After a nearly Hot Finish to the week, a Cooler Weekend Arrives–but No “Polar Vortex”September 2nd, 2014 at 11:03 pm by Don Paul under 4 Warn Weather
Aside from the Farmers Almanac and a certain private forecasting company’s hype, along with a newspaper article or 2, there is still no sign of any lengthy period of prematurely chilly weather through the 17th of September. I chose that date because that is the limit of the time range (as of this posting) of more reliable global models for forecasting temperature patterns which are of some use, with some reliability. By Thursday and Friday this week, summery temperatures will be back. Readings will be well above average for that time period. Following passage of a cold front Friday night, weekend temperatures will fall back to several degrees below average. In fact, the average high in early September is around 76, so we won’t be too far off the mark. During a near sultry Friday, another cold front will be crossing the Great Lakes and may trigger some scattered showers & tstorms in the afternoon. This activity will become more likely in the late afternoon and evening, and we’ll have to monitor some of those tstorms for intensity. Lingering showers behind the cold front may mar a portion of Saturday. There is uncertainty how long the showers will hang around before drier air pushes in from the west during the afternoon…they’re more likely to linger longer south & east of the metro area. Sunday is more of a sure bet, with dry & seasonably cool air in place, and abundant sunshine likely. Temperatures will slowly edge up during early and mid week, next week. Readings should again be above average by Wed-Thursday, when shower chances will increase again. Somewhat cooler (but NOT cold) air may return by the following weekend.
As for “what’s shakin’” with el nino (this section is for more technically oriented bloggers), key nino region 3.4 has seen an increase to 0.4 degrees above average over the last 2 weeks, which is still .1 degree shy of an earlier peak of 0.5 degrees for an SST anomaly. In any case, ENSO is still neutral at this time–that is, there is no el nino threshold being passed, aside from the necessary 3 months duration of 0.5 degrees above average for el nino conditions to be accepted as ongoing. Probabilities are still at 65% for el nino conditions to develop by early autumn into early winter, down from earlier modeled estimates of greater than 70%. Most ensemble members favor a weak el nino when it develops, but a moderate el nino remains possible (and a relatively small minority of model members show this).
All that aside, much of the warming over the last few weeks is due to the downwelling/warm phase of a Kelvin wave which–eventually–will be followed by some degree of an upwelling/cool phase of that wave. Now, back to general interest for any readers, not just the technically-oriented.
I found it unfortunate that our best and only daily local newspaper chose to publish more nonsense about an utterly unscientific Farmers Almanac winter forecast which I saw while I was on vacation. We may end up having another colder than average winter in the east, but no one has shown reasonable forecasting skill in this time range, under these conditions, to make a scientifically based winter outlook. As silly as the Almanac forecast is, it is even sillier this year, showing cold to colder than average temperatures across the entire lower 48 states. Owing to the ridges and troughs (undulations in the polar jet stream) such near uniformity in cold temperatures across the entire country is all but physically impossible. That’s just not the way the jet stream sets up over any extended period. Personally, I even found some of the rebuttals to this junk hype to be overly tepid, including some remarks from some NOAA people that the Farmers Almanac “might be wrong.” That’s giving them entirely undeserved credibility. Like blind choices in a multiple choice exam, when the F.A. is right, they’re right for the wrong reasons. And they’re wrong, they’re wrong for the wrong reasons. Junk, period.