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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

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: 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: Brief Calm This Weekend, Multiple Rain Chances Next Week

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Good Evening and Happy Friday! 

Today has been yet another pleasant and rather seasonable day, and the good news is these conditions look to last well into this weekend. The bad news is that we do appear to be headed into yet another unsettled and dreary period staring late Sunday, and into the work week next week. Additionally, the negative phase of the North Atlantic Oscillation that we have been covering for over a week now looks to bring about another unseasonably cool airmass for the majority of next week. However, in the extended range we may begin to see a switch back to seasonable temperatures and more stable conditions.

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Recap and This Evening

Earlier today we saw mostly sunny skies and light winds from the north and west due to an area of high pressure moving through the Ohio Valley and western portions of the Mi-Atlantic states. Just to the east of the high pressure system, a large upper level low was situated over northern New England and portions of Canada, which was helping to usher in cool and dry air in the mid-levels of the atmosphere. As the day progressed and the surface levels of the atmosphere began to warm up, this caused a similar scenario that we have seen a few times in the past few weeks where the warmer air near the surface quickly rises into the cooler levels of the atmosphere and begins to form clouds.

With very marginal upper level support, some converging moisture boundaries over the area, and an area of energy rounding the base of the upper level low, we actually began to see some congested cumulus and ragged cumulonimbus form over portions of New York, New Jersey, and Connecticut. Due to the dry air being entrained in from Canada, these showers and storms were generally pretty tame in nature and did not have muhc lasting power, but due to the cold mid to upper levels, some pea-sized hail and gusty winds were reported mainly to the north of New York City.

Moving on, with rather abundant sunshine, light gusty winds, and a relatively dry airmass, highs today were able to climb into the mid to upper 70’s once again, with the exception of coastal New Jersey and portions of Long Island. As we move into the evening hours, the breezier conditions left over from a frontal passage will gradually subside. Additionally, skies should begin to clear out quite significantly as dry air and diurnal heating begins to wane over the area. These conditions will be quite favorable for radiational cooling to take place this evening, so expect overnight lows to drop quite a bit with temperature ranging from the low to mid 50’s across much of the area, with 40’s possible in locations north and west of the city.

This evenings latest visible satellite imagery, regional radar mosaic, station plots, and watch/warning information. Note the rather tranquil conditions after a few brief showers and storms earlier this afternoon (Courtesy of College of DuPage)

This evenings latest visible satellite imagery, regional radar mosaic, station plots, and watch/warning information. Note the rather tranquil conditions after a few brief showers and storms earlier this afternoon (Courtesy of College of DuPage)

Saturday Into Sunday 

As we head into tomorrow morning, another disturbance from Canada will begin to work its way down south, and towards our area. This upper level system may have enough energy associated with it to produce some overcast and showers, but this system will be rather progressive in nature and will likely move out by late morning due to its close proximity to the aforementioned high pressure system exiting to out east. Any rainfall accumulations should be quite light in nature, with more dry air reinforcing itself over our region directly from Canada once again. Gusty winds from the north and northwest behind the tiny, but relatively strong area of energy may become quite widespread over the region tomorrow. As skies clear out and the dry air works its magic, we should see highs climb back into the middle to upper 70’s once again, with the off-chance that some locations may reach the 80 degree mark if the initial disturbance is quicker than currently forecast. Clear to partly cloudy skies are likely Saturday evening, with temperatures falling back into the upper 50’s to around 60 near New York City, and urban areas reaching down into the lower to middle 50’s over much of region.

Sunday looks to start off with mainly clear conditions as marginally dry air from the north and west continue to feed into the region. Clouds will likely begin to increase throughout the day as moisture advances ahead of the third in a series of strong mid level disturbances. As the day marches on, the threat for showers will increase, especially through the late afternoon and evening hours as the mid level disturbance begins to strengthen just to the west of our area. As this mid level system begins to strengthen during the evening hours of Sunday, an area of low pressure will likely form over the Great Lakes region, and this low pressure will be capable of advecting an impressive amount of water vapor over our area, which may set the stage for potentially heavy rains Monday morning.

High resolution North American Model showing a very large area of moisture gathering just to the south of a developing low pressure system in the Great Lakes, which is usually a very strong indicator for moderate to heavy rains (Red and pink areas delineate very moist air-mass)

High resolution North American Model showing a very large area of moisture gathering just to the south of a developing low pressure system in the Great Lakes, which is usually a very strong indicator for moderate to heavy rains (Red and pink areas delineate very moist air-mass)

Monday and Beyond 

With all this moisture gathering to the south of the area on Sunday and into Monday morning, a strong mid to upper level disturbance strengthening over our area, and a favorable upper level jet streak to the north, the writing is on the wall for a wet and dreary day on Monday, with periods of moderate to heavy rainfall quite likely. The main question in this forecast appears to be just how far north the area of low pressure in the Great Lakes moves as it pushes up against an area of confluence located over Canada. Where this confluence sets up will also likely dictate how much, and where the heaviest rains fall on Monday.

There is a small chance that the confluence-or blocking could be positioned further south than currently forecast, and this would allow for a possible scenario where another surface low redevelops off of the Mid Atlantic coast and enhances the rain potential. Confidence in this scenario is low at this point, but we will provide updates on the storm as we draw closer.

Some unsettled weather with scattered showers and possibly some thunderstorms could continue into Tuesday and Wednesday with the upper-level low still lingering over the Northeast. Temperatures will likely run near or below normal depending on amount of clouds and rainfall each day.

This afternoons European model showing the system that will likely produce a heavy rain threat on Monday still lingering over the Northeast on late Tuesday evening. This system could produce more rain later in the week depending on how long it meanders around

This afternoons European model showing the system that will likely produce a heavy rain threat on Monday still lingering over the Northeast on late Tuesday evening. This system could produce more rain later in the week depending on how long it meanders around

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 weekend!

Steve Copertino

Miguel Pierre

5.26 Late-AM Zones Update: Some Unsettled Weather for Memorial Day Weekend

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Happy Friday! Low pressure that brought more rain with some thunderstorms overnight, is now moving east of New England late this morning. Clouds and showers are clearing, with drier, downsloping northwest winds, behind this system. This will support temperatures to rise into the lower to middle 70s across much the region. However, with daytime heating the atmosphere will become more unstable under a cold-pool aloft. So a few scattered showers and thunderstorms could pop up across the region this afternoon and early evening.

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