Doug Simonian

Onshore flow and Unsettled Weather Remains, but Light at the End of the Tunnel

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Good evening, everyone! Unfortunately, the onshore flow and unsettled regime from the past several weeks has re-entrenched itself across the area, giving our area plenty of clouds, fog, drizzle, as well as scattered showers and thunderstorms. But as we mentioned in our premium article on Saturday night, there would be some subsidence in the area between a departing coastal storm and the core of a mid-level disturbance well to the northwest. This is why our area is not seeing any rain right now. However, plenty of deep onshore flow will keep a lot of low-level clouds and moisture around, which will lead to drizzle and fog continuing for the night. Some of this fog could be dense along the coast, as this moisture will get trapped underneath a strong inversion aloft. Temperatures will generally remain in the low 60s for most of the overnight, and any rain and thunderstorms associated with the main mid-level disturbance will mostly remain in Orange and Dutchess counties and northward. But as the mid-level disturbance slowly pivots southeast, storms will gradually get triggered a bit further south as the overnight goes on.

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Doug Simonian

Update on Sunday into Monday’s Rain Event

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We hope you’re having a great weekend so far! This article is going to be a quick blurb on the latest regarding the upcoming rain event. It still appears that most of Sunday’s batch of rain will miss to the north, as most of a small shortwave will miss to the north and get shredded out when it tries to approach our area. The thermal gradient via a warm front will be quite impressive, which will lead to a lot of lift in the atmosphere. Thus, some heavy showers and thunderstorms are possible in our northern suburbs from northern Westchester County on northward — perhaps more focused on Orange and Dutchess Counties or even further north, where some heavy rain is possible.

The NAM model valid for Sunday afternoon shows some heavy rain in northern suburbs along a tight 850mb gradient.

The NAM model valid for Sunday afternoon shows some heavy rain in northern suburbs along a tight 850mb gradient.

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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

Steven Copertino

Public Analysis: Unsettled Conditions Persist, Another Cool Shot Looming?

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Good Evening! 

After a very dreary past two days, mostly due in part to a stalled front to our south and persistent cool winds coming off of the Atlantic, today was finally a nice change with highs finally climbing to just below seasonable levels! More seasonable conditions should persist through the end of this week and into the beginning of the weekend, but this should be rather short-lived as a complex disturbance from Canada dives down our way and brings a chance at some increasing clouds and showers once again by late Sunday into early Monday. Beyond that, there are hints that below normal temperatures and more rain threats will likely persist into at least the first half of June, as high-latitude blocking near Greenland and Central Canada take shape once again!

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After seeing overcast and mostly cloudy skies with some patches of drizzle embedded in some spots this morning, a cold front moving past the region ushered in a drier Canadian air-mass. This dry air in the mid levels of the atmosphere worked to significantly weaken the cloud deck across much of the area, which allowed most areas to start to see breaks in the clouds. As the afternoon progressed on, these breaks became more numerous, and most locations broke out with full-blown sunny skies. These sunny skies, light winds from the south, and warmer temperatures aloft allow for highs today to make quite the rebound, with most areas seeing temperatures rise into the mid-upper 70’s, with low 60’s to lower 70’s across some coastal locations. These cooler readings were felt primarily along the south-facing shores of Long Island and Connecticut, but even these locations managed to see clearing take place at one point or another during the day.

With this clearing taking place this afternoon, in addition to some more moist air being lifted over north and west portions of the area, we have also seen the return of summer-time thunderstorms developing ahead of yet another cold front. The environment over the area this afternoon has been characterized by rather marginal instability and some decently strong wind shear. There is also a piece of energy swinging through portions of Pennsylvania that will act as a trigger to set off any potential storms later this afternoon and into this evening.

The best chance for any organized severe thunderstorm activity will likely be north and west of the city, but it would not be impossible to see some residual activity work its way down into the New York City metro area, as some short-range models are hinting at. The main risks with these storms will likely be some gusty winds around 50 mph, small hail, and frequent lightning. The Storm Prediction Center in Norman Oklahoma has placed locations north of the city in a Severe Thunderstorm Watch until 9pm this evening. As night falls, any residual storms should begin to rapidly weaken, and any storms that happen to approach the coast will also begin to rapidly weaken due to a much more stable airmass in place over those locations.

This afternoons latest regional radar mosaic, surface observations, visible satellite imagery, and watch/warning information. Note the yellow boxes and lines, which delineates Severe Thunderstorm Warnings (solid) and Watches (lines)

This afternoons latest regional radar mosaic, surface observations, visible satellite imagery, and watch/warning information. Note the yellow boxes and lines, which delineates Severe Thunderstorm Warnings (solid) and Watches (lines)

Thursday and Friday 

The cold front that is responsible for these showers and thunderstorms will begin to overspread the region very early tomorrow morning, around 5-8am. More dry air will likely be reinforced over the area as an area of high pressure also works its way towards the Northeast, thus giving way to mostly sunny conditions. These dry and relatively calm conditions tomorrow will allow highs to once again reach into the mid to upper 70’s, with some inland locations likely reaching into the 80’s by late-afternoon. Though things look rather tranquil, there is a very slight chance that some showers or thunderstorms could pop-up during the afternoon hours as another piece of energy embedded in a large upper-level low over our area rotates through. Any shower activity would likely be very limited in coverage and quite short-lived.

Much of the same is expected on Friday, with highs likely staying in the same range as Thursday, but the shower threat may be slightly increased as there will be some more available moisture and lift to trigger possible thunderstorm/thundershower development across the area. However, another cold front looks to push through the area later in the evening, so this shower threat does not look like it will have much potential to linger around at all, as a dry and stable air-mass will likely establish itself and remove any lingering activity.

This afternoons European model showing a closed upper level low sitting over the region on Friday, with associated pulses of energy rounding the base of the trough, which may provide a chance at some afternoon thunderstorms (Valid Friday 2pm)

This afternoons European model showing a closed upper level low sitting over the region on Friday, with associated pulses of energy rounding the base of the trough, which may provide a chance at some afternoon thunderstorms (Valid Friday 2pm)

This Weekend and Beyond

More unsettled weather is likely later this weekend and into early next week as a frontal boundary will be draped to the south of the region with an upper level jet streak placed in a favorable spot to provide divergence in the upper levels, which looks to support at least multiple waves of low pressure developing along the boundary and affecting the area with the potential for more moderate to heavy rain. This afternoons model guidance is quite bullish with the development of a rather large area of low pressure that then begins to transfer to the coast with time. This would provide the area with quite a bit of heavy rain, but other computer models diverge with the handling of this system, but it does seem like we may have to watch the period of early next week for our next heavy rain threat.

Unfortunately, it seems like any prolonged period of summer-like warmth will be denied once again due to high-latitude blocking over Greenland and Central Canada providing yet another cool shot for the eastern half of the country starting next week. The long range ensemble models have been holding onto this period of below-normal temperatures and increased precipitation for what looks to be the first half of June. While the details are very far from final right now, the overall atmospheric pattern that we are in, combined with what has happened the past few weeks would support such an event.

We will continue to update you on the next possible heavy rain threat next week in addition to the potential cool shot looming next week!

or 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