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NYC Nor’easter Snowstorm – Jan 28-29, 2022

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Synopsis

A major winter storm is expected to hit the Northeast primarily Saturday with a strong nor’easter developing and deepening as it tracks offshore. This will bring a swath of > 8″ accumulations from NYC through points north and east, with the bullseye likely over southern New England where snowfall totals could exceed 2 feet locally. Gusty north winds will accompany this storm, leading to some blowing and drifting snow. In line with most other forecasts this morning, my own forecast is for 7-10″ of snowfall in NYC but with the potential for a sharp gradient possibly cutting through the city itself, where the western part of the city could see below 6″ while eastern sections see closer to 10″ or more.

As with the last round of accumulating snow we had, antecedent conditions support enough cold air in place to result in an all snow event. With a storm track offshore enough so there should be no mixing, the primary uncertainty in snow totals arises from storm track. Model runs today should help us determine if the storm will track on/near the 40ºN 70ºW benchmark (more snow), or to the east (less snow). Overnight, model consensus has shifted west, supporting higher snow totals than were forecast at this time yesterday. If we see some consistency across runs today supporting this solution, confidence will grow in a significant snowfall for NYC. Mesoscale banding will bring bouts of intense snow with this storm, and the exact placement / duration of these features will determine where the highest snow totals occur.

GEFS ensemble plumes for total snow accumulation at LGA. The mean here is about 7″ with a significant spread between 3″-14″ between ensemble members.
SREF ensemble plumes for total snow accumulation at KLGA. The mean here is much higher than GEFS, 18″, with similarly large ensemble spread between 2-35″!
NWS Blend of Models total snowfall forecast ending 1 AM Sunday, showing about 11″ for NYC.
NAM model total snowfall forecast ending 1 AM Sunday, showing 8″ for NYC.
GFS model total snowfall forecast ending 1 AM Sunday, showing 7″ for NYC.
ECMWF model total snowfall forecast ending 1 AM Sunday, showing 12″.
WPC probabilities of > 6″ of snow accumulation by 1 AM Sunday
WPC probabilities of > 12″ of snow accumulation by 1 AM Sunday
NWS New York Office official forecast as of this morning, mainly calling for 6-10″ in the city proper.

Forecast Details

At the Surface

Models are projecting a couple shortwaves merging and developing as a coastal low off of the Carolinas later today and tonight. This storm is forecast to intensify and track a little east of the 40ºN 70ºW benchmark overnight, a position that historically signals the best snowmaking potential for NYC during coastal winter storms. The forward speed of this storm has picked up in model runs recently, but it is expected to be a strong storm with minimum pressures falling to the 960s by Sunday. A tight pressure gradient is expected between the intensifying low and high pressure to the north, which should cause gusty north winds to help advect cold air down to the coast.

Weather Prediction Center surface forecast valid for 7 AM Saturday
Weather Prediction Center storm track forecast.
ECMWF “Euro” model surface forecast for 7 AM Saturday
GFS model surface forecast for 7 AM Saturday

850 mb – 700 mb Level

A robust 850 mb low-level jet flowing onshore from the northeast is forecast. This should provide the storm with good moisture content, aiding the formation of snow. Strong 850 mb and 700 mb temperature advection and frontogenesis is also evident in all models, occuring during the morning Saturday. This should induce heavy snow bands to develop for a few hours early on Saturday. These bands could produce 1-3″ per hour snowfall rates, and as always, areas where these bands set up and persist the longest will ultimately pick up the higher end totals.

GFS model 850 mb relative humidity & winds at 7 AM Saturday. A strong LLJ flowing onshore from the northeast is visible.
GFS moidel 700 mb temperature advection at 7 AM Saturday.
ECMWF “Euro” model 500 mb height and vorticity at 11 AM Saturday
ECMWF “Euro” model 300 mb winds. Two jet streaks are evident in the vicinity of this storm, north and south of the storm’s projected center.

500 mb Level

This storm will benefit from a deep, synoptic scale trough that will acquire a slight negative tilt. This trough will eventually form a closed low at this level. This will aid the low in intensifying by increasing divergence at this level, facilitating upward movement of air over the surface low, leading to lower surface pressures.

