3km NAM Simulated Radar
Steven Copertino

Updated: Heavy rain likely today, cold and calm weekend

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Soaking Rains Likely on Thursday

High-resolution model guidance has been consistent in the suggestion that an area of heavy rain associated with an area of low pressure moving along a cold front will be located near the area for the rest of the morning. A strong upper level jet streak will be positioned just off to our north and west. This will provide ample lift for pockets of moderate to occasionally heavy rainfall during the early afternoon hours. In fact, there may even be a line of heavy showers and thunderstorms within this main area of rain that could produce some gusty winds of up to 30-45 mph and flash flooding–especially for locations with poor drainage. Accordingly, the National Weather Service has issued a Flash Flood Watch for the entire NYC metro area through 6 pm.

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Steven Copertino

Bitter Cold Gives Way to Heavy Rain on Thursday

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Good Evening!

Today has been a brutally cold day across much of the East Coast as an impressive Arctic airmass blasted into the country on Sunday. Additionally, the messy storm system that affected the area this past weekend is now rapidly intensifying off to our northeast. This intensifying system is creating an impressive pressure gradient with the Arctic high pressure currently located over the Ohio Valley. The result has been strong, gusty winds of up to 40 mph creating wind chills anywhere from five to ten degrees below zero across the New York City area today. The extremely dry airmass in place has cleared out virtually any remaining clouds over the Northeast, which made for a classic frigid January day. High temperatures were only able to rise into the teens and single digits across the forecast area, with Central Park getting to around 14F, which is twenty-four degrees below normal! 

Winds will gradually begin to diminish this evening as the area of low pressure off to our northeast begins to drift further away weakening the pressure gradient over the area. With clear skies and diminishing winds, radiational cooling will take over, causing temperatures to fall back down into the single digits for the immediate NYC area, and likely in the 0-5 degree range off to the north and west. Elevated locations of NW NJ and SNY may even drop back below zero tonight. Even with weaker winds, wind chills will likely still be 5-15 degrees below zero tonight, so definitely bundle up if you’re planning to head outside tonight!

Surface Map

Surface map from this evening showing the Arctic high pressure system moving through the Ohio Valley.

Tomorrow (Tuesday) will start off as another bitterly cold morning for the AM commute with temperatures in the teens and single digits for the immediate metro area. High pressure will likely be overhead at this time, so winds will be substantially weaker than the previous 24 hours. As the surface high and mid-level ridge passes overhead tomorrow afternoon, the cold northwesterly flow will be replaced with westerly and eventually southwesterly flow. This change in source region will allow temperatures to moderate a bit during the day. Highs will likely still be cold, with temperatures likely getting into the lower to middle 20’s for the majority of the NYC area. Mostly sunny skies and cold temperatures will last into the evening and overnight hours, making for a cold but pleasant day. Radiational cooling will once again take over Tuesday night, causing lows to drop back down into the teens and lower 20’s for the entire area, which is around 10 degrees below normal for late January.

Wednesday will be a day of transition as a large mid level trough moves into the Central United Sates. As this trough digs in an amplifies, a ridge will build over much of the East, allowing for much warmer temperatures to move in. A weak surface low will cut off to our west during the morning and afternoon hours on Wednesday, leading to a warm front passing through the Northeast. This warm front will aid in the development of some scattered showers during the day on Wednesday, with the potential for some light freezing rain during the onset for elevated locations well off to the north and west of the city. Once the warm front moves through, highs will likely rise into the upper 30’s to lower 40’s for the entire area, which will be 10-15 degrees above normal!

The aforementioned mid level trough will gradually shift east during the evening on Wednesday causing a deep area of moisture to begin to stream up through the Southeast and into the Northeast. The scattered light to moderate showers will eventually give way to more steady rain overnight and into Thursday morning. A wave of low pressure may try and develop along the frontal boundary draped over the Northeast, which could introduce a round of moderate to occasionally heavy rainfall during the morning and afternoon hours of Thursday. This frontal system will finally shift off to our east Thursday evening, bringing an end to the precipitation from west to east. Highs on Thursday will be quite mild, with temperatures reaching into the middle 40’s before dropping back down into the 30’s by Thursday evening.

