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Steven Copertino

Cool Conditions Give Way To Warmer Weekend Weather

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Good Evening! 

We had quite the chilly start to the day today after the area experienced near ideal conditions for radiational cooling that allowed temperatures to drop well into the 30’s across much of the area. Some frost was reported in locations that saw lows drop into the low 30’s which lasted until just before the morning commute-a sign that we’re quickly approaching the start of the winter season. As the rest of the day went on, the area of high pressure that had been in control over the past three days finally began to lift out of the Northeast. This caused low level warm air to funnel in behind the high, which brought in not only numerous clouds over the area, but also some mid level moisture surging northward that helped to create some spotty showers over the western areas of the Northeast. The combination of thick cloud cover and increased shower activity allowed temperatures to stay relatively cool today, with most stations reporting mid day highs in the lower 50’s to middle 60’s. The large temperatures dependency over portions of southern New Jersey is due to an approaching surface warm front that will likely be working over the area later this evening and into tomorrow.

Given then increasing low level moisture and cool air trapped just below the warmer layer aloft, there may be some patchy areas of fog developing late tonight which could possibly last into the early morning hours. Some light showers may also be possible highly dependent on the exact timing of the warm front. If the front is quick to overspread the area, then showers may become more likely, but if the front crashes into the cooler/more dense air over Pennsylvania, then showers will become much less likely this evening and into the early morning hours. Regardless, expect mostly cloudy conditions continuing into sunset, with lows tonight topping off around the middle 50’s for most of the area. again, depending on the progression of the front, areas west of the city may see cooler temperatures if the front begins to slow down over Pennsylvania.

Surface pressures, surface observations, and surface fronts, showing a rather large temperature differential as the high pressure system in purple lifts out

Surface pressures, surface observations, and surface fronts, showing a rather large temperature differential as the high pressure system in purple lifts out

Thursday Into the Weekend

Thursday morning will likely start off cool for most of the area, but with increased mid level riding beginning to develop overhead, any fog or leftover stratus clouds should quickly dissipate as more stable air gives way to clear skies by the mid morning hours. With clearing skies and warmer mid level temperatures, highs tomorrow will likely be a good deal warmer than they were today, with highs likely ranging in the upper 60’s to lower 70’s. Tomorrow should also remain free of precipitation throughout the entire day, so expect calm and mild conditions to last into the evening hours where lows should only be able to drop into the lower to middle 50’s across much of the area.

As we work our way to the end of the work week on Friday, relatively clear conditions are expected during the day, and with an enhanced southwesterly flow in the low level, we expect the day to get a head start on warmer temperatures than Thursday. Low level flow will likely be maximized ahead of another approaching cold front that should be located over western portions of Pennsylvania by Friday afternoon, so the day should have a nice and warm feel to it, with highs likely reaching into the 70’s across much of the area. Locations closer to the ocean like Long Island and coastal Connecticut may have to deal with some cooler offshore winds that may bring highs down a bit, but overall Friday will likely be the nicest day of the week for any outdoor activities. Later in the day, the cold front should begin to pass over the region, with a chance at some scattered/isolated showers with the front. Most of the energy associated with this front will be disjointed and weak, so widespread rainfall is not likely at this time. High pressure should begin to build back in during the night on Friday, so expect conditions to be cooler behind the front with lows dropping into the middle to upper 40’s.

This afternoons GFS model showing above-average temperatures across the area over the next 48 hours

This afternoons GFS model showing above-average temperatures across the area over the next 48 hours

Saturday will likely start off rather calm and cool, with winds coming mainly from the cooler Atlantic. These cooler winds will likely run into some residual moisture from the weak cold front, so it will not be out of the realm of possibilities for some broken/scattered clouds to make an appearance during the day. Despite some cloudier conditions, Saturday will likely remain dry, with highs likely staying in the 50’s area-wide.

On Sunday, a warm front looks to march back over the region from the south, putting a cap on the short cool period. This front looks to come through during the very early morning hours, and could carry some lift with it, so we may have to watch for spotty showers to develop as the warm front takes over. Sunday may feature some partly cloudy conditions, but this will ultimately depend on just how strong the warm front is, in addition to how far inland it can advance. Overall, expect highs to rise into the lower to middle 60’s during the day, with only a slight chance of rain at this time.

