2019-2020 WINTER FORECAST

What Is In This Post?

It is that time of the year!! We are quickly approaching the winter months and the mountains have already have a couple small snow events!

In this post you will find detailed analysis of what could be in store for the Carolinas (and the US) this winter. We will break down several weather indexes that can give us clues into the patterns ahead. From those indicators we will try to predict the temperature, precipitation, and storm track that we will see across the US this winter. PLEASE REMEMBER! This is like a blindfolded dart throw. It could completely change before December. Weather is fluid. It is never going to be easily deciphered, but we will give it our best!!

PLEASE READ THE ENTIRE POST! WE WILL NOT BE ANSWERING QUESTIONS.

First Index: ENSO Status

The very first thing we always look at is the ENSO region. This is the temperature of the water in the Pacific along the equator (roughly the rectangle we drew below).

This is pretty much the biggest driver (one of many) for weather across a large part of the planet but specifically for the US. It has three main configurations:

El Nino: This area is warmer than normal (red/orange). Typically we associate El Nino with cooler winters and wetter winters. (For Carolinas)

La Nina: This area is cooler than normal (Blues). Typically we associate La Nina with warmer winters and dryer winters. (For Carolinas)

Neutral: This area is a mixture of warm and cool. This is a toss up. The ENSO being neutral allows other drives to come to the front and change the patterns. (For Carolinas)

These DO NOT always have the impacts we think or expect but its a great start in looking toward winter.

tropicaltidbits.com

Current ENSO Status

The image above is the current map of sea surface temperatures. You can clearly see the ENSO region is a mixture of orange and blue. Below is a cross section of the ocean along the equator. Notice the warmth in the red rectangle.

ENSO is currently in a warm neutral/weak El Nino state. We expect ENSO this winter to continue to be in weak El Nino or warm neutral state given the warmth below the surface in the picture below!

PMEL buoy data

Computer model forecasts indicate the ENSO will stay about where it is or maybe even weaken slightly as we head towards the heart of winter and early spring. This can sometimes create a bit more of a chaotic and hard to predict winter forecast (more than usual) due to no strong driving force from the ocean.

Summary of ENSO

Our ENSO will likely stay warm neutral and may even weaken some to neutral or cool neutral. Historically, an El Nino helps bring cool temps and more precipitation to the East Coast. Such a weak ENSO state can leave the door open for other drivers to have greater influence for our weather.

Second Index: QBO (quasi-biennial oscillation)

This is a measurement of the zonal winds along equator. These winds shift from easterlies to westerlies on a pretty steady pattern and can influence our weather.

This is a fairly complicated index for weather across the US. We found this image years ago and have used it to show the relationship between the QBO and temperatures in the US.

In short:

A falling QBO tends to bring normal and cooler temps to the Eastern US.

A rising QBO tends to bring above normal temps to the Eastern US.

weatherops.com

Current State of QBO

The QBO is measured many ways. Here is the latest numbers each month.

June July August September October

14.36 10.96 9.97 8.25 7.27

As you can see above the QBO is slowly falling toward negative numbers. It typically accelerates as it nears 0 and heads into negative territory.

Below is a map of soundings taken in Singapore over the last 3 years. Here you can actually see the progression of the QBO. Yellow is positive and Blue is negative. You can see at the end of the graph that we are in the beginning of the negative QBO phase.

TYPICALLY these phases continue for over a year. That is not always the case though!

Summary of QBO

The QBO is currently slowly falling toward negative. We expect this to continue and that the QBO will fall into negative numbers by February.

This can influence the temperatures in the Eastern US to be cooler than normal.

Third Index: Solar Activity

It is no surprise that the sun plays a HUGE role in the weather patterns!

It is a common thought process that solar activity (sunspots etc.) can have small impacts on weather patterns in the Northern Hemisphere.

Low Solar: Typically associated with an increased chance of blocking in the north. (more blocking to our north leads to a better chance that cold air masses make it down to the Carolinas).

High Solar: Typically associated with a decreased chance of blocking in the North (less blocking to our north leads to a lower chance of cold air masses making it down into the Carolinas).

Below is the current solar cycle. This is the count of sunspots on the surface of sun.

We are at the lowest point of the solar cycle known as a solar minimum.

Summary of the Solar Cycle

We are in a solar minimum which can help increase the chances of blocking to our north which allows cold air to make it down into the Carolinas.

Our Winter Forecast

REMEMBER! We are simply taking the above weather cycles (and several others) and predicting the pattern we will see in winter. THIS IS basically a blind dart throw and very difficult to accurately predict!

Storm Track

Overall we expect the primary storm track to feature a lot of storm systems that cut up the mountains or to the west of them. This will be due to a combination of ridging in the Atlantic pushing them inland along with an active jet helping to fuel stronger storm systems that are prone to cutting. This will keep NC in the warm sector with the heaviest rains in the green zone. The black line is the primary storm track we expect but the blue lines are the other type we will see occasionally.

December

December we expect to be a warmth month with just brief shots of cooler air. The pattern may end up being a zonal flow where warm air from the Pacific Ocean floods across the US or with a broad ridge across the US. Many models and analogs indicate all the colder than normal air may evacuate out of North America and head for Russia/Europe during the month of December. There’s always the chance you can get a storm perfectly timed in December for snow later in the month but this pattern would make it much more difficult to get that if it verifies.

January

For January the pattern should begin shifting to a cooler one, especially mid to late January. Cold shots of air will become more frequent and intense and the storm track will begin shifting south. Snow threats will begin popping up and with the pattern we anticipate some ice storms may pop up as well. Some of our QBO data suggests a very chaotic month with warm/cold air really battling for dominance and usually there are some big ice and snow storms that pop up in a chaotic pattern. This will be the month to watch very closely as usual.

February

The coldest air will be focused over the Great Lakes but occasional Arctic intrusions into the southern US will bring with it a chance for wintry weather. Some of the data we looked at suggested much of the southeastern US could be well below normal and February could be the coldest month. However, we decided to go on the warmer side of things since a neutral ENSO state and the southeast ridge may keep the cold air more to our north. This is probably the most uncertain month in our forecast!

CONCLUSION

Overall we expect a winter that is near to slightly above normal. The biggest driving factor that could help things end up colder is the QBO phase heading into negative territory along with the solar minimum. Research into these fields and how it affects our weather is still quite limited thus we went more on the warm side of things for January and February (instead of very cold like some QBO data indicates for February).

SNOWFALL

We expect snowfall to be close to normal but areas in the mountains and western NC may end up seeing a bit more than usual if the pattern unfolds as we expect.

Most of all remember that winter forecasts like this are HIGHLY uncertain and difficult to predict. Everyone knows how hard it is to predict 3-4 days out what will happen let alone 2-3 months in advance. Hopefully this winter will be one that will make all those who love wintry weather quite happy!