GFS PWAT

This evenings GFS model showing an impressive plume of moisture aimed at the Northeast on Thursday.

Temperatures look to drop back down to seasonable levels on Friday as a cold front moves through the Northeast. These seasonable temperatures are expected to last through this weekend, with the potential for some snow showers on Sunday as an energetic upper level system moves through the Great Lakes and into the Northeast.

There are some indications that we may have to monitor the East Coast next week for our next storm threat as an abundance of energy drops into a trough located over the Central United States. While we will likely still be lacking any kind of blocking for this time period, we are quickly approaching a time period that is traditionally favored for increased storminess across the east!

The ECMWF model showing a period of increased troughiness across the eastern half of the country (courtesy of Tomer Burg)

Thanks for reading and we’ll have an update on Wednesday!

-Steve Copertino

3km NAM Storm
Steven Copertino

Multi-faceted winter storm to impact the region this weekend

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Highlights: After light snow today, a more notable winter storm approaches for the weekend, with arctic air moving in behind it and a colder and active weather pattern to follow. 

Good Evening!

Today has been a rather gloomy and cold January day across much of the Northeast as the weak system that dropped some light snow across portions of the metro area this morning continues to quickly head offshore. As discussed in previous updates, this system was likely to only produce a trace to one inch of snow over the area, and that is exactly what has been reported as of this afternoon.

As the snow departed late this morning, mainly cloudy conditions remained overhead with mid level flow increasing out of the southwest. These southwesterly winds have allowed for a slightly more marginal airmass to overspread the area today. Coupled with the persistent cloudy conditions, this caused highs today to rise into the middle to upper 30’s across much of the forecast area-with 40’s reported closer to the coast. Cloudy and slightly above-normal temperatures will continue into the evening hours before a mid level disturbance passes well to our north. This system will be accompanied by a cold front that should help to clear out some of the remaining clouds tonight and usher in colder temperatures from our northwest.

Lows will likely drop back down into the lower to middle 20’s for the majority of the area this evening, which will be right around normal for this time of year.

3km NAM Simuawips

This evenings high resolution NAM model showing lows backing down into the 20’s and lower 30’s for the NYC area

Complex and Impactful Winter Storm This Weekend

While tomorrow (Saturday) will likely start off quite calm and clear, the winter storm we have been talking about for nearly ten days now will be quickly approaching from the west. By 8 am, the storm will be centered over the Tennessee valley, with moderate to heavy snow expanding into much of the Ohio Valley. While the main shortwave trough associated with this system will not be able to completely interact or phase with the larger system over Canada, it does appear that there will be just enough of an interaction to keep the bulk of the heavy snow well off to the north and west of the immediate NYC area.

As we head into Saturday afternoon, the surface low over the Tennessee valley will be picking up steam and intensifying. As it does so, a large area of warm/moist air will begin to stream northward over much of the Southeastern states. All of this warm and moist air just above the surface will collide with a strong Arctic high pressure system over southern Canada and cause a moderate to heavy band of snow to develop over portions of New York and Pennsylvania. Light snow will likely begin to move into portions of Eastern New Jersey by 3-4 pm, with the snow quickly picking up in intensity over time. This band will continue to head east by 4-5 pm, likely overspreading the entire metro area by that time. All of the warm/moist air moving into the Northeast and colliding with colder air to the north will cause an enhanced area of lift within this band of snow, which could push snowfall rates into the 1-2″ per hour range–especially over portions of EPA, SNY, and NW NJ.

This area of moderate to occasionally heavy snow will likely continue into the evening hours of Saturday. It is at this time that precipitation types will start to become an issue. Due to the SW to NE orientation of this system thanks to the modest interaction with the system located over Canada, warmer air in the lower levels of the atmosphere will begin to overspread much of Southern and Central New Jersey, and eventually into the immediate NYC area. While the overall track of this system and the actual degree of interaction with the aforementioned Canadian system will determine the timing of this changeover, much of the metro area will likely see a change to a mix of sleet, freezing rain, and plain rain by 11 pm to 1 am. Locations off to the north and west of the immediate NYC area could potentially hold onto pure snow few a few more hours, causing a steep snowfall gradient to develop over our area.

