Teleconnections What the Heck Are They Part 3

 I have a confession. I had started this series a long time ago, but never finished it. A recent question on my Facebook Weather Page, led me to find I needed to finish part 3. So here it is.

This isn't designed to give you a complete understanding. It is only intended to give you a quick understanding of the processes involved; so you can have a better understanding of teleconnections, when you hear or see them used by myself and other weather outlets.

This is written  as simple and clear as I can make it. As always, I'm willing to answer questions to try and clear up any confusion. Here are links to the other parts.   

Part 1

Part 2 

El Nino Southern Oscillation (ENSO):

 

The ENSO deals with the relative sea surface temperatures (SST) in the equatorial Pacific Ocean. There are three phases… EL Nino, Neutral, and La Nina.

El Nino (La Nina) is a phenomenon in the equatorial Pacific Ocean characterized by a five consecutive 3-month running mean of sea surface temperature (SST) anomalies in the Nino 3.4 region.

An El Nino is declared when the SST is equal to or above +0.5°C

A Neutral ENSO is 0.5°C above down to -0.5°C below the center line.

An La Nina is declared when the SST is equal to or below -0.5°C.

 SST are monitored in four regions along the equator:

Nino 1 (80°-90°W and 5°-10°S)

Nino 2 (80°-90°W and 0°-5°S)

Nino 3 (90°-150°W and 5°N-5°S)

Nino 4 (150°-160°E and 5°N-5°S)

These regions were created in the early 1980s. Since then, continued research has led to modifications of these original regions. The original Nino 1 and Nino 2 are now combined and is called Nino 1+2. A new region, called Nino 3.4 (120°-150°W and 5°N-5°S) is now used as it correlates better with the Southern Oscillation Index and is the preferred region to monitor sea surface temperature.

 The changes in sea surface temperatures during El Niño and La Niña are caused and helped along by changes in the trade winds, which normally blow from east to west across the tropical Pacific Ocean.

El Nino and La Nina episodes typically last 9-12 months. They both tend to develop during the spring (March-June), reach peak intensity during the late autumn or winter (November-February), and then weaken during the spring or early summer (March-June).

Both El Nino and La Nana can last more than a year, but it is rare for El Nino events to last longer than a year or so, while it is common for La Niña to last for two years or more.

El Nino:

During an El Nino event, warmer than normal SSTs occur across the central and eastern equatorial Pacific. During El Nino the trade winds weaken or may even reverse. As a result, convection (thunderstorms) shifts east. This causes weaker upwelling, which keeps the warmer water on the surface.

When temperatures are warmer-than-normal it is called an El Nino, which is normally wetter and cooler across the Northeast. Outbreaks of very cold Arctic air are much less common during an El Nino winter.

During El Nino, the jet stream along with vertical windshear and other factors become more hostile during the Atlantic hurricane season which runs from June to the end of November. This helps lessen the number and strength of Tropical Cyclones.

 The neutral phase:

In the neutral state (neither El Nino nor La Nina) tropical Pacific SSTs are generally close to average.  The trade winds blow east to west across the surface of the tropical Pacific Ocean, bringing warm moist air and warmer surface waters towards the western Pacific and keeping the central Pacific Ocean relatively cool. The thermocline is deeper in the west than the east.

During the neutral phase, the jet still can bring colder air into the Northeast. However, storms don't get as much help from the southern subtropical jet. One thing I've noticed is there is a lot of Greenland blocking during an ENSO neutral winter. Moisture out of the Gulf tends to move to the SE coast where it can move up the coast.  In a neutral ENSO the southern jet stream plays a huge rule in ice/snow events in the Northeast, timing of cold air outbreaks and storms is critical.

 La Nina:

During an La Nina event, warmer than normal SSTs occur across the central and eastern equatorial Pacific.  This leads to stronger trade winds that shift the convection farther west.  The conditions allow for stronger upwelling, which brings colder deep ocean water to the surface.

When in a La Nina, typically we see a warmer and drier winter in the Northeast. During La Nina the polar jet stays up around Alaska and then drops down into the Northern part of the US. During La Nina Arctic and Siberian air will at times intrude into the Northeast. 

