The month of December was generally a quite active and unsettled month, though a few drier stretches also occurred at times. There were some brief cold shots that allowed for minor wintry systems and light snow accumulations, especially to begin the month and for areas north and west of the I-95 corridor, but the bigger story was the unseasonable warmth that reigned supreme. Additionally, precipitation anomalies across the Northeast were off the charts in terms of a surplus, with many heavy rain producing systems throughout the month leading to extensive stream/creek and river flooding.
One of the first wintry events of the month involved a system on the 3rd and while it was rain for most of the Northeast, precipitation came in as more of a mix into southern NH producing some scattered coatings and generally light accumulations. A few days later, the 5th saw ocean effect snow showers move into southeastern MA owing to an onshore flow regime. This produced a thin swath of 1 - 2" of snowfall, with some lighter amounts also occurring north and east of the Boston metro area. A quick hitting clipper system then followed into the early morning of the 7th, impacting Pennsylvania, parts of New Jersey, the Hudson Valley, and northeastern MD with some snow showers. For most it was light, leading to some scattered coatings up to 0.5" of snow accumulation, though portions of Eastern PA did see amounts of 1 - 2". One of the more memorable events of the month involved a dynamic disturbance traversing the east coast on the 10th bringing strong winds, flooding, and winter weather. 2 - 3"+ of rainfall fell along much of the I-95 corridor though it was areas across Richmond, VA and Long Island / Connecticut that saw the biggest rainfall totals, where a deluge of 4 - 5" fell. This led to poor drainage/roadway flooding and some stream/creek issues. Colder air then wrapped in on the backside of this activity, allowing for a changeover to wet snow across the interior Northeast. As such, a few tenths up to 0.5" of snow fell across parts of the Mid Atlantic giving these cities their first measurable snowfall on the season with areas in Maryland seeing as much as a quick inch or two. Meanwhile, lighter amounts also occurred in Eastern PA, Northern NJ, and the Hudson Valley, though elevation was key with this storm with the Poconos seeing as much as 4 - 5" of snow!
Snow continues to fall at our office here in Sterling, VA. Slushy snow will continue to accumulate on some roads and grassy/elevated surfaces. Use caution if traveling early this morning. Snow comes to an end from west to east by around sunrise. #VAwx #DCwx #MDwx #WVwx pic.twitter.com/3q2KuOcw2H
— NWS Baltimore-Washington (@NWS_BaltWash) December 11, 2023
Snowflakes flying at the NWS Baltimore Washington office early on the morning of December 11th, 2023.
A quieter stretch briefly followed into the middle part of the month before a robust coastal system took aim at the Northeast late on the 17th and into the 18th. Temperatures continued to moderate ahead of this allowing it to predominantly be a rainmaker with hefty rainfall totals falling along the Eastern Seaboard of 2.5 - 5"+. This paired with the prior system and already saturated / vulnerable grounds caused numerous stream/creek and river flooding problems, with some rivers cresting into moderate flood stage and even into major flood stage days after the rainfall! The other notable component to this storm involved the strong winds with gusts of 50 - 60+ mph rather common along the Jersey Shore and across much of New England, resulting in downed trees, powerlines, and power outages. In fact, an astounding 90 mph gust was recorded near Boston, MA! Drier weather then prevailed for most into the Christmas holiday. The only caveat to this was a weak and disorganized system the 23rd - 24th that brought some light mixed sleet and spotty freezing rain showers to portions of northeast PA, northern NJ, and New England leading to some spotty coatings and patchy icing. The brief break from the rain was short-lived with another bout of heavier rain occurring in conjunction with a system on the 27th - 28th, further exacerbating flooding problems. Totals of 2 - 3"+ were prevalent along and northwest of the I-95 corridor from Baltimore, MD to New York City. Appreciable totals also extended into Long Island and Western Connecticut as well, but the majority of renewed stream/creek and river flooding issues occurred across eastern PA and northern NJ. Some lighter showers came in the days that followed, but conditions were otherwise generally tranquil heading into New Years Eve.
Here is a map of the highest wind gusts from yesterday's storm. The strongest winds were across eastern MA. Blue Hill Observatory had the highest wind gust of 90 mph, a factor of the elevation of the observation as well as proximity to the storm. pic.twitter.com/SLIXPZOKR8
— NWS Boston (@NWSBoston) December 19, 2023
Tweet from NWS Boston showing recorded wind gusts during a high wind event on December 18th, 2023.
Overall, unseasonable warmth dominated throughout most of the month of December with highs and lows running as much as 10 - 20 degrees above average at times. This included a daily record high in the low 60s set across many climate sites on the 10th. As such, high and low temperatures generally ran 4 - 8 degrees above normal. Additionally, given the multitude of heavy rainfall producing systems, precipitation anomalies for many ran 3 - 5"+ above normal monthly values. There were a few spotty exceptions to this where anomalies were not quite as high, such as across southeastern MA that saw values run 1 - 2" above normal.