300 mb Level

The storm’s center is expected to lie downstream of an exit region of a jet streak, and also upstream of an entrance region of another jet streak to its north. This is ideal placement for maximizing divergence at this level of the atmosphere over/near the low’s center, and supports the development of a strong surface low.

NYC Snowfall Forecast – Jan 6-7, 2022

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Synopsis

A relatively fast moving offshore low is expected to bring this winter’s first round of accumulating snow in NYC. Fairly good agreement among different models suggests decent confidence of totals NYC in the range of 3-5″, and it is worth noting that trends have been towards a higher total in overnight model runs. In fact, both the Euro and GFS agree on about 5″ of snow for NYC by the end of this event, and I tend to agree with this end of the forecast range at this time.

Antecedent conditions with a shallow but decently cold air mass in place means the primary uncertainty arises from storm track. Subsequent model runs should help us determine if the storm will track on/near the 40ºN 70ºW benchmark, slightly inside (more snow), or to the east (less snow). The timing of the snow during the overnight hours into the early AM rush will help boost totals since we will have enough cold air in place. Moderate and potentially heavy snow is likely during a 3-4 hour window starting around 4 AM.

GEFS ensemble plumes for total snow accumulation at LGA. The mean here is about 3.2″ with a significant spread among ensemble members both higher and lower than this.
SREF ensemble plumes for total snow accumulation at KLGA. The mean is also about 3.2″, with similarly large ensemble spread..
NWS New York Office official forecast as of this morning, mainly calling for 4″ in the city proper.

Forecast Details

At the Surface

Models are projecting a storm to develop off of Cape Hatteras and move close to the 40ºN 70ºW benchmark overnight, a position that historically signals the best snowmaking potential for NYC during coastal winter storms. This storm isn’t projected to be particularly strong, perhaps only dipping to 996-998 mb at its closest approach to the city, and it will be a relatively fast moving storm, both of which are factors that limit its potential to deliver large snowfall totals.

Weather Prediction Center surface forecast valid for 7 AM Friday
Weather Prediction Center storm track forecast.
ECMWF “Euro” model snowfall total for NYC from this event.
GFS model snowfall total for NYC from this event.
High resolution rapid refresh simulated radar valid at 4 AM Friday, depicting the strengthening storm hitting a swath of the Mid-Atlantic (including areas already walloped by this weekend’s major storm) and New England with a band of potentially heavy snow.

850 mb Level

There isn’t a strong sign of a robust 850 mb low-level jet with this storm. That’s in line with the profile of a weaker storm with less intense precipitation. However, most models are depicting strong 850 mb and 700 mb temperature advection and frontogenesis occurring for a few hours just south of the city, which could signal the possibility for some heavy snow bands to develop for a few hours overnight. It’s within these bands that we could see up to 1″ per hour snowfall rates, and as always, areas where these bands set up and persist the longest will ultimately pick up the higher end totals.

GFS model 850 mb temperature advection and frotogenesis as modeled by GFS valid at 4 AM Friday.
GFS model 500 mb height & vorticity at 4 AM Friday
ECMWF “Euro” model 300 mb height and wind at 10 PM Thursday

500 mb Level

Another supporting factor for a decent round of snow with this storm is that there will be a negatively tilted 500 mb through developing upstream of the surface low. This should aid the low in intensifying, though as stated above, it still won’t be a particularly potent one at the surface when it’s nearest to us.

300 mb Level

The 300 mb level shows a an exit region upstream of the surface cyclone preceding the event. The WPC does discuss a coupled jet scenario with the jet streak at this level eventually helping induce a lower-level jet which would boost snowfall totals, but the this might happen after the storm really impacts us.

NYC Weather Update – Dec 6, 2021

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Surge of spring-like warmth today ahead of a cold front. Showers and gusty winds accompany the passage of the front and usher in a much colder air mass Tuesday. High temps dropping from mid-60s today to low-40s tomorrow. Wed, we could get clipped by outer precip bands from an offshore low, with enough cold air in place to cause some snow flurries.

