La Nina

Is La Nina Making The Atlantic Hurricane Cyclone Season Worse?

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This year has seen a lot of record setting events from the COVID-19 Pandemic, to the horrific wildfires, to the continuing Tropical Cyclone Season that has seen so many named storms that the Greek Alphabet has to be used. The National Oceanic and Atmospheric Administration (NOAA) has explained that the already prolific “Hurricane Season” could be enhanced by the phenomenon known as La Nina. The NOAA bulletin issued on September 10th suggested that La Nina would weaken the wind shear (Definition shown later) over the Caribbean Sea and the tropical Atlantic Basin which enables storms to develop and intensify. That’s according to Mike Halpert who is the Deputy Director of NOAA’s Climate Prediction Center. The La Nina could last into the winter which could have a serious effect on the kind of winter we here in the Pacific Northwest will be experiencing.

El Nino
El Nino Warm Water Pool (Shown In Red/Orange) | Image by agnook.com

We should go over the terminology involved in order to better understand what this means. El Nino is defined as a warm water current (shown in red/orange) that appears annually, around Christmastime, along the coasts of Ecuador and Peru. The name El Nino means the boy child and refers to the “Christ Child” who’s birthday is celebrated in December when the warm water pool extends itself closer to the South American coast. It was first discovered or noted by the fisherman who found warmer water where they usually would catch fish.

La Nina
La Nina Cold Water Pool (Shown In Blue) Off South America | Image by NOAA Coral Reef Watch

La Nina is defined as a cold water current (shown in blue) that appears annually, around Christmastime along the coasts of Ecuador and Peru. The name La Nina means the girl child and is the opposite of El Nino and is the cool water pool that extends itself closer to the South America in December.

It seems obvious that El Nino and La Nina can’t occupy the same area along the South American coast at the same time. That is where another term comes into play. The ENSO or El Nino-Southern Oscillation. El Nino is often called the warm phase of ENSO while La Nina can be called the cold phase of ENSO. Often the sea surface temperatures waver between the two in the same season.

What would you call it when neither El Nino nor La Nina come to visit the West Coast of South America? I guess you could call it the “nothing” and that is just what they decided to call it. In Spanish it is La Nada.

The Winter El Nino Jet Stream | Image by ww2010atmos.uiuc.edu

El Nino’s warm water pool actually deflects the Jet Stream in the Winter in such a way as to set up a high pressure ridge over the Pacific Northwest. That ridge keeps the cold air and the Winter storm track to our North or South and tends keep us warmer and drier. During an El Nino year there is usually less tropical storm activity in the tropical Atlantic due to increased vertical wind shear over the area.

Vertical Wind Shear
Vertical Wind Shear Diagram | Image by AMOL/NOAA

Vertical wind shear is the change of wind direction with height. In order to build the storm clouds it takes to produce a hurricane there must be steadily rising columns of air and the change of wind direction as the air is rising tends to stop the development of the storm clouds.

LaNina Jet
La Nina Winter Jet Stream Path | Image by NOAA Climate.gov

La Nina’s cold water pool has the opposite effect and deflects the Jet Stream so as to send the Winter storms right at us. I know what you are expecting me to say next. Which one is controlling our weather now and what kind of Winter can we expect? The experts say we are in the La Nina now. It is too early in the season to make a solid prediction for Winter. The best time to do that is mid-November when the sea surface temperatures are set up for the Winter months. That prediction would be for the actual Winter months of December, January, and February.

We could even see a moderate La Nina which might give us some winter storms, but not the strongest heavy snow producing storms. As for how much more severe the Atlantic hurricane season will get that will become obvious very soon. We’ll just have to wait to see what will actually happen.

Let me know what you would like me to talk about or explain. You can comment below or email me at: [email protected]

Not Much Winter Weather Until Now. What’s Going On?

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You might remember that I wrote past column articles about what causes winter weather patterns over the Pacific Northwest. In 2013 the article was titled ” Whose Fault Is It? El Nino, La Nina, Or Even La Nada?” Those three terms give meteorologists the tools to determine what kind of winter we will have and whether the current winter weather pattern will continue as is or change to another one.

