Say hello to my next outlook for North America, enjoy…
We see Alaskan ridging develop on EC Weeklies, with a Western US a troughing pattern and a Eastern US ridging pattern angled in from the North Atlantic.
Similar scenes of Alaskan ridging – Western US troughing – Eastern US ridging in this particular period.
The strong Western US trough weakens, along with the strong +AO/+NAO, yet there remains two dominant ridges on the East Coast and south of Alaska.
Then comes the school of thought, that shows the Alaskan ridge starting to suppress snowfall for the PNW/BC region, with more snowfall for the SW. The East Coast ridge dominates the central and eastern parts of the US.
30th Jan – 3rd Feb
The -EPO (British Columbia) ridge weakens snowfall for the Northern parts of America. A SE ridge weakens snowfall chances for the East Coast except in New England.
Again ridging dominates over the PNW, and much of the East Coast as well, with the best snowfall in this period to be found in the SW states and in New England.
We are currently seeing some sort of Phase 7-8 MJO influence, which is giving a bit of a helping hand for the Eastern US over the next 10 days or so. It’s also behind the -SOI drops, that have been seen going around.
A dominant Indian Ocean suppresses a significant pattern change in mid-January. So more of the same really, a weak winter in the Eastern US and a decent winter in the Western US.
We may see conditions improve for the PNW, but we also need to be wary of incursions of ridging in the Aleutian region towards the West Coast.
We see signs of a more dominant Western Pacific in late January, which would improve conditions in the Eastern US for February.
We are currently in the positive phases of the GWO, which gives us some moments for troughing in the Eastern US, and then you get a -EAMT > Aleutian ridging > Western US troughing > Eastern US ridging regime for much of January.
We have GWO Phase 5, but that will head to Phase 8 in the next week, and then go for another orbit in the neutral/negative phases in the first two weeks of January. Then you have to wait for the next orbit of the GWO probably later in January and early February to see more positive values for the GLAAM.
This is likely to lead to reasonably good conditions for snowfall in the first 10 days of January for the Eastern US, before Aleutian ridging and a reduction in momentum makes conditions less suitable for the majority of the rest of January for the Eastern US.
This is likely to bring upon Western troughing for the middle two weeks of January, with potentially the best snowfalls in the PNW and in British Columbia, but still reasonably good potential in the Rockies and the Southwest.
Like the EPS modelling acknowledges, there is potential that the Alaskan ridge reaches over into the BC/PNW region later in the month, and to therefore suppress snowfall there.
Stratosphere and Arctic Oscillation
The stratosphere is pretty neutral, and the best chances of a SSW are further down the road.
The overall model consensus is that the Stratospheric Polar Vortex is likely to strengthen over the next two weeks. There is a still a good chance for a SSW in February however, just not during the current climatic conditions.
This is keeping a +AO intact, which is reducing the chances for Eastern US snowfall, and increasing the chances for Western US snowfall.
EC Weeklies are forecasting a consistent positive Arctic Oscillation through to February.
The main conclusions to draw here is that the Eastern US will have a decent chance in early January, then a weaker pattern for the rest of the month, with a potential improvement in February.
The PNW will find the next two-three weeks good, but lesser so later in Jan perhaps. The rest of the Western US will do fine, but it could get better again later in January.
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Disclaimer: There is low skill asssociated with using long range model forecasts to find snow systems.
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