Rest of today – unseasonably warm and mostly cloudy with highs rising to the low-mid 60s. Breezy southerly winds 10-20 mph with higher gusts. Overnight lows dropping rapidly into the mid-30s behind the passage of a cold front, bringing showers around 7-9 PM tonight.

High Resolution Rapid Refresh simulated radar valid at 7 PM this evening, depicting a narrow band of fast moving showers approaching the city attendant to the passing cold front.

Tuesday – much colder with high temperatures topping out in the low-40s. Clearing skies, partly cloudy. Overnight lows in the low-30s.

Wednesday – snow showers likely, with possible light accumulations up to 1″ in the city (more likely on unpaved areas) due to the impact of an offshore storm. The GFS model seems more bullish on colder air/heavier precip while the Euro shows more of a dusting. High temperatures in the mid-30s. Overnight lows in upper-20s.

GFS 24 hour snowfall accumulation ending 7 AM Thursday.

Thursday – mostly sunny with high pressure building briefly in. High temperatures in the low-40s. Overnight lows in the upper-30s with rain chances increasing going into Friday as another storm system approaches from the west.

NYC February 18-19 Snowstorm Forecast – Feb 17, 2021

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Synopsis

A very active weather pattern this month brings yet another chance for decent accumulations of snow in NYC. This storm will be on the weaker side, and will slow down as it tracks offshore of the region. The result should be a long duration but likely a generally light to moderate snowfall event. Snowfall totals around NYC will probably be in the range of 4-6″, though with every storm this season, some potential exists for both higher and lower totals. If colder scenarios and better lift are realized, we could see > 8″. A warmer scenario would see more mixing and totals below 4″. Light snow should spread over NYC during the afternoon hours with periods of moderate and potentially heavy snow in the early evening. Mixing with sleet and rain even is possible during the early overnight hours. Snow and sleet could continue into the early afternoon hours Friday.

  • Weather Prediction Center 48 hour median snowfall accumulations for the NYC metro region ending 7PM Friday. This is showing about 4-6″.
  • Weather Prediction Center 48 hour 90th percentile snowfall accumulations for the NYC metro region ending 7PM Friday, showing 6-8″.
  • GEFS ensemble plumes for total snow accumulation at KLGA. The mean here is about 7″ with a significant spread among ensemble members both higher and lower than this.
  • SREF ensemble plumes for total snow accumulation at KLGA. The mean is about 5.5″, with similarly large ensemble spread..

Forecast Details

At the Surface

Deep arctic air precedes this storm, which will form along a frontal boundary stretching from the Gulf Coast to offshore of the Mid-Atlantic. This low will be on the weak side, only hitting around 1012-1000 mb. For reference, the last couple storms that hit us were about 10-15 mb deeper. Over the course of the week, models have trended colder with the storm, pushing its trajectory further offshore, close to or outside of the 40ºN 70ºW benchmark that signals the best snowmaking potential for NYC during coastal winter storms. It is important to note that even with the track trending colder, mixing is still likely at some point during the storm, and significant mixing would lower overall totals. If we have an overall colder scenario, we may see closer to 8″ by this time Friday.

  • ECMWF “Euro” model surface precipitation/type at 1PM Thursday.
  • GFS model 1000-500 mb pressure, thickness, and surface precipitation/type at 7PM Thursday.
  • NAM model 1000-500 mb pressure, thickness, and surface precipitation/type 1PM Thursday.
  • Weather Prediction Center storm track forecast.

850 mb Level

There isn’t a strong sign of a robust 850 mb low-level jet with this storm. That’s in line with the profile of a weaker storm with less intense precipitation. However, most models do show the 850 mb warm nose setting up just south of the city, which would favor the strongest precipitation occurring as mostly snow over the city during the Thursday afternoon-early evening time frame.

