DELAWARE VALLEY REGION Philly South Jersey Delaware DELAWARE VALLEY REGION Philly South Jersey Delaware

2016-2017 Winter Forecast

Discussion started by PhillyWeather13 3 months ago
Overview: Last winter was one of the warmest winters that we had seen in recent memory with some areas being 15 degrees above normal in December thanks to the strongest El Nino we have ever witnessed. Despite that, we also had a blizzard back towards the end of January which dropped about 95% of last season’s snowfall for the region. This year I expect things to be much different compared to last year as I believe we get an early start to winter in December this year compared to this past January. I also believe that we will be in a wintry regime for the majority of the winter. How do I come to this conclusion??? Here are my top 6 factors which have led me to my forecast.

1. ENSO state
Last year we endured the strongest El Nino that I think any of us had ever seen, spearheaded by one of the warmest Decembers on record in which it felt more like Florida on Christmas Day instead of what it should be this time of year. This year however, we have done a complete reversal and we are now in a weak La Nina which ultimately won’t have as much of an impact on us as there would normally be. So with La Nina not much of a factor, we look to other factors which may drive the winter.

2. NAO/PNA Combo

This combination is responsible for the way that our winter weather patterns develop here in the Northeastern United States. When we have a –NAO/+PNA combo, we tend to see colder and stormier conditions with an enhanced risk for coastal storms. However if we have a +NAO/-PNA combo, we tend to see warmer conditions with storms cutting up to the west across the Appalachian Mountains or even Cutting across the Great Lakes States. In the aforementioned scenario, we occasionally see severe thunderstorms. Yes, Severe Thunderstorms in the winter…… It has happened. This winter however, I am forecasting a higher than normal chance of a –NAO/+PNA combo to give the Northeastern US a colder winter.

3. Arctic Oscillation(AO)
This index is also a good indicator with regards to how cold the overall winter could be. If we are in a –AO regime it tends to be colder across the Northeast United States as arctic air masses make their way down from Canada and Siberia, however if the AO is too negative, it tends to suppress any potential winter storms that would attempt to move in our direction. Likewise, with a +AO index, it tends to be on the warmer side because all of the cold air is locked up in Canada. This winter I tend to believe that we will end up with a –AO for an average through the winter months.

4. Siberian Snow Cover
When it comes to winters across the Northeastern United States, we tend to look towards this area in October and Early November to gather any clues that would be helpful. The faster the rate of growth in areas south of 60 degrees north, the higher the probability of a colder winter for the Northeast. This October, the SAI index finished with the highest growth rate we have seen since 1998. However the Super El Nino we has last year trumped the SAI index hence the warmer winter. This year, we expect things to be different thanks in part to a Weak La Nina as well as a –NAO/+PNA combination.

5. Quasi Biennial Oscillation(QBO)
The Quasi-Biennial Oscillation is one of the most remarkable phenomena in the Earth's atmosphere. High above the equator, in the stratosphere, strong zonal winds blow in a continuous circuit around the Earth. At a given altitude, the winds might start as westerlies, but over time they weaken and eventually reverse, becoming strong easterlies.
Looking at different heights, we see that the peak amplitude of the westerly winds migrates slowly downwards, with the zone of easterly winds coming behind it also migrating downwards. When the winds approach the base of the stratosphere, at around 80 hPa, they dissipate. New bands of zonal winds appear in the mid-stratosphere, at around 10 hPa, to replace the bands which migrate downwards. At any one time, there is one region of easterlies and one region of westerlies. The whole cycle progresses at a fairly (but not entirely) uniform rate, taking on average 26 months to return to the starting state. This I believe will be a major wild-card factor with this forecast as even a subtle shift in the winds will have an adverse effect on our weather.

6. Madden-Julien Oscillation(MJO)
While the MJO is a lesser-known phenomenon, it can have dramatic impacts in the mid-latitudes. Several times a year the MJO is a strong contributor to various extreme events in the United States, including Arctic air outbreaks during the winter months across the central and eastern portions of the United States. Unlike ENSO, which is stationary, the MJO is an eastward moving disturbance of clouds, rainfall, winds, and pressure that traverses the planet in the tropics and returns to its initial starting point in 30 to 60 days, on average. This atmospheric disturbance is distinct from ENSO, which once established, is associated with persistent features that last several seasons or longer over the Pacific Ocean basin. There can be multiple MJO events within a season, and so the MJO is best described as intraseasonal tropical climate variability (i.e. varies on a week-to-week basis).