An early look into next week shows that we may have to watch an area of low pressure and associated mid level trough for the next measurable rain potential across the east. Additionally, heights will likely rise considerably once again along the coast, which should elevate temperatures into the 70’s-with a shot at middle 70’s at some location early in the week.

This afternoons ECMWF model showing the tail end of an area of ridging parked over the east for this weekend, with slightly above-normal conditions expected.

This afternoons ECMWF model showing the tail end of an area of ridging parked over the east for this weekend, with slightly above-normal conditions expected.

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Have a great night!

Steve Copertino

Steven Copertino

Cooler Conditions Hanging On, Changes Coming This Week

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Good Evening! 

The storm that bombarded portions of the Northeast over the past day is quickly moving out over eastern Canada, but the storm certainly left its mark. Most of the Northeast saw heavy rainfall totals in the range of about 2-5″, but the main event from this system were the winds that roared in overnight last night. As the low pressure area rapidly deepened and moved ashore over NJ and eventually progressed into New York state, it carried a large an impressive area of high winds just above the surface over portions of Long Island, Connecticut, Rhode Island, Massachusetts, Vermont, and Maine. As the storm began to fill in with warmer air and weaken, these winds just above the surface were able to rapidly crash down to the ground and cause an impressive amount of tree damage. Hundreds of thousands of folks are still without power in many of the states above, with over 400,000 customers without power in Maine alone. While these winds were rather impressive, the main story west of the immediate area of low pressure were the torrential rains that fell. Deep tropical moisture streamed northward into the Mid Atlantic and Northeast states, and when this moisture was met with the strong dynamics aloft, heavy rain became focused over New Jersey and portions of New York for several hours. Some locations were able to rack up rain totals in the 4-5″ range when all was said and done, with some minor street and river flooding noted. As we stated last week, the reason that these rains were not a bigger story was because an existing minimal drought muted out the overall impacts.

Sunday nights radar near the peak of the coastal storm that brought heavy rains and high winds over the region

As day broke today, a strong westerly jet associated with the backside of the low pressure system was working its way over the Northeast. Due to more mixing of dry air in the atmosphere, this low level jet was able to bring gusts down to the surface in the range of 30-40 mph, which brought some additional tree damage to the region. It also made for a cooler and more classic fall day as cooler Canadian air was briefly tapped. With partly sunny skies and cooler temperatures aloft, highs were able to make it into the middle 50’s across much of the region, but cooler conditions to the north and west kept highs down in the low to upper 40’s-with some stations in New York state even reporting snow showers! As the massive low pressure system continues to pull away this evening, wind have shifted from northwest to southwest as high pressure begins to build in from the south. As the winds shift, the gusty 20-30 mph conditions will begin to die down as the pressure gradient from the two opposing systems weakens with time. Given the clear skies and low humidity, conditions will be marginally supportive for radiational cooling to occur tonight which should knock temperatures down into the upper 30’s and lower 40’s across the area.

High resolution visible satellite imagery and surface observations over the northeast showing cooling and windy conditions

High resolution visible satellite imagery and surface observations over the northeast showing cooling and windy conditions

Tuesday and Beyond

The area of high pressure just south of the area will continue to build north throughout the day tomorrow, which will allow for dry conditions and generally clear skies. Highs will likely be limited to the middle to upper 50’s  during the day tomorrow despite winds coming from southwest winds at the surface, but cooler Canadian air continues to work in at the lower levels of the atmosphere. Winds will also likely die down completely by tomorrow afternoon, so as we work our way into the evening hours, we should see ideal conditions for radiational cooling to take place over the entire area. Low level temperatures will likely be below freezing already, so expect lows to drop into mid to upper 30’s, with some of the more interior locations possibly even dropping below-freezing and into the upper 20’s. With little to no winds, frost will be increasingly likely the farther away from the coast you move.

