winter forecast

Is La Nina Making The Atlantic Hurricane Cyclone Season Worse?

/////

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]

Will This Winter Be Like Last Winter?

/////

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].

Groundhog Day Report

/////

Yesterday was Groundhog Day and I checked in with many of the groundhogs to see what they had for a forecast.

Punxsutawney Phil | Photo by zapit.com
Punxsutawney Phil | Photo by zapit.com

“Punxsutawney Phil” led the group that did not see their shadow predicting an early Spring. The others in that group are Malverne Mel, Holtsville Hal, General Lee, Sir Walter Wally, Staten Island Chuck, and Dunkirk Dave (Who actually is a female named Sidewinder). Those seeing their shadow predicting 6 more weeks of Winter are Dunkirk Dave, Buckeye Chuck, and my own Spencer Butte Bob here in Eugene. Even Wiarton Willie from Ontario Canada predicted 6 more weeks of Winter by seeing his shadow. That’s 7 to 4 in favor of an early Spring.

Spencer Butte Bob, The South Hills Groundhog | Photo by Tim Chuey
Spencer Butte Bob, The South Hills Groundhog | Photo by Tim Chuey

For those of you who might not remember Spencer Butte Bob is my personal groundhog (actually a plaster statue). It was quite sunny this morning so Bob did see his shadow predicting 6 more weeks of Winter, but if the rest of Winter is like what we have had so far that’s not too bad. A special note: One groundhog missing from this report is Sun Prairie Jimmy. When making his prediction last year he bit the ear of the Mayor, who was holding him at the time, so they had to let Jimmy go back into the wild. I guess they didn’t find a replacement since I couldn’t find their report. Remember, these predictions are about as accurate as flipping a coin, but it is fun to check this out each year.

You can comment below or email me at: [email protected].