During hurricane season (June to November), upper-level winds are much lighter, and therefore more favorable for tropical cyclone development in the Caribbean and Atlantic.

These ENSO phases peak during the winter and early spring, but weaken as summer approaches. So even if an El Nino developed in January or February it wouldn't make a difference for snow in the Northeast.

 These ENSO phases peak during the winter and early spring, but weaken as summer approaches. So even if an El Nino developed in January or February it wouldn't make a difference for snow in the Northeast.

The Southern Oscillation Index (SOI):

The SOI is a measure of the atmospheric pressure difference between sea level pressures at Darwin, Australia, and Tahiti. Large negative values of the SOI are associated with El Nino and large positive values associated with La Nina. The SOI index, being a simple measure of pressure differences, is highly variable, much more so than other indices such as ocean temperatures. So, the SOI will at times be positive during El Nino events and negative during La Nina events. As such, a multi-week running average of the SOI can provide a better indicator of overall ENSO conditions.

 

The Eastern Pacific Oscillation (EPO):

The EPO is a dipole pattern similar to the NAO in the Atlantic, but located in the eastern Pacific. There is a tendency for heights/pressures/temperatures to be higher to the north and lower to the south in the negative phase and lower to the north and higher to the south in the positive phase. The negative phase corresponds to widespread cooling over central and eastern North America and the positive phase to warming. During the positive phase we typically see negative geopotential height anomalies, and a negative phase in which the opposite is true.

Geopotential height approximates the actual height of a pressure surface above mean sea-level. Therefore, a geopotential height observation represents the height of the pressure surface on which the observation was taken. Since cold air is more dense than warm air, it causes pressure surfaces to be lower in colder air masses, while less dense, warmer air allows the pressure surfaces to be higher. Thus, heights are lower in cold air masses, and higher in warm air masses.

A negative EPO regime corresponds to ridging over the northeastern Pacific, and a positive EPO regime corresponds with a trough in the same location. The negative phase corresponds to widespread cooling over central and eastern North America and the positive phase to warming. Most major cold waves in winter are associated with a negative EPO.

 

Negative EPO:

The EPO pattern opens the door to very cold Arctic and Siberian air into the US. Here's an image that depicts the negative phase of the EPO.

Positive EPO:

The weather pattern in the positive phase is just the opposite of the negative, and so you have low pressure over high pressure which gives the central and eastern US a different outcome.

  

The Atlantic Multidecadal Oscillation (AMO):

The AMO is a series of quasi-periodic (not completely regular) variations, The AMO signal is based on spatial patterns in SST variability after removing the effects of anthropogenic forcing on temperature, revealing natural long-term patterns in SST. The AMO is characterized by warm and cool phases with periods of approximately 20-40 years. The AMO index is related to air temperatures and rainfall over North America and Europe and is associated with changes in the frequency of droughts in North America and the frequency of severe hurricane events. A positive phase of the AMO is associated with above average water temperatures across the northern half of the Atlantic basin and increased tropical activity, while a negative phase of the AMO is associated with cooler water temperatures and decreased tropical activity.

 

In the positive (warm) phase of the AMO, sea surface temperatures are typically above normal in the Atlantic Main Development Region (MDR), the eastern subtropical Atlantic, and the far North Atlantic. Sea surface temperatures are typically below normal or near normal in the western subtropical Atlantic near the United States East Coast.

  

 In the negative (cold) phase of the AMO, sea surface temperatures are typically below normal in the Atlantic MDR, the eastern subtropical Atlantic, and the far North Atlantic. They are typically near or above normal in the western subtropical Atlantic.

  

  

Pacific Decadal Oscillation Index (PDO):

The PDO is often described as a long-lived El Nino-like pattern of Pacific climate variability. As seen with the better-known ENSO, extremes in the PDO pattern are marked by widespread variations in the Pacific Basin and the North American climate.