By Wednesday some changes will be in the works as a large area of low pressure begins to move towards the Great Lakes region. As this low heads northeast, it will bring a surge of warmer air along a warm front over the area, which should work to bring highs back into the upper 60’s and lower 70’s once again. Given the breadth of this system, we will likely be in between the cold front and warm front until Friday, when the cold front will finally pass, bringing a marginal chance of showers during the afternoon hours. Highs will likely remain in the upper 60’s to lower 70’s through this period, before the cold front knocks temperatures back down to more seasonable levels.

By this weekend temperatures should once again cool down with northwesterly flow returning from Canada, but we may have to watch for a threat of showers once again later in the weekend as a potential wave of low pressure rides north along a stalled cold front over the area. There is still considerable uncertainty with this solution and we’ll have more details by Wednesday as the model guidance converges on a more clear solution.

Snapshot from the 12z ECMWF model showing slightly above normal temperatures during next weekend with the return of higher heights in the east

Snapshot from the 12z ECMWF model showing slightly above normal temperatures during next weekend with the return of higher heights in the east

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Have a great night!

Steve Copertino

Steven Copertino

Strong Fall Storm Likely To Impact the Northeast This Weekend

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Good Afternoon! 

Today was another in a series of cooler and more fall-like days after the passage of a strong cold front earlier in the week that has worked to keep temperatures rather seasonable and the humidity low. Most of the area is currently under the influence of a large area of high pressure currently situated off of the North Carolina coast, which extends northeast into the Atlantic. This area of high pressure has been providing much of the Northeast with light winds out of the south/southeast this afternoon, which has allowed for slightly warmer mid level temperatures to work their way northward. These ever-so-slightly warmer mid level temperatures in conjunction with relatively clear skies have allowed highs to only reach into the low to middle 60’s across the Northeast. The rest of the day should remain quite clear and clam, with only a few high cirrus clouds likely during the day due to strong sinking air associated with the high pressure to our south. This evening should also be quite pleasant in terms of sensible weather as low dewpoints, clear skies, and light winds dominate the area. These conditions will also allow for radiational cooling to take place once again this evening, but not quite as expansive/severe as last night due to slightly warmer temperatures located a few thousand feet above the surface. Lows tonight will likely range in the upper 30’s to middle 40’s across the area, with the lowest temperatures located to the north and west of the immediate city.

Tomorrow (Saturday), we should see a pretty clear and pleasant start to the day, but southerly flow will increase in earnest ahead of a strong cold front which will be located over the Ohio Valley. As the southerly flow increases, we can expect mid level clouds to develop by the afternoon hours, but with even warmer mid level temperatures, highs will likely warm up into the upper 60’s to lower 70’s tomorrow despite the cloudier conditions. As we head deeper into the afternoon and early evening hours, the strong cold front will likely be located over western/central Pennsylvania with moderate to heavy rain over that region. Closer to the metro area, we can expect overcast to take over before dark, with a chance at a few showers over the region. Humidity will be on a rapid increase Saturday evening, and the strong frontal system begins to funnel deep tropical moisture to the north, associated with a tropical system down near Florida.  The increase in cloud cover and the additional moisture will lead to temperatures remaining relatively mild for this time of year, with lows in the middle to upper 50’s.

This afternoons high resolution visible satellite imagery, regional radar mosaic, and surface observations showing a relatively calm day to end the work week

This afternoons high resolution visible satellite imagery, regional radar mosaic, and surface observations showing a relatively calm day to end the work week

Sundays System 

Conditions should begin to deteriorate quite quickly across much of the Northeast on Sunday as the upper level system currently located over the Great Lakes region begins to intensify. As this system intensifies Sunday morning, the rain associated with the original cold front will begin to increase in intensity as well as coverage. Simultaneously,  the remnants of a tropical system will be drawn northward into the coast of the Carolinas. As these two features gradually merge over the Mid Atlantic states, a very potent upper level jet streak located tens of thousands of feet above the ground will also intensify with wind speeds of around 190 mph. This intense jet streak will provide excellent upper level divergence and surface convergence for the developing low pressure near the Mid Atlantic states, which should cause the system to intensify quite quickly as we head into the afternoon hours of Sunday.