El Nino
El Nino Jet Stream Pattern | Image by www.washingtonpost.com

Let’s review the three terms and what they mean. El Nino is defined as a warm water current (shown in red/orange) that appears annually, around Christmastime, along the coasts of Ecuador and Peru. The name El Nino means the boy child and refers to the “Christ Child” who’s birthday is celebrated in December when the warm water pool extends itself closer to the South American coast. It was first discovered or noted by the fisherman who found warmer water where they usually would catch fish.  El Nino’s warm water pool actually deflects the Jet Stream in the Winter in such a way as to set up a high pressure ridge over the Pacific Northwest.  That ridge keeps the cold air and the Winter storm track to our North or South and tends keep us warmer and drier. During an El Nino year there is less tropical storm activity in the tropical Atlantic due to increased vertical wind shear over the area.

La Nina
La Nina | Image by pmel.noaa.gov

La Nina is defined as a cold water current (shown in blue) that appears annually, around Christmastime along the coasts of Ecuador and Peru. The name La Nina means the girl child and is the opposite of El Nino and is the cool water pool that extends itself closer to the South America in December.

Vertical Wind Shear
Vertical Wind Shear Diagram | Image AMOL/NOAA

Vertical wind shear is the change of wind direction with height. In order to build the storm clouds it takes to produce a hurricane there must be steadily rising columns of air and the change of wind direction as the air is rising tends to stop the development of the storm clouds. La Nina’s cold water pool has the opposite effect and deflects the Jet Stream so as to send the Winter storms right at us.

La Nada
La Nada | Image by weather.gov

It seems obvious that El Nino and La Nina can’t occupy exactly the same area along the South American coast at the same time. That is where another term comes into play. The ENSO or El Nino-Southern Oscillation. El Nino is often called the warm phase of ENSO while La Nina can be called the cold phase of ENSO. Often the sea surface temperatures waver between the two in the same season. When neither El Nino nor La Nina come to visit the West Coast of South America it is called La Nada which in Spanish translates as nothing. That means the current is stable, neither warm or cold.

What these currents do is deflect the Jet Stream in such a way to either bring the colder air and the Winter storms our way or to act as a barrier to protect us from the stronger Winter storms and keep us warmer. So what’s been going on these last few months? A USA Today article posted February 9, 2018 and written by Doyle Rice touts that the LaNina has ended and now we are being controlled by La Nada. That’s according to climate scientists interviewed for the story. The short-lived La Nina did bring unusually cold air in December and January to Alaska, western Canada, and the Northern plains. La Nina usually brings more precipitation to the Pacific Northwest and Northern California, but that did not happen.

Sea Surface Temperatures
Eastern Pacific Ocean Sea Suyrface Temperature Amomaly | Imagr ospo.noaa.gov

Historically we have had La Nina winters in the Pacific Northwest which were more on the dry side and even warmer than expected. Instead the rain hit Central and Southern California ending in a declaration by Southern California that the drought was officially over.

The ski areas in the central part of Oregon have been suffering from a serious lack of snow cover while the Sierra in California have been experiencing one of their snowiest winters ever recorded. That shows that the deflection of the jet stream is such that the areas receiving significant snowfall were to the south and north of the southern Willamette Valley. That suggests that the Jet Stream was deflected, but the Pacific Northwest was protected from the storms by having a high pressure ridge over the Eastern Pacific and a parade of upper level Low Pressure Troughs which brought us some rain, but also kept temperatures above normal for quite some time. For some reason the Jet Stream set up to being the cold Arctic air down through Canada into the Midwest and as far south as the Gulf Coast states. Snow and record temperatures punched well into the Deep South, but nothing for us.

Feb-April Temperatures
February Through April Temperature Probability| Image by weather.gov
Feb-April Precip
Precipitation Probability February Through April 2018 | Image by weather.gov

The National Weather Service Temperature and Precipitation outlooks for February through April give us a look into our possible weather future. The temperature graphic shows about a 40% chance of below average temperatures and the precipitation graphic shows about a 40% chance of above normal precipitation. Does this give us a handle on what the rest of our winter will be like? Not really. The potential is still there for the intrusion of much colder air moving down through Canada (this past weekend) and if there is sufficient moisture available from the South and West at the same time we could still see significant snowfall in the mountains and possible valley snow if the conditions are right.

