Conditions have improved substantially across much of the Northeast this Friday afternoon as a rather weak cold front cleared out any remaining cloudy & unsettled conditions.
Good evening!
After a dreary and foggy weekend, we started the December work week off with much improved conditions across much of the Northeast. A weak cold front associated with an area of low pressure over eastern Canada moved through the Northeast and Mid Atlantic states early this morning, which effectively cleared out any lingering moisture from this weekend. Despite having the weak cold front move through this morning, the cold air behind the front was lagging behind just enough to allow for relatively mild conditions along the I-95 corridor. With mostly sunny skies and a above-normal mid level temperatures, we saw highs reaching into the lower to middle 50’s across much the region, with locations well north and west of the city seeing highs in the middle 40’s. These temperatures were above-normal for this time of year, but this may be the last day with above-normal temperatures for some time.
A weak and strung-out area of upper level energy is currently moving through the Northeast and Mid Atlantic this evening, which has brought an increase in clouds, with some rain and snow showers being reported over portions of western and northern NY state. While increasing clouds are likely for the remainder of this evening and into the overnight hours, any chance of precip will remain well to our northwest. The increasing clouds will likely quash any chance we have at getting decent radiational cooling during the overnight hours, so expect overnight lows to stay generally in the middle to lower 30’s for much of our area. Lows in the upper to middle 20’s will be possible for locations well to the north and west of the NYC area.
Radar, WV satellite, and surface temperatures as of 5pm over the Northeast.
Tuesday through Thursday
The weak area of mid to upper level energy moving over the area will likely begin to kick out of the Northeast by 8am tomorrow, which should pave the way for a clear, but cold start to Tuesday morning with temps likely in the lower 30’s for much of the New York metro area. With northwesterly flow in place, colder air will move down from Canada which will only allow for a rather limited increase in temperatures over the Northeast. Highs will likely only reach the middle 30’s during the afternoon hours Tuesday, which will be slightly below-normal for early December. Clear conditions will continue throughout the evening and overnight hours, with lows reaching down below freezing all the way to the coast for the entire Northeast. While the city itself and locations closer to the coast should get down into the upper 20’s, lower to middle 20’s will be likely for portions of northeast NJ and southern NY.
Wednesday should start off as yet another clear but cold day with highs staying in the middle to upper 30’s. Another elongated and disorganized upper level system will approach our area during the afternoon hours from the west, which may bring an increase in cloudiness, especially over portions of the Mid Atlantic and southern New Jersey. As this disorganized upper level system approaches the coast later in the day on Wednesday, it may have a chance to strengthen just a bit while its centered over the Delmarva peninsula. While most of the model guidance has any organization of this feature occurring well offshore Wednesday evening, there is a chance that this system is able to spawn an area of light snow showers over parts of the Mid-Atlantic and portions of southern New Jersey. While there is a relatively low chance of this happening, the mid to upper level setup shown on the reliable model guidance is one that has been known to cause whats is known as an “inverted trough”. These are incredibly difficult to predict even just a day or two out, but we will continue to monitor this potential in subsequent updates.
By Thursday, we should see another reinforcement of slightly below-normal temperatures as an incoming shortwave trough moves to our north over southern Canada. Available moisture looks to be very limited with this shortwave, so we’ll likely stay dry and clear for the vast majority of the day on Thursday. However as we head into the evening and overnight hours, we may see an increase in clouds and possibly some snow showers to the north and west of the city as upper level energy from the incoming trough begins to work its way in.
This afternoons ECMWF model showing increased moisture and lift near the NJ coast later in the afternoon on Wednesday.
Watching for a Potential Storm along The East Coast Later This Weekend
Once we get to Friday, our attention will begin to turn our West where an upper level low will be moving in over southern California. This system has been on our radar for quite a few days now as almost all of the reliable model guidance has shown this system becoming an impactful snowstorm for portions of the South and East later this weekend.
While model guidance has been highlighting the potential for a snowstorm over various points during the past couple of days, the delicate nature of the upcoming pattern has really allowed for significant run-to-run changes of where exactly along the South and East has the best chance of seeing significant snow. Despite this afternoons operational models and ensembles showing the bulk of this potential system impacting locations south of the I-95 corridor and into portions KY, NC, SC, VA, WV, we did see some changes from previous runs that may support this threat inching to the north to some degree over the next couple of days. The final outcome will ultimately rely on exactly where and when key pieces of energy will drop into the CONUS and (possibly) interact with the main energy over the South in addition to the positioning of a crucial low pressure system near Greenland (the “50/50 low”).
