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

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

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

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

 

Public Analysis: Heavy Rainfall Likely Tomorrow, Unsettled Weather Continues

Good Evening! 

An area of low pressure and its associated moisture moved through our area this morning and brought some light to moderate rain for most locations. While the low pressure and the abundance of moisture was handled well by our computer guidance, the amount of mid-level forcing associated with a weak frontal system was severely underestimated, therefore leading to most, if not all computer guidance not showing any measurable precipitation during this time period. Once this front and its associated dynamics began to move away from our area and started to decay, the rain and cloud-cover began to gradually decrease leading to partially sunny skies. Despite the rain and prolonged overcast, temperatures were able to rise back into the mid to upper 60’s and lower 70’s for most of the area.

Cloud cover has once again begun to increase as a large area of low pressure located in the Ohio Valley continues to drag a copious amount of moisture northwards, directed at our area and will likely impact the next thirty-six hours or so. Cloud cover should begin to increase steadily this evening, and winds increasing from the east will allow temperatures to drop into the 50’s for the entire region, which will once again be below-normal for our area. With increasing moisture ahead of a warm front down to our south, some showers may be possible very late this evening and early this morning as forcing associated with the warm front begins to steadily increase.

This evenings latest temperatures and regional radar mosaic, showing mostly dry and comfortable conditions over much of the area.

This evenings latest temperatures and regional radar mosaic, showing mostly dry and comfortable conditions over much of the area.

Thursday Into Friday

The latest short-range model guidance continues to hint that the first wave of rainfall associated with the large and anomalous area of troughing/area of low pressure will likely continue to spread northwards during the very early morning hours tomorrow, moving over portions of Virginia, Delaware, and Maryland. This batch of rain should begin to move into southern New Jersey and southern Pennsylvania by 6am or so, and continue moving northward through the morning, likely reaching New York City around 8am  While the overall dynamics of the system have trended more disorganized than they were forecast, there is a very solid transport of deep tropical moisture, so some areas that do see the more favorable dynamics could see some locally heavy downpours early tomorrow morning.

In addition to locally favorable conditions for heavy downpours, the addition of some weak instability associated with the warm front may also bring he chance of some convection/thunderstorms, which would only work to increase the potential for heavy downpours tomorrow morning.  Localized flash-flooding in poor drainage, low-lying areas is possible with these isolated thunderstorms. Otherwise not much more than some typical ponding on roadways is anticipated across the region.

As we work our way into the afternoon hours, more dry air will begin to move its way in behind the heaviest rain, which should be able to gradually reduce any remaining rain to isolated showers and drizzle, possibly lasting into the early evening hours. With the potential for heavy rain, overcast through most of the day, and increasing easterly winds off of the cool Atlantic, highs tomorrow should be uniformly stuck in the 60’s across the entire area. Temperatures in the 50’s may be possible during some of the more intense downpours, in which cooler air from a few thousand feet up is brought down to the surface.

Later in the day, the original low pressure system over the Ohio Valley will begin to decay and die-off. This will allow a transfer of energy just off the New Jersey coast. where a secondary low pressure will gradually become established. This new, developing low pressure system will bring another chance at some isolated showers and thunderstorms across the area into late tomorrow evening as the system continue to strengthen due to a hefty amount of upper level energy rounding the base of the large upper level system that we have been talking about for well over a week now. As this low continues to deepen over the evening hours, it will begin to advect warm air northwards, which may help to increase instability locally enough for a few storms to have some gusty winds and possibly some pea-sized hail.

Overall, tomorrows rainfall totals will likely range quite a bit, mostly depending on whether or not convective rains can develop and just how long these rains can stick around. Additionally, a tightening pressure gradient from the developing coastal low and a high pressure system in Canada will cause winds to increase a bit during the afternoon and evening hours, to around 25-40 mph. While these winds are not all that impressive, they will last a while near the coast, and this will promote a heightened threat of some coastal flooding due to the complications from an astronomical high-tide. the National Weather Service has issued a Coastal Flood Advisory for the potential for minor flooding of the most vulnerable waterfront locations.

This evenings High Resolution Rapid Refresh Model, showing a batch of very heavy showers and isolated thunderstorms moving across the area during the morning commute hours

This evenings High Resolution Rapid Refresh Model, showing a batch of very heavy showers and isolated thunderstorms moving across the area during the morning commute hours

Friday Into Saturday

Once we move on to Friday, the low pressure will continue to linger over much of the Northeast, gradually meandering into portions of New England. As this low slowly moves away from our area, this will likely cause steadier rain taper-off from southwest to northwest during the morning commute. Clouds will likely start to break as a stout northwesterly flow begins to develop from Canada, ushering in cooler and drier air. Some scattered showers and thunderstorms could develop again later in the afternoon and early evening due to colder air in the mid levels of the atmosphere and heating occurring near the surface, especially for any locations that see prolonged sunshine. Some of these thunderstorms could potentially  produce gusty winds and some small hail . High temperatures will likely reach the upper 60s to lower 70s across much of the region, with slightly higher temperatures likely for those locations that see earlier/prolonged clearing.

An area of weak high pressure and mid-level ridging will likely build  over the region on Saturday, this will support more sunshine to mix with clouds over the region. High temperatures are expected to be in lower to middle 70s. One fly in the ointment is that some of the latest models today, are indicating a mid-level disturbance over Northern Mid-Atlantic region. If this disturbance track near us and there is enough moisture, some scattered showers may develop again later in the day. But at this time we believe that this is unlikely for now, but will be monitoring this system very closely over the next few days.

