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Steven Copertino

Public Analysis: Stormy Start to the Holiday Weekend, Possible Break for the Fourth of July?

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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)

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

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

Steven Copertino

Public Analysis: Above Normal Temperatures and Thunderstorm Threats Return for the Holiday Weekend

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Good Evening! 

Today was yet another beautiful day across the Northeast due to a weak area of high pressure to our south bringing in low humidity, mild temperatures, and light southerly winds for the entire region. Highs today were generally limited to the low to upper 70’s across our area due to cooler temperatures aloft associated with a deep area of mid level toughing located just to our north. As we get deeper into the evening hours across the area, high altitude cirrus clouds should begin to move in from the west, signaling the beginning of another pattern change. With clear skies, low dewpoints, and light winds from the west, conditions will be near-perfect for radiational cooling to take place, so expect low tonight to fall into the middle 50’s to low 60’s across the area, with some locations well-removed from the coast possibly sinking into the low 50’s during the early morning hours.

This afternoon/evenings latest high-resolution visible satellite imagery, surface observations, and regional radar mosaic, showing relatively calm and mild conditions for your Wednesday evening.

Thursday is looking more like a rather large step in the direction of above-average temperatures for the entire region as mid level ridging to our south and east begins to build northward over our area, especially during the afternoon hours. The same high pressure that provided the area with extremely comfortable weather over the past few days will begin to turn on us by directing winds from the south and southeast. This will lead to much higher dewpoints overtaking the tri-state area, which will lead to a muggier feel for tomorrow. In addition to the increasing humidity, rising heights will also allow mid level temperatures to rise significantly. The combination of warm mid level temperatures, a muggier airmass, and southerly winds will lead to high temperatures likely reaching all the way into the middle to upper 80’s tomorrow with some potions of Notheastern New Jersey and southern New York state likely seeing temps pass that 90-degree mark.

In lieu of all this warmer weather, a pretty tight pressure gradient will set up shop over the area as the aforementioned high pressure system begins to move off of the Mid-Atlantic Coast and an area of low pressure in the Great Lakes Region continues to gradually move north and east. This will likely increase winds to around 15-25 miles per hour, with gusts likely reaching into the 30-40 mph range during the day. Some isolated wind gusts will be capable of taking small twigs off of trees and blowing around lawn furniture. Additionally, this strong southerly flow may be able to limit just how warm south-facing shores of Long Island and Connecticut can get tomorrow if the winds kick in during the early afternoon hours as opposed to later in the day.

Later tomorrow evening, increasing mid level moisture as well as the enhanced southerly flow should create some increased cloudiness, with any chance at some showers limited to the far northern regions due to a total lack of forcing for any kind of thunderstorm development. Tomorrow evening will be quite warmer than Wednesday evening as temperatures are only likely into the middle to upper 60’s, with some 70 degree low temperatures possible in the more insulated locations.

This evenings North American Model showing relatively high wind gusts tomorrow afternoon and into the evening hours due to an increasing pressure gradient overhead. Please refer to the NWS for any potential Wind Advisory's tomorrow

This evenings North American Model showing relatively high wind gusts tomorrow afternoon and into the evening hours due to an increasing pressure gradient overhead. Please refer to the NWS for any potential Wind Advisory’s tomorrow

Friday looks to be yet another warm and borderline hot day as mid level ridging continues to build over the area. With the high pressure firmly off of the Mid Atlantic coast by this time, winds from the south should continue to usher in very warm and moist air in the lower levels of the atmosphere that will push a frontal system well to our north. With this frontal system located to our north, any potential pieces of energy that will be capable of triggering any shower and thunderstorms will also remain north of our area during the day. Regardless, Friday will likely be another increasingly muggy and warm day with mostly sunny skies leading to highs in the upper 80’s, and possibly even 90 once again for portions of New Jersey and southern New York. Friday evening looks to be a warm, but bearable one as humidity decreases ever so slightly, but temperatures will likely remain in the low to middle 70’s for lows.

As of now, it appears that the more unstable day appears to be on Saturday as a frontal system associated with some energy from an approaching mid level trough over the Great Lakes region heads eastward. Saturday will also likely feature rich tropical moisture, increasing instability, and some improved wind fields that will be necessary for thunderstorm development towards the afternoon hours. While the thunderstorm threat will definitely need to be revisited on Friday, there does seem to be support from the NAM, GFS, and ECMWF for this scenario. Anyway, Saturday will likely feature mostly sunny condition’s, with increasing clouds towards the afternoon hours once again. Highs will likely be able to eclipse Fridays highs, with 80’s and lower 90’s looking possible.

Sunday also looks to be rather unsettled with increasing cloudiness and an enhanced threat of showers and thunderstorms as yet another lobe of energy rounds the base of the trough located in southern Canada. This lobe of energy will send off some energy through the Ohio Valley, which will act as a trigger and potential development zone for precipitation during most of the day. Due to the enhanced clouds, Sunday will likely be only slightly cooler than the previous two days, with highs likely reaching into the mid 80’s.

This afternoons European model showing yet another possible Canadian disturbance dropping southward and potentially increasing the threat for showers and thunderstorms for the later half of the holiday weekend (Courtesy of AccuweatherPro)

This afternoons European model showing yet another possible Canadian disturbance dropping southward and potentially increasing the threat for showers and thunderstorms for the later half of the holiday weekend (Courtesy of AccuweatherPro)

Drier conditions appear possible for Monday as a subtle mid level ridge builds in behind the weekend system, but this afternoons model guidance has been hinting at the potential for another system to work its way in and potentially provide another chance for some showers and thunderstorms on the 4th of July. We will have a full update on the Holiday Weekend and beyond on Friday afternoon!