As of right now the overall threat for an impactful snowstorm for the NYC area is low. It is important to note that we’re also six days out and confidence is also very low at this time. The low confidence in this forecast is not only due to model inconsistency but also due to the fact that we have seen this kind of scenario many times in the past where a system is forecast to stay well to south around a week out, only to trend more organized and further north as we draw closer. We will be keeping a very close eye on this system during the remainder of this week so make sure to check back for updates!
12z ECMWF showing the potential winter storm organizing over the Southeast on Sunday morning
Have a great night!
Steve Copertino
Good Evening!
Today we saw the development of numerous showers and thunderstorms across the southern half of the metro area, with some of the storms being on the strong to severe side. These storms were fueled by the remnant frontal boundary that sank southward to portions of southern NJ earlier this morning. Deep tropical moisture was able to remain anchored within this boundary, and as daytime heating took over, instability was able to increase quite markedly over portions of southern Pennsylvania and New Jersey. As the last in the long series of mid level disturbances embedded in the west to east flow approached this very moist and unstable airmass, thunderstorms rapidly developed-bringing large hail, damaging winds, and very heavy rainfall. Some localized reports of wind damage were reported in Pennsylvania, Delaware, and portions of New Jersey, but overall it wasn’t a huge day for severe weather.
The showers and thunderstorms gradually moved into a more stable marine airmass near the coast, which caused them to weaken below severe thresholds and limited impacts to mainly heavy rain and frequent lightning. These showers will continue to head off the coast later this evening, giving way to more mild and cloudy conditions. As we head deeper into the evening, a shortwave trough and the accompanying energy will begin to push into the region, and due to the fact that there is still some residual moisture/instability, we cannot rule out a couple showers and even a late thunderstorm developing. Any storms that form would almost certainly remain below severe limits, with the main threats just being heavy rain and gusty winds.
Lows this evening will remain right around what the current temperatures are due to thick cloud cover and residual low level moisture trapped due to a temperature inversion a few thousand feet up in the atmosphere. Some patchy fog may try to develop this evening for some locations, but overall development should not be all that widespread.
This evenings latest regional radar mosaic, surface observations, and high resolution visible satellite imagery, showing the bulk of the showers and thunderstorms moving off the Mid Atlantic coast (Courtesy of Simuawips)
This Weekend
Improving conditions are expected starting on Saturday as the upper level trough that has been providing the area with numerous rain chances finally swings through early in the morning hours. This will cause any residual fog to quickly dissipate as the low level moisture is quickly swept out of the region. Clouds should also begin to decrease in earnest as an area of high pressure begins to gradually build in from the west, centered over the Ohio Valley. Conditions tomorrow should feel much improved from the past few days, with dewpoints dropping quite considerably, giving way to a much more comfortable airmass. With increasing sunshine, a warm mid level airmass, and low moisture content in the atmosphere, temperatures should be able to rise to around seasonable levels-with lower to middle 80’s likely areawide.
High pressure will continue to build over the area as we head into the evening hours, allowing for even clearer conditions to develop just in time for sunset. The high pressure will also allow winds to become quite calm by the early evening hours, and with calm winds, low dewpoints, and clear skies, its looking quite likely that some radiational cooling will take place tomorrow evening, which should allow temperatures to drop into the middle 60’s across the entire area, which is just around normal for this time of year.
Sunday will likely be repeat of Saturday, with clear skies, low dewpoints, and light winds being the theme once again. The mid level airmass will be a little warmer on Sunday due to winds shifting to the west/southwest, so we expect highs on Sunday to be a little warmer, with temps reaching into the upper 80’s and lower 90’s across the region. Sunday evening will also be near-perfect, with clear skies and light winds, which will allow for cooler temperatures to return. Overall, it’s looking likely that this weekend will be quite beautiful and should be great for any outdoor activities as we undergo a temporary airmass change!
This afternoons high resolution North American Model, showing light northwesterly winds, warm temperatures, and an overall pleasant airmass over the area, which should make for a beautiful day!
Next Week
The next threat of rain looks to come early in the week next week, as an upper level trough approaches from the west and drags another humid airmass from the south. This will greatly increase instability over our area, which will set the stage for afternoon thunderstorms, capable of heavy rain and gusty winds. This afternoons model guidance disagrees with regards to the handling of this piece of energy as it heads towards our area, but it seems possible that the threat of showers and thunderstorms stays around until at least Tuesday. Temperatures for the beginning half of the week should be around-normal, but this will be highly dependent on the amount of cloud cover and rainfall that we may receive.
