Feb 8-9, 2013 Blizzard Summary

February 8-9, 2013 Blizzard

The first northeast US blizzard since January 2011 affected the area on February 8-9, 2013, as two low pressures, one in the interior and another off the coast, phased over the region. This combination brought heavy snowfall for the area, with the worst of the storm focused over Long Island into southern New England where blizzard conditions were observed with snow totals over 18-24 inches. In the area, 8 to 16 inches of snow fell west of NYC, with 16 to 32 inches, locally as high as 40 inches, in Long Island and southern CT.

 

 

 


February 8-9, 2013 Storm Archive

Regional Radar

 


Storm History

The low pressure originated in the central US region on Wednesday night, February 6. By Thursday, February 7, there were two separate low pressures, a low near the northern Ohio Valley producing widespread moderate-heavy snow, and a strong coastal low over the Southeast US producing heavy rain and thunderstorms. Both lows continued to steadily track to the northeast.

On Friday, February 8, the two low pressures began to interact as the coastal low increased its northern track component and intensified, with minimum pressure down to 997 millibars. Meanwhile, the interior low also slightly intensified while tracking into NW Pennsylvania and later western New York. In the morning hours, the two lows maintained separate precipitation shields, although the merging of the storms became more evident by the afternoon and evening hours as the coastal low continued to intensify and became the dominant low pressure, with minimum pressure near 983 mb by the evening. The coastal low continued to slow down and intensify overnight while heavy snow bands spread into central and eastern New England creating near blizzard conditions, especially in Connecticut. By Saturday morning, the low became nearly vertically stacked while reaching its peak strength with a minimum pressure near 977 mb, weakening afterwards as it continued to move away from the region.

 


Forecasting The Storm

February 4 – Snow Again Tonight, Tomorrow
February 5 – Significant Storm Possible Friday
February 6 – Friday Storm Forecast Update
February 7 – Blizzard Expected Tomorrow Night
February 8-9 Storm Updates

Post-Storm Analysis

The 2/3 0z run of the ECMWF was the first to show a significant storm affecting the region. Image from PSU e-Wall.

Medium Range: Forecasting the blizzard in advance was more difficult than usual, as typically hints of a major storm show up on the model guidance at least more than a week in advance, but in this case there was no model showing a significant storm until only 120-144 hours (5-6 days) out, when the 2/3 0z ECMWF run showed a major nor’easter tracking over NYC and Boston with heavy rain for the coast and a major snowstorm inland. At that time, the ECM was the only model suggesting such an outcome; the rest of the models as well as prior ECM runs were in agreement with showing a weak clipper tracking from the Midwest into the Northeast with 1-3 inches of snow in central-northern New England, with no sign of a coastal low pressure to the south.

Through the rest of the 2/3 and 2/4 runs, the ECM remained the only model to show a major nor’easter, although it gradually trended further southeast with each run, at one point showing the blizzard conditions limited to southeastern New England and eastern Long Island while the rest of the region saw less snowfall. The ECM ensembles, which originally supported the operational ECM runs with the major nor’easter, also gradually trended southeast to show a weak and progressive coastal low. Meanwhile, the rest of the model guidance continued to show a dominant northern stream system with a weak and fast moving low pressure producing 3-6 inches of snow in the central-northern Northeast and light rain in the NYC area. The 2/4 evening runs, only 90 hours away from the storm when typically a significant storm would have more solid model support, began to show a weak coastal low, but kept both northern and southern streams separate, with a clipper quickly moving through the Northeast and the coastal low staying offshore.

Short Range: The rest of the model guidance did not begin to trend to a major nor’easter until the afternoon runs on 2/5, only 78-84 hours away from the storm, and even then was still inconsistent with the scenario. The 2/5 12z run of the GFS was the first to show a major coastal storm, showing a moderate rain/snow storm for the area and heavy snow in SE Massachusetts. The CMC also began to show a strong coastal low around that time, but was still too progressive, showing a quick moderate snow event in the interior Northeast and light-moderate rain for the NYC area. The ECM remained mostly consistent with its scenario of a major snowstorm while the ensemble mean also trended back to a similar output, showing Connecticut into Rhode Island and Massachusetts under the heaviest snow.

