As many of you have been discussing all day, we have a shot of chilly air (at least for this early in the season) headed towards us for the last few days of the week. A deep trough of low pressure drops well down into the Western USA Thursday and Friday. This is unusually far south (and deep) for this time of year. Yes, I went back and looked at the first half of October 1985. We have a neat little program that shows 500mb, 700mb, 850mb, and Surface maps, plus all the COOP data. Well, the pattern around the 8th is almost exactly like this upcoming pattern. I see the temp dropped to 30 at PDX and 22 at Hood River with the dry offshore flow behind the trough. I'm getting old and conservative, so went with a low of 35 for PDX Saturday morning. It sure could be lower. Skies have to clear out, dewpoints have to drop at least close to 30, and we have to keep the east wind from picking up too much. Looks like that MAY happen.
As the trough drops in, I'm really thinking Thursday will be a very chilly day. We're forecasting only 54 for now, which would be a record low maximum for the day. Strong onshore flow and a disturbance moving inland midday should keep us cloudy most or all of the day. Snow should stick down to around 3,000' by Thursday evening too. Wow, is it time to send reporters up to Government Camp to cover OCTOBER SNOWSTORM '08? I'm exhausted just thinking about it…Mark Nelsen