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Behind coastal storm, more snow possible Tuesday

Two atmospheric disturbances within a relatively short distance of one another will impact the area early this week, with the first and more powerful storm grazing the area on Monday. That storm system will strengthen off the East Coast and shift northeastward, bringing periods of heavy snow to Long Island on Monday. The bands of steady snow should graze New York City and the NJ Coast, as the fringe of precipitation sits near the area.

Behind this storm system, precipitation will remain in the forecast — not the typical dry air and clearing that we often see behind Nor’Easters. Instead, another atmospheric disturbance will drive southeastward from the Great Lakes to a position near the Mid Atlantic on Tuesday, and a surface low pressure area will develop off the coast of the Northeast US yet again.

NAM model showing a low pressure area extending westward toward the coast on Tuesday, with snow in parts of NJ.

NAM model showing a low pressure area extending westward toward the coast on Tuesday, with snow in parts of NJ.

This surface low will be rather weak compared to the prior storm, but it will act upon an area of moisture and atmospheric energy. This area of lift extends back westward from the surface low which will form offshore on Tuesday, also known as in “inverted trough”. Essentially, a trough of lower pressure extends west from the surface low which will be off the coast — and allows for steadier lift and precipitation hundreds of miles away from the storms center.

Exactly where this inverted trough sets up will be critical to the forecast moving forward. Forecast models have struggled with pinning down the positioning of the feature, which has a lot to do with the exact track of the prior storm and intricate details of the atmospheric disturbance itself. Some models keep this energy farther south over Southeast Pennsylvania and New Jersey, while others bring it farther north over Northeast New Jersey and New York City.

NAM model showing light to moderate snow on Tuesday evening from a  weak coastal storm.

NAM model showing light to moderate snow on Tuesday evening from a weak coastal storm.

Within this zone of lift on Tuesday into Wednesday, several inches of snow will be possible. These areas of lift (or “inverted trough’s” can often produce steady to heavy precipitation over an area for a prolonged period of time. Over the next 12 to 24 hours, we will have to pin down the exact location and intensity of this feature using mesoscale analysis and short term forecast models.

Stay tuned for updates throughout the day.

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