  • NAM model 850 mb winds and relative humidity at 1PM Thursday.
  • GFS model 850 mb temperature, height, wind at 1PM Thursday
  • ECMWF “Euro” model 500 mb height & vorticity at 1PM Thursday

500 mb Level

A longwave trough that reflects the very cold air over the central part of the US will be in place upstream of this low. There will not be any negatively tilted trough at this level providing enhanced lift for this low, thus explaining the weaker profile of this storm.

300 mb Level

Similarly, the best support for strong lift at this level of the atmosphere won’t come until late in this storm’s evolution. There are no clear entrance or exit regions co-located with the storm early on, signifying an absence of enhanced lift from divergence at this level.

NYC Weekend Snowstorm Update – Feb 5, 2021

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Synopsis

Another accumulating snow event is possible during the day Sunday this weekend, with accumulations somewhere in the 2-4″ range currently most likely. If this storm tracks a bit closer to shore, we could see totals more in the 4-6″ range. The timing of this storm is much faster than the previous one, with onset of snow early in the day Sunday, lasting potentially through the early afternoon hours. As a weaker system, without as strong a high pressure system downstream, winds should also not be as robust as with the Monday storm.

  • Weather Prediction Center 48 hour 50th percentile snowfall accumulations for the NYC metro region ending 1AM Wednesday
  • Weather Prediction Center 48 hour 90th percentile(median) snowfall accumulations for the NYC metro region ending 1AM Wednesday
  • GEFS ensemble plumes for total snow accumulation at KLGA. The mean here is about 4″ with a significant number of ensemble members showing lower amounts.
  • SREF ensemble plumes for total snow accumulation at KLGA. The mean is about 2″, with similarly large numbers of ensemble members showing lower amounts.

Forecast Details

At the Surface

Low pressure developing over the Southern Plains will emerge offshore of the Carolinas later tonight. This surface low will strengthen modestly as it tracks quickly northeast. Current thinking is that the storm track takes it outside of the classic 40ºN/70ºW benchmark that leads to maximized snowfall for nor’easter type systems in this area.

  • ECMWF “Euro” model 1000-500 mb pressure, thickness, and surface precipitation/type at 1PM Sunday.
  • GFS model 1000-500 mb pressure, thickness, and surface precipitation/type at 1PM Sunday.
  • NAM model 1000-500 mb pressure, thickness, and surface precipitation/type 1PM Sunday.
  • Weather Prediction Center storm track forecast.

850 mb Level

At this level of the atmosphere, it’s apparent that this storm is much less of a headline maker than Monday’s snowstorm. It’s evident from various models that while there should be enough moisture to sustain precipitation, the winds at this level are not forecast to be anywhere near as strong as on Monday. The lack of a truly robust low-level jet will make for an overall slightly drier scenario.

  • ECMWF “Euro” model 850 mb winds and relative humidity at 1PM Sunday.
  • GFS model 850 mb winds and relative humidity at 1PM Sunday.
  • NAM model 850 mb winds and relative humidity at 1PM Sunday.

500 mb Level

Unlike the last storm, the 500 mb level flow for this upcoming storm is more progressive. This will lead to the storm moving faster through the area. One notable factor contributing to the potential for a decent storm this time is that there will be a negatively tilted trough at this level, indicative of a maturing and deepening low. This feature will serve to enhance divergence at this level and induce surface lift in response.

300 mb Level

As was the case with Monday’s storm, a curved jet streak should set up just north and east of this storm’s surface low. The entrance region of this jet streak should allow stronger divergence and enhanced lift as a result.

NYC Nor’easter Snowstorm Update – Jan 31, 2021

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Synopsis

A significant snowstorm in store for NYC Monday into early Tuesday morning. Current trends point to 8-12″ likely for most of the city. There is uncertainty with possible mixing late Monday that could cut into this over Long Island, and if the mixing line pushes further northwest, which The European model portrays, this could lower totals in the city to more of the 6-10″ range. It is worth noting that the 850 mb set up suggests the possibility for much bigger totals closer to 18″ if the colder scenarios play out. The timing of this storm is such that the most intense snowfall should occur during the day. A narrow, intense deformation band could remain nearly stationary over some parts of the region during the daytime hours Monday. Strong northeasterly winds will accompany this storm despite relatively modest pressure falls, due to the presence of a 1034 mb high pressure center over eastern Canada creating a tight pressure gradient.

