Coming into this winter the talk was about how a La Nina would result in lower than normal snowfall amounts across the northeastern quadrant of the United States. Many predictions had snowfall totals at 75% or less compared to seasonal averages. So what happened?
Well, February happened! This one month alone set the tone for a well above-normal season snowfall-wise for most of the northeastern quadrant. Lower heights extended across the North Pacific and into the Gulf of Alaska through January favoring a strong Pacific Jet and flooded the Continental United States (CONUS) with warmer air and a lack of wintry weather. However, that all changed in February when this positive Eastern Pacific Oscillation (EPO) pattern reversed to negative. This negative EPO pattern allowed heights to build in the Gulf of Alaska which in turn caused the jet stream to dip across the North Central United States bringing in cold, arctic air and setting up a snowier pattern across the northeastern quadrant of the United States. The Madden-Julian Oscillation (MJO) pushing into the Phase 7 Octant likely played a role in this reversal too allowing for a solid February when it comes to the snow and cold.
What all of this led to is a blockbuster season snowfall-wise for portions of Mid-Atlantic, particularly around the Interstate 78 and 80 Corridors in Eastern Pennsylvania and the Tri-State Area. Scranton/Wilkes-Barre and New York both saw seasonal totals around 125% normal. Meanwhile, mesoscale dynamics (i.e. dynamics on a smaller scale) around Allentown drove one of those aforementioned blockbuster snowfall seasons which nearly doubled what’s considered normal. Mesoscale dynamics led to much higher than normal seasonal totals just north and west of Philadelphia too, but at the airport, the season ended up pretty normal overall. Further up the Interstate 95 Corridor interior portions of New England saw near-normal numbers, but maritime locations, like Logan Airport in Boston, ended falling below-normal with totals more aligned with early-season predictions. Even in Boston, most of the season total came during one month…February. Those numbers were more supercharged to the south where Eastern Pennsylvania and Tri-State Area saw well more than half of the seasonal total come in February. Allentown’s February monthly total alone was more than 6″ higher than a normal season snowfall total for the city. Further to the west, Cleveland and Pittsburgh also saw near or above-normal snowfall totals this season, but lake-effect snow events and events earlier in the season led to the distribution of snow begin more frontloaded.
In March, the high latitude blocking broke down leading to a milder flow for all of the CONUS. While this didn’t completely end snowfall for the season, it dramatically reduced snowfall production throughout the month.