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The storm is forecast to hit the northeast Sunday into Monday

Impacts are all based on precise timing in all layers of the atmosphere

CNN  — 

Sunday marks the five-year anniversary of when Superstorm Sandy hit New Jersey and New York. And Sunday night into Monday morning, it’s looking more likely that another big storm will lash the Northeast.

But – possibly like your Facebook relationship status – it’s complicated.

This forecast banks off newly-formed Tropical Storm Philippe in western Cuba, a low-pressure system swinging a cold front across the eastern United States and a large dip in the jet stream – which is due to former Typhoon Lan now off the coast of Alaska – all merging at the same time near the Northeast Coast. The magnitude of the impact depends on whether the weather all lines up.

As these systems come closer together, you may hear people begin to reference the “perfect storm” – a term used by meteorologists when everything in the atmosphere comes together just right to produce dangerous conditions.

“This is no longer a perfect storm, this is an imperfect storm,” CNN Meteorologist Chad Myers said Friday.

The forecast models are still showing a significant storm; it just won’t be “perfect.”

But don’t take the storm lightly. Tropical storm-force winds, coastal erosion and flooding rains are still likely from the Mid-Atlantic through New England. One thing is for certain: This storm system is not forecast to be as strong as Sandy.

The uncertainty lies in the timing

The National Hurricane Center found enough of a circulation Saturday morning to declare the Caribbean system a tropical depression and by 5 p.m. Saturday, it had strengthened to become the 16th named storm this year in the Atlantic.

Philippe isn’t expected to become a hurricane and is forecast to quickly move parallel to the East Coast.

Now, this is when it gets more complicated, but stay with us:

Tropical Storm Philippe will funnel tropical moisture, helping to strengthen the amplified upper-level trough in the jet stream – the level that airplanes fly – and it will dip far enough south to launch the new low pressure rapidly up the East Coast and act as a bowling lane with the pins set up in the Northeast.

The CNN meteorologists think a low-pressure center that forms off the coast of the Carolinas early Sunday will move up the coast. As it does, it will gather energy and strength from a few different places: The same upper-level system will aid in bringing with it what is called a jet streak – which simply means an area of very confined, very fast winds. The storm will gather fuel from the warm ocean temperature in the Gulf Stream and it will pick up speed from a weak point in the surface pattern.

But wait, there’s more.

At the surface – the part of the atmosphere we experience – a cold front will swing through the eastern half of the United States. This front will come out of the same system that is bringing one of the first tastes of winter to the Midwest. This system is typical this time of year and brings rain, sometimes severe storms and behind it, cold crisp air.

By Sunday evening, the storm is off the coast, threatening the Mid-Atlantic. Impacts will begin Sunday evening and last through Monday morning for the major metro areas of Philadelphia, New York and Boston. By Monday midday, the system will quickly exit the US and move to Canada.

How it will impact you

Most of the impacts, again, depend on timing and location. However, some things are inevitable.

The southern tip of Florida will get an increased amount of rainfall throughout the day on Saturday. Everywhere along the East Coast, from Florida to Maine, will experience rain to some varying degree between Saturday and Monday. There could also be a few isolated tornadoes. One struck just southwest of Miami on Saturday afternoon, damaging a few homes and knocking over trees and power lines.

As the low pressure moves up the East Coast, there will be an increased amount of rainfall from Philadelphia to Boston. There will not be enough cold air in place to have snowfall along the coast. Either way, New York City residents will wake up Sunday wondering what happened to the sunny skies of the day before.

The cold air will move in swiftly after the system passes.

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    Temperatures in New York City will go from the upper 60s this weekend to the 50s on Monday.

    Gusty winds will move in with the front on Sunday, but the ferocity of the winds’ speed is dependent on where the low pressure comes ashore.

    There is still a bit of uncertainty with this system. We are, thankfully, nearing the end of a very active hurricane season.

    But winter is knocking at the door.

    CNN Meteorologists Gene Norman, Monica Garrett and Taylor Ward contributed to this report