  • Weather Prediction Center 48 hour 10th percentile snowfall accumulations for the NYC metro region ending 1AM Wednesday
  • Weather Prediction Center 48 hour 90th percentile snowfall accumulations for the NYC metro region ending 1AM Wednesday
  • Weather Prediction Center 48 hour 50th percentile(median) snowfall accumulations for the NYC metro region ending 1AM Wednesday

Forecast Details

At the Surface

A low pressure center that tracked through the Midwest this weekend will transfer its energy as it hits the Appalachians to a secondary low offshore of Virginia tonight. The low will then slowly track to the northeast as it deepens somewhat. This isn’t a particularly strong low, and it will elongate, translating eastwards overnight into Tuesday morning (see the last image in the gallery below). The North American models (GFS, NAM) suggest a colder scenario that would see higher snow totals (2nd, 3rd imges below), while the European model (1st image) shows potential for mixing Monday evening. Strong northeasterly winds will accompany the storm.

The presence of very cold air this weekend should help lead to better chances for big totals, however, the cold air will be retreating ahead of this storm, and cold air damming will be modest.

  • ECMWF “Euro” model 1000-500 mb pressure, thickness, and surface precipitation/type at 7PM Monday.
  • GFS model 1000-500 mb pressure, thickness, and surface precipitation/type at 7PM Monday.
  • NAM model 1000-500 mb pressure, thickness, and surface precipitation/type at 7PM Monday.
  • Weather Prediction Center storm track forecast.

850 mb Level

At this level, a strong easterly low-level jet will bring plenty of moisture into the cold conveyor belt of the storm. The advancement of the warm nose of the low will be key to where the greatest potential for deformation banding and the heaviest snowfall rates set up during the day Monday. The GFS and NAM models (2nd, 3rd images below) depict this warm nose staying just offshore. This would favor the best potential for a mesoscale band setting up right over NYC and slightly north as these bands are typically situated just on the cold side warm nose of a low.

500 mb Level

Part of the reason the surface low of this storm will progress so slowly, bounce around, and elongate is due to the presence of a closed 500 mb low accompanying it. This isn’t really a “classic” set up for a big nor’easter blizzard here, however, the closed low does help keep cold air aloft and help enhance lift via increasing the lapse rate between the surface and this level.

300 mb Level

A curved jet streak should set up just north and east of the developing low during the day Monday. The entrance region of this jet streak should allow stronger divergence and enhanced lift for this low.

NYC Weekend Weather – Jan 29, 2021

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An arctic chill with bitterly cold winds kicks off the weekend as strong high pressure moves in. Overnight lows in the teens and high temperatures in the 20s will range 10-15ºF below normal for this time of year. This cold air could set the stage for a nor’easter bringing significant snowfall to the region, with totals > 6″ possible Monday into Tuesday. As usual, track details on this storm will be pivotal, and are not clear at this time.

Rest of today – mostly clear, cold, and windy with high temperatures in the low-20s. A strong arctic high and a departing low will create a tight pressure gradient that ushers in stiff northwesterly winds 20-25 mph. Wind chills will hover around 0ºF. Overnight temperatures drop into the mid-teens with wind chills likewise dropping below zero.

Weather Prediction Center surface forecast for 7AM Saturday. A strong area of high pressure is parked over much of the Eastern US.

Saturday – winds abate with high pressure moving more directly overhead. Sunny, but still cold with high temperatures around 30ºF. Overnight lows will be in the upper-teens under increasing cloud cover.

Sunday – mostly cloudy as the next storm system starts to work in. High temperatures around 30ºF. Overnight lows in the upper-20s with the possibility of snow developing overnight into Monday morning.

