Winter 2017 Archives - New York Metro Weather

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Zonal Pattern Gives Way to More Extremes Across the Country

December 18, 2017/1 Comment/by Steven Copertino

Good Evening!

A weak area of mid level energy moved quickly through the Northeast last evening and into the early morning hours today, which had just enough kick left to it to bring some isolated and relatively light areas of precipitation. Depending on your location, this precipitation varied from plain rain, freezing rain, or even some light snow. Any frozen precipitation accumulations were extremely light, but still made for a slick morning commute today. The quick-moving west to east flow that has become established over the majority of the country will be responsible for bringing some more weak mid-level energy over the region through the rest of the day, which has led to a rather dreary and warmer day than the past couple of days. West/southwesterly flow has allowed mid level temperatures to rise over much of the Mid-Atlantic and Northeast, which has allowed surface temperatures to respond accordingly throughout the day. We have seen highs across much of the Northeast rise into the lower to middle 40’s across the majority of the area, with higher readings around the 50’s observed in portions of southern New Jersey. These mostly cloudy and slightly-above normal temperatures should continue into the evening hours, with a chance of some patchy fog across the area as some moisture may become trapped within a low level inversion.

Expect temperatures this evening to fall back into the upper 30’s and lower 40’s across the immediate NYC metro area, with cooler temperatures likely well to the north and west.

This evenings latest regional radar mosaic, GOES 13 visible satellite imagery, and surface observations showing a more mile and dreary end to the day across much of the Northeast

Tuesday Into Thursday

A deep cyclone moving through portions of central and eastern Canada will continue to drag a rather stout southwesterly flow over the Northeast tomorrow afternoon, which should also bring in more dry air to clear out the low-mid levels of the atmosphere. This should allow for a vast majority of the clouds to dissipate as the day goes on tomorrow. This deep southwesterly flow and relatively clear skies across the area should allow temperatures to rise into the “well-above normal” territory as highs will likely get into the middle-upper 40’s-with some 50-degree readings possible. Thankfully, moisture will be quite limited across the east, so we expect a generally calm and mild day tomorrow for much of the Northeast. Later in the day, a cold front associated with the same cyclone in Canada will begin to creep into the Northeast. This front will work east through the area throughout the overnight hours, but will likely bring lows down into the upper 20’s to low 30’s just in time for the morning commute on Wednesday.

Wednesday should be a much cooler day by contrast as northwesterly flow behind the cold front ushers in fresh, Canadian air. A vigorous little area of mid level energy will be opening up from its time as a closed upper level low and will begin to quickly head east across the southern half of the country. This strong west to east flow across the nation will ensure that this area of energy becomes sheared out, with all of its rain staying well to the south of the Northeast. In fact, conditions will remain very dry across the Northeast, and there may be a couple of strong post-frontal wind gusts in the early part of the day. The renewed northwesterly flow, clear skies, and dry air should allow temperatures to stay relatively cool across the majority of the region, with highs in the middle to upper 30’s likely. Locations to the north and west may in fact see highs stuck in the lower to middle 30’s as some deeper Canadian air becomes trapped. These calm and cooler conditions will last into the evening hours on Wednesday before another weak cold front begins to move into the east. This front will be severely moisture starved, but will be capable of reinforcing the cold air already in place. With dry low/mid levels, cold air aloft, and light northerly winds, conditions should be supportive of some radiational cooling to take place. This should bump lows down into the middle to upper 20’s , with upper teens to middle 20’s likely off to the north and west.

Thursday morning will see the reinforcement of colder air over the Northeast, with the morning commute likely starting off quite crisp in the 20’s. A mid-level ridge will begin to build over the Ohio Valley in response to an area of Pacific energy digging into the west coast, but conditions over much of the Northeast will likely remain quite cool and clear as high pressure begins to build and expand over southeastern Canada. This should lead to another pleasant day with highs mainly in the upper 30’s to lower 40’s. Mid level flow will begin to shift to the southwest during the evenings hours on Thursday, which will begin to set the stage for another above-normal period of temperatures.

Loop of this evenings NAM model showing a brief period of cooler temperatures over the Northeast, followed by another warm surge by the end of the week.

