilucent Cloud (NLC) outbreak Saturday and Sunday Nights. NLC's are formed by meteor smoke mixing with ice crystals essentially at the edge of our atmosphere, 80+ kms altitude. They also correlate to low solar activity. This outbreak was historic because NLCs in the northern hemisphere are normally seen at 50 degrees North and higher. Occasionally in years where the atmosphere is cooler they can be seen into the mid 40 degree latitudes. I have seen them two other times here at 45N in 2008 and 2011. This year's outbreak was unprecedented though in that they were seen into the mid 30 degree latitudes. Observers in Central California and Oklahoma snapped pictures of NLCs over the weekend.
I went back into my weather station data for those years and Noticed that in 2008 and 2011 we experienced earlier and more frost days. We average 2 frost days usually in the closing days of October here and in those years the first frost days were in the first week of October and we had 10 in 2008 and 8 in 2011. I was wondering if anyone else had long term weather station data that could look at those years and see if they experienced a similar early onset to the fall frost season.