At this point in time I’d say a flip of a coin could predict the snow chances for the rest of our winter about as accurately as the combination of the sea surface temperatures and the exact position of the jet stream over the Eastern Pacific Ocean and the Pacific Northwest. Hang on it will still be an interesting ride.

Let me know what you would like me to talk about or explain. You can comment below or email me at: [email protected].

Will This Winter Be Like Last Winter?

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Recently I have had people asking me what is in store for us this winter. Will it be like last winter with the great mountain snow cover? So far, I don’t have a definitive answer, but there has been some chatter in the professional journals  about the potential of another El Nino winter just like the one we had last winter.

It’s been quite a while since I discussed the mechanism that determines what kind of winter we experience here in the Pacific Northwest. We should start with the terminology used in meteorology to describe the variables that control our fate in winter.

El Nino
El Nino | Image by pmel.noaa.gov

The first term, which I’m sure you remember is El Nino. El Nino is defined as a warm water current (shown in red/orange) that appears annually, around Christmastime, along the coasts of Ecuador and Peru. The name El Nino means the boy child and refers to the “Christ Child” who’s birthday is celebrated in December when the warm water pool extends itself closer to the South American coast. It was first discovered or noted by the fisherman who found warmer water where they usually would catch fish.

La Nina
La Nina | Image by pmel.noaa.gov

The second term is La Nina which is defined as a cold water current (shown in blue) that appears annually, around Christmastime along the coasts of Ecuador and Peru. The name La Nina means the girl child and is the opposite of El Nino and is the cool water pool that extends itself closer to the South America in December.

It seems obvious that El Nino and La Nina can’t occupy the same area along the South American coast at the same time. They tend to alternate which is dominant. That is where the third term comes into play. The ENSO or El Nino-Southern Oscillation. El Nino is often called the warm phase of ENSO while La Nina can be called the cold phase of ENSO. Often the sea surface temperatures waver between the two in the same season.

La Nada
La Nada | Image by weather.gov

I have one more definition that is almost never mentioned. What would you call it when neither El Nino nor La Nina come to visit the West Coast of South America? I guess you could call it the “nothing” and that is just what they decided to call it. In Spanish it is La Nada.

Now that you have the key definitions we need to find out how they can make our lives more pleasant or more difficult in winter. What these currents do is deflect the Jet Stream in such a way to either bring the colder air and the Winter storms our way or to act as a barrier to protect us from the stronger wInter storms and keep us warmer.

El Nino’s warm water pool actually deflects the Jet Stream in the Winter in such a way as to set up a high pressure ridge over the Pacific Northwest. That ridge keeps the cold air and the Winter storm track to our North or South and tends keep us warmer and drier. During an El Nino year there is less tropical storm activity in the tropical Atlantic due to increased vertical wind shear over the area.

La Nina’s cold water pool has the opposite effect and deflects the Jet Stream so as to send the Winter storms right at us. Which one is controlling our weather now and what kind of Winter can we expect?

Sea Surface Temperatures
Sea Surface Temperatures Image by ospo.noaa.gov
Note blue color off Pacific Coast of South America (cooler pool that stretches westward)

According to an ElDoradoCounty.com report issued September 14, 2017 “A majority of the models in the IrI/CPC suite of Nino-3.4 predictions favor ENSO-neutral through the Northern Hemisphere 2017-18 winter. However, the most recent predictions from the NCEP Climate Forecast System (CFSV2) and the North American Multi-Model Ensemble (NMME) indicate the formation of La Nina as soon as the Northern Hemisphere Fall 2017. Forecasters favor these predictions in part because of the recent cooling of the surface and sub-surface temperature anomalies, and also because of the higher degree of forecast skill at this time of year. In summary, there is an increasing chance (55-60%) of La Nina during the Northern Hemisphere Fall and winter 2017-18.”

90-Day Temperature Outlook
90-Day Temperture Outlook | Image by ccp.ncep.noaa.gov
90-Day Precipitation
90-Day Precipitation Outlook | Image by ccp.ncep.noaa.gov

It is a bit early in the season to make a solid prediction for Winter. The best time is mid-November (that is more than a month away) when the sea surface temperatures are set up for the Winter months. That prediction would be for the actual Winter months of December, January, and February. So for the predictions seem to be for a small chance of above normal temperatures and precipitation. Now we just have to believe that this winter should be a lot like last winter, until proven otherwise, with plenty of snow in the Cascades producing a bountiful snow pack for the spring thaw producing plenty of water for the reservoirs and area rivers.

