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Multi-faceted winter storm to impact the region this weekend

January 18, 2019/1 Comment/by Steven Copertino

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.

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.

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

Light Snow Friday Morning, All Eyes on This Weekend

January 16, 2019/1 Comment/by Steven Copertino

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.

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.

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:

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.
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 for this weekends system

Have a great night!

Steve Copertino

Watching Two Snow Threats Later This Week and Into the Weekend

January 14, 2019/2 Comments/by Steven Copertino

Good Evening!

Today has been quite cold and calm across much of the Mid-Atlantic and Northeast as the storm system that impacted much of the Central US to the Mid-Atlantic moved offshore very early this morning. High pressure has now begun to build in from the west in this system’s wake, ushering in colder mid-level temperatures from the Northwest. With cold mid-levels and mainly clear conditions in place today, highs were able to only reach into the upper 20’s to lower 30’s across much of the New York metro area-which is just slightly below-normal for this time of year.

Continued clear skies, cold mid-levels, and light winds will aid in the development of decent radiational cooling during the overnight hours. Low temperatures should drop steeply into the middle teens to lower 20’s across much of the forecast area tonight, with single-digit readings possible for elevated locations well off to the north and west of the city.

This evenings high-resolution regional radar and surface observations showing a cold, but very calm evening in place for much of the Northeast (Simuawips)

Cold and Clear Through Midweek

High pressure will remain in control for much of the day on Tuesday before a very weak and moisture-starved system begins to approach the Northeast from Canada. As this system approaches the area, lower to mid-level winds will shift from northwesterly to more westerly, allowing for only slightly “warmer” air to move in. This system may also have a chance to briefly increase cloudiness over the Northeast during the afternoon hours. Some slightly increased cloudiness and westerly flow aloft will likely allow for highs tomorrow to head into the middle 30’s to lower 40’s across much of the forecast area. While these temperatures are slightly warmer than today’s highs, they will still be right around normal for this time of year. As this weak system moves through moves through tomorrow afternoon/evening, there may be some light snow showers over portions of New York State and Northern Pennsylvania, but the entire New York metro area should remain dry. Once this system moves on through the area, a weak cold front will then quickly move from west to east, eliminating any remaining clouds in the area. With a relatively more mild airmass overhead tomorrow night, highs will likely only be slightly warmer than this evening’s, with readings in the upper teens to middle 20’s likely.

Wednesday will start off much like Tuesday with calm, clear, and cold conditions in place for the morning commute. Temperatures will be rather cold, with lower to middle 20’s likely for much of the immediate metro area. Another weak mid-level system will be moving very quickly well to our north on Wednesday afternoon, with the potential for some increased cloudiness over the area. Highs will reach the middle to upper 30’s, with lower 40’s likely closer to the coast.

The potential will exist for some light snow snow showers off to the north and west of the city on Wednesday afternoon/evening, but it is highly unlikely that these snow showers are able to make their way south into portions of New Jersey and New York City due to the best dynamics remaining well off to our north. As the evening continues on, another weak cold front will move through during the evening and overnight areas, bringing in another reinforcement of drier conditions. Wednesday night will likely be another cold and mostly clear night for the area, with lows dropping down into the lower to middle 20’s.

~Updated Weekly Planner for the NYC area~

Watching Two Potential Snow Threats Later This Week and Into the Weekend

Conditions will likely remain quite calm and cold through the middle of the week and into the first half of Thursday. However that looks to quickly change as we shift our attention towards the Ohio Valley. A weak northern stream disturbance will be moving quickly from west to east, with just enough moisture moving up from the south to produce a swath of light precipitation. Additionally, an area of high pressure will be located over New England, which should help this system continue on eastward towards the New York City area by Thursday evening. Light precipitation should move into the metro area by 7-9 pm, with most of the area starting as light snow. Initially, the aforementioned high pressure area should help the entire forecast area stay as mostly snow, with locations over Southern New Jersey possibly experiencing some mixing issues.

As we head deeper into the overnight hours, warmer air may continue to work its way into the immediate New York City area, causing a mix or change to rain. Precipitation will likely continue into the AM commute on Friday before quickly tapering off from west to east. At this time it does appear that this system could drop a quick coating to an inch or two across portions of the NYC metro area, with some locally higher amounts for elevated locations off to our north and west. The exact amount of snow/rain will be highly reliant on the track of this system, and we will have an update tomorrow as more data becomes available!

This evenings GFS model showing a weak disturbance producing an area of light snow over the Northeast late Thursday night and into Friday morning

Lastly, we mentioned the possibility of a “larger” system that could impact the East Coast this upcoming weekend all the way back on Friday. Since that time, the reliable computer model guidance has shifted away somewhat from a significant/pure-snowstorm, to more of a “thump” of moderate to heavy snow-along with a mix of sleet, freezing rain, and plain rain for much of the forecast area.

