Snowstorm Recap and a Look Ahead

Discussion: There comes a time where a forecaster like me needs closure. I began tracking and discussing yesterday’s snowstorm signal on January 8 and it’s been a long process of data analysis and live observations leading right up through the ending flakes last night. But before I step away for a little break, I need to mentally assess what happened and I’m hoping this can bring closure and peace of mind to other snow lovers out there looking to complete either a learning experience or perhaps you need closure like me. This article will provide such closure with a winter status summary and recap of yesterday. Additionally, we’ll talk briefly about the current Arctic air mass and the next storm signals of interest.

It has obviously been a cold winter so far, outside of a few transient 2–3-day warmups here and there. On November 20, the snow season kicked off with a NWNJ elevation-dependent event that dropped 12-20 inches of snow on NJ’s highest elevations running from Sussex County into N Passaic County. The rest of NJ saw cold rain. Then between Thanksgiving and about Dec 24, we saw continued colder temperatures with a series of smaller light snow events, mostly clippers and weak wave events. One of them even gave NNJ and parts of CNJ a weak, but White Christmas. Then we saw a mild break between Dec 25 and about January 2. Jan 2-13 was a period where a negative phase of the Eastern Pacific Oscillation (-EPO) teamed up with favorable phases of the Madden Julian Oscillation (MJO) to produce a favorable snowstorm pattern that ultimately was wasted for most of NJ. We saw some snow squalls kick off the pattern on Jan 2, a S Mid-Atlantic snowstorm (5-8 inches from Atlantic City down through Cape May – trace/light for the N 2/3 of NJ), and a system that did not phase but still produced light snow accumulation Jan 10. We then saw a cold and dry period from Jan 11-18 outside of a light accumulating clipper on Jan 16. And then we had yesterday.

Yesterday unfolded exactly as I expected from an atmospheric point of view. A N stream shortwave tracked across the N Midwest US and met up with a SW US surface low. The pieces of energy combined over the Mid-Atlantic US to produce a progressive moving synoptic storm system that tracked offshore and threw precipitation to its NW side over NJ. Originally, this system was to be more of a Monday thing, later in timing and happening in a colder environment. Throughout last week’s model analysis, it became apparent that the system moved forward in time to more of a Sunday thing rather than Monday. Originally, Friday, Saturday and Sunday were expected to be warm, which they were (highs in the 40s). So this set up a warm morning-afternoon into a cold night situation for the storm. Here’s how I think that hurt part of our snow map expectations.

First, urban heat island effect is a very real thing. Urban cities like Philadelphia, Trenton, New Brunswick, NYC, etc. (mostly along I-95) are made up of more manmade materials (concrete, pavement, building structure, etc.) than other suburban/rural areas of NJ. These materials hold onto heat longer than natural land. In the summer we see this as I-95 big cities stay warmer into the night, In winter, a warm day can mean that the manmade nature of the city areas hold onto above-freezing temperatures longer than areas around them. I fully believe this is what contributed to lower totals along city environments of the I-95/NJTP corridor. Last night I was boggled why some near these cities only ended up with 1.5-2 inches while everyone around them were instead verifying the 5-8 and 3-5 ranges. Furthermore, this additional heat needs to escape upwards (heat rises). When the city heat did so yesterday, it contributed to a precipitation type of sleet and/or graupel (what the Philadelphia Eagles commentators did not know how to describe during the game). One of them described it as fuzzy dip n dots lolol. So, I believe that in addition to the heat island effect of a warmer surface near the bigger cities, that the heat also rose (has to escape somewhere) to the point of changing precipitation type from snow to sleet/graupel as high as 925mb (~1800 feet up). This explains IMO why Philly, through Brunswick/Old Bridge, into NENJ (close to NYC) saw about 50-70% of their lower range number of our expected snow map. Outside of these areas, a lot of NJ (about 80%) verified within their range. But each of our areas (C through F) has some areas (about 20%) where there were either ground temp issues or temporary sleet. I was a little surprised how many people expected a lot of snow to fall SE of 95 prior to 5pm/sunset. I thought I laid that out pretty clear in the detailed forecast discussion articles. The snow/rain line and line of freezing at the surface was always expected to start out near I-95 and only start pushing to the coast around 5pm. An afternoon dry slot did open up at first in SNJ in response to an area of heavy lifting over S/C PA and N/C MD, but that only took away pre-5pm rain from SNJ, not snow. I can better myself for the future by remembering what happened should we see another warm day lead to a snowstorm with Arctic air pushing in through it.