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Have a great evening!
Steve Copertino
Good Evening!
As was mentioned all the way back on Monday, today has featured quite an extensive development of showers and thunderstorms over much of the Northeast. These storms were fueled mainly by the built up heat and humidity which created modest levels of instability to build during the afternoon hours today. Additionally, the storms were aided by strong vertical wind shear in the atmosphere, which helped some storms to produce damaging wind gusts, and even some rotation which prompted at least three tornado warnings. Radar images also indicate that there is a rather high amount of moisture in these showers and thunderstorms, which can be attributed to the impressive resurgence of tropical moisture over the area that occurred yesterday when the high pressure that was over our area on Tuesday began to back away to our east, causing winds to surge from the south. As opposed to most days this year that featured decent convective development, these storms were generated by a strong mid level short wave at around 700mb, in contrast to the traditional cold front.
While the vast majority of any actual severe weather was confined to areas well north and west of our area, some locations in southern New York and portions of Connecticut did see some wind damage, frequent lightning, and very heavy rainfall. As the evening rolls on and the sun gradually fades away, the heat and instability that we had will begin to drop off quite significantly, and any remaining strong storms will weaken below severe limits, while heading generally eastward. Some storms in southern Connecticut may still be capable of producing damaging winds as they feed off residual instability and favorable parameter space that had not been touched by previous cells.
The rest of the evening should feature improving conditions, with partly cloudy skies likely for most of the area. Due to the lack of a coherent frontal system, the humid airmass that spawned these storms will linger around and make for another muggy night, with lows likely staying in the lower 70’s and into the middle 60’s.
Animated loop of the evenings latest regional radar mosaic, regional surface observations, and high resolution visible satellite imagery (Courtesy of College of DuPage)
Saturday should start off quite nice, with a mix of sunshine and scattered clouds to start off the day. Although, with warm mid level temperatures, winds from the south, and a humid airmass in place, the conditions will be ripe for temperatures to quickly rise into the upper 80’s and even pass the 90 degree mark in locations like NE NJ and SNY. As we go through the late morning and early afternoon hours, a shortwave trough and associated cold front will be working its way east towards the area. This will set the stage once again for instability to begin to pool up ahead of the frontal system, which will act as a forcing mechanism for thunderstorm development later into the afternoon. Like today’s threat, the best wind shear and parameters are likely to stay to the North and West of the immediate New York City area, but more isolated strong storms will be possible towards the area as the day progresses on. The main threats tomorrow appear to be gusty winds, frequent lightning, and very heavy rainfall. Due to this risk, the Storm Prediction Center in Norman, Oklahoma has placed locations to our north and west in a Slight Risk for severe thunderstorms.
Showers and storms may continue to longer through the late afternoon and evenings hours as the lift associated with the cold front will trigger additional shower and possible thunderstorm development if there is any left over instability to work with. The main threat from these storms later in the day appear to be confined to gusty winds and heavy rain. Lows tomorrow evening will remain quite warm, with upper 60’s and lower 70’s likely.
This evenings latest Rapid Precision Model, showing scattered showers and thunderstorms developing mainly to the north and west of the city tomorrow afternoon/evening (Courtesy to WSI)
Sunday should feature a less humid start to the day as the cold front moves through during the early morning hours and mixes out the tropical airmass that has been lingering over the past few days. As dry air behind the front moves on in, mostly sunny conditions are likely to hold up for the rest of the day on Sunday. With mostly sunny skies and a much less humid airmass over the region, high temperatures will gradually build up towards the upper 80’s-with some locations possibly reaching that 90 degree mark once again!
Monday will likely features much of the same conditions as Sunday, with low humidity, clear skies, and an overall low threat for afternoon storms. Highs should also be quite similar, with temperatures likely peaking around the middle to upper 80’s. Overall, both days will be very pleasant and a great lead up to Independence Day.
Tuesday (Fourth of July) – the day that everyone has been wondering about for over a week now actually looks to have quite an excellent setup in place during the day! A stationary front-the remnants of the cold front that passed on Sunday-will be located to our south, which will leave a large area of high pressure in control for the day, providing light winds, low humidity, and clear skies! Highs should continue their warm, but not outrageously hot trend, with temperatures likely reaching the middle 80’s over much of the area! In summary, it should be an excellent outdoors day, with near perfect conditions for firework-viewing, with only high cirrus clouds likely during the day!
We hope everyone has an excellent Holiday Weekend!
A quick summary of the conditions for the Fourth of July-orange colors denote areas of higher than normal pressure
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Have a great evening!
Steve Copertino