 

 

The PDO is detected as warm or cool surface waters in the Pacific Ocean, north of 20° N. During the positive phase, the west Pacific becomes cool and part of the eastern ocean warms. During the negative phase, the opposite pattern occurs. It shifts phases on at least inter-decadal time scale, usually about 20 to 30 years.

When SST's are anomalously cool in the interior North Pacific and warm along the Pacific Coast, and when sea level pressures are below average over the North Pacific, the PDO has a positive value. When the climate anomaly patterns are reversed, with warm SST anomalies in the interior and cool SST anomalies along the North American coast, or above average sea level pressures over the North Pacific, the PDO has a negative value.

The impacts of the PDO are similar to those associated with ENSO events. When in the positive phase during the winter, the Aleutian low is deepened and shifted southward, warm/humid air is advected along the North American west coast and temperatures are higher than usual from the Pacific Northwest to Alaska but below normal in Mexico and the Southeastern United States. Winter precipitations are higher than usual in the Alaska Coast Range, Mexico and the Southwestern United States but reduced over Canada, Eastern Siberia and Australia. McCabe showed that the PDO along with the AMO strongly influence multi-decadal droughts pattern in the United States, drought frequency is enhanced over much of the Northern United States during the positive PDO phase and over the Southwest United States during the negative PDO phase in both cases if the PDO is associated with a positive AMO.

 

 

The Quasi-Biennial Oscillation (QBO):

The QBO is a measure of the oscillation in wind direction about 15 miles up (generally where atmospheric pressure is between 10 and 100 mb) around the equator. These winds reverse direction (oscillate) roughly every other year (quasi-biennially) between easterly (negative-phase QBO) and westerly (positive-phase QBO).

Effects of the QBO include mixing of stratospheric ozone by the secondary circulation caused by the QBO, modification of monsoon precipitation, and an influence on stratospheric circulation in northern hemisphere winter (mediated partly by a change in the frequency of sudden stratospheric warmings). Eastward phases of the QBO often coincide with more sudden stratospheric warmings, a weaker Atlantic jet stream and cold winters in Northern Europe and eastern USA whereas westward phases of the QBO often coincide with mild winters in eastern USA and a strong Atlantic jet stream with mild, wet stormy winters in northern Europe. In addition, the QBO has been shown to affect hurricane frequency during hurricane seasons in the Atlantic and research has also been conducted investigating a possible relationship between ENSO and the QBO.

The Western Pacific Oscillation (WPO):

During winter and spring, the pattern consists of a north-south dipole of anomalies, with one center located over the Kamchatka Peninsula and another broad center of opposite sign covering portions of southeastern Asia and the western subtropical North Pacific. Like the EPO, the negative phase favors colder weather across the eastern portions of North America. However, on average, the westward extent of cold is greater during a negative WPO compared to a negative EPO. At times, the WPO and EPO will be in phase, both being negative or positive at the same time.

Well I hope that helps in your understanding of the teleconnection patterns that effect our weather patterns. But remember all these teleconnections work to together, so little changes in one teleconnection can allow other teleconnections to have greater influence on the weather pattern.  

 

Winter 2018 2019 Preliminary Outlook Part 2

A couple of weeks ago, I posted on my Facebook weather pages, dealing with my preliminary outlook and why my outlook is so different from so many others. I received flak for that post....and I most likely will receive some because of this post. But that goes with the territory and I'm used to it.

Winter-2018-2019-preliminary-thoughts

Preliminary thoughts for winter 2018-2019 part 3  

This post will add to the preliminary outlook, showing more of my thinking and what the pattern looks like right now, and seems to be heading.

The El Nino Southern Oscillation (ENSO):

 

 

Images from Tropical Tidbits:

 

 

ENSO 4 is starting to get very warm. The ENSO 1+2 is still cooling. This puts more credence into my idea of a Modoki El Nino will be in place later this fall and winter. As I've been saying for a long time, the odds favor a weak El Nino event. The warmth should start to extend into ENSO 3.4 at some point. But there is a chance El Nino doesn't form, meaning we would see El Nino neutral conditions. Typically we see a more active southern sub-tropical jet during a El Nino Modoki than we do during a regular El Nino. The added lift the Modoki adds to the jet pattern, does increase the odds somewhat for East Coast storms.

