Tuesday, September 30, 2014

How things look to be heading for winter 2014-2015.

Here are some of the current conditions and the way things look to be unfolding at this time.
Teleconnections and sea ice:
Refer to the above image, for content below

We've had some early season snowfall in the Rockies and Plains. In fact the northern Rockies will be seeing more today and tomorrow.  This is not abnormal ...the pattern is shifting to a fall one, with cold air draining in from Alaska and Canada.

There is warming going on across the equatorial pacific.  But we also have cooler SSTs in the southern hemisphere from the middle Pacific to the central South American Coast. 

The trade winds are falling off in the Pacific and the signs do point toward a  strengthen El Nino.  I do feel we will see El Nino declared sometime in October. 

An El Nino would strengthen the southern jet...which would allow more moisture move into the Northeast.

The PDO which involves the water south of Alaska and the Pacific Northwest.  The SSTs here are very warm.  Temps are 5-7 degrees above normal south of Alaska.  Normally when we have a El Nino the SSTs off the Pacific Northwest are cooler.   We have a positive PDO when the SSTs south of Alaska off the Pacific Northwest are warmer than average.

This setup would indicate a strong ridge over the west coast , just like we saw last winter.  This would  funnel in cold air over the Eastern US.

SST's over the north Atlantic are showing a pattern that would support the idea of a negative NAO setting up this winter.... There are warm SSTs south of Green land , cooler water south of that, and warmer water over the tropical Atlantic .  This is called the Tripole method,  because it is based upon  a warm and cold  sea surface temperature anomalies occurring in a  particular pattern. Normally we see this pattern this time of year, we're going to see a - NAO.
But that's not set in stone, NAO, PNO EPO... all change weekly so we would will have to see how the trend goes. 

For October I think we're going to see cold outbreaks and  warm outbreaks throughout the month.

Pacific blocking which would induce cold air outbreaks from Alaska and the Northwest Territories for late fall and into the winter of 2014-2015.

Sea Ice:

Sea Ice extent is also pointing to a chance for a cooler winter . Arctic sea ice reached its minimum extent on September 17, 2014  (1.94 million square miles). The ice extent will now climb through the rest of autumn and winter. Though the extent of sea ice is higher than the record low of 2012, it's the sixth-lowest extent record since satellites started measuring the Artic in 1979. 

Normally, sea ice keeps heat energy from escaping the ocean and entering the atmosphere. When there’s less ice, more energy gets into the atmosphere and weakens the jet stream. The Polar Jet helps keep the cold polar air from wandering south. So as we saw last winter the cold air breaks off, allowing small pieces of the polar vortex to move south into the CONUS.


The way El Nino looks to be heading is weak to moderate...as I indicted in my last post on the ENSO ....I feel this will be a weak El Nino.... Along with the sea ice extent and possible seeing a negative NAO

Would further indicate the odds for a colder than average winter across New York State, Pennsylvania, Mid Atlantic, and western and southern New England...Northern Maine and New Hampshire look to see more in the way of average temperatures.    

Looking back  when we have a +PNA/-NAO ...Northeast winters are often cold with drier conditions....But when we have a weak El Nino winter precipitation is above average...... So if everything keeps going the direction it's heading ...we would see  an equal chance for average or slightly above average winter precipitation this winter.

This far out, winter outlooks are only marginally better than reading tea leaves . So this is only how things look at this time....... I will  release my official winter outlook late late October, So stay tuned.

No comments:

Post a Comment

Thank you for taking the time to comment, I will answer as soon as I can.