Uncertainties Arise for Christmas Weekend

If you’re on social media and follow some of the various weather pages out there, you’ve likely seen the numerous maps and forecasts that show a massive area of Arctic air dropping into the west, while a large area of warmth rises over the east. While the exact details of how this weekend will play out are still a couple days from being hashed out, what we know about this setup is that there will be a substantial amount of Pacific energy dumping into the west by Friday. All this energy injected into the flow will begin to carve out a large trough over the western/central US, while the downstream response will likely result in a ridge forming over or just off the southeast coast. This pattern will be supportive of increased heavy precipitation over the Southeastern to Northeast US as the gradient between the cooler airmass over the central US clashes with the relatively warmer airamss over the east on Friday and Saturday. Shortly after, the models begin to diverge on just how much the trough and accompanying cold is able to move east by Sunday/Monday. The other major question here will be where exactly does the ridge over the southeast set up? A ridge over the southeast will almost certainly guarantee an above-normal Christmas day, while a ridge off the eastern seaboard may allow cold to creep into the picture just in time for Christmas. These details will take a couple more days to flesh out, and we will certainly be monitoring them over the course of the week.

This afternoons European Ensembles showing a rather significant amount of spread in the overall 500mb pattern for Christmas day, showing nothing is set in stone yet.

Stay tuned for further public updates! . Also join us at 33andrain forums for free discussion on everything weather-related.

Have a great night!

Mild and Dry Conditions Settle In, Signs of Change?

November 27, 2017/1 Comment/by Steven Copertino

Good Evening!

Today was a nice start to the work week as an area of high pressure moved over the East, which prompted an increase in temperatures and calmer conditions over the entire Northeast. Much of the day was characterized by a mix of sun and clouds as a cool mid level airmass from Canada moved south on the heels of a weak cold front. This cold front is relatively weak and does not have any substantial moisture associated with it, thus any showers or flurries were extremely isolated in nature and did not last long. Otherwise, most of the New York metro area saw highs in the upper 40’s to lower 50’s, with lower to middle 40’s further north and west. These temperatures are just around normal for this time of year, with only a couple stations going slightly above normal.

The rest of the evening should remain quiet and cool as the high pressure remains firmly planted in place over the Tennessee valley. With the recent cold front passage, dewpoints have lowered and winds have also dropped a bit. This will set the stage for some stout radiational cooling to take place across the Northeast despite some warmer air in the mid levels trying to creep in overnight. Lows should be able to drop into the middle 30’s for the immediate New York City area, with upper 20’s and lower 30’s likely for the suburbs. Locations well to the north and west may see more efficient radiational cooling this evening, and could even drop into the upper teens and lower 20’s.

Real Time Mesoanalysis Temperatures for the Northeast this evening showing an impressive gradient over the area. Notice readings in the middle teens over northern New England , with 50’s closer to the coast! (Courtesy of Simuawips.com)

Tuesday Into Thursday

Tuesday will likely start of with clear skies and cool conditions area-wide, as the area of high pressure located to our south begins to move over and east of the region by the morning commute. The center of the high pressure will likely be situated just off the coast through the morning and into the afternoon hours, and this should introduce more southwesterly winds in the mid levels of the atmosphere. These southwesterly winds should be capable of ushering a warmer airmass over the region, but the degree of this warmth should be muted somewhat by return flow from the Atlantic. This should keep highs in the area mild, but not too warm. Expect temperatures to get into the lower to middle 50’s during the afternoon hours tomorrow, with some locations having a shot at middle to upper 50’s near the coast. Calm conditions should last throughout the day, with warm air advection increasing once again by the time we head into the overnight hours. With the high pressure located offshore and warmer mid level temperatures working their way in, expect lows to be warmer tomorrow night with readings likely in the upper 30’s to lower 40’s, with some locations north and west staying in the 30’s.

Wednesday looks to be a full-on above normal day as the strong southwesterly flow begins to surge northwards during the day. Mid level dry air will be present tomorrow afternoon, and this will help warmer mid level temperatures to reach the surface and cause highs to rise into the middle to upper 50 across much of the New York Metro area, with some locations closer to the coast possibly getting to the 60 degree mark by the afternoon hours. As the day goes on, another weak cold front looks to push through the area. This front should be another moisture starved front, so any showers will be isolated and weak in nature.

