Winter Outlook 2018-2019

As a kid there were two things I looked forward to every fall….Sears & Roebuck catalog (the toys section) and the Old Farmers Almanac for their winter forecast. I was particularly impressed with their winter forecast being broken down into multi-day forecasts and the years when a snowstorm was forecasted around Christmas. While there is absolutely some science involved with their forecasts (Sunspot cycles), to break down winter week by week is impossible.

Enter JR into the Winter Outlook fray…..

While I won’t be able to break down winter week by week, I am confident the following will happen:

* There will be a big snowstorm (or three)
* At some point, temps will hit 60
* Twitter will be irate that both have happened

Where to begin? I think with any winter forecast, it’s best to start with the state of the tropical Pacific ocean for the upcoming winter. The El Nino-Southern Oscillation (ENSO). For this upcoming winter, it appears like a weak (perhaps moderate El Nino) will be in play. El Nino is a warming of sea surface temps (SST) along the equatorial Pacific.

This is not a classic El Nino tho, but rather what is known as Modoki El Nino (Modoki is Japanese for pseudo btw).

Say what?

Check this out….this is an example of a classic El Nino. Notice the warm SST’s tucked up against South America in the eastern Tropical Pacific.


Now with a classic El Nino, that typically does mean mild weather for much of New England during the winter as seen here:


That map is a composite for 3 classic (and strong) El Nino’s. Rather toasty.

Check out where those warm waters (SST) are located in a Modoki El Nino…

 

Notice much farther west toward the central equatorial Pacific and not as warm as a classic El Nino. Now take a look at what a Modoki El Nino means for New England temperatures during the winter:

That map is a composite of four Modoki El Nino winters. No sign of toasty feelings with that.

Next up…..The Blob! The blob is a reference to a warm pool of water located in the northeast pacific Ocean in recent years. It’s there again this year and really sticks out…

That blob was in a similar location back in late 2013 and lasted into 2015. It was one of the reasons (if not THE reason) for the cold winter of 2013-2014 (and subsequent cool summer 2014) for Eastern United States…

This warm blob has been show to promote High Pressure across NW Canada and Alaska setting up what is known as a positive Pacific-North America Pattern (PNA). Here is an example of what that looks like at the jet stream level..

 

 

Those warm colors located over western North America is the High Pressure system. That, in turn, funnels cold air out of western Canada and into the eastern part of the United States. This is expected to happen for the upcoming winter. It’s likely the jet stream will take on this configuration..

Again, rather chilly.

OK….so that’s the cold….what about snow? In El Nino Winters, classic or otherwise, precipitation is above normal along the southern tier of the United States and up the east coast. Here all all El Nino winters since 1982-83 with precipitation…

 

You notice right along the east coast, above normal precipitation..you also notice below normal precipitation across northern New England. That is a signal of some of the juicier storms missing northern New England. What about our friend Modoki El Nino?

Again, you can see above normal precipitation up along the east coast. IF the cold air is present, it is understandable to advertise above normal snowfall (conversely, if cold air is lacking—and for some storms it will, then rain would be the main event).

There are some Wildcards to take note of as well. First up…what about all this rain?! Will there be any moisture left in the storm track pipeline for winter? It is a valid question and wet falls do tend to transition into a dry winter (in terms of snowfall) but I was curious to see if a dry fall meant snowy winters…Nope. Of the 10 driest falls for Boston, 8 of them went on to produce below normal snowfall. Also, with that El Nino signature present this winter, moisture should be available for the storms.

Next up is what is known as the Madden-Julian Oscillation. I won’t bore you too much with detail but essentially it is a planetary wave that travels across the tropical portion of the world. The atmospheric wave can enhance precipitation and suppress precipitation, depending on its phase. The MJO can also influence the position of the jet stream across North America leading to enhanced warm and cold spells, depending on the phase the MJO is in. Knowing which phase the MJO will spend winter in is difficult to at best but for short term clues, look to Australia! When thunderstorm activity around Australia (ocean, not land) is low, the MJO is normally heading to a cold phase for eastern North America. When thunderstorm activity is enhanced, odds favor a non-arctic pattern for eastern North America. Looking at this recent satellite pic from Australia (Monday Nov 19th), that looks rather quiet.

Warmth is not likely for the next 1-2 weeks but knowing beyond that is nearly impossible.

The other wildcard is my old friend, the NAO..North Atlantic Oscillation. I have been following this atmospheric index for years now. The NAO also has multiple phases and greatly influences our weather here in New England. The Positive Phase often means mild weather, while the negative phase leads to cold and stormy weather. (Any guesses as to which phase the NAO is in right now…;o) ) First up the positive phase…

 

Next up, the negative phase of the NAO:

 

This NAO index is difficult to predict beyond 10-15 days. But looking into early December, it appears the NAO index will be staying in the tank as seen here..

Me thinks December is going to offer quite a bit of cold and snow. Ho Ho Ho.

OK…..so…..with all that….my thoughts on winter are:

*Cold….with variability but perhaps warm-ups more muted than past winters
*Stormy…Storm track up along east coast..some storm out to sea..some big hitters
*Snowfall above average with some cities & towns getting close to these numbers:

Boston 61.4”

Stow 70.4”

Worcester 80.3”

There you have it! See you next spring!

~JR