Frequent updates will be posted below on the heavy snow and rain event affecting the region today. Radar images are from the Pennsylvania State University e-Wall.
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Final storm snow accumulations in NYC: (Updated 7pm)
Central Park – 8.0″ | LaGuardia – 7.7″ | JFK Airport – 6.7″
4:50 PM: Snow Moving Out
Since the previous update, the back end of the precipitation shield has entered the western parts of the area, with snow lightening up especially west of NYC. The back end of the precipitation shield will continue to spread east into Long Island and CT, where moderate snow continues to fall; most locations are expected to dry up by 6pm. The latest reports suggest widespread snow totals around 6-8 inches in north NJ, NYC and Long Island, with locally higher totals towards western New Jersey, sharply decreasing to 2-4″ in SE NY and interior Connecticut.
This is the final storm update for today. A brief forecast update will be posted this evening, with the next full forecast discussion and final outlook for Wednesday’s storm to be posted on Tuesday morning.
2:40 PM: Storm Update
Snow rates have slightly decreased west of NYC as the back end of the steady moderate-heavy snow has shifted into Long Island and Connecticut, continuing to move east; moderate snow continues at times west of NYC but has become somewhat more scattered in coverage area. The back end of the precipitation shield is near central PA and gradually moving ENE; at its current rate, snow is expected to begin to taper off around 4-5pm. By the time the storm ends, the highest snow totals in the area are likely over northern NJ and Long Island, generally in the 6-10 inch range, locally up to 10-12 inches in some spots.
Snow to liquid ratios were generally near to slightly less than 10:1 given liquid precipitation totals of near an inch, which was more than anticipated, especially with the earlier onset of heavy precipitation and slightly heavier precipitation rates than expected. With the marginal temperatures and the lower ratios, the snow that accumulated today was generally wet heavy snow, which can lead to downed trees and potential power outages. Any snow that melted may refreeze tonight with lows in the mid 10s-low 20s expected for most of the area.
1:10 PM: Snow To Gradually Lighten Up
The latest storm reports posted by the National Weather Service were at 11:30 am; at that time, most of the area had 3-5 inches of snow, peaking at 5.0″ in Mount Sinai and Albertson, NY (Long Island) and 4.9″ in Tenafly, NJ (Northeast NJ). Since then, there have been additional reports of up to 6-7″ in northern New Jersey and parts of Long Island.
The back end of the moderate-heavy snow is currently near the NJ/PA border, and is gradually progressing eastward; by 2-2:30pm, most of the area is expected to see gradually decreasing snow rates as the low pressure continues to push offshore and the mid level shortwave trough moves overhead, pushing the favorable dynamics and lifting for precipitation offshore as well. Snow is expected to gradually decrease in intensity, ending for most locations by 3-4pm.
11:00 AM: Heavy Snow to Soon Move Out
Moderate to heavy snow has spread into the area from Pennsylvania, but with the tight precipitation gradient setting up near NW NJ into Putnam county in SE NY and central CT, where the heavier snow has struggled to expand north as the heavy precipitation bands are further south than most of the short range models indicated, especially the HRRR, which placed almost all of northern New Jersey under reflectivity of over 30+ dBZ on the radar which would reflect the heaviest snow in these locations. Storm total reports as of 10-11am are generally in the 3-5 inch range for most of northern NJ, NYC and Long Island with lower totals to the north.
The steady moderate-heavy snow is expected to end by at least 12:30-1pm, but with occasional periods of moderate snow continuing through at least 3-4pm before ending from west to east. Forecast accumulations remain unchanged for most, but have been slightly decreased to 2-5″ in NW NJ into SE NY.
9:15 AM: Additional Snow Moving In
Over the last few hours, the heavy snow spread into NYC and Long Island, where some accumulations have begun, although lighter rates have been reported further inland as heavy precipitation banding set up near far southern PA into south-central New Jersey, which is slightly south of where most short range models depicted the band, especially the HRRR and RAP which depicted near 1 inch of additional liquid-equivalent precipitation near NYC which is most likely too high. Additional moderate to heavy snow is developing over central PA and will expand ENE to cover the area between 9:30am through at least 12pm, with snow rates expected to gradually decrease afterwards. Forecast accumulations remain unchanged at this time.
6:15 AM: Heavy Snow Entering Area
As of 6am, the low pressure is near western North Carolina. Minimum pressure is near 1008 mb, and the low is steadily tracking east/ENE. The low will slightly deepen before emerging off the Mid Atlantic coast and quickly continuing to track east-northeast.
As the latest regional radar reflectivity to the left shows, the heaviest snow is currently centered from western Maryland into central Pennsylvania and northern NJ. Further south, heavy precipitation is currently falling, but the slow decrease of temperatures behind the cold front is keeping the boundary layer warm enough to support rain from northern Maryland into Philadelphia and central NJ. These locations will continue to slowly cool down today, but with indications supporting the southern end of the accumulating snow zone setting up further north than anticipated yesterday.
Over the area, rain has changed over to a moderate wet snow in northeast NJ, with the changeover to snow currently underway in NYC and Long Island. Due to warm ground temperatures, the snow is struggling to accumulate, with no accumulations reported in NYC as the snow melts on contact, but with accumulations quickly increasing northwest of NYC, with reports of up to an inch of wet snow just northwest of NYC in Tenafly, NJ (Bergen) and up to 1.5-2 inches into Passaic county. Snow will continue to spread across the area, with the peak of the heavier snow rates expected between 8am and 12-1pm. Moderate snow is expected to continue through 3-4pm before gradually tapering off from west to east.
Comparing the model guidance with the latest observations, the 6z RGEM, 0z RAP and high-resolution NAM are fairly close to the latest observations; the 10z RAP and HRRR, which depict near an inch of liquid-equivalent precipitation over NYC, are a little too far north with the current banding. This would support the heaviest snow totals from around south-central PA extending ENE into central NJ and just west of NYC between I-78 and I-80, with accumulations of 6-10 inches expected within this zone, locally up to 12 inches. Over the NYC area, accumulations of at least 5 to 8 inches are expected along northern NJ into NYC and Long Island, locally higher up to 10″ especially west of NYC; 4 to 7 inches in extreme northern NJ towards the NY/NJ border; 3-6 inches in southern CT and lower SE NY; and 2-4 inches into the lower-mid Hudson Valley. An updated snow map will be posted shortly, focused on the NYC area.
Forecast Update: Today’s storm is the first in a series of three major snowstorms likely to affect the region over the next week. The next storm is expected on Tuesday night into Wednesday; at this time, thinking has not significantly changed since yesterday’s update, with light-moderate accumulations in NYC and Long Island followed by a changeover to rain on Wednesday morning; moderate snow (generally up to 6-8″) accumulations in the north/west suburbs of NYC and south CT changing to ice and/or rain on Weds morning; and significant snow (generally up to 10″) with a changeover to ice in NW NJ/SE NY. Given the timing of the storm, this will have to be monitored for impacts on the morning commute as well, especially inland of NYC. The third snow potential exists on Sunday; both the 0z ECM, CMC and GFS depict a major snowstorm affecting the region on Sunday, continuing recurring signals that have shown for this time frame over the last few days for a significant storm potential. As this is almost a week away, specific details cannot be determined at this time, but potential for another widespread snowfall exists in this time period and will continue to be monitored.