I've said repeatedly there are different flavors of El Nino's and no two are exactly alike. I've also said, there are big differences between a normal El Nino and an El Nino Modoki. But on average this is how they work out.

Other Teleconnections:

The Quasi-Biennial Oscillation (QBO):

January to July the QBO was strongly negative (east based). If this continues into winter it's a good indication for a colder than average December - February. 

When the QBO is easterly, the northern jet is typically weaker; This increases the odds of sudden stratospheric warming (SSW)events to occur. When we have a SSW event the polar Jet often weakens (this jet is often called the polar vortex); this leads to the likelihood of cold polar air to break off and spiral southward into the Midwest and Northeast. An easterly QBO increases the odds for more frequent negative Arctic Oscillation (AO) outbreaks which further increases the odds for a colder than average December through February.  There is a strong correlation between a weak/neutral ENSO and an east based QBO to colder winters here in the Northeast and Middle Atlantic. 

A negative factor for cold this upcoming winter will be the fact that we look to have an east based QBO with an El Nino.  El Nino's tend to negate the influence from the QBO. But this being a Modoki El Nino it will help offset that impact somewhat.  

Here is an image that shows how we fair during a normal and Modoki El Nino event. I also show how east based QBO of various strengths impact the region.

 

 

 

 

 

Arctic Oscillation (AO):

The AO measures the differences in atmospheric pressure between the Arctic and mid-latitudes. As all oscillations it has a positive and a negative phase. In the positive phase arctic air on average stays locked up to the north. Whereas the negative phase on average sees a greater likelihood of more cold arctic outbreaks. In this regard it would work with the Modoki El Nino and QBO helping to up the odds for a colder winter.

Pacific warm spot:

We have that blob of warm SST south of Alaska. This is a good sign that we will see upper level ridging develop in western Canada. This would also up the odds for colder air in Siberia and northern Canada to flow downstream along the trough that extends eastward.  How far eastward is one of my biggest question marks right now. One other thing about Modoki El Nino's is they also help punch that upper level ridge pattern over the West Coast. 

Sunspots:

It's been awhile since I've talked about solar activity and its impact on global weather.  But as I've said before, the sun and solar activity do play a big role in terrestrial weather and climate. There is correlation between low solar activity and upper latitude blocking near Greenland and Iceland.  Given that we're heading into the minimum  those odds do increase. The last time we were in a  solar minimum phase was 2007 to 2009.  The winter of 2009-2010 also had a somewhat moderate El Nino. That winter saw a lot of cold and snow in the Mid Atlantic Region. 

 

Great Lakes:

Lake Erie and Lake Ontario are very warm. Lake Surface temperatures are in the 70's. This will play a role in the upcoming winter as well, especially during the first half of winter as cold air moves over those warm lake waters.

Atlantic Mult-decadial Oscillation (AMO): 

I've been talking a lot about the AMO. I do believe the pattern in the North Atlantic is showing a change occurring in the AMO. This cool ring in the northern Atlantic is further evidence for a cooler winter for the East Coast along with Europe.  The increasing snowpack over Greenland and those cold SST in the far northern Atlantic are a sign that the AMO is switching from a positive AMO to a negative AMO. If this is indeed the case; we could be on the cusp for many colder winters in the years ahead.

As a side note the winter of 2002-2003 is one of my analog years. Right now, the pattern is closely matching up with that winter. If this continues it could mean a bit of warmth during December. But 1977-1978 was another analog, that stayed cold from November to March....so we will see.  

Remember this isn't a real outlook/forecast. This is only where my thoughts are right now and some of the things I'm looking at and considering as we move along. it is all subject to change as things evolve and the pattern adjust. But I think October will see a big turn toward cooler weather, with perhaps many of us seeing our first snows of the season. 

I will stop here; but I will in all probability release one more post dealing with more signals on where we are heading and how I think that will work out, before I release my 2nd winter outlook for the winter of 2018-2019. I still plan on releasing my final winter outlook end of October or the first part of November.   