By Thursday, we see the pattern across the United States become rather progressive and zonal in nature, meaning that the jet stream will be flat and west to east oriented. This will allow the high pressure behind the cold front to quickly move offshore, providing more return flow from the south once again. This time there should be more Gulf moisture involved with this flow, and this should only increase as another disturbance works its way east across the country. The system should be located in southern Canada by Thursday evening, with a cold front extending down into Pennsylvania. Light to moderate showers will likely extend along this front as it moves through the Northeast, with only minor rain accumulations expected.

The rain should quickly head offshore by the early morning hours of Friday, with improving conditions thereafter.

This afternoons ECMWF ensembles showing the rather flat nature to the pattern over the US, leading to rather calm and mild conditions.

Major Long Range Questions

Some of you have likely heard the buzz on social media that this boring weather pattern is likely to change and snap into a colder and potentially stormy one. While any potential pattern changes are a long ways out, we do have to mention that there is a growing consensus among the more reliable long range computer models that pattern across the Globe will shift to one that is much more supportive of at least a brief period of below normal temperatures across much of the country. This period looks to start during the second week of December and could possibly continue into the rest of the month depending on how other larger factors behave. At this time, we think that the models do have a relatively good grasp on the pattern at hand, and other outside factors like the MJO, and Stratosphere support the ideas being put forth by these models. We will continue to monitor this potential change as it moves up in time and will provide updates on any developments when they come up!

This afternoons ECMWF ensembles showing a major change to a much colder pattern with the potential for some winter weather threat to take shape by the middle of the month.

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Have a great night!

Steve Copertino

Warmer Conditions Arrive Tuesday, How Does Thanksgiving Day Look?

November 20, 2017/1 Comment/by Steven Copertino

Good Evening!

Today was another cold and breezy day across much of the Northeast, as the strong low pressure area that affected our region earlier this weekend continues to move off to the east and over the martime regions of Canada. The interaction between this low pressure system and a high pressure system to our south has created a steep pressure gradient which has been the source for these gusty conditions over the past day or so. Strong northwesterly flow in the mid levels of the atmosphere has also contributed to colder air aloft blowing over the Great Lakes, which has produced some lake effect snow showers that have mainly been focused across far northern New York state and Pennsylvania. However, some of these “lake-effect” snow showers moved over portions of the New York metro area, producing some of the first flakes of the year for most locations. While surface temperatures over the area were not at or below freezing, cold mid level temperatures allowed precipitation to remain mostly frozen, with ice pellets also being recorded in northern New Jersey. While these snow showers did catch some people by surprise, they weren’t anything more than “mood flakes”, or just some light flurries that do not stick to any surfaces-allowing travel to proceed as usual.

The rest of our Monday was rather chilly, with a mix of clouds and sun keeping our temperatures limited to the lower to middle 40’s across much of the area. Winds have really begun to weaken over the entire northeast as the pressure gradient between the two surface systems really diminishes with time as the systems grow further apart. As we head into tonight, the area of high pressure located over eastern Carolina will remain in control of our weather, bringing lighter winds out of the southwest and clearer skies. Lows tonight will likely have a range to them, with the far northwestern locations likely dropping below freezing and into the upper 20s, while locations near New York City willy likely get down into the lower to middle 30’s.

RTMA Analysis of the current temepratures over the Northeast, with surface observations finally showing a change from the gusty NW winds we have been seeing for the past day or so (Credit: Simuawips)

RTMA Analysis of the current temperatures over the Northeast, with surface observations finally showing a change from the gusty NW winds we have been seeing for the past day or so (Credit: Simuawips)

Tuesday morning will likely start off rather cool, but mostly sunny as the area of high pressure that we’ve been following moves offshore and into the western Atlantic by the morning commute. This will mean that as the day goes on, warmer mid level air from the southwest will move into the Northeast, allowing temperatures to moderate quite a bit when compared to today. Additionally, a vigorous area of mid level energy will be diving down from Canada by the afternoon hours of tomorrow, which will be accompanied by a moisture-starved area of low pressure at the surface. As this system heads east with time, it will increase the strength of the southwesterly flow, leading to an increase in winds across much of the Mid Atlantic and Northeast by the late afternoon hours. The relatively clear and conditions and warmer mid level temperatures from the south will allow highs to climb into the lower to middle 50’s tomorrow, with the warmest readings likely just inland from the coast.