The 2/6 and 2/7 runs, only 1-2 days prior to the storm, continued the theme of model inconsistencies aside from the ECM, which remained the most consistent and accurate model. While some runs of the ECM were a little too far east and north with the heavy snow axis, it performed the best out of the model guidance, especially in the medium range when it was the only model to correctly depict a major coastal storm despite no support from other models and even its ensemble mean at one point. The GFS’ depiction of a major snowstorm was short lived, as most of its 2/6 runs were too far east, too weak and too warm with the coastal low, showing a rain to light-moderate snow event for the area with the major snowfall from the coastal low limited to southeast Massachusetts. Its 2/6 18z run was the most accurate, showing heavy snow over central Long Island and CT into Boston, but the rest of the 2/7 runs, only 1 day before the storm, were too far east with the coastal low, keeping the deformation band (which in reality was over central CT into Maine) offshore, barely clipping coastal New England, with a moderate to locally heavy snow event. The runs on the day of the storm, 2/8, were also too far southeast, with 4 to 8 inches of snow in NYC/northern NJ and 8 to 14 inches of snow in southern New England. The CMC and UKMET also had a similar issue with temperatures too warm and keeping the heaviest snow offshore, with the CMC showing a mostly rain event for NYC prior to the 2/7 12z run. The UKMET also showed a relatively insignificant event across the region with its 2/7 runs, depicting the coastal low too far southeast.

The 2/8 0z run of the NAM at hour 27, showing the heaviest banding of 3+ inches/hour over NYC and northern NJ. In reality, this band set up in central-eastern LI and central CT. Image from NCEP Model Analysis and Guidance.

The NAM, which had a poor performance overall in the winter of 2012-13, continued to show a weak clipper with a disorganized coastal low, not showing a major coastal storm until its 2/6 12z run, only 54-60 hours before the storm, and began a trend of inconsistent and highly inaccurate runs, showing a wide swath of 60-65 inches of snow from Boston to Maine with its 2/6 runs. The NAM did not show moderate snow accumulations in the NYC area until its 2/7 6z run, the day before the storm, when it showed the storm too far west with the heavy snow axis from New Jersey into eastern NY with 24-36 inches of snow. As recently as the 2/8 0z run, only 12 hours before the storm started, it was too strong and too far west with the storm, with a storm maximum of 36-45 inches of snow in NW NJ and SE NY, and only showed a reasonably correct scenario for the first time with the 6z run. While on a regional scale, the NAM was exaggerated with snow totals due to its typical wet bias, showing widespread 24-48 inches across the region, on a localized scale it was more reasonable with the maximum snow totals under the heavier banding, as Hamden, CT recorded 40 inches of snow.

 


Storm Timeline in the Northeast

Regional radar image from 12:08 PM, from the National Weather Service, showing the two separate areas of precipitation. Moderate snow fell north/west of NYC with a mix from NYC and south/east.

Precipitation began to affect the region early in the morning of Friday, 2/8, with two distinct areas of precipitation; one was heavy rain in the coastal Mid Atlantic region associated with the coastal low pressure, and the other was heavy snow in western NY state associated with the northern Ohio Valley low pressure. In the NYC area, precipitation initially developed in the early to mid morning hours; this was mostly moderate snow in northern NJ and southern CT, but a wintry mix of rain, snow and sleet in NYC, Long Island, and most of New Jersey south of I-80. This setup continued through at least 2-4 PM, with at least 2 to 4 inches of snow slowly accumulating in northern NJ, SE NY and southern CT.

 

Regional radar image from 5:18 PM, from the National Weather Service, showing heavy snow from the coastal low spreading into Long Island and CT while locations further west were drying up.

During the late afternoon and evening hours, the coastal low continued to intensify while merging with the interior low pressure, and the two areas of precipitation began to connect, first in New York state and later spreading further south. As the coastal low intensified, heavy snow bands spread onshore into Suffolk county, where very heavy snow rates developed in some areas with sleet in others, while moderate snow continued in the north/west suburbs of NYC. The freezing line gradually dropped further south, with NYC and the rest of Long Island gradually changing over from rain to snow/sleet. The track of the coastal low pressure was a little too far east for most of the area to receive heavy snow, and the precipitation shield shifted east by the mid-late afternoon so that aside from far northeastern NJ, almost the entire state of NJ was dry by 7 PM.