By Sunday evening, the energy in the base of the upper level trough will begin to swing eastward and take on a more negative orientation, which will further promote the development and expansion of precipitation over the Mid Atlantic and Northeast states. This afternoons model guidance has shifted westward and a bit stronger with the overall system, indicating that the low pressure area will be located in the vicinity of Atlantic City, NJ by 8pm Sunday. This scenario would lead to very heavy rainfall rates over the entire Northeast, with strong, gusty winds from the east also increasing through the evening. This afternoons European ensembles, which is a blend of 51 models with different initial conditions shows that the low will then take a track to the NNW into New Jersey, and then Pennsylvania by late Sunday night and into the early morning hours of Monday. The storm would likely be intensifying while still heading inland, with the European model showing pressures in the low 970’s-which is common for an Atlantic hurricane. Widespread heavy rainfall and strong winds will likely continue as the low heads inland over portions over southern New York state and finally begins to weaken into the day on Monday.

This afternoons European model showing a very strong storm tracking inland over NJ/PA Sunday evening with very heavy rains and damaging winds

This afternoons European model showing a very strong storm tracking inland over NJ/PA Sunday evening with very heavy rains and damaging winds

Impacts

As of this afternoon, it appears that this low pressure system has the potential to bring rainfall in excess of 2-4″ across much of the New York metro area, with locally higher amounts possible over Long Island. With a system like this, usually the heaviest rains will be on the western side of the low pressure track, while the strongest winds will be on the eastern side. With that said, much of New Jersey, New York, Connecticut, and the rest of SNE could see strong wind gusts in the 40-60 mph range. This could be conservative in some locations, where some of the high resolution models have winds nearing hurricane force (around 75 mph+) over portions of Long Island. However, the exact magnitude and extent of the winds will likely be under question until tomorrow afternoon when we get into the prime range for our model guidance and the tropical system down south is better resolved. Regardless, these kinds of winds could easily down small tree limbs, and potentially down a couple trees due to saturated grounds. In addition, the heavy rains will likely cause some small-stream flooding and ponding of water in roadways, but a marginal drought over the region should be able to soak up enough of the storms rain so that widespread flooding is not likely.

Preparedness– Due to the possibilities of strong winds and the time of year, it is recommenced that any Halloween decorations are either taken down, or secured so that do not blow around and cause damage to property. Also, make sure that you do not have any weak, or lose branches near utility lines that may cause lose of power. Make sure to stay up to date with your local NWS office for any potential warnings and updates on the forecast over the next 36 hours. There are still some questions regarding the overall evolution of this system, so make sure to check back to get the latest on this system!

Total rain accumulation from the Weather Prediction Center

Total rain accumulation from the Weather Prediction Center

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Have a great and safe weekend!

Steve Copertino

Steven Copertino

Active Pattern Kicks In With Multiple Heavy Rain Threats

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Good Evening! 

Today was likely the last in the series of nice warm fall days that we have managed to string together over the past five days or so. Mots of the day was rather calm and clear with winds out of the south/southeast, bringing in more moist dewpoints into the area. With mid level temperatures rising ahead of a strong mid level trough located in the central part of the country, we were able to get temperatures to rise into the lower to middle 70’s this afternoon-which is slightly above normal for this time of year. As we progressed into the late afternoon and early evening, mid level clouds began to increase substantially as the vigorous mid level system that we have been talking about since last week began to intensify and pivot towards the east. As of this evening, heavy showers were located in portions of the Mid Atlantic states, and reaching into western Pennsylvania. This heavy shower activity is being fueled by a strong upper level jet in conjunction with an impressive low level jet, working to transport deep tropical moisture northward into the East. As we continue into the night tonight, this activity will likely continue to gradually move northeast, and eventually make its way into eastern Pennsylvania around 5am or so. By this time, moisture transport from the source region of the Caribbean will be maximized, and the upper level jet over-top this anomalous moisture will be to expand and promote surface convergence, which will promote heavy/intense rainfall to develop. High resolution model guidance disagrees on the exact evolution of these features, but signs point to possible low-topped convection forming over eastern Pennsylvania and quickly heading northeast into the NY metro.

