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A Winter Rebound?

I'm sure you've been hearing or soon will be hearing a lot about the Madden-Julian Oscillation (MJO) over the next several weeks as many are pointing out we are entering a phase that maybe favorable to pull the Northeast out of its Winter slump. But first, what exactly is the MJO and what does it do?

The MJO is an atmospheric phenomenon that occurs in the tropics and affects weather patterns across the globe. The MJO is a large-scale eastward-moving disturbance of atmospheric winds, clouds, and precipitation that typically cycles between active and inactive phases every 30 to 60 days. The MJO is characterized by a large-scale circulation pattern that moves eastward across the tropical Indian and Pacific Oceans. During its active phase, the MJO brings enhanced rainfall and storm activity to some regions, while other regions experience drier than normal conditions during the MJO's inactive phase.

So, how does this MJO affect our weather in New Jersey? The MJO has 8 phases, and each phase has a different cause/effect across the globe.

Above are temperature correlations to each phase and how it affects different areas of the United States. We've been sitting in phases 3,4,5, and 6 for the past several weeks, which has lead to above normal temperatures the entire Winter.

This Winter has been a big disappointment for snow lovers and time is not on your side as we are already into March and daylight is becoming longer every day, which leads to longer day-time heating and less chances of accumulating snowfall unless under the ideal conditions. So, what do we need to possibly get a rebound for Winter before we officially break into Spring?

MJO Phase Forecast

Above is forecast for the MJO and what phase it is forecasted to be in. The GFS(blue line) and ensemble GEFS (green line) are both agreeing we will be entering a phase 7 and into 8 towards the middle of March. The notable factor is the strong phase 8 forecast, which points to one ingredient for a favorable wintry pattern. When the MJO is in phase 8, it can disrupt the typical winter weather patterns in the Northeast and lead to colder and snowier conditions.

Phase 8 of the MJO is characterized by enhanced convection and precipitation in the western Pacific, which can strengthen the subtropical jet stream and cause it to dip farther south than usual. This can result in a pattern of cold air outbreaks across the eastern United States, which can bring snow and ice storms to the Northeast.

During the winter of 2021-2022, the MJO entered phase 8 in mid-December and remained in this phase for much of January. This led to a prolonged period of cold and snowy weather in the Northeast, with several major snowstorms affecting the region during this time. Unfortunately, we are not in the middle of Winter but heading towards beginning of Spring so the MJO setting up in a favorable pattern does not automatically put us in a Winter rebound situation but one of a few indices on our side does peek the interest for me.

Next, we have Teleconnections (NAO, AO, PNA, AAO) that also help forecast different atmospheric pressure patterns that may impact our weather here in New Jersey region. The most popular that you hear are the NAO (North Atlantic Oscillation & AO (Arctic Oscillation). If you want a cold and snowy pattern setup, you are looking for a negative NAO phase and a negative AO phase.

North Atlantic Oscillation (NAO)

With a negative NAO phase, you have an increased likelihood that you will have high latitude blocking in the North and a dip in the Jet Stream that will push down the arctic air over the Mid- Atlantic, which will then give you overall ingredients for a potential wintry setup.

NAO Forecast

Above is the 14-day forecast for the NAO and it gives us an idea what forecast models maybe seeing in the future. Currently, we are in negative NAO, which looks like to continue to get stronger and then level off to even towards mid month. A favorable setup would be a -2 NAO.

Arctic Oscillation (AO) Left = Positive. Right = Negative

When the AO is in a negative phase (see right image above), it causes a weaker polar vortex, allowing frigid Arctic air to move southward into the mid-latitudes. This can lead to colder than normal temperatures in the Northeast region of the United States, as well as increased snowfall and storm activity.

AO Forecast

Same as the NAO, we have the forecast for the AO, which shows us a negative AO through the beginning weeks of March and leveling off to even around mid March. So far, we have a few indices that are aligning to raise an alarm that we maybe seeing some potential storm activity for the Northeast in the first half of March.

Another Popular teleconnection is the Pacific-North American Pattern (PNA). PNA is characterized by high pressure over the Pacific and low pressure over the central and eastern parts of North America. The high pressure over the Pacific helps create a ridge over the West coast, which then creates a trough in the Jet Stream over the Midwest, which help create a path for storms to dig South and feed into the Gulf moisture and ride up the coast.

Postive/Negative PNA Example

PNA Forecast

Above is the forecast the PNA through Mid March, which shows the PNA being in more of a negative phase through the first half and beginning to climb more into a positive phase by mid March. So far, we the MJO, NAO, AO, and now the PNA all showing signs of something maybe brewing towards the middle of March.

I'll continue to monitor mid month potentials and see what the GFS & Euro may say about Winter making a return before Spring arrives.

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