~Last few later winter circulation pattern vanished.
~North Hemisphere current prime CTNP has been anchored North Central Siberia for a long time
~2021 spring summer weather will of course be different in many locations.
At present, the great Canadian Archipelago Spring CTNP (coldest vortice) has a hard time establishing itself, largely because there has been a constant streaming of North Pacific warm cyclones destroying its formation, on every 2 or 3 days of build up this vortice gets banged up by cyclonic heat advection. As a result Siberia has dominated as CTNP prime region, shifting the entire circulation picture of North America, from mainly cold to much warmer:
NOAA daily composite March 1 to 17 picture at 600 mb temperature, roughly the weighted temperature of the entire troposphere, has morphed from, 1977; when the North Pole was CTNP prime vortex, 2012: by continental split vortices, very bad for sea ice, 2016; very strong El-Nino year , again with the spit cold temperature vortices, 2020, really 2018, 19, 20 dominant Archipelago CTNP.,to 2021 the North Pacific flow year so far. Basically if this continues, and there are no signs otherwise. It will be a dry summer for much of North America, particularly mi-west eastwards. What really matters for California coastal fires is the green to yellow threshold, basically the jet stream hangout region, in 1977 it was close to Mexico USA border, now well to the North. The early preliminary tentative outlook is for very warm weather to come, refraction measurements of vertical sun disks also suggest this will be warmest year in history yet again. WD March 21 2021...