 

El Nino, PDO, and the AMO

The El Nino Southern Oscillation deals with the fluctuations in the  Sea Surface temperature (SST) in the equatorial Pacific. It has two phases, El Nino the warm positive phase, La Nina the cool negative phase.  

The El Nino is getting impressive... I must admit... it is getting stronger than I said it would....You can't win them all.

 

We've had strong El Nino's before.  1972-1973, 1982-1983, 1997-1998. The strongest on record was the 1997 El Nino. Right now, our current El Nino looks to be just a bit weaker than 1997...but all the July readings aren't in yet.

In my Facebook weather group, I've fielded questions and discussed on the current El Nino.

During an El Nino, the southern jet stream comes farther north. This allows for a better chance for phasing the northern and southern Jet streams. Phasing is when a disturbance in the northern jet and a disturbance in the southern jet merges and becomes one very powerful storm.  When we have a very strong El Nino the southern Jet is even farther north. Last year we had a very positive (warm) Pacific Decadal Osculation  (PDO). The PDO promoted ridging over the western  Continuous United States ( CONUS) and troughing over the eastern CONUS. This allowed more cold air to come down out of Northwestern Canada and Alaska. With the ENSO bringing the southern jet closer to the northern jet. This is want happened during the winter of 2014-2015. We saw a lot of Nor'easters and major coastal storms.

1997 was a extremely warm winter in the Northeast. The reason was in part because of the strong El Nino. Here is a chart showing the SST. You can see the warmth in the tropical Pacific look very similar.

 

 

I've talked about on my Facebook weather pages....even though we have a very strong El Nino, many other conditions in the Pacific and Atlantic are completely different.  

We have a strong (PDO) and a negative Atlantic Multidecadal Osculation (AMO).

 

The PDO was a little stronger a month ago... But since then, the PDO has seen some weakening on its northern edge. Also, the  SST's around Australia and into the Indian Ocean are starting warm up. This will aid the El Nino to get stronger. Six weeks ago the waters around Australia were cooler. The fact that these SST are warming ...will give this El Nino issues. During the 1997 El Nino the waters around Australia were cooler. With that said, I know I was saying this El Nino would be moderate to strong....but I was wrong...it looks like this current El Nino will end up warmer than the El Nino of 1997. 

El Nino and La Nina are short term cycles..... whereas the PDO and AMO are long term cycles.

Here are a couple of charts that show the cycles.

 

  

We're in a positive PDO and a negative AMO.... if you look at the top left (chart below) you will see how things are matching up to what we would expect from that pattern.

 

When we have a positive PDO, we tend to see more strong El Nino's, fewer hurricanes in the Atlantic, and a less active tornado season. 

 

When we have a negative AMO, we tend to see strong LA Nina's, fewer hurricanes, and tendency for a positive North Atlantic Osculation (NAO) and positive Atlantic Osculation (AO).

 

Far too many meteorologist rely and trust only weather models. Models are great tools, but they are only part of what should be looked at. Looking at teleconnections, sea ice, solar activity, and other things are is very important as well. I based by Spring Summer outlook on all of these things.  Just as I use them when I make a winter outlook. If you've been following my post. Then how last winter turned out...and how this year is turning out....should be no surprise.

For the last few months I've been talking about the long range pattern; so far things are going as I outlined.  I've been saying we will see cooling as we move into August, and  things still seem to be trending that way. We will stay in this transient weather pattern well into August.  But as we head into the end of August and for September, we will see more in the way of long lasting warming.  The NCEP CFS V2  for August and September, show this to be the case.

The NCEP CFS V2 :

August,

 September,

 

As we head toward and get into the coming winter, the current teleconnection pattern of the PDO and AMO would indicate more in the way of cold..... So this year's El Nino shouldn't allow for the type of warm conditions we saw in 1997. The warm water near Australia would indicate on average higher pressure, with lower pressure on average in the tropical Pacific. This sort of setup would allow the warm water off the West Coast of South America to  move more to the west, as we get closer to this coming winter.