Back from vacation (which ended with my truck being towed on a flatbed) and it’s go time here as Winter is quickly approaching. You wouldn’t believe it with the weather lately. Reno had one of the warmest Septembers on record and we were pretty warm up here as well. Lot’s to go over here this evening and it’s all fun stuff filled with lots of pictures.

First the weather here will begin a cool down into the weekend. Highs in the 80′s will be replaced by highs in the 60′s. The ridge off the coast that keeps us dry all summer will begin to retrograd back allowing really cold air to pour into North America and cooler air all the way down to the Sierra. The Fall is forecasted to be cold this year as I posted on a few posts ago along with a shot of the Weatherbell Fall temp forecast. Here is the Accuweather October temp forecast and you can see we may flip from Summer to Fall really quick.

We should see the first snows of the season this week in the Northern Rockies, upper Mid-West, and maybe even the mountain tops in the Northeast. Here is the GFS snowfall forecast for this week.

There will be a cut-off low that will form off the coast and the forecast models are now bringing it slowly inland over Central CA by the middle of next week. It will be moisture starved, but it should be cold enough at the core to bring snow above 7,000 ft so maybe our first dusting.  Then the last few runs of the GFS have been showing the ridge shifting to just South of the Aleutian Islands which is where we love to see it in the Winter.  It has a cold snowstorm hitting us around the 17th.

That is still 2 weeks away but something to keep an eye on because in a weak El Nino year we do tend to get an early start to the snowfall before we fizzle out going into the Winter.  During the 06/07 season we had snow on Thanksgiving and then not much more until the middle of February.  We could see a cold and snowy Fall here before the El Nino split flow pattern sets up with the jet to our South and the other way up into Alaska.  One thing is almost certain, this will not be anything like the last couple years in the Pacific NW and could be really dry.

There does seem to be a little controversy as to where the Southern jetstream will setup this Winter.  During El Nino seasons it usually sets up anyplace between Mammoth and Northern Mexico.  In my Winter forecast from the last post I used historical averages that showed a lean towards a more Southern route to the jet with conditions similar to those forecasted for this Winter.  6 of the 8 years I came up with as analogs were below average snowfall, BUT 2 of them were huge years.

Paul Pastelok over at Accuweather just did an analog Winter forecast using some different years then mine, but coming up with a similar forecast.  He shows average snowfall for us with below average just to our North and above average in the Southern Rockies and up the East Coast which you would expect with the storm track coming in to our South and then East and North.

That also allows colder air into the Eastern CONUS.  We may start cold in the Fall but in El Nino Winters we tend to get a little warmer into the heart of Winter.  Here is the Weatherbell graph for this Winter’s temp departures from average.

So now onto the Winter snowfall forecasts that just came out from Accuweather and Weatherbell.  This is usually everyone’s favorite part of the Fall.  They both seem to have the storm track into Central and Southern CA, a bit furthern North than where I have it and thus show the above average snowfall a bit further North.  This may be from the Central Pacific centered El Nino this year and they also may not be factoring in the negative QBO which is what dragged down the snowfall forecast in my forecast.  If you take that out then historically my analog years would show that we will have 95%-105% of average snowfall.

Here is the Weatherbell snowfall forecast for this Winter.  I think he went a little too high here as it should be well below average in the Pacific NW.  Last year if you remember Weatherbell had us right on the Southern edge of the above normal snowfall.

Here is the Winter snowfall forecast for this Winter.  It’s a similar overall pattern forecast.  Last year they predicted an average snowfall season for us.

So now we will wait and see what Winter brings.  Obviously everyone bombed on their Winter forecast last year so hopefully this will be a redeeming year, or hopefully not in my case and we do get a big Winter.  For now I’m sticking with my forecast of 75%-85% of average snowfall with an early start to the cold and snow and then a more even spread out Winter.  I don’t think we will see too many of those 100″ weeks like in 2010-11, and hopefully no 6 week droughts like last January.

Stay tuned on the forecast for a possible dusting next week and possibly and accumulation the week after….BA


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