Western North America on the long term 17th Feb

This is the second last North American long Range Snow outlook. Welcome, and I hope you enjoy this analysis of the models and the drivers that matter for the North American continent.

2-6 March

EC Monthly shows a front crossing over the BC/PNW on the 2/3 March. A second front crosses onto the PNW/BC on the 4th, these two fronts providing moderate-heavy snowfall. The second front progresses into the Rockies over the 5th. This brings light-moderate snowfall to CO/UT, NoCal and Interior PNW. It leaves the Rockies by the afternoon of the 6th. GFS shows snowfall over the 2-4 March period, with snowfall over Tahoe and the PNW on the 2nd, progressing to snow in Utah and the Interior PNW over the 3rd and 4th, before clearing out.

6-9 March

On the 6th, another front is shown by EC Monthly to cross over the PNW/BC and brings moderate-heavy snowfall until the 9th. This system fails to move onto the Rockies, but brings a nice dump to the PNW and BC resorts. CFS shows light-moderate snow showers in Tahoe and the PNW on the 6th, as well as on the 8th and early on the 9th.

9-13 March

Later on the 9th, EC Monthly shows a front hitting California, bringing moderate-heavy snowfall to the Sierra Nevada. It weakens to light-moderate snowfall over the 10th and 11th, slowly moving towards UT/CO, and then moving towards the Interior PNW states on the 12th and 13th. By the end of the 13th, the last snow showers occur in Wyoming and Idaho. CFS shows a proper cold front crossing into California on the 10th, weakening to light snow on the 11th and 12th over CO/UT. CFS also shows moderate snow in the PNW/BC on the 11th, increasing to heavy snow on the 13th, with a proper front entering the landscape.

16-18 March

A fairly deep low on EC Monthly brings a huge front from Southern BC to SoCal on the 16th, bringing moderate-very heavy snowfall to all of the Western ski areas, except Interior BC. The low moves towards the Rockies over the 17th, and clears the Western states over the 18th, easing snowfall across the Western side of the US. CFS shows a system bringing moderate-heavy snowfall over the PNW/BC on the 16th, moving to moderate snow showers over the Interior PNW and CO/UT on the 17th and 18th, not weakening in the Rockies until the 21st of March.

Climate Drivers

The MJO is currently at Phase 7, and is forecast to weaken and go to Phase 8, and then go into the weak circle by GEFS. EPS shows a full progression of the MJO from Phase 7/8 to Phase 2, which would have a different impact, and one that supports the East snow-wise. So the GEFS shown above is the preferred option for the West.

The GWO is currently in Phase 7/8, which means it is losing atmospheric angular momentum(AAM). If the MJO moves to Phase 2, a further drop in the AAM is more likely. A drop in the AAM would bring less snow for the Western US.

The drop in the stratospheric zonal winds on the chart below, indicates a Sudden Stratospheric Warming event. This brings a -AO event, which favours more snow in the East.

The EC Monthly AO forecast shows a negative AO from Late Feb-Mid March, mainly from impacts of the SSW. As said before, this favours the East, compared to the Western US.

A summary of the long term situation is a battle between the SSW and AAM influences. If the AAM stays positive, that could help the Western US get more snow. This counters the SSW effect of less snow in the Western US. My opinion is less snow for the Late Feb-Mid March period, but still potential for snow outbreaks. Beyond that, it looks better, but Spring will weaken the chances of significant snowfall.

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.

2 thoughts on “Western North America on the long term 17th Feb

  1. Addicted to ur forecasts, checking the blog three times a day now, waiting eagerly for the European forecast which should be due any moment now 🙂 Once I see it will do my booking, as always 😉 Al the best….

    Like

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