December 14-15, 2013 Storm Summary

December 14-15, 2013 Snow/Ice/Rain

12.15.13_0218After multiple minor snow events, the first significant winter storm of the season affected the region on December 14-15, with widespread moderate-heavy snow developing with very cold surface temperatures, in the 10s and 20s, later on changing to rain near the coast, freezing rain in the north/west suburbs of NYC, and sleet inland. 4-8 inches of snow were recorded across a large part of the NYC area, with ice totals up to 1/4 inch in the north/west suburbs of NYC and SW CT.

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December 14-15, 2013 Storm Archive

NWS Regional Radar
WPC Surface Analysis


Storm Synopsis

dec14trackSynoptic Setup: The system formed as a result of the interaction of three systems; a northern stream shortwave trough over the northern US, and two southern stream shortwaves, which as of December 12, the leading southern shortwave was stalled just off southern California, and the trailing southern shortwave was entering the northwest US. By the 14th, the leading southern shortwave entered the Ohio Valley and continued to track northwest while interacting with the northern stream trough entering the Midwest, with a surface low developing near Missouri and tracking into Ohio. Late into the day and early on the 15th, the trailing southern energy caught up with the rest of the system, which along with a strong surface high pressure over the northeast US led to a transfer to a developing coastal low pressure just off the coast, which then quickly deepened as it exited the region and entered Nova Scotia.

Regional Setup: An arctic cold front moved through the northeast US early on the 14th with a strong cold air mass following behind it, which along with a strong high pressure initially stationed over northern New England resulted in a cold air damming setup near the surface, with temperatures in the low-mid 20s across the NYC area and single digits/low 10s further inland when precipitation began to fall. By the evening hours, with the development of the coastal low pressure, a strong east/ESE wind developed near coastal areas, leading to a changeover to rain over Long Island and NYC with temperatures quickly surging into the 40s and 50s overnight. Despite the presence of low level cold air elsewhere in the region, however, the mid level low pressure took longer to transfer to the coast, with southerly winds and warm air advection aloft resulting in a changeover to freezing rain in the north/west suburbs of NYC and sleet further inland, extending as far north as the northern Hudson Valley and parts of Connecticut.



Forecasting The Storm

December 9 – Snow Likely Tomorrow
December 11 – Cold Returns, Storm This Weekend
December 12 – Snow, Ice, Rain Expected Saturday
December 13 – Significant Snow, Ice Tomorrow
December 14-15 Storm Updates


Post-Storm Analysis

This section will be added soon.



Storm Timeline in the Northeast

Regional radar image from 11:18 AM EST 12/14, from the National Weather Service. Widespread light snow covered the region, with the heaviest precipitation still in the Ohio Valley.

Temperatures up to the storm were unseasonably cold, falling into the single digits across the interior Northeast as an arctic front slowly moved south through the region on Friday night, December 13, allowing some of the frigid Canadian air to spill into parts of the region. With the heaviest precipitation still centered over the Ohio Valley, overrunning light snow spread across the region on Saturday morning, 12/14, with totals locally up to 1-2 inches in southeast NY by the late morning hours associated with localized bands of moderate snow. Temperatures were initially in the low-mid 20s as snow began, and steadily fell into the mid-upper 10s inland and the low-mid 20s across the rest of the area by the afternoon hours.


Regional radar image from 6:28 PM EST 12/14, from the National Weather Service. Moderate to heavy snow covered most of the NYC area, while the mixing line gradually shifted north.

Snow steadily intensified across the region, becoming moderate over the area by 3-5pm and heavy at times by 6-7pm. By that point, the coastal low pressure had organized over North Carolina and began intensifying and tracking up the coast, with precipitation redeveloping and intensifying over Virginia, while the primary low pressure entered Ohio. Widespread moderate to heavy snow began to spread into New York state and later New England.

