Welcome back!  After my almost 3 month Summer vacation from weather it is time for us to start looking at the change in the season approaching next month and the potentials for early season snow.  Also we can start to put together some clues for the upcoming Winter. 

This time of year we tend to look at the Pacific Ocean surface temps to get an idea of what the pattern may look like going into Winter.  Right now through the Tropical Pacific the temperatures are fairly normal with ENSO neutral conditions.  That is with colder than average temps in the Eastern Equatorial Pacific and warmer further West.  Over the North Pacific we are still looking at -PDO conditions with cold water still along the West Coast.

In the immediate future we should see this cold trough that has been hanging around back off the coast with the ridge over the Rockies shifting towards the West Coast.  That will bring back warmer temps the second half of the month.  The long-range forecasts are hinting at the return of a trough in the beginning of September and even some precip making it into the Pacific NW.  Chance of a dusting up high?  Maybe, we'll have to watch as we get closer to September.

The long-range climate models have a warm and dry Fall forecasted overall.  The CFS starts to warm the water in the NINO regions towards El Nino conditions going into Winter, and warms the water off the West Coast.  The Jamstec is slower with the warming along the Equator and still cold along the coast. 

The difference in the pattern forecasted is the more neutral ENSO conditions and cold water off the coast is similar to the latter 2/3rds of last Winter.  We saw a trough from British Columbia down to the Pacific NW and we saw colder but dry weather here in Tahoe.  The warmer Sea Surface temp scenario shown by the CFS allows the subtropical jetstream to get involved and bring precip further South into CA.  It also would cause lower heights across the Southern U.S. with colder air Rockies East and warmer air for the West Coast.  The areas that saw all the precip last Winter would be drier than average to our North with more ridging in the Northeast Pacific. 

The latter scenario of the CFS is shown here in the latest December to February precip forecast.

I think the forecast for a slower warming of the equatorial waters has a lot of merit so we should be cautious about getting excited about the CFS forecast this far out. 

Normally I make a Winter prediction in October.  I forecasted a big Winter 3 years ago and below average Winters the last 2 Octobers.  3 for 3 so far so I'm hoping the formulas I normally use come up with some good analogs for this Winter.  Even an average Winter would be better than what we saw the last 2 seasons.  There are a lot more signals factored in the Winter forecast than just the ocean temps.

It's too early to start putting together a Winter forecast but I thought I would give you what I know so far and what we'll be watching going into the Fall.  Many of you are starting to think about Winter already.  Another post later in the month to look more closely at September and any new data that may give clues to the upcoming Winter.

Stay tuned....BA