Regional radar image from 9:38 PM, from the National Weather Service, showing widespread moderate-heavy snow as the two storms merged. The intense snow band can be seen over south central CT.

While a dry slot temporarily spread into New Jersey and SE NY, very heavy snow associated with the coastal low continued to fall across Long Island and Connecticut. A very intense band of precipitation with reflectivity as high as 50dbz spread into south central CT falling as plain snow, which is unusual for such an intense band. Snow rates as high as 4-6 inches per hour or even locally higher were reported in those areas, where ultimately the highest totals from the storm were observed. As the storms continued to merge with the coastal low becoming the sole low pressure, snow redeveloped by 9 PM north and west of NYC, and by 10-11 PM the entire area observed heavy snow, falling temperatures, and windy conditions with blizzard-like conditions especially east of NYC. During this time period, parts of Long Island that saw precipitation types flipping from snow to sleet changed over to plain snow as well.

Towards 1-3 AM, a narrow but intense band of snow tracked southeast from NY state into the area, from northwestern NJ towards NYC; while this band was quick moving, snow rates up to 3-4 inches per hour were reported, dropping a quick inch of snow within only 15-20 minutes. The snow gradually ended afterwards through the rest of the overnight and morning hours as the snow shifted into New England.

 


Storm Impacts and Precipitation Totals

2.8.13_snowThe storm produced the most significant snow totals in the NYC area and southern New England since January 2011, when a nor’easter produced 12 to 20 inches of snow along the I-95 corridor. There were two axes of heavy snow; one was from the initial Ohio Valley low pressure, with 8 to 16 inches of snow in north and western New York state, and the second and larger axis was associated with the coastal low in New England.

The worst of the storm took place in Connecticut, where the storm ended up as one of the biggest snowstorms on record, and in some locations breaking that record. Widespread snow totals of 20-30 inches were reported from Long Island into Connecticut, Rhode Island, Massachusetts, and coastal New Hampshire and Maine. The most significant totals were found in New Haven county in Connecticut as well as northwestern Suffolk county in Long Island, where widespread 30+ inches were reported under the intense snow bands in the evening and early overnight hours. The highest storm total in the NYC area and the region was from Hamden, CT, with 40 inches. Totals were more variable in Long Island; locations in the southern and western parts of the island, which had mixing with sleet lowering snow totals, ended up with at least 8 to 16 inches of snow. Towards NE Nassau and northern Suffolk counties, which were affected by the heavier snow bands, totals of at least 16 to 30 inches have been recorded, with a maximum of 33.5 inches in Medford, NY.

feb8snownycFrom NYC and further west, snow totals were less significant, relatively moderate compared to other parts of the region. Snow totals of about 8 to 15 inches have been reported across northern New Jersey, NYC, and interior SE NY (Rockland/Orange counties); Central Park, which has seen little snow since the November snowstorm, reported a total of 11.4 inches. Westchester county, on the edge of the heavy snow bands in Connecticut, recorded snow totals between 10 and 23 inches of snow. Lighter snow fell south of the area, with 4 inches down to central New Jersey and an inch down to central New Jersey. No snow fell in Washington DC and Baltimore, which have seen very little snow in the winter.

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:
16.8″ – Rivervale, NJ (Bergen)
14.2″ – Roselle, NJ (Union)
14.0″ – Verona, NJ (Essex)
13.2″ – West Milford, NJ (Passaic)
12.5″ – North Bergen, NJ (Hudson)

Southeast NY:
23.3″ – Port Chester, NY (Westchester)
15.5″ – Cornwall On Hudson, NY (Orange)
13.0″ – New Hempstead, NY (Rockland)
12.3″ – Putnam Valley, NY (Putnam)

New York City:
15.0″ – Fieldston, NY (Bronx)
15.0″ – Middle Village, NY (Queens)
12.4″ – Sunnyside, NY (Staten Island)
11.4″ – Central Park, NY (Manhattan)
9.0″ – Sheepshead Bay, NY (Brooklyn)

Long Island and South CT:
40.0″ – Hamden, CT (New Haven)
35.5″ – East Haddam, CT (Middlesex)
35.0″ – Fairfield, CT (Fairfield)
33.5″ – Medford, NY (Suffolk)
31.0″ – Colchester, CT (New London)
18.0″ – East Norwich, NY (Nassau)

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