As we progress into Tuesday evening, we should see moisture being to develop in the southern states as another messy batch of disorganized mid level energy moves in behind the first system in the Great Lakes. As this takes place, a cold front associated with the system in the Great Lakes region will continue to move east and into the Northeast by the end of the day. This front will remain relatively dry as it moves over the Northeast due to the system to the south and west of it stealing most of the moisture deep in the Gulf of Mexico.

Things may become a little more interesting during the very early morning hours on Wednesday when the upper level jet streak from the Great Lakes system begins to interact with the energy over the south and moisture begins to flow more northerly. The question with this time period is just how much will the precip expand and move west as the new low develops to the south? Today’s model guidance diverges a bit on the extent of the precipitation shield on Wednesday, but as of right now it looks like the immediate coasts of NJ and LI could see some steadier rain, with showers possible further North and West. Since these two systems will remain mostly independent from one another, this is very unlikely to be a big deal, but even slightly more interaction with these systems and a healthier upper level jet streak could promote the development of precipitation further inland, and this will have to be monitored. Otherwise, highs on Wednesday will likely remain in the lower to middle 50’s despite the incoming cold front. The front should clear the area by late Wednesday afternoon, with any residual shower activity quickly leaving the scene as well. Wednesday evening should be a cold one, with lows likely dropping into the middle to upper 20, with warmer readings near the coast.

18z NAM 500mb loop showing the initial energy with Wednesdays cold front quickly moving east while more energy drops down into the Gulf of Mexico and becomes “stuck”

Thanksgiving Day and Beyond

A colder airmass from Canada will be in place over the Northeast behind Wednesdays cold front, which should cause the day to start off rather cold in the upper 20’s and lower 30’s. Left over dry air in the wake of the cold front should allow mostly sunny conditions to take over on Thanksgiving day. A colder airmass, clear skies, and calm winds should only allow temperatures to rise into the upper 30’s and lower 40’s across much of the New York metro area, with warmer readings located over portions of Long Island. From a historical standpoint, this Thanksgiving should be a rather cold one, as highs will likely come in 10-15 degrees below-normal! Conditions during the remainder of the day should be quite pleasant as a weak area of high pressure moves in from the west. This area of high pressure will cause winds to shift back to a more southeasterly component by the evening, which will signal the arrival of another warmer mid level airmass. Lows during the evening hours should drop into the middle to upper 20’s, with some warmer temperatures likely across locations closer to the coast.

Calm and cool conditions are expected through Saturday afternoon, before another strong area of low pressure over southern Canada drags a cold front through the region early on Sunday. As of right now, this cold front also looks to be moisture-starved, but the big deal with this system will be the temperatures, not the precipitation. With a large area of high pressure over the western Unites States, this cold front will have the potential to dump some impressive cold over the east, which could drop the area down into the lower 30’s and upper 20’s for highs. Though its just under a week out right now, this cold shot does look to be on the quick-hitting side, as the upper level trough associated with the cold air will quickly move out by the middle of next week.

This afternoons ECMWF model showing the potential for a potent, but quick-hitting cold shot by the end of next weekend.

Have a great night!

Steve Copertino

Record Cold Quickly Departs, Potentially Stormy Pattern Setting Up In the Long Range?

November 10, 2017/by Steven Copertino

Good Afternoon!

The Arctic front that we have been talking about for around a week now has finally cleared the entire Northeast, leaving well-below normal temperatures in its wake. Earlier this morning, the front blasted through the region with some rain and snow showers, some of which were heavy up towards the central locations of upstate New York. These showers were quickly undercut by much more dry and dense Arctic air from Canada and promptly dissipated. Todays high temperatures were actually set in the early morning hours just ahead of then cold front, with most locations peaking in the lower to middle 40’s. After the front blasted through, temperatures promptly dropped a good ten to fifteen degrees across the entire area, with temperatures in the upper 20’s to lower 30’s being reported from most stations. Temperatures just behind the front change quite a bit with height, which has allowed stronger low level winds to mix down to the surface and cause conditions to become quite blustery, with gusts in the 25-35 mph range this afternoon. This has allowed for wind chills in the metro area to fall into the lower 20’s and teens. As mentioned earlier. the Arctic air has brought in a significantly drier airmass, so any shower activity into this evening will be confined to locations near the Great lakes, where the temperature differential will support the growth of some gusty snow squalls.