The mid level low was still centered over the Ohio Valley, bringing a strong surge of mid level warmth into the region while the surface temperatures remained in the 10s and 20s. Long Island was among the first locations to change over to rain by 8-9pm with a strong easterly wind ahead of the coastal low, with temperatures rapidly surging into the 30s and 40s, while NYC only slightly warmed up into the 30s with a changeover to sleet and rain by 9-10pm. Other parts of the area continued to see snow, but with pockets of lighter precipitation rates preventing heavy snow from continuing uninterrupted.

Regional radar image from 12:18 AM EST 12/15, from the National Weather Service. Heavy rain covered NYC and the coast with freezing rain in the suburbs and sleet further inland.

By the late evening and early overnight hours, temperatures surged into the 40s and 50s over Long Island as winds temporarily shifted to the east/SE, while cold air remained in place near the surface over NYC and further inland, with temperatures still in the mid-upper 10s in NW NJ/SE NY and the low-mid 20s elsewhere, only starting to rise by the late evening. With mid level warm air advection continuing, a changeover to freezing rain occurred in NE NJ, Rockland county in NY and SW CT by 11pm-12am, while interior NW NJ and SE NY changed over to sleet. By that point, the heavy snow spread into the Hudson Valley and central New England, where the highest snow totals were observed. Moderate to heavy precipitation continued over the area past midnight, ending between 2-4am from southwest to northeast.



Storm Impact and Precipitation Totals

12.14.13_snowThe storm produced widespread moderate to significant snow accumulations across the region, as well as heavy rain in coastal southern regions and freezing rain over eastern Pennsylvania into parts of the NYC area and southern New England. The most significant impacts came in the form of heavy snow, as this was the most significant snowstorm since March 18-19, 2013 to affect the region. Widespread snow totals of 8 to 14 inches were observed from northeast Pennsylvania into central NY and central-northern New England, with 4 to 8 inches elsewhere in the northeastern US. Snow totals were much lower south of the MD/PA border into central New Jersey, generally less than an inch except for higher elevations. A notable aspect of the storm in the northeastern US was the temperatures, as very cold air persistently stationed over Canada throughout December partially entered the region, with temperatures in the single digits when the storm arrived, only warming into the 10s by the peak of the storm despite mid level temperatures approaching the freezing mark.

In the NYC area, the storm produced a wide variety of impacts ranging from heavy snow and cold temperatures inland to a wintry mix and a surge of warmth and wind in coastal regions. At least 4 to 8 inches of snow fell across northern NJ, northern parts of NYC, SE NY and Connecticut, with 1 to 4 inches in Long Island and coastal NYC. Up to at least 1/4″ of freezing rain was observed in northeast NJ and SW CT, peaking at 0.30″ in New Haven, CT, while eastern Long Island saw temperatures spiking into the low 50s with gusts up to 30-40 mph.

Below is a list of selected snow reports across the area from the National Weather Service, listed by highest total from each county:

Northern NJ:
6.3″ – East Rutherford, NJ (Bergen)
6.3″ – West Milford, NJ (Passaic)
6.3″ – Cranford, CT (Union)
6.0″ – Newark, NJ (Essex)
5.5″ – Kearny, NJ (Hudson)

Southeast NY:
8.5″ – New Windsor, NY (Orange)
7.6″ – Armonk, NY (Westchester)
7.5″ – Kent Cliffs, NY (Putnam)
5.0″ – Sloatsburg, NY (Rockland)

New York City:
7.1″ – Bedford Park, NY (Bronx)
6.0″ – Upper West Side, NY (Manhattan)
4.7″ – LaGuardia Airport, NY (Queens)
3.0″ – Sheepshead Bay, NY (Brooklyn)

Long Island and South CT:
7.3″ – Haddam, CT (Middlesex)
7.2″ – Weston, CT (Fairfield)
7.2″ – North Haven, CT (New Haven)
6.1″ – Bayville, NY (Nassau)
4.0″ – Gilman, CT (New London)
5.0″ – Wading River, NY (Suffolk)

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