This evenings North American Model Showing yet another upper level system approaching the region over the weekend

This evenings North American Model Showing yet another upper level system approaching the region over the weekend

More scattered showers and thunderstorms are more likely to be around for Sunday and Memorial Day a low pressure tracking over Great Lakes send a couple of frontal boundaries through region. However, much of time will likely be dry with some sunshine and mixing with clouds each day. This will temperatures get into at least into the upper 60s and 70s through the region. Sea-breezes may keep coastal sections a little cooler. So no washouts are expected for the holiday weekend as of now.

Make sure to stay tuned for more detailed updates regarding the 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

Public Analysis: Much Quieter and Drier, Summerlike Conditions Possible Midweek

Good Evening!

We are finally starting to see the last of the lingering effects of the large Nor’Easter that brought heavy rains, gusty winds, and just dreary conditions in general over the past few days to the entire Northeast. Today was a rather large improvement across much of the area from this previous weekend as clouds began to diminish from west to east earlier in the day, giving way to mostly clear skies. Due to the lack of clouds and a much drier air-mass in place, temperatures were able to climb into the middle 60’s and even the low 70’s across the area. Today was also quite gusty at times across the region due to a rather impressive pressure gradient over the area as a developing area of high pressure began to move in over the Great Lakes and the decaying coastal storm began to slowly move out to the east over the open Atlantic.

As we continue on through this evening, mainly clear conditions are expected, with the exception of eastern portions of Long Island and Connecticut due to lingering clouds from the area of low pressure off of Cape Cod. The area of high pressure over the Great Lakes will move over portions of western Pennsylvania just after sunset, so we can expect any remaining windy conditions to die-off considerably after dark. As the high pressure moves in, it will also usher in drier air throughout all levels of the atmosphere which will allow for rather clear conditions to persist throughout the evening. With clear skies, dry air, and light winds, we can expect temperatures to drop quite a bit this evening through radiational cooling. Low temperatures should drop into the upper 40’s to low 50’s across the majority of the area, with some locations (especially in the Pine Barrens and to the NW) dropping well into the 40’s.

Current regional radar mosaic, surface temperatures, and visible satellite imagery showing much-improved conditions across much of the area

Current regional radar mosaic, surface temperatures, and visible satellite imagery showing much-improved conditions across much of the area

Tuesday Through Wednesday

Tomorrow will be the start of a rather significant warm-up across the region as a strong ridge of high pressure begins to build over our area through the next few days. Tomorrow will likely start off rather cool, but with clear skies and winds shifting from the west, to more southerly throughout the afternoon, temperatures should be able to climb quite significantly. Highs will range from the middle 70’s to lower 80’s across much of the region, with even coastal sections seeing the much warmer temperatures, as sea-breezes will likely hold off until later in the day. The dry and warmer conditions will last throughout the day and into the evening, with the southerly flow aiding in temperatures only falling into the middle to upper 50’s tomorrow night.

As the ridge begins to flex its muscles on Wednesday, we will see much of the same conditions once again, with temperatures quickly rising by late morning and into the early afternoon hours. As mid-level temperatures rise quite significantly, highs will soar well into the 80’s under clear skies and southwesterly winds. Some locations to the south of the city may actually get quite close to 90 degrees on Wednesday, with the most likely spots being in southern New Jersey and Southeast Pennsylvania. Again, the southwesterly flow will limit lows on Wednesday, and possibly keep them in the lower 70’s across much of New Jersey and Connecticut, with coastal sections of Long Island and Connecticut seeing lows drop down in the 60’s.

Afternoon European model showing the strong mid-level ridging taking shape over the Northeast United States on Wednesday (Valid 2pm Wednesday)

Afternoon European model showing the strong mid-level ridging taking shape over the Northeast United States on Wednesday (Valid 2pm Wednesday)

Thursday and Beyond 

Thursday is likely to be the warmest day of the year thus far, with the ridging over our area likely to be at its peak. This should allow mid-level temperatures to become quite high over the area, which will allow for temperatures to once again soar into the upper 80’s and even lower 90’s across the entire area by the late afternoon hours on Thursday. Thursday should be quite beautiful with, light southerly winds, clear skies, however it may become more humid during the afternoon as dewpoints reach into the lower 60’s across the region. These high temperatures will be quite anomalous for this time of year, with departures likely reaching 20-30 degrees above normal. It is worth noting that afternoon sea-breezes will be capable of knocking down temperatures a good 10-15 degrees in a short period of time near coastal sections of Long Island, Connecticut, and New Jersey on Wednesday through Thursday.

This afternoons latest model guidance continues to suggest that a cold front may sweep through the region later in the day Thursday and into the early morning hours on Friday. Whether or not we see any measurable precipitation will be highly dependent on the overall timing of the frontal system, but there will be the possibility for some showers and even some thunderstorms ahead of the front, which could have the potential for some gusty winds and locally heavy rainfall, but at the moment, this activity is not expected to be widespread. Temperatures on Friday and the weekend will likely drop a bit, with highs in the 70’s seeming possible at this time.

Overall, the latest guidance suggest that some high-latitude blocking will return again over next couple weeks. This will support more troughs with periods of cooler or unsettled weather over Northeast and Mid-Atlantic region. So enjoy another taste of summer weather this week. As it will be short-lived again. No prolonged warmth or heat appears to be coming the foreseeable future. Stay tuned for more forecast update through this week!

European Model 500mb Height Anomalies, showing a return to high-latitude blocking and a return to cooler weather once again

European Model 500mb Height Anomalies, showing a return to high-latitude blocking and a return to cooler weather once again

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