The area are of low pressure that brought the Arctic front through the area begins to occlude and weaken while pulling east, the pressure gradient between the Arctic high and the low pressure will decrease significantly, leading to winds steadily decreasing by sunset. As the winds calm and high pressure takes over, we should have near-ideal conditions for steep radiational cooling to take place across the entire Northeast. This will mean that lows will quickly drop off into the teens and even single digits for locations off to the north and west. These temperatures will likely break record lows for many stations across the Northeast, with some readings likely being 15-30 degrees below-normal for this time of year! Any locations that have not yet had their first freeze this Fall will certainly experience a hard freeze this evening, with any vulnerable plants quickly succumbing to the below-freezing temperatures.

RTMA temperatures showing the near-record cold readings across the area in conjunction with the gusty winds behind the Arctic front

Saturday morning should start off quite cold and clear with the area of high pressure developing right over the Northeast. Winds will likely be much calmer than they are this afternoon, so we may start off a little more pleasant than originally thought. Mid level temperatures will begin to increase a bit, but still be cold enough that much of the Northeast experiences somewhat below normal temperatures tomorrow with highs likely staying in the middle to upper 30’s, with some locations hitting the 40-degree mark. The day as a whole should be relatively calm as a more west-east oriented jet stream sets up aloft, which should shift winds to the east/northeast as the day goes on. Later in the evening, the area of high pressure should be located just offshore of the Mid Atlantic coast, which will be the area more of an onshore flow. This could cause some low level moisture to work into coastal sections of NJ, CT, and NY, but the very low dewpoints in place may keep much of this marine airmass at bay. Regardless, expect another cold night with lows likely dropping back down into the lower 30’s and upper 20’s farther north and west, where radiational cooling will be prevalent. As a side note, the somewhat increased moisture and calm winds may allow for patchy frost to develop, especially across the interior.

High pressure will likely still remain just offshore by Sunday morning, with clear skies and cool temperatures likely. As we head into the afternoon hours of Sunday, a weak disturbance will be caught in the very quick west to east oriented jet stream that we talked about. Without any kind of blocking to slow this system down and let it organize, it will likely remain sheared out and weak as it nears the area later in the day on Sunday and Sunday night. This disturbance will likely cause a slight increase in temperatures during the day Sunday, with hgihs likely hitting the lower to middle 40’s. An increase in clouds is also expected as the day goes on Sunday afternoon, with some light showers possible across the southern locations of the Northeast and Mid Atlantic states.

This afternoons ECMWF model showing the very quick west to east positioned jet stream. This pattern has no blocking to slow down any mid level disturbances to allow them to organize and strengthen.

As we head into the beginning of next week, the west to east jet stream will likely stick around, allowing for a large area of mid level ridging to develop across the Central part of the United States and into southern Canada. This should bring temperatures up a bit, with highs likely rebounding back into the upper 40’s and 50’s through Wednesday or so. This area of riding and quick mid to upper level flow will also prevent any major rain events in the medium range, so expect at least the first half of next week to remain calm and dry.

Long Range

As we get deeper into next week, we may see a pattern shift towards more blocking near Greenland, which would not only slow down the flow across the country, but also allow for below-normal temperatures to start to creep back into the country. The models and their ensembles have been keying in on this type of blocking pattern to set up for about a week now, and things may kick off as early as next weekend. In addition to the blocking near Greendland, some higher heights over the North Pole may also help to drain cold air southward by next weekend and beyond, which could allow for cooler temperatures and even a few wintry precipitation events to exist near the Thanksgiving time period over the Northeast. While this has been advertised for a while on a variety of the models, this is still over a week out and things could very quickly change due to the chaotic nature of the jet stream over the Pacific. Regardless, we expect an increased chance for below average temperatures and above-normal precipitation over the east starting the end of next week and heading into Thanksgiving. This is a developing pattern, so make sure to check back for further updates!

Long Range ECMWF Ensembles centered on next weekend illustrating an active pattern with potential cold air intrusion.

Have a great night!

Steve Copertino

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