Wintry pattern change coming by late next week
For any readers who want to know more about any potential rain tonight, as well as the weather for Friday and the weekend, check out our latest forecast discussion. There may even be some scattered showers and isolated thunder with a cold pool aloft, as mid-level lapse rates will be near 7C/KM tomorrow afternoon.
While our area sits in low level moisture and clouds, former Super Typhoon Nuri has transitioned into an extratropical storm, but is forecast to fall to pressures below 920mb! This would be one of the strongest extratropical cyclones on record.
This extremely strong cyclone will help to release plenty of latent heat and energy towards the Poles, which will generate an anomalously strong ridge in Alaska and western Canada. In short, as the extratropical system becomes a behemoth both at the surface and aloft, the strong jet stream and digging trough in the mid and upper levels create an anomalous ridge to their east, pumping a ridge from the West Coast into British Columbia. This ridge will be so strong that it will also flow into the Arctic, tanking the Arctic Oscillation. This allows the Polar Vortex to be weakened and sent to the south on the downstream side of the ridge.
Accordingly, forecast models are in good agreement that the Polar Vortex will split into two, with a piece sagging southward toward Southern Canada during the middle to latter part of next week.