
But this is exactly what CC predicts, it’s not about a uniform change but about disrupting the upper atmosphere circulation patterns. Destabilize the jet stream and let it wobble and there you go. That is what we are seeing.
The dynamic character of an enstrophy-based diagnostic, previously used in the study of atmospheric blocking, is examined here, in near-term future simulations from the Institut Pierre Simon Laplace Climate Model version 4 (IPSL-CM4) and version 5 (IPSL-CM5) climate models of the Northern Hemisphere flow for moderate climate change scenarios. Previous research has shown that integrated regional enstrophy (IE) increases during blocking onset and decay, which is a reflection of planetary-scale instability. In addition, IE has been shown previously to increase during flow regime transitions in general, even those not associated with blocking events. Here, a 31-year IE diagnostic time series is examined for changes in short term (5–40 days) planetary-scale variability that may correspond flow regime changes in an increased carbon dioxide environment. The time-series analysis herein indicates that the IE diagnostic provides evidence for approximately 30–35 atmospheric flow regime transitions per year in a warmer climate, which is similar to that of the control run and the latest 30-year observed climate, as derived from re-analyses. This result has implications regarding the predictability of weather in a warmer world.
and yet 1/2 way around the globe Calgary is freezing in -20s & -30s which are 20 deg below normal.
jawagord wrote:Newfie I don't know how anyone, especially a Canadian could believe your comment unless they are a Micheal Mann disciple and totally deluded, look at the past weather history of Calgary. The current weather variability is the same as past weather variability before "climate change". Natural variability swamps any of man's influence on weather and climate.
Tuike wrote:This winter is super mild. Barely any sub zero C temps. I watched weather forecast from tv last evening and the meteorologist said the temperature is 10C above average. Climate change switched to turbo boost.
jawagord wrote:Newfie I don't know how anyone, especially a Canadian could believe your comment unless they are a Micheal Mann disciple and totally deluded, look at the past weather history of Calgary. The current weather variability is the same as past weather variability before "climate change". Natural variability swamps any of man's influence on weather and climate.
From 2019's - last year's Calgary cold snap:
Most of southern and central Alberta remain under extreme cold warnings.
"Skies are forecast to clear tonight for many areas, especially over eastern and central regions, allowing temperatures to plummet," the agency said on its website.
There's nothing really new about it being super cold in Calgary this time of the year.
Here's a look back at how people in Calgary have endured — and enjoyed — our frigid winter weather as far back as the late 1800s.
https://www.cbc.ca/news/canada/calgary/ ... -1.5014229
yellowcanoe wrote:jawagord wrote:Newfie I don't know how anyone, especially a Canadian could believe your comment unless they are a Micheal Mann disciple and totally deluded, look at the past weather history of Calgary. The current weather variability is the same as past weather variability before "climate change". Natural variability swamps any of man's influence on weather and climate.
You need to look at data over long enough periods to average out natural variability and identify any actual increase in average temperatures. David Phillips from Environment Canada did just that for Ottawa. He took weather records for the last 70 years and computed average daily high and average daily low for ten year periods. For the first four ten year periods there was no significant variation in the average highs and lows. For the last three ten year periods the average temperatures were consecutively higher. It only confirms what was becoming more and more obvious -- while we still get periods in the winter and early spring where temperatures are well below normal the general trend has been for temperatures to be higher. As a cross country skier I really notice the change -- I used to be able to get through the entire winter using waxable skis with some type of fresh snow hard wax. Now I use waxless skis almost all the time because the snow conditions are usually not ideal for waxing. It's a pretty dramatic change considering that for the first 20 or so years of my skiing career I didn't even own a pair of waxless skis!
jawagord wrote:
Canoe I'm trying to determine if your anecdotal stories are supporting Newfie's "climate change is distorting the Polar Vortex causing cold snaps" theory or deflecting away from it? Or is it Ottawa is getting warmer winters and also getting more cold snaps, the old have my cake and eat it to meme?
jawagord wrote:As an ex-skier I'm thinking waxless skis must be an improvement over the old waxmore skis, no more measuring snow temperatures and picking from a palette of wax colours?
Extreme cold weather at this time of year in Southern Alberta is certainly not unknown in the past but I think Western Canada has also seen periods in recent years where the jet stream has locked in place resulting in an unusually long period of cold weather.
Jennifer Francis, a Rutgers meteorologist, is a researcher of Northern upper air patterns. She is very level headed, pragmatic, and not prone to exaggerate.
No significant decrease in planetary‐scale wave phase speeds are found except in October‐November‐December, but this trend is sensitive to the analysis parameters. Moreover, the frequency of blocking occurrence exhibits no significant increase in any season in any of the three reanalyses, further supporting the lack of trends in wave speed and meridional extent. This work highlights that observed trends in midlatitude weather patterns are complex and likely not simply understood in terms of Arctic amplification alone.
Synthesis
Whether recent Arctic surface warming and sea ice loss has significantly impacted the midlatitude jet-stream is still a topic of much debate. The weight of evidence suggests that if there has been Arctic influence on the midlatitude circulation to date, it has probably been small compared with internal atmospheric variability. It is our opinion that no study (or set of studies) has sufficiently demonstrated a significant Arcticinfluence on the jet-stream and that many alternative hypotheses exist that can account for the observed variability that are well supported by fundamental atmospheric dynamics theory and model experiments.
Tanada wrote:Northwest Ohio has had a very mild winter this season with far more rain than snow. Today is January 14 and the ground has yet to form a solid frozen frost crust. Typically we would have frozen over in early December meaning this season is running five to six weeks behind average.
Return to Environment, Weather & Climate
Users browsing this forum: No registered users and 15 guests