Wednesday's nor'easter is a classic warm air system that will track up the coast and bring with it a mix of rain, sleet and snow to the area. The forecasting challenge will be where the snow/sleet and rain/sleet lines set up and move.
These storms are typical. The three early season winter storms that produced all snow in an unusually cold La Nina winter were atypical. The key ingredient to forecasting this storm is getting the track right as well as the amount of cold air. Keep in mind that this storm comes right after the northeast experienced its coldest temperatures of the season. Reuters news reported that Saranac Lake, NY recorded minus 36 degrees on Monday morning. There is also a fresh snowpack on the ground. Forecast models show that there will be plenty of cold air in the upper layers of the atmosphere.
Forecast
The current National Weather Service forecast for Central Park:
Snow Wednesday morning, turning to rain, sleet and snow after noon. Less than half an inch accumulation of snow/sleet. High 37, East wind 6-14MPH. The mix becomes all snow after 9PM with the temperature dropping to a low 29. Winds increase to 16-18MPH overnight with snow accumulating 4-8" and ending by 7AM and gusts as high as 25MPH.
These storms are typical. The three early season winter storms that produced all snow in an unusually cold La Nina winter were atypical. The key ingredient to forecasting this storm is getting the track right as well as the amount of cold air. Keep in mind that this storm comes right after the northeast experienced its coldest temperatures of the season. Reuters news reported that Saranac Lake, NY recorded minus 36 degrees on Monday morning. There is also a fresh snowpack on the ground. Forecast models show that there will be plenty of cold air in the upper layers of the atmosphere.
Forecast
The current National Weather Service forecast for Central Park:
Snow Wednesday morning, turning to rain, sleet and snow after noon. Less than half an inch accumulation of snow/sleet. High 37, East wind 6-14MPH. The mix becomes all snow after 9PM with the temperature dropping to a low 29. Winds increase to 16-18MPH overnight with snow accumulating 4-8" and ending by 7AM and gusts as high as 25MPH.
Analysis
This nor'easter will move up the coast Tuesday night and develop into two very strong low pressure systems off the NJ coast and further offshore Cape Cod Wednesday night. However, the major energy of the system and deepest low will be far enough offshore that we should only see moderate snow accumulations. The National Weather Service upped their morning forecast from 3-5" to 4-8". Six inches sounds about right. In addition, there is very warm air associated with the system (850mb temps 10C) that will create a rain/sleet/snow mix during the peak times of precipitation. This will pack down accumulations as well as hold down the totals. That said, the track is far offshore and the 18Z models indicate that this storm will have more cold air to work with than the 6Z or 12Z. A slight track further inland with enough cold air and this thing could easily give us a foot of snow. Too far inland and Long Island and the NJ coast will get a lot of rain and maybe 2 or 3 inches after the change over back to snow. This storm is a real forecast challenge.
I like the way this is coming together though and I think inland (Rockland, Orange, NW NJ) will see a foot of wet heaving snow overnight tonight. The city will get at least 6 inches and possibly 8-12"+ if the timing works out. Long Island and coastal sections of NJ will get 2-5 inches with the lowest totals near the Atlantic coast.
I like the way this is coming together though and I think inland (Rockland, Orange, NW NJ) will see a foot of wet heaving snow overnight tonight. The city will get at least 6 inches and possibly 8-12"+ if the timing works out. Long Island and coastal sections of NJ will get 2-5 inches with the lowest totals near the Atlantic coast.
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