Let me know what you would like me to talk about or explain. You can email me at: [email protected].

Whose Fault Is It? Could It Be El Nino, La Nina, or even La Nada?

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Is it El Nino, La Nina, or maybe even La Nada? You have heard those terms bandied about by meteorologists and news anchors alike, but what do they really mean and why should you care. The three terms describe the sea surface temperatures in the Pacific Ocean which have a significant effect on the weather patterns around the world and particularly over the Pacific Northwest.

I’ll start off with the definitions of the terms so we can then use them to explain how they specifically control our weather patterns, particularly during Winter.

Latest Sea Surface Temperatures Pacific Ocean | Image NOAA
Latest Sea Surface Temperatures Pacific Ocean | Image NOAA

El Nino is defined as a warm water current (shown in red/orange) that appears annually, around Christmastime, along the coasts of Ecuador and Peru. The name El Nino means the boy child and refers to the “Christ Child” who’s birthday is celebrated in December when the warm water pool extends itself closer to the South American coast. It was first discovered or noted by the fisherman who found warmer water where they usually would catch fish.

La Nina is defined as a cold water current (shown in blue) that appears annually, around Christmastime along the coasts of Ecuador and Peru. The name La Nina means the girl child and is the opposite of El Nino and is the cool water pool that extends itself closer to the South America in December.

It seems obvious that El Nino and La Nina can’t occupy the same area along the South American coast at the same time. That is where another term comes into play. The ENSO or El Nino-Southern Oscillation. El Nino is often called the warm phase of ENSO while La Nina can be called the cold phase of ENSO. Often the sea surface temperatures waver between the two in the same season.

Just when you thought I was finished giving you definitions I have one more. What would you call it when neither El Nino nor La Nina come to visit the West Coast of South America? I guess you could call it the “nothing” and that is just what they decided to call it. In Spanish it is La Nada.

The Jet Stream | Image ww2010atmos.uiuc.edu
The Jet Stream | Image ww2010atmos.uiuc.edu

Now that you have the key definitions we need to find out how they can make our lives more pleasant or more difficult. What these currents do is deflect the Jet Stream in such a way to either bring the colder air and the Winter storms our way or to act as a barrier to protect us from the stronger WInter storms and keep us warmer.

El Nino’s warm water pool actually deflects the Jet Stream in the Winter in such a way as to set up a high pressure ridge over the Pacific Northwest. (See Picture to left)  That ridge keeps the cold air and the Winter storm track to our North or South and tends keep us warmer and drier. During an El Nino year there is less tropical storm activity in the tropical Atlantic due to increased vertical wind shear over the area.

Vertical Wind Shear Diagram | Image AMOL/NOAA
Vertical Wind Shear Diagram | Image AMOL/NOAA

Vertical wind shear is the change of wind direction with height. In order to build the storm clouds it takes to produce a hurricane there must be steadily rising columns of air and the change of wind direction as the air is rising tends to stop the development of the storm clouds.

La Nina’s cold water pool has the opposite effect and deflects the Jet Stream so as to send the Winter storms right at us. I know what you are expecting me to say next. Which one is controlling our weather now and what kind of Winter can we expect? The experts say we are in the La Nada now. It is a bit early in the season to make a solid prediction for Winter. The best time is mid-November when the sea surface temperatures are set up for the Winter months. That prediction would be for the actual Winter months of December, January, and February. As of now the sea surface temperatures indicate neither El Nino or La Nina so that leaves us with La Nada continuing and neither the cold water nor the warm water dominating. That makes for a difficult forecast. My best guess is that this Winter will be very similar to last winter. That means no major snowfall down on the Valley floor. Remember that this is only an educated guess at best and should be updated when the new winter prediction computer model from the National Weather Service produces the national forecast for October, November, and December. That should be ready soon. It takes a very small change in data for an unexpected storm to appear. That is what makes weather forecasting such a challenge.

Let me know what you would like me to talk about or explain. You can email me at: [email protected].