Latest update here the first week in September:
The atmosphere is already in a weak La Nina mode. The official La Nina is a lagging indicator.
By metmike - Sept. 3, 2025, 3:48 p.m.
The map below is from the last 12z GFS operational model at 500 mb (18,00 feet) for Thursday morning. That deep low just north of Lake Superior is a huge piece of THE POLAR VORTEX!
We can see a huge kink in the lines, along the ND border with Canada from a strong perturbation/reinforcing wave with the colors representing powerful, positive vorticity(spin) associated with it. It's a strong reinforcement of this very chilly air that is rotating around the backside of the main/parent Low just north of Lake Superior.
This is more like a Winter pattern.
Here's the 250 jet stream(33,000 feet). Note it diving straight south/southeast, transporting air from much higher latitudes/the Arctic to the mid latitudes. The small pink color embedded within the jet stream represents a 150 mph jet streak!!
The piece of polar vortex at this level is also seen just north of Lake Superior.
A jet stream like this in 3+ months means brutally cold temps and a major Winter storm east of the trough line and/or associated with the lift from the jet stream dynamics. We can make out that kink in the isoheights that is northwest of the 500mb level, now much higher up, around the Alberta/ Saskatchewan border in Canada!
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Global temperatures August 2025
Started by metmike - Sept. 3, 2025, 7:34 p.m.
I'm betting this is WRONG because it doesn't fully show the La Nina signature but nobody gets long range forecasts right most of the time.
When we have a STRONG El Nino or STRONG La Nina, it does in fact increase forecast skill a great deal. This La Nina will be WEAK.
Here's the last NWS Winter forecast. MUCH different than above because they use the La Nina for much of their reasoning!
https://www.cpc.ncep.noaa.gov/products/predictions/long_range/seasonal.php?lead=4
