Nor’easter Jonas Evening Forecast Addendum

Additional details on the New York / New Jersey Metro Area

Getting it right with “minor” versus “moderate” flooding is particularly important when there is ice and freezing temperatures, as NOAA’s definitions (see below) suggest some evacuation may be needed when they designate flooding as moderate.

As mentioned in the prior post, areas in New York Harbor and up the Hudson like Hoboken, as well as the New Jersey Meadowlands have a good chance of minor flooding, but have a very low chance of moderate flooding.  However, some other parts of the Metro Area have a reasonable chance of “moderate flooding” like the New Jersey coast – sites that are close to the ocean, or in Newark Bay and Arthur Kill.  Examples are Jamaica Bay, Raritan Bay, the south end of Newark Bay, and Arthur Kill.  These areas are likely to have minor flooding and have a good chance (about as likely as not) to see moderate flooding levels (e.g. over 5.4 feet NAVD88 or 8.7 feet MLLW at Inwood, Jamaica Bay).  Detailed forecast plots for these sites are all available on the Stevens Flood Advisory System (

NOAA’s definitions for flooding are:

Minor Flooding – minimal or no property damage, but possibly some public threat (e.g., flooding of roads).

Moderate Flooding – some flooding of structures and roads near stream. Some evacuations of people and/or transfer of property to higher elevations.

Major Flooding – extensive flooding of structures and roads. Significant evacuations of people and/or transfer of property to higher elevations.


NY/NJ Snow Forecasts

The Global Forecast System (GFS) and ECMWF higher spatial resolution model (HRES) are both showing a range of approximately 4-10 inches of accumulated snow in the Northern parts of New Jersey and the New York City area.

The snow is to begin in the morning of Saturday, January 23 and the end of snow accumulation is expected around early Sunday morning (1:00 am – 5:00 am EST). The highest snow rates are expected on January 23 (between 6 pm and midnight EST) from what the models are showing.

The areas in Southern New Jersey and Trenton are more likely to receive up to 20 inches of snow based on the ECMWF model. However the GFS model is indicating an accumulated snow of 12-16 inches.


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