Western North America on the long term 29th Jan

Hello everyone, sorry it’s has been so long since my last update. But now we are going for an in depth look at the long range models and drivers, that forecast the weather. Let’s get right into it….

13-15 Feb

GFS shows a disturbance across the US West Coast, that brings precipitation across the Southwest and into the UT/CO Rockies on the 13th. An associated trough hits Tahoe and the PNW that night, which I expect to move inland over the 14th and 15th. EPS Control favours a trough hitting the BC/PNW on the 11th and 12th, with lingering light snowfall over the 13th in the Inland PNW.

19-24 Feb

EC Monthly shows light snowfall for higher elevations around Tahoe on the 19th, before a strong front brings heavy snowfall to the PNW/NoCal on the 20th. Another front on the 21st, with moderate snowfall for the PNW and very heavy snowfall for Tahoe. The system moves inland over the 22nd towards UT/CO/WY, before going further south towards AZ/NM on the 23rd. The system dissipates around the 24th morning. Apart from some light snow showers intermittently over the Rockies, CFS shows nothing of note in this period.

23-25 Feb

Another front on EC Monthly hits the PNW and the BC Coast on the 23rd and 24th, bringing moderate-heavy snowfall. The system weakens as it hit the Rockies, with light snowfall for the US Rockies on the 25th, before disappearing later that day. CFS shows moderate-heavy snowfall for Tahoe, the BC Coast and the PNW over the 24th and 25th, thanks to a strong system coming in, but it fails to cross into the Rockies much.

Climate DriversThe Stratosphere continues to weaken over the next 15 days on EC and EPS, with the polar vortex warming several times. This should favour an increasing -AO outlook, that favours the Eastern US for more snowfall.

The EC46 shows the AO to be negative for mid February, before starting to go more positive for the late month period.

CFS on the other hand, shows a -AO outlook until Mid March.

The AAM(Atmospheric Angular Momentum) is currently going positive towards a more +AAM budget. This is caused by more Frictional and Mountain Torque, particularly the Rockies and from East Asia. This improves the likelihood of snowfall events for the Western half of North America, by strengthening the North Pacific jetstream.

The MJO is moving into the Phases 6 and 7, as a very strong signal. Then EC Monthly shows it weakening later in February, in Phase 8, thanks to La Niña. These phases favour snowfall for the Eastern US, but the MJO weakening opens up oppurtunity for the Western US.

So Mid February looks like the Eastern US’s turn, with MJO favourability and a weakening polar vortex. But the positive AAM could create some oppurtunity for the West Coast. Interesting times, as we head towards busier times in US and Canadian resorts. Late Feb could be better on preliminary outlooks, you will need to tune in next time….

Thanks so much for reading. I hoped you enjoyed reading it.

Disclaimer: There is low skill asssociated with using long range model forecasts to find snow systems. All systems you see here will change, as the date gets closer and may not eventuate all together. I don’t give much accuracy to these forecasts, but you can give these a bit of your time and your dreams might come true 😉 I find the chase of these long range snow systems awesome, so come and join me! The climate driver forecasts tend to have a bit more skill than the model forecasts, but certainly don’t put all your money on them. However, climate drivers are an awesome tool to explain the weather around us.

Thanks again for reading this North American long range snow forecast, follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above.

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