The MJO consists of two parts, or phases: one is the enhanced rainfall (or convective) phase and the other is the suppressed rainfall phase. Strong MJO activity often dissects the planet into halves: one half within the enhanced convective phase and the other half in the suppressed convective phase. These two phases produce opposite changes in clouds and rainfall and this entire dipole (i.e., having two main opposing centers of action) propagates eastward. The locations of the convective phases are often grouped into geographically based stages that climate scientists number 1-8. For us in the Northeast US that want cold and snow during the winter, we want the MJO to be anywhere from Phase 7 through phase 2. However, this is very difficult to predict on a week to week basis.

So, after analyzing all of the data and after taking all factors into consideration, I think that it is now safe enough for me to release my 2016-17 winter forecast for the Northeast United States. I will be breaking this down into 2 sections: Overall outlook, and also amounts for select cities for this region as well. So with that in mind, here is my official forecast for the Winter of 2016-2017 for the Northeastern United States.

NJ/Delaware Shore Areas, Eastern Shore of MD- Sorry to bring you bad news guys, while I do see you seeing some snow this winter, I feel that your snowfall will be below normal due largely in part to several rain events due to the influence of the Atlantic Ocean and it’s somewhat warmer than average temperatures. Not saying that you won’t see any snow, I just feel that you will be in a situation where you’ll be more wet vs white.

Interstate 95 Corridor from Richmond VA to Portland ME & areas up to 30 miles N&W- This will be a very interesting area as I feel we will see a lot of mixing events as we go through the winter. This area will see everything from Snow, to Sleet, to Freezing Rain and even an occasional Rain event when temperatures are warm enough. Overall I see snowfall for the winter ending up near average to slightly above average. I can also see the potential for a few icing events, one of which could be a rather significant Ice Storm for this area.

Central PA, Northeast PA, Central & Western Massachusetts, Central and Western Connecticut & West Central Virginia
This particular area will be above normal with regards to Snowfall for this winter as it will be colder in these areas more frequently. There may also be a few icing events as well in these areas as warm air attempts to erode the cold air which should be in place for these events.

Northern Tier of PA, New York State, NW Pennsylvania, NH, VT, Northern Maine
You guys are in the jackpot zone for this upcoming winter. What I mean by that is that you will experience the worst overall conditions as you will have to endure with some very harsh winter temperatures, as well as the most snowfall. Areas along the lakes will see quite an invasion of Lake Effect Snow as well as Snowfall from Synoptic storms as well.

Select Snowfall for Certain Cities (Average/Prediction)
Washington D.C- Average: 15.4” Prediction: 18”
Philadelphia PA- Average: 22” Prediction: 25”
Allentown PA- Average: 33” Prediction: 40”
Harrisburg PA- Average: 33” Prediction: 45”
New York City- Average: 25.1” Prediction: 27”
Albany NY- Average: 59.1” Prediction: 70”
Buffalo NY- Average: 94.7 Prediction: 120”
Boston MA- Average: 43.8 Prediction: 46”
Worcester MA- Average: 64.1 Prediction: 75”
Nashua NH- Average: 54.9” Prediction: 75”
Portland ME- Average: 61.8” Prediction: 65”
Bangor ME- Average: 66.1” Prediction: 80”

What could go wrong???
1. QBO further strengthens and becomes more strongly positive. This would increase the chances of the AO remaining predominantly positive

2. The PDO drops toward neutral or negative faster than expected. This would allow for a warmer 2nd half of Winter starting earlier in February instead of late February or March, as warm Pacific air will flood the country in a +EPO configuration

3. Blocking is not realized which allows storms to move more quickly instead of slowing down/stalling out

4. The AO becomes too strongly negative. This is also possible, where too much cold air overwhelms the pattern, and suppresses storms south of the region.

5. The PDO maintains positive/warm longer than expected, keeping the cold and snow around longer than expected.

6. We see a monster blizzard which like in previous years would skew higher snowfall totals than what is being projected.

So there you have it…………My 2016-17 Winter Forecast. A very difficult forecast to make, but if it plays out the right way, I think we will all reap the benefits in some form from Mother Nature this winter.

Editor's Note: I had maps for the actual forecast as well as some of the sections regarding my top 6 factors,however they did not load on here so I apologize for that in advance.
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Dean D Davison
Dean D Davison
very good write up Thank you for blogging
3 months ago

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