Warm/moist air will continue to push further north into the forecast area overnight on Saturday and into the early morning hours of Sunday. Locations around the immediate New York City area have a good chance to flip to all rain at this time, with locations to the north and west potentially changing over to a dangerous mix of sleet and freeing rain. In fact, the freezing rain threat will be quite high over this area, with up to a tenth to a quarter of an inch of freezing rain possibly falling by Sunday morning. 

The combination of moderate to heavy snow and freezing rain will likely cause very significant travel disruptions north and west of the city on Sunday morning.

Total Snow Forecast

Our latest total snowfall accumulation map for Saturday and into Sunday morning. The hatched area denotes the potential for significant freezing rain and sleet accumulations.

Dangerous Flash Freeze Possible Sunday and into Monday

Precipitation will likely still be ongoing by 8 am Sunday morning, with rain mostly expected for the vast majority of the forecast area as the surface low pressure system will likely be over Southern New Jersey at this time. Despite the change to plain rain, much colder air will be quickly approaching the area as the surface low begins to pull to our east during the afternoon hours on Sunday. Temperatures will quickly fall well-below freezing and into the lower to middle 20’s from west to east, likely causing any standing water to refreeze. Any residual precipitation over the area will need to monitored, as a flip to snow would be possible.

Regardless, true Arctic air will work blast through the entire forecast area by Sunday night, with lows dropping down into the single-digits! Winds will also be quite strong behind this system, with gusts up to 35 mph possible. If significant ice accumulations do occur over portions of the area, then there could be an enhanced threat of power outages Sunday night.

The colder than normal weather pattern is very likely to remain in place into next week, as a piece of the polar vortex fractures and settles in to the north of the region. This will keep cold and potentially active weather in the forecast as we move toward the back half of the week, and especially into next weekend.

We will Continue to provide updates on this storm over the next day or so. Please stay tuned to our social media accounts for up to the minute information!

Thanks for reading!

-Steven Copertino/John Homenuk

ECMWF Sunday 2am
Steven Copertino

Light Snow Friday Morning, All Eyes on This Weekend

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Good Evening!

Today has been another calm and relatively cool day across much of the Northeast as high pressure remains in control of our sensible weather. Partly cloudy skies and mid-level flow coming out of the west allowed for temperatures to rise into the upper 30’s to lower 40’s for much of the NYC metro area, which is slightly above-normal for this time of year. A weak cold front is currently situated over portions of New York and Pennsylvania and has been gradually moving to the southeast during the course of the day. This cold front is expected to arrive later this evening, which will usher in a fresh batch of cold air into the region. There really isn’t much in the way of moisture associated with this front, so this will likely be another dry and cold night. Occasionally breezy conditions will set up behind the front with clearing skies from northwest to southeast tonight.

With a fresh cold air mass in place and clearing skies, radiational cooling will take over tonight, allowing temperatures to fall into the lower 20’s in and around the city, with teens possible for locations off to the north and west.

Simuawips

This evenings current radar and surface observations

Light Snow Likely Tomorrow Night and Into Friday Morning

Tomorrow (Thursday) will likely start off quite chilly with temperatures in the lower 20’s for the immediate New York City metro area. Continued breezy conditions will yield wind chills in the teens for the entire area tomorrow morning, so it’s definitely going to feel quite cold for the morning commute. High pressure will remain in place for the majority of the day which will allow for partly sunny skies and gradually diminishing winds into the afternoon hours. Highs will likely be hard-pressed to rise above-freezing tomorrow afternoon, with locations to the north and west of the city likely staying in the middle to upper 20’s.

