Thursday, November 17, 2005
I See Light at the End of the Tunnel...Eventually
In regards to this stubborn and surprising Blocking Ridge, as all of you know, this has been a popular subject in our discussions and will continue to be so as time goes on. Now, looking at the latest Euro and GFS, models break down the Ridge by the end of next week. So expect a pleasant thanksgiving week. This will be a tough ridge to break through and it is fairly unlikely but not unheard of for this kind of pattern to occur while we are close to a La Nina like state. Although other opinions say otherwise, looking at all the other indices such as the SST, NAO and others seem to discount the likes of such strong ridges. But it is not uncommon, such that Brian, a daily reader of the blog brought up to me that Seattle experienced a strong ridge like this in 1995 and look at what happened later that year (Snow Events and Severe Flooding). So this may be a derterrant for now, but I still expect a fairly good winter with good cold outbreaks, and maybe for extended periods at times? We will keep an eye out on this. Also in the news is the fact that we have not had fog in the morning as predicted. Why is this? Well honestly..I don't know. Something I am going to research right after I get done, which is, well right now. Take Care!
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Looking back at a some of the consistently coldest winters in NW Oregon and SW Washington, 1949-50 and 1985-86 actually stand out with similarities to this season so far. Both of these years had very mild preiods, most likely assoicated with anomalously strong high pressure ridges, in the month of November. In fact,the November of 1949, before one of the coldest winters ever recorded in Portland, was actually quite dry and mild, with temperatures in the mid and even upper sixties for the first six days of the month and temperatures remaining well above normal the entire month. Same with November 1985. Just weeks before the notorious Thanksgiving cold snap and snowstorm of '85, PDX was basking in temps in the mid sixties for consecutive days. This leads me to wonder, do mild November spells mean a sudden plunge in temperatures to come? Well this has been the setup so far this year, and by the looks of it was probably the same in 49-50 and 85-86. Zonal flow through October and some of November allows arctic air to beome bottled up to the north and grow colder and colder. Check out the temps in Fairbanks the past couple weeks if you don't believe me. Suddenly, a ridge pops over the west, dislodging this icebox and bringing chunks of it down over the east. After this ridge sits over us for a couple weeks or more, giving a dry, mild period, like we're in now, retrogression occurs and bam, we've got ourselves a ridge out over the mid-pacific, directing on its western flank airmasses of arctic origin straigt from the Yukon to the Northwest. By the looks of it this is what happened by the end of November '49 and '85, and it may happen again by the end of November '05. Check out the latest GFS and accuweather.com forecast for Portland for the weekend after Thanksgiving. Snow, highs in the thirties? Food for thought...
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