  • GFS model total snowfall accumulation as of 7AM Tuesday
  • ECMWF model total snowfall accumulation as of 7AM Tuesday
  • UKMET model total snowfall accumulation as of 7AM Tuesday

Monday – stiff northeasterly winds developing along with snow. High temperatures in the low-30s. The storm possibly bringing us significant snow came ashore over the west coast yesterday and will be transiting the country the next couple days. It is eventually forecast to spawn a coastal low, bringing a nor’easter into our region. Even though cold air will precede this storm, offshore waters are still mild, in the low 40s-50s, and with the storm likely to bring southerly/northeasterly flow at the outset, we could see enough warming to mix to rain at the coast. Storm track and strength will be vital to the eventual snowfall totals. Models seem to signal a very tight banding feature bringing heavy snow – you’ve heard this before but these bands are notoriously difficult to pinpoint even a day ahead of the event. If the optimal scenario plays out, we could see a storm with similar or possibly bigger totals than the one in December. Overnight lows Monday shouldn’t budge much, in the low-30s, with some warm advection associated with portions of the storm.

NYC Weekend Weather – Jan 22, 2021

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A cold and breezy start to the weekend with a cold front ushering in below average temperatures mostly in the mid-30s. High pressure builds and keeps things dry during the weekend. However, the upper-level pattern shifts to allow a shortwave trough to push through early next week, leading to a storm that could bring some accumulating snow overnight Monday into Tuesday.

Rest of today – partly cloudy with high temperatures in the low-40s. A moisture-starved cold front will work its way through the region. The main impact of this front will be to induce a shift in winds to the northwest, and trigger some decent cold air advection. This will lead to overnight temperatures plummeting into the mid-upper 20s.

Weather Prediction Center surface forecast for 7AM Saturday

Saturday – high pressure builds in behind the cold front, giving us a mostly sunny day. This high pressure and a low off to the northeast over the Canadian Maritimes will lead to a fairly tight pressure gradient, and the result should be breezy winds from the northwest, sustained in the range of 15-20 mph at least. So despite the sun, the cold start to the day will lead to temperatures in the low-30s and a much colder feel with wind chills around 20ºF. Overnight lows will be the coldest in quite some time, in the low-20s.

Sunday – windy conditions continue at least part of the day with high temperatures in the mid-30s. Once the center of the high moves over us, winds should subside. Overnight lows in the mid-20s with clouds building in.

GFS model 500 mb height and vorticity animated loop valid 7PM Sunday through 7PM Monday, showing a de-amplifying shortwave trough ejecting from the southwest towards our region.

Monday – as the high pressure eventually moves off, a shortwave trough will be progressing towards our region. The accompanying surface low will bring mostly cloudy skies. Temperatures should peak in the mid-30s. Overnight, the storm is positioned to possibly bring us some light accumulating snow. Currently, it’s hard to pin down a total, but the following images from GFS and ECMWF models suggest something on the order of 3-5″ is possible. Low temperatures in the upper-20s should support all snow during this event, so storm track will be key here.

  • GFS model 24 hour snowfall total ending 1AM Wednesday
  • ECMWF model total snowfall ending 1AM Wednesday

NYC Weather Update – Dec 14, 2020

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A quick hitting storm passes south of the city today bringing some rain and mixed precipitation, with no accumulating snow expected. Colder temperatures then take hold in the mid-30s behind this storm Tuesday as a strong area of high pressure builds over Quebec. This sets the stage for a potentially significant snowstorm developing Wednesday into Thursday with 8″+ totals possible along the I-95 corridor (with higher amounts north and west). However, there is still a good deal of uncertainty with the eventual track of this storm that could result in large differences in outcomes.

Rest of today – temperatures dropping through the low-40s into the 30s with mostly cloudy skies and a steady, chilly rain, possibly mixing with some wintry precipitation. No accumulation is expected. Overnight lows around the freezing mark with precipitation ending as high pressure begins building in.

Weather Prediction Center surface forecast for 1PM Monday. An area of low pressure is seen exiting the east coast, bringing us a period of rain and possible mixed precipitation, with snow further inland.

Tuesday – proverbial calm before the storm as high pressure dominates, giving us a mostly sunny day with high temperatures around 40ºF. Overnight lows again in the upper-20s with cold northerly winds flowing around the east side of this high.