For more information and posts like this one, make sure you sign up for Premium Forecasts — where multiple detailed articles, videos, and interactives are posted each day. Also, come interact with our staff and many other weather enthusiasts at 33andrain.com!

Have a great evening!

Steve Copertino

Steven Copertino

Public Analysis: More Dreary Weather Likely Thursday, Improvements This Weekend?

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Good Evening!

Most of the area saw a rather damp and dreary start to the work week today as areas of moderate to heavy rainfall moved over portions of the Mid-Atlantic and Northeast. This is due in part to a large upper level system over the central part of the country that will be gradually strengthening and progressing eastward over the rest of the week. This should allow for more damp and unsettled conditions down the line, especially on Thursday and Friday. A break from this pattern may be possible by the time we reach the Memorial Day Weekend, but this will all depend on the evolution of the previous systems this week.

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Today Into Tonight

Most of the tri-state area and portions of southern Pennsylvania saw a rather damp and cool day today with highs only reaching into the mid 50’s to lower 60’s. Though much of the area saw rain today, the heaviest bulk of the rain was concentrated to portions of central and southern New Jersey, where localized amounts over 2″ were seen. Further north totals were more in the trace to half-an-inch mark, especially in northwestern New Jersey, southern New York, as well as Connecticut. The rain has begun to pull away from the area, with only coastal sections of New Jersey and Long Island still stuck under steadier showers. Drizzle is likely to last for some locations until after dark, but overall conditions should begin to improve despite mostly cloudy skies. Some clearing may take place towards the late evening hours, or early tomorrow morning, but the cloud cover should be able to hold overnight lows into the lower to middle 50’s for much of the area, including the coast.

A cold front will pass through the area later this evening and usher in a much drier, but also temporary air-mass from the north and west that will work to end any lingering showers that may exist over the area. An area of weak high pressure just north of the region in addition to the introduction of drier air will decrease cloud cover tomorrow afternoon. A weak wave of low pressure will develop along the cold front that passed over our area and this low pressure will begin to move northeastward by later tomorrow afternoon.

Most of this afternoons model guidance keeps this small area of low pressure to the south and east of the area, but there is the possibility that at the very least this low will lead to an increase in cloudiness, but some rain showers are possible along the coastal sections of New Jersey and Long Island. Highs tomorrow will be just slightly warmer than today as highs are able to reach into the upper 60’s and lower 70’s across the area, and some locations may see slightly warmer highs if they are able to experience prolonged periods of clearing. These highs will be slightly below-normal over much of the region, with departures around 5 degrees below-average. With increased cloudiness and windier conditions possible, lows tomorrow evening will likely remain in the middle to upper 50’s, with the possibility of isolated locations holding in the low 60’s.

Latest regional radar data, stations plots, visible satellite imagery , and temperature plots as of this evening showing cloudy, cool, and damp conditions persisting over portions of the area (Courtesy of College of DuPage)

Latest regional radar data, stations plots, visible satellite imagery , and temperature plots as of this evening showing cloudy, cool, and damp conditions persisting over portions of the area (Courtesy of College of DuPage)

Wednesday and Thursday 

Some light rain showers may linger along the coast on Wednesday morning, but as the weak area of low pressure begins to pull away, any potential impacts will begin to diminish. This will lead to improving skies during the afternoon hours with peaks of sunshine, allowing highs to reach into the upper 60’s to middle 70’s over the entire area.

The large upper level low that we have been talking about for over a week now will likely be rotating into the Great Lakes region and portions of the Northeast by late Wednesday evening or very early Thursday morning. As this large system begins to lumber towards us, it will drag up an impressive amount of moisture from the Gulf of Mexico and southwestern Atlantic and begin to transport it northward towards our area. Once this upper level system begins to mature and strengthen, it will spawn a primary area of low pressure over the Appalachian mountains, and potentially another low that may develop just off the Mid-Atlantic coast.

There are some uncertainties regarding this system, but steady, heavier rain is likely during the day on Thursday, especially if the secondary low develops off the coast. However, if the system turns out to mature quicker and becomes more disorganized once it reaches our area, then the rain may be more sporadic and in the form of convection, but will still have the chance to produce some heavy rain.

This afternoons American model showing very impressive upper level jet structure that looks to be quite favorable for heavy rainfall over portions of our area on Thursday (Valid 8am Thursday)

This afternoons American model showing very impressive upper level jet structure that looks to be quite favorable for heavy rainfall over portions of our area on Thursday (Valid 8am Thursday)

Friday and Beyond

This area of low pressure looks to begin to fill-in and stall somewhere over the Northeast on Friday morning due to the high-latitude blocking that has persisted near the Canadian Maritime region and portions of Greenland. This should allow cloudy conditions, cooler temperatures, and  the threat of showers to last throughout the rest of the day as the low lingers around the region during the day.

Some improving weather looks likely for the start of the first big holiday weekend of the Summer,  at least on Saturday and no washouts are anticipated each day. So don’t cancel or change any outdoor plans yet!

However, there may be some left over blocking and some upper level ridging over the West Coast, which may continue to support a somewhat unsettled and potentially active weather pattern into this weekend. At this time, model guidance is beginning to suggest that another storm system tracking northwest of region, that could bring some showers to the region, sometime on Sunday or on Memorial Day. But more forecast details will likely be fined tuned throughout the week.

This afternoons American model showing showing yet another potential system working its way down from Canada around the Memorial Day time frame

This afternoons American model showing showing yet another potential system working its way down from Canada around the Memorial Day time frame

Stay tuned for another for more updates, with discussion on later this week and Memorial Day Weekend!

For more information and posts like this one, make sure you sign up for Zone Forecasts — where multiple detailed articles, videos, and interactives are posted each day. Also, come interact with our staff and many other weather enthusiasts at 33andrain.com!

Have a great evening!

Steve Copertino