Radar and surface observations from around the Northeast and Mid Atlantic states showing the vigorous Pacific system finally getting ready to impact the region with heavy rain and strong winds.

Radar and surface observations from around the Northeast and Mid Atlantic states showing the vigorous Pacific system finally getting ready to impact the region with heavy rain and strong winds.

This area of heavy showers with embedded convection will have the potential to produce very heavy rain, gusty winds, and localized road flooding due to leaves clogging areas of poor drainage as it heads northeast. As this activity moves onward, the stout mid level jet will be strengthening through the morning hours, and this will help to promote strong, gusty winds in the 30-50mph range even outside of the strongest area of activity. These winds could easily take down small tree limbs that still have leaves on them and could possibly cause localized power outages. For this reason, the NWS has issued numerous Wind Advisorys for the Northeast. The bulk of the activity should be located just west of New Jersey by 8-9am, and we may see renewed activity begin to form from the south over the Atlantic and possibly move inland over New Jesery and Long Island. Eventually, this activity looks to become focused along a frontal system that will likely be set up just to the east of New York City by later in the day on Tuesday. This activity will have the same very moist precipitable water feed that the morning activity had, as well the strong mid-upper level winds, so very heavy rain and strong, gusty winds will also be possible along with some rumbles of thunder mixed in as well. This frontal system will likely be slow to move later in the day tomorrow, and we could see training of showers and thunderstorms over the same regions, which would put areas that see multiple rounds of rain under a heightened threat for flooding.

Isolated locations on Long Island could see upwards of 2-4″ of rain, with a very sharp gradient on the east and west side due to the northward movement of the showers and thunderstorms. It is also important to note that we will have to watch any organized thunderstorms moving off the ocean for possible tornado/waterspout activity, as there may be just enough low level turning to support a brief/weak spin-up along the NJ/LI coasts.

This afternoons RPM model showing the evolution of the heavy rain and wind threat tomorrow afternoon/evening

This afternoons RPM model showing the evolution of the heavy rain and wind threat tomorrow afternoon/evening

Wednesday and Beyond 

After this first system, high pressure looks to build in behind the exiting upper level trough, which should help to bring in much cooler temperatures and low humidity courtesy of a fresh Canadian airmass. This should allow temperatures to become quite seasonable across the region, with highs likely staying the upper 50’s to middle 60’s for the remainder of the week. Conditions should also become quite calm as well, with mainly sunny conditions expected. Each night should feature fair to excellent conditions for radiational cooling to take place, so expect overnight low temperatures to drop down into the middle 30’s to low 40’s, with some areas likely seeing another round of patchy frost-with the best chance being on Thursday.

After this bout of calmer weather, we then turn our attention back to the Pacific northwest as another vigorous mid level system crashes into the West coast. This system will gradually move into the central part of the country by the end of the work week, and should likely phase with another piece of mid level energy located over the southern Plains. As the energy consolidates and begins to strengthen, it will begin to deepen a trough over the eastern third of the country, which will once again draw up a very impressive amount of tropical moisture from the Gulf of Mexico and Caribbean. This mid level system will likely be much more impressive than this current one, as it should have enough cold air on the back side of the trough to potentially drop a good amount of snow on the northern tier of the country. This storm system will likely track into the Great Lakes region by Saturday afternoon, but the models show a potential wild card to this forecast. Due to the enhanced convection over the Caribbean and Gulf from the strong Madden-Jullien Oscillation pulse over the area, we could potentially see some kind of tropical system become tangled up with the cold front draped over the southeast US.  As the front heads east towards our area, we could see copious amounts of rain from the tropical system riding the front up the east coast, but this will likely change and will be highly dependent on just where the front sets up. Regardless, there is a heightened potential for a cool and stormy weekend ahead, and we will have further updates on this system during the week!

This afternoons European Ensembles already showing a high probability of 1" or greater of rain for this weekend

This afternoons European Ensembles already showing a high probability of 1″ or greater of rain for this weekend

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Have a great night!

Steve Copertino