Tag Archive for: Freezing rain

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.

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. 

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!

Have a great night!

Steve Copertino