At this time we feel that the mostly likely scenario based on all available data is that another large storm system will develop over the Midwestern states on Friday night, with a large swath of moderate to heavy snow extending along the northern edge of the precipitation shield. This system will then have the potential to interact with a much larger mid-level system over Canada on Saturday, which will likely cause it to strengthen a bit as it tracks over the Southeast. A large and expansive upper level jet streak will help to “vent” this system out, allowing for precipitation to expand into the Northeast by Saturday afternoon. Thermal profiles appear to be cold enough for precipitation to start and stay as mostly snow for the NYC area during the afternoon and early evening hours. There is the potential that the snow could eventually change to a mix of sleet, freezing rain, or even plain rain by the overnight hours of Saturday or early Sunday, but this is where the models begin to diverge significantly. Depending on just how much this system interacts with the large tropospheric polar vortex over Canada will dictate just how much cold air can get involved and where exactly this system will track.

There is still quite a bit of time to track this system, and we could still see a shift towards either side (colder with more snow or warmer with more rain) over the next few days, so make sure to check back for updates!

This afternoons ECMWF model showing a large area of wintry precipitation breaking out over the East Coast on Sunday

Have a great night!

-Steve Copertino

Mid-Atlantic Snow, Cold Weather Holds Tight Into Next Week

January 11, 2019/0 Comments/by Steven Copertino

Good Evening!

We have finally seen the return of more seasonable temperatures across much of the Mid-Atlantic and Northeast today as an Arctic high pressure system continues to dominate our sensible weather. Temperatures early this morning were in the teens to lower 20’s across much of the NYC metro area, which really brought a harsh reminder to many that we are still in the middle of January and it does get cold-despite the past few weeks of warmer temperatures. As we worked through the day today, temperatures were only able to rise into the middle to upper 20’s with some lower 30’s closer to the coast and over portions of Southern New Jersey-which is right around normal or just slightly below-normal for this time of year.

Continued clear skies and dry conditions will last well into the evening and overnight hours tonight which will set the stage for near-ideal radiational cooling conditions to take place. Temperatures will likely plummet once again back down into the teens for much of the forecast area, with lower to middle 20’s for portions of Southern New Jersey. Even with subsiding winds into the overnight hours, windchills will still be quite low-with readings likely getting down into the lower teens and single-digits over NNJ, SNY, and Connecticut!

Needless to say, if you’re planning on heading out tonight, remember to bundle up!

This evenings HRRR model showing the predicted low temperatures for this evening and into the early morning hours tomorrow

Snowstorm Takes Aim at the Mid-Atlantic

The system we have been discussing for the better part of a week now is well underway across portions of the Midwest this evening where up to 12-18″ of snow will be possible by Sunday morning over portions of Missouri.

As this system continues to head east over the next 24 hours, it will begin to become more disorganized and strung-out due to an upper level system over Canada gradually pressing down onto it and increasing the speed of the flow out ahead of this storm. While light to moderate snow will continue to spread east over portions of the Midwest and Ohio Valley through tomorrow afternoon and into the evening hours, it will continue to feel the effects of this Canadian system.

This will cause precipitation to become more light in nature once it reaches the Mid-Atlantic states late Saturday night. An impressive 1040 mb high pressure system will be located over Southern Canada as this storm heads towards the Mid-Atlantic, which will essentially guarantee that precipitation will be in the form of snow. This strong high pressure system will also help keep the vast majority of the steady snow well to the south of the NYC area during the morning/afternoon hours of Sunday.

Locations to the south of NYC could possibly see some marginal/light impacts from the northern-fringe of this system, with a general coating to two inches possible to the south and east of Philadelphia. Locations from Philadelphia to New York City have may see some brief and very light snow during the day on Sunday, but any accumulation potential seems extremely limited at this time.

This evenings high-resolution NAM model showing the evolution of the Mid-Atlantic snowstorm this weekend

Cold and Clear Conditions Dominate New Week…More Active Times Ahead?

High pressure will once again take control as this weekends storm gradually moves off the Mid-Atlantic coast on Monday, which will usher in a new round of cold and calm conditions. Temperatures for the majority of the week next week will be right around normal or just below-normal, with highs in the middle to upper 30’s. Though we are relatively far out at this point in time, we may see a frontal system approach the area late next week around Friday that may provide our next shot at some wintry precipitation.

Our attention then shifts towards next weekend as most of the reliable models and their respective ensembles show a growing threat for a sizable storm system to impact the eastern half of the country. While the overall synoptic pattern will be in the process of transitioning to a more favorable one for snow, there are signals showing up that would lend some support to this overall idea of a heightened storm potential next weekend. Since we are nearly ten days away still, we cannot nail down any specifics at this time other than the fact that we will likely need to closely monitor the pattern next week to see how this increasingly interesting period unfolds!

The ECMWF ensembles showing a heightened potential for a potential storm system the East Coast next weekend

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

Have a great weekend!

-Steve Copertino

Tag Archive for: below normal

Posts

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!

Complex and Impactful Winter Storm This Weekend

Good Evening!

Light Snow Likely Tomorrow Night and Into Friday Morning

Potentially Impactful System Shaping Up for the Weekend

Watching Two Potential Snow Threats Later This Week and Into the Weekend

Good Evening!

Cold and Clear Conditions Dominate New Week…More Active Times Ahead?