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Light snow likely Tuesday, frigid conditions arrive Thursday

Good evening!

Today has been a rather calm and seasonably cold day across much of the Northeast as a weak area of high pressure located to our north remains in control of our sensible weather. Spotty upper level clouds associated with a quick-moving shortwave trough moved through the southern portions of the area earlier this morning and into the afternoon hours, but quickly gave way to mostly sunny skies. Mostly clear skies and residual northwesterly flow aloft allowed highs this afternoon to stay in the upper 20’s to lower 30’s-with the vast majority of the region staying below freezing. High pressure to our north is expected to quickly move to the east through this evening and into the overnight hours. Surface flow will gradually begin to shift from the north/west, to a more southerly/southeasterly component during the overnight hours, which will help to increase cloudiness over the area. Overnight temperatures will likely be able to fall a few degrees, with readings likely staying in the lower to middle 20’s for the majority of the immediate NYC area.

Weekly Planner

~Updated Weekly Planner~

Light Snow Likely North and West of NYC Tuesday

Our attention shifts to the Great Lakes region by tomorrow morning as an area of mixed precipitation along a cold front will be moving quickly to the east towards our area. The overall setup has become much less impressive since our last update, with only light snow accumulations expected well to the north and west of the immediate NYC area. Surface winds tomorrow morning will be out of the south and east, which will help to warm temperatures into the lower to middle 30’s all the way into NE NJ and SE CT. While precipitation may start off as a mix of light rain and snow for most of the area, a quick transition to a cold rain is expected for all locations outside of elevated portions of Northern New Jersey and the Lower Hudson Valley.

Precipitation will remain predominately light to occasionally moderate in nature into the evening hours before the front begins to move across the area. We may see an increase in precipitation rates as warmer air coming in from the coast interacts with the cold/dense incoming Arctic airmass off to our west. This could create a narrow band moderate snow that moves from west to east over the area, possibly producing a quick coating to an inch all the way down to the coast as temperatures quickly fall below freezing. Precipitation will quickly end from west to east during the very early morning hours of Wednesday with the main impacts from this system primarily being felt well off to the north and west of the NYC area.

Conditions behind the cold front will be quite blustery on Tuesday night, with wind gusts potentially getting into the 30-40 mph range as temperatures drop into the lower 20’s and upper teens. The rapidly falling temperatures and gusty winds will create the potential for any residual standing water to quickly freeze on untreated surfaces-possibly creating some hazardous travel conditions.

Impact Map

Our latest impact map for the light mix event tomorrow. The main impacts from this system will primarily be felt well off to the north and west of the city

Frigid Arctic Air Arrives Thursday

The long-awaited “polar vortex” will be located just to the north of the Great Lakes by Wednesday morning, with very deep westerly flow overspreading the Northeast. The cold front associated with the weak surface low to our north will be exiting off the coast Wednesday morning just in time for the AM commute, allowing for gradually clearing skies. While the airmass behind this first front will be quite cold, the main Arctic front will wait until the afternoon hours of Wednesday to work its way into the NYC area. Southerly flow at the surface will overspread the NYC area ahead of the main Arctic cold front, allowing for temperatures to rise into the lower to middle 20’s Wednesday afternoon.

The aforementioned deep westerly flow directly associated with the strong tropospheric vortex to our west will cause mid level temperatures to plummet over the Northeast before surface temperatures have a chance to respond. This will create impressive “lapse rates” (change in temperature with height) Wednesday afternoon over the majority of our area. Furthermore, some weak mid level energy will be edging into portions of the Mid-Atlantic and Northeast during Wednesday afternoon. This setup will create the potential for some snow squalls to develop and quickly move from west to east around 12pm -4pm on Wednesday. Some of these squalls could be quite heavy in nature, producing very low visibilities at times and potentially dropping a quick coating to an inch for some locations. The Arctic front will finally blast through the NYC area during the late afternoon and early evening  hours of Wednesday. Winds will quickly increase to around 20-30 mph, with gusts up to 40 mph as overnight low temperatures rapidly fall into the single digits across the entire forecast area–with temperatures likely falling below zero for elevated locations off to the north and west.

Thursday will be one of the coldest days of this winter season as highs struggle to make it out of the lower to middle teens for virtually the entire Northeast. Highs will be anywhere from 20-35 degrees below normal across the Northeast Thursday afternoon-which may wind up breaking a few records across the region. Wind chills will also be extremely cold, with readings likely anywhere from 10-20 degrees below zero by Thursday morning. Frigid and calm conditions will continue into the evening/overnight hours of Thursday, with lows in the single digits over the entire area.

Temperatures will moderate a bit on Friday, with highs likely getting back into the lower to middle 20’s, before a more significant warm up takes place later on this weekend.

2m Temp Anomaly

ECMWF model showing surface temperatures anywhere from 24-36 degrees below normal on Thursday morning (AccuWx)

We’ll have an update on this Arctic airmass as well as a look at this weekend’s weather on Wednesday!

Have a great night!

-Steve Copertino

Bitter Cold Gives Way to Heavy Rain on Thursday

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

Tuesday PM Update: Frigid temperatures arrive, snow chances ahead

Good evening! Are you cold yet? High temperatures today throughout the Northeast ranged from the 20’s to lower 30’s, well below normal for late December. Even colder weather is on the way for the rest of the week, so get ready to bundle up and dress in layers. A few storm chances will likely follow – and we’ll dive into the forecast model depictions, including which make sense and which don’t.

For tonight, arctic high pressure will build over the Northeast states, supporting mostly clear skies and calmer winds. Temperatures are likely to drop into the teens overnight many areas – some of the interior valleys (including the Pine Barrens) may drop into the single digits. Forecast models suggest the core of this airmass, characterized by 850mb temperatures between -20 and -25 C, will move over the Northeast states late this week. High temperatures will fall all the way into the teens and lower 20’s, with single digit temperatures overnight.

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