Second noreaster in as many weeks to strike Wednesday Night

NAM Model showing forecast 10m winds (just above the surface) with a major storm system just off the New Jersey Coast on Wednesday evening.

A nor’easter which would usually be the weather story of the month will impact the area on Wednesday and Thursday, but it will remain overshadowed by the effects of Hurricane Sandy. Only a little over a week after Hurricane Sandy wreaked havoc on the area, another major nor’easter is poised to move just off the coast of New Jersey. Another strong atmospheric disturbance moving off the coast of the Southeast US will phase with a disturbance dropping south from the Mississippi Valley, and strengthen rapidly offshore. As it moves north periods of moderate to heavy rain are likely to spread northwest from the Atlantic Ocean towards New Jersey, New York, and Connecticut. In addition, cold air in place could allow for the development of frozen precipitation especially just inland away from the shores and in the higher elevations if NJ and NY. Wind will also be a big concern near the shores — and this will depend greatly on the exact track of the system. Check out the details below…

How is this storm system developing? A piece of energy over the Southeast United States will swing eastward towards the coast, while another disturbance drops south out of Canada into the Tennessee Valley and phases with it. Yes, we’ve heard these terms before. The phase will allow the storm to strengthen off the coast once again. This time, the blocking to the north won’t be strong enough to force the storm well inland (it’s also not a tropical system hybrid) but the storm system is still forecast to be plenty strong as it develops off the coast and then gets tugged near the shore. In fact, some of the recent forecast models are beginning to show the storm turning northwest and making a very close approach near the coast of NJ and Long Island.

What are the main threats with the system? This nor’easter will provide a myriad of threats.  The system will be entering a very cool airmass which is in place across the region (check out how chilly it is tonight), and the high pressure will shift to the north and do its best to keep the cold air in place. This, with the storm system strengthening offshore, creates a threat for wind and rain along the coast, some storm surge, and the possibility of frozen precipitation for a period of time especially inland.

  • Rain: The system looks to  provide moderate amounts of rainfall throughout the entire area, with the potential for some heavier rain along the coasts and on Long Island. The one caveat to this is that the storm’s best period for strengthening and heavy precipitation will be south of the area, so after an initial thump of heavy rain as the storm comes in, there may be a lightening of precipitation as the “cold conveyor belt” weakens over the area.
  • Wind: This is not something you want to hear, we know. But the storm system looks to have a significant amount of wind with it, especially aloft. The difference between this storm and Hurricane Sandy other than the size and intensity is that the atmosphere will be less favorably set up for mixing these winds down to the surface. However, there may still be gusts over 60 miles per hour especially near the coasts. These type of wind gusts are still dangerous and could cause some downed trees and power lines, especially ones weakened by Sandy. The wind should be less of a threat over inland areas due to the stable northerly wind component, but still capable of gusts near 40-50mph. This creates a significant hazard especially for those areas which are still recovering from Hurricane Sandy.
  • Storm Surge/Flooding: This storm will occur, luckily, at a period between full moons and astro-low tides, whereas  Sandy occurred during a full moon at high tide. However, such a strong storm system as this one can still often produce a storm surge…yet it should be at least somewhat mitigated by the fact that the system is expected to remain offshore. That being said, prepare for the possibility of some coastal flooding once again — to repeat…we are not expecting widespread storm surge/coastal flooding..but it remains a distinct possibility that it will occur, to a lesser extent than it did during  Sandy.
  • Snow: Yes, snow is actually a threat with this system. Recent model runs have cooled the thermal profiles and support a period of snow even in areas such as NYC and Central NJ stretching as far west as Philadelphia. The prolonged snow and light accumulations look most likely over interior NJ, Eastern PA, and Southeast NY/CT. But a slushy inch of snow cannot be ruled out even in the immediate suburbs of Northeast NJ and Central NJ as well.

Timing: Rain is expected to begin across the New Jersey shore as early as Wednesday afternoon and will spread north towards Long Island and NYC/NJ. The rain will quickly become moderate to heavy with a noticeable increase of wind as well near the coast. As the intensity increases, snow and sleet will mix in with precipitation across the suburbs and inland. The snow and sleet could continue for several hours across the suburbs especially farther inland. In the city and along the coast, after a period of snow it is expected that the snow will change back to a light rain or sleet for a period of time late Wednesday Night. Overnight, the precipitation is expected to remain light to moderate with rain and wind near the coast, sleet and rain mix just inland, and mostly snow across the interior. By Thursday Morning, precipitation is expected to lighten as the storm pulls away. Total snowfall accumulations of 1 to 3 inches at the most are expected with lesser amounts in most areas. Wind gusts of 40 to 50 miles per hour are possible near the coast with some higher gusts to near 60 miles per hour in isolated areas.

What are some of the forecast uncertainties? The exact track of the storm will have huge impacts on the sensible weather in the area. A closer to the coast track will mean warmer air working in (limiting the snow to the far inland areas) and much stronger winds near the coast. A farther offshore track will mean less wind, but more available colder air and more frozen precipitation would be likely even into the immediate suburbs of NYC, NJ, CT, and Philadelphia. Stay with us over the next 12 hours as the storm rapidly approaches and we begin to get a better idea as to the exact track of the system.

 

 

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