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.
Conclusion:
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.