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Winds gradually subsiding, light snow possible by Wednesday

Good evening!

Strong, gusty winds have continued throughout the  majority of today as an area of low pressure off to our northeast continues to intensify. Thankfully, this looks to change as more cold and relatively calm conditions settle in before we have to worry about some light snow threats later this week.

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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

Cold front arrives Saturday, watching two light snow events around Christmas

Improving conditions Saturday, watching a system to our west on Sunday night

After the passage of a cold front this morning, temperatures are falling and wind gusts are picking up. Clouds will also be diminishing throughout the day as well, allowing for mostly clear skies to overtake the region by the mid/late afternoon hours. The combination of these factors will mean that today will be much cooler than the previous couple of days, but not quite “cold”. After the passage of the cold front, most of the area should see temperatures drop into the middle to upper 30’s, with some 40 degree readings possible along the coast. Conditions will remain calm and clear for the remainder of the day, with any residual gusty winds dying down tomorrow evening. This should allow for temperatures to drop back into the upper 20’s and lower 30’s tomorrow night, which is right around normal for this time of year.

Sunday should start off as an excellent day, with sunny skies and temperatures in the lower to middle 40’s across the entire forecast area. However, we will have to watch a shortwave trough off to our west that will be moving through the Ohio Valley by Sunday evening. Model guidance diverges significantly on the exact evolution of this system, but there is a low chance that this system is able to cause an area of light rain/snow to develop over portions of the Mid-Atlantic and Northeast late Sunday and into the very early morning hours on Monday. This system will be moving very quickly from west to east, will not have a lot of moisture associated with it, and the airmass it will be moving into will be quite marginal for snow. It appears that any potential for anything outside of a brief coating of snow is quite low, and this system should not cause significant travel issues overnight Sunday and into the very early morning hours of Monday before moving off the coast by daybreak Monday.

NAM Simulated Radar

This afternoons NAM model showing an outside chance for a potential light rain/snow event Sunday night/Monday morning

Another weak system passes through Wednesday, conditions go downhill once again late next week 

Conditions should be quite pleasant for much of the area on Tuesday (Christmas Day), with mostly sunny conditions and highs in the upper 30’s to lower 40’s expected. Calm and cool conditions should last throughout the entire day, with lows eventually dropping down into the middle to upper 20’s-with coastal locations likely in the lower 30’s. By the time we head into the overnight hours, our attention turns to the Ohio Valley once again. Yet another moisture-starved northern stream shortwave trough will be quickly moving from west to east, possibly causing an area of very light rain and snow showers to develop from west to east Christmas night and into the very early morning hours of Wednesday. Once again, due to the quick-moving nature of this system and the marginal airmass in place, any accumulation potential will be very low for the New York metro area.

A large area of high pressure will begin to build over much of the east on Wednesday as the next major storm system begins to build over the Plains states. This system looks to take a track predominately up over the middle of the country, which should once again drag a warm/moist airmass from the south and up into the Northeast. Though this system is still a week out, there appears to be a heightened threat of yet another dreary and wet end to the week next week across much of the eastern half of the country.

ECMWF 850mb Winds/Temps

This afternoons ECMWF model showing another exspansive storm system moving off to our west, bringing unsettled and above-average conditions to much of the East

We’ll have an update on the potential light snow events and any other threats that may arise by the later half of this weekend! 

Have a great Holiday Weekend! 

 

Steve Copertino

Light wintry mix possible tomorrow, dreary weekend ahead

Good afternoon!

The cool and quiet conditions that have been with us for the past week or so continue over the Northeast this afternoon, with the only real changes being that cloudiness has increased in earnest and highs today are only slightly warmer than the previous couple of days. Despite temperatures running a few degrees above what they have been, we’re still seeing highs across the New York metro area in the upper 30’s to lower 40’s, with lower to middle 40’s over portions of Southern New Jersey. Conditions should stay rather cloudy this evening and overnight as a shortwave trough over portions of the Great Lakes continues to head to the east, dragging up warmer mid-level air from the south. Temperatures this evening should remain cool, but not nearly as cold as the past few nights thanks to the increased low/mid-level clouds limiting any potential for radiational cooling. Expect lows to generally stay in the upper 20’s to lower 30’s for most of the New York City area-with middle to upper 20’s well to the NW and middle to upper 30’s over portions of SNJ.

7-day Weekly Planner

Weekly Planner for the next 7-days

Light wintry mix possible tomorrow morning/afternoon

During our previous update we introduced the possibility of a period of light snow/rain moving through the Northeast on Thursday, and since that time we have seen models become a bit more bullish on this event. The same shortwave moving through the Great Lakes this afternoon/evening will be over portions of PA/NY by early tomorrow morning, with light snow likely breaking out over Central Pennsylvania.

Though this shortwave is rather dry, it will be given small boost of moisture from relatively warm and moist air advecting into the Northeast. This should allow the small area of snow to sustain itself during its journey through Pennsylvania tomorrow morning, possibly reaching New Jersey by 7-9am. Once we get to around 10-11am, we should see precipitation expand into New York City and portions of Long Island. Given the limited dynamics/moisture available with this system in addition to very marginal surface temperatures, this system will not be an areawide snow producer. As of right now, it looks like locations mainly to the north of Trenton, New Jersey to NYC should begin as snow, but the same warm air advection that will be causing the precipitation will also help to gradually change precip over to light rain or a wintry mix from south to north.

Locations to the north and west of the immediate New York City area should have the best shot at staying mainly light snow for most of the morning/early afternoon, in addition to locations with greater elevations. While snow will likely be in the air tomorrow, the vast majority of the area should see issues with the snow sticking, outside of colder surfaces given the very marginal airmass. Additionally, snow growth a few thousand feet above the surface will be far less than ideal, meaning that snowflakes could be very small and malformed. This only further complicates any accumulation talk, but at this time a general coating to two inches is expected from Pennsylvania and into portions of NNJ/SNY (with the potential for locally higher amounts for elevated locations).

The timing of the precipitation ending will be highly dependent on when the shortwave outruns the best WAA (warm air advection), but this looks to be during the late afternoon hours. Any remaining precip during the late afternoon hours should change to a light wintry mix for the remainder of the area. All in all, this should not be a highly impactful system, but it could cause some slick road conditions, so please use caution when traveling tomorrow.

3km NAM simulated radar

Loop of this afternoons NAM model showing the light snow/mix event for tomorrow morning and afternoon. Note how most locations around New York City end as rain.

Weekend storm likely to deliver wet and dreary conditions through Sunday

Back on Monday we mentioned the potential for heavy rain from an approaching upper level low over portions of the Southeast, however since that time the reliable computer models have trended weaker/more disjointed with this system as a whole. The result of a weaker system for the Northeast means that the strong low level jet that was forecast to occur over the East coast is now much less likely which severely limits the heavy rain/wind threat.

While we will likely see moderate to possibly locally heavy rain move into the area by Friday night and into Saturday morning, the risk for widespread heavy rain and potential flooding is now much lower. As the upper level low exits the coast on Sunday there will be the chance for some additional rainfall, especially along the coast. Interestingly enough, some models develop a coastal storm late Sunday and into Monday that could potentially extend the wet/unstable period a bit longer, but this remains quite uncertain at this time. We will continue to monitor the progress of this system as more details become clear in subsequent updates.

12z ECMWF PWATS

This afternoons ECMWF model showing a weaker/disjointed low level jet over portions of the East Coast early Saturday morning

We will have further updates on tomorrow light mix event and this weekends rain event by tomorrow! 

Have a great evening! 

Steve Copertino