So, in summary, about 80% of NJ made it into their forecasted ranges (either just made it or solidly). About 20% of NJ saw 50-70% of their forecasted range. In the world of forecasting, that’s a win, especially since we work with incomplete data sets. We’re not working with finite tax return numbers here lol. This is a predictive trade which means there are no 100% correct forecasts. At best we can give you a range of possibilities for what to expect, and hope that the information contributes to an increase of safety awareness. That’s how we grade ourselves, not on 100% accuracy but on the ability to make you a little more prepared and safer. So, for the keyboard warriors and Monday morning armchair quarterbacks who say “I wish I could get paid to be wrong,” I’m going to direct you to this part of the article so that you, just like I, can better yourself. And that completes the closure I seek for yesterday’s snowstorm recap.

Let’s move forward. It’s cold…coldest air mass of the winter so far. It started to move in last night behind the clearing snowstorm but we’re still, even today, in first gear. Tonight into tomorrow morning will be the next gear. I expect below-zero temps possible for NWNJ elevations and single digits/low teens even down to the SENJ coast by around 6-7am tomorrow (Tuesday) morning. This very cold air mass should last through Wednesday and then relax to just average cold into this coming weekend. Here is a model image representing 850mb temps for the next few days (this week). So, while we are seeing afternoon highs in the teens/20s and overnight lows ranging from 0-15 on the ground, it will be negative 20-25F just 5,000 feet above us. This kind of cold is only made possible in a few ways, one of which is Siberian-sourced Arctic air via cross polar flow over the top of the N Hemisphere.

Next storm signals? A storm system is either going to just miss or possibly graze SENJ with some snow showers Wednesday. This would be the end result of the winter storm currently targeting the N Gulf states, NW and N Florida, and the SE US tonight (Monday) through tomorrow (Tuesday). I don’t have any model data to support snow making it into NJ this Wednesday (Jan 22) but the NW extent is close enough to SENJ to say that snow showers are possible with little-to-no accumulation likely. Meteorologically, there’s too much cold air suppression to allow a storm to turn N enough up the coast for NJ snow impacts. Jan 24 is another signal for a meridional tracking coastal storm system but that too is now advertised too far S and E to affect NJ…also due to the cold air mass being too strong and suppressive. I will report accordingly if anything changes but for the most part, the Jan 22 and 24 storm signals have died off of model guidance. There’s some noise for ~Jan 28 that I will casually monitor but otherwise, we may be in for a dry stretch through the rest of January.

Winter is far from over no matter how you look at it. Today is day 29 through the 90-day calendar winter season. We’re day 50 of 90 in meteorological winter. We’re day 50 of 120 for what I consider to be the Dec 1 – March 30 baseball game analogy. That means we are just starting the 4^th inning. And with many areas above-average for this time of year on snowfall, along with other areas just short of average (the smaller 1-2 inch clippers stack up), I’d say we are a few runs ahead in this winter’s baseball game. Again, a silly time to leave the stadium.

In English: Another NJ snowstorm in the books. 80% or more of our entire coverage area verified on our snow map however about 20% did not either due to urban heat island effect or sleet/graupel issues (see above discussion for more). Arctic air has moved into place over NJ and will be here for at least a few days. SENJ could see a grazing pass of snow showers Wednesday (Jan 22) from what could have been another snowstorm. If this changes I will report accordingly but that’s only two days away and mostly locked into a S and E miss for NJ. The Jan 24 system is also currently a miss. In all honesty, I could use a little break. Despite lower accumulating events since about Jan 2, it’s been a period of relentless weather data tracking and analysis. There’s a lot of winter left even beyond the end of January. February is statistically the snowiest month for NJ and we all know how March can go (see 2014, 2017, and 2018). Everyone please enjoy the rest of your Monday (Martin Luther King Day) and be safe! JC

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