East Coast Wintertime Cyclones

Here is an informative gallery of historical, cold season cyclones that have impacted the Mid Atlantic region and East Coast.  Big extratropical storms will be presented reverse-chronologically.

2020, Dec 16-17 Nor’easter

Blockbuster snowstorm, breaking records across NY and PA.  Numerous snow totals exceeding 40 inches in the Binghamton, NY region.  On the backside of this storm, an intense snowband parked itself for many hours, dropping snow in the same locations at rates exceeding 3"-4"/hr.  

Endicott, NY - epicenter of 41" snow total:

                                    Tom Nichols

Binghamton, NY:

                                   @Stormwx1

Many forecast models were used by various agencies and the high resolution models, such as IBM's GRAF, did the best job in nailing down the location and intensity of the heavy snowband (more so than the American and European models):

                    @MJVentrice

With this event, and Arctic high pressure system over Eastern Canada and New England provided a deep, subfreezing air mass...while an intensifying coastal low (a.k.a. Nor'easter) imported very moist air off the Atlantic and forced the air to rise in an intense, narrow zone across NY and PA.  A plume of very mild, humid air fed the storm from western Atlantic waters that were anomalously warm. Meanwhile, very cold air on the storm's northwestern flank ensured that snow to liquid ratios (SLR) were quite high - generating copious amounts of dry, fluffy snow that piled up to great depth.

Nor'easters generate kinetic energy from strong temperature contrasts along the East Coast, which become amplified in the winter months (cold air off North America, warm Atlantic water).  Within the jet stream, there were twin pockets of fast-moving airflow (called jet streaks) that interacted in a perfect manner.  At the "S-bend" of the jet stream (between trough and ridge), these jet streaks became "coupled" such that air rose vigorously between them.  This is where the heaviest snow fell. These features are shown below.

In Nor'easters, the heaviest snow rates are often generated in a narrow snowband about 150-200 miles northwest of the storm's center.  Even though the parent storm is moving along, the snowband can become stationary for hours.  So the snow starts to pile up over the same locations, typically at 2"-3"/hr.  In this storm, snow rates may have approached 5"-6"/hr for a time!  We turn to the highest resolution prediction models to help us decide where and when a narrow snowband may unfold. Sometimes the models miss this feature, other times they provide clues. Radar shows these bands and can be used to provide very short term guidance (2-3 hrs) on where the heaviest snow totals, and thus snowfall gradient, will unfold.  The devil really is in the details!

2016, Jan 23-24 “Snowzilla” Nor’easter

 

This intense coastal storm brought widespread heavy snow to the interior Mid Atlantic - with over 30 inches along the Mason-Dixon Line – and damaging winds reaching 70-75 mph from coastal Virginia to New England (Figure 1).  This storm delivered Baltimore’s all-time greatest snow accumulation of 29.2 inches.  The storm also broke snow accumulation records in New York City.  For a time, true blizzard conditions unfolded in D.C. and other locations along I-95.  

Figure 1 Snow accumulation map (NOAA).

 

The meteorology of the event featured a wedge of deep, subfreezing air that became emplaced east of the Appalachians – courtesy of an Arctic air mass – followed by development of low pressure in the southeast U.S. (Figure 2). The low pressure system then transferred its energy to a coastal low off Cape Hatteras (Figure 3) which pulled in vast amounts of water vapor off the Atlantic Ocean, fueling heavy snow rates over land. 

Figure 2 Surface weather map Jan 22 7 am (NOAA).

Figure 3 Surface weather map Jan 23 7 am (NOAA).

 

In the upper atmosphere (Figure 4) a large wave of low pressure became so amplified that it “cut off” from the main jetstream flow.  This large feature - and a coupling of dual, super-fast pockets of “jet streak” airflow - led to vigorously rising air over the Mid Atlantic and coastal New England.

Figure 4  Upper level flow Jan 23 7 am (NOAA).

 

The Nor’easter slowed as it moved northward and a heavy snow band became parked over the Baltimore-Philadelphia-New York City region on the backside of the storm (Figure 4).  Meanwhile, an extreme pressure gradient lashed coastal regions with peak wind gusts in the 65-75 mph range.

Figure 5 Radar showing stalled, heavy snow band late on Jan 23 (weathertap.com).

 

Significant blowing and drifting of light, powdery snow created a major dig-out operation for residents up and down the I-95 corridor from D.C. to New York City (Figure 5).

Figure 6 The “Big Dig” in Baltimore trying to unbury cars lost between snow drifts (Baltimore Sun).