By the early afternoon hours, our attention will shift to the west over the Ohio Valley. A weak and disorganized mid-level wave will be quickly heading to the east during the day with an associated area of light snow. This system will continue to gradually move into our area tomorrow evening, with increasing clouds towards sunset. Cloudiness will continue to increase during the overnight hours as moisture to our south begins to overspread the area. Light snow will quickly move into the NYC metro area, likely around 2am or so. The entire forecast area will likely stay snow for the first couple of hours, but as moisture continues to trickle in from the south, warmer air will also be on the rise. Coastal locations will likely change over to a mix of rain and snow by 6am Friday, with locations to the north and west of NYC likely staying as light snow. Precipitation will quickly head off to our east by 8-10 am, with some residual spotty snow/rain showers remaining for the rest of the afternoon.

Due to the progressive nature of this system, marginal amounts of forcing, minimal precip amounts (.1″ to .25″ of liquid), and increasing surfaces temperatures, snow totals are expected to be low. At this time, a quick coating to an inch of snow will be possible in and around the immediate NYC area, especially on colder surfaces. Once we head off to the north and west, mainly 1-3″ of snow is expected–especially for elevated locations over NW NJ and SNY.

Due to the timing of this light snow event, it seems possible that some delayed openings may be called for portions of NW NJ and SNY. 

3KM NAM Simulated Radar

High resolution NAM simulated reflectivity showing the evolution of the light snow event tomorrow night and into Friday morning

Potentially Impactful System Shaping Up for the Weekend

The overall setup for this weekends potential system has not changed much since our last update. A large and energetic system that is currently located off the California coast will move into the Rocky Mountains by Friday morning, producing an area of low pressure over the Southern Plains at the surface. As this energetic system begins to head east during throughout Friday and into Saturday morning, another large upper-level system located over Canada will begin to shift to the south. This large system over Canada will help to inject a massive amount of cold air into the Central US, leading to a large area of moderate to heavy snow developing over the Midwest on Saturday afternoon. Things become a little more hazy later in the day on Saturday as the western edge of the Canadian system tries to interact or phase with the shortwave over the Southern Plains/Midwest. This potential interaction will be absolutely crucial for the overall impact for much of the Northeast.

As of right now there are two main solution on the table:

  1. The system over Canada DOES interact and phases with the shortwave to its south late Saturday and into Sunday morning. This causes the surface low to gradually strengthen and track from the Southeast and eventually moves to the west of our area. While an initial thump of moderate to heavy snow would be possible for locations to the north and west of NYC, precipitation would then quickly flip to rain for the remainder of this storm. This solution would have a rather limited impact for our area, with heavy rains likely during the day on Sunday.
  2. The system over Canada DOES NOT interact with the southern stream system and misses the phase. This would allow for the surface low to move to the south and east of our area, bringing in much colder temperatures into the Northeast. A thump of moderate to heavy snow would be likely for most of the Northeast late Saturday night and into Sunday morning. Snow would potentially change to sleet and freezing rain from south to north during the day on Sunday as warmer air in the mid levels of the atmosphere moves over temperatures that are still below-freezing at the surface. This would create a potentially hazardous situation for the immediate NYC area, with a thick layer of ice on top of snow. In this scenario, locations to the north and west would have a good shot at staying mostly snow as cold air from the north rushes into the area. This solution would obviously have a much higher impact for all locations outside of the immediate coast.

This afternoons model guidance did trend towards a solution with less interaction between the Canadian system and the main shortwave, which allowed for some more cold solutions to show up. Additionally, the models have been advertising that the magnitude of cold air just to our north will be quite impressive Saturday night and into Sunday. This cold air will be very dense, and computer models usually tend to move this cold air out of the Northeast much too quickly, leading to an underestimate of frozen precip.

At this time we feel that the trends towards a less-phased system have merit, and there will likely be a period of moderate to heavy snow late Saturday and into Sunday. While there is a high amount of uncertainty regarding what happens after that point, snow could gradually flip over to freezing rain and rain during the day on Sunday for much of the area, which would open the potential for a hazardous solution. This scenario would have the majority of the impacts mainly to the north and west of the city.

**It is important to note that this system is still a couple days away and we will still likely see some significant changes in that time. We will continue to closely monitor the progress of this system and provide updates as new data becomes available!

Impact map

Impact map for this weekends system

Have a great night!

Steve Copertino