Wednesday – high pressure yields to a developing coastal storm. Partly sunny to start with increasing clouds. High temperatures in the mid-30s. Overnight lows drop into the mid-20s. The big story is the potential for a significant snowstorm with accumulations possibly over 8″. GFS and the Euro model have come into agreement for much higher totals, 14-15″. However, NAM shows a warmer scenario with warmer air working further north, thus cutting into overall totals (only 7″). It’s also possible that the low tracks close enough to shore that we end up with a good deal of rain mixing in at the coast, cutting snow totals even further.

Part of the energy fueling this storm is coming all the way from a shortwave with origins over the Pacific Ocean. This has only just made landfall in the US today. As this energy gets sampled by upstream soundings (weather balloon launches) and other means, the forecast models should get a better sense for how this storm will evolve. At this time, there’s enough uncertainty in the forecast to still not buy into any specific totals. If you look below, you can see there’s a lot of spread in the models in terms of the track of this storm. This then translates to a wide range in ensemble forecast totals. In addition, with a coastal storm like this, where there’s a lack of deep, Arctic cold air ahead of the storm, there’s a sharp gradient between areas where the event would be all snow vs. a mixed event. If you see the 24 hour probabilities of > 8″ accumulation, you can see that a 50 mile shift in the storm track further south and east would give us much higher chances for big snowfall totals, while a shift the other way could result in a bust on snow totals. Suffice to say, this storm will bear close monitoring today and tomorrow as more data comes in and models have a chance to digest it.

  • ECMWF “Euro” model surface pressure, precipitation and type for 1AM Thursday
  • ECMWF total snow accumulation at 7AM Thursday, showing 14″ of snow in NYC.
  • GFS model surface pressure, precipitation and type for 1AM Thursday
  • GFS total snow accumulation at 7AM Thursday, showing 15″ of snow in NYC.
  • NAM model surface pressure, precipitation and type for 1AM Thursday
  • NAM total snow accumulation at 7AM Thursday, showing 7″ of snow in NYC.
  • Weather Prediction Center probabilities of > 8″ total accumulation in 24 hours leading up to 7AM Thursday
  • Weather Prediction Center storm track forecasts, note the cluster of blue crosses associated with a surface low near the Delmarva Peninsula. This is the storm that could bring us snow.
  • GEFs ensemble model plumes showing a huge range of possible snowfall totals at LGA during this storm. The mean is 7.83″.

Thursday – depending on the speed and track of the storm, we could see precipitation lingering into the morning hours, with additional accumulation possible. Highs should hover around the freezing mark. Overnight lows drop into the mid-20s with reinforcing cold air advection on the backside of the departing storm.

NYC Weekend Weather – Jan 16, 2020

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This weekend coming up will see a dramatic contrast from last weekend’s record-breaking warmth. Temperatures during the next few days will be average to below normal. Overnight lows in the low-20s for this period. A “warm up” will happen as we enter the warm sector of a passing storm Saturday going into Sunday, but reinforcing cold air arrives to start next week.

Rest of today – partly sunny with strong northwesterly winds. Temperatures will drop from around 50ºF into the low in the mid-20s overnight. A trough extending west from a departing area of low pressure that’s bringing the strong winds may touch off some rain.

Friday – a cold, sunny day with high temperatures starting off in the low-20s and only expected to reach 30ºF under the continuing influence of northwesterly winds .

Saturday – a large storm system will move through. Temperatures starting off in the low-20s will warm into the upper-30s with southerly flow ahead of the main cold front associated with this low. Thermal profiles will support snow to start, with a light accumulation possible before temperatures warm enough at the coast to transition to all rain overnight. Overnight lows aren’t expected to move much, dropping into the mid-30s.

  • GFS model 500 mb height anomalies for 7AM Monday
  • GFS model 300 mb heights and winds for 7AM Monday – the orientation of the jets stream mirrors the position of 500 mb height anomalies

Sunday – improving conditions with high temperatures in the upper-30s and partly cloudy skies. Overnight lows in the low-20s as a second and stronger blast of Arctic air flows in behind Saturday’s storm.