Steven Copertino

Public Analysis: Remnants of Cindy Likely to Bring Heavy Rain, Seasonable Conditions Return Next Week

/by

Good Afternoon and Happy Friday! 

Getting right into things, earlier this week we highlighted the potential for some heavy rain associated with the remnants of Tropical Storm Cindy, which made landfall along the Texas coastline early Thursday morning. At that time, we stated that there were two scenarios that were likely to play out, one being that the remnants of Cindy would not hold up all that well after landfall, and the other being that they would. Over the past twelve to eighteen hours or so, it has become apparent that the remnants of Cindy have remained quite robust as they traveled over the Ozarks and into the Tennessee Valley, at least in the mid levels of the atmosphere. With very deep, tropical moisture streaming north from the Gulf of Mexico, the significance of having a more coherent remnant system means that the leftover energy will spark widespread showers and thunderstorms through this evening and into Saturday. In addition to the remnants of Tropical Storm Cindy, which has been downgraded to a remnant low pressure area, we also have a cold front surging through the Ohio Valley.

This cold front has been working to funnel all of the moisture from the Gulf of Mexico to the north and east, allowing it to pool up over the eastern third of the nation over the past two days. This has made for a very soupy and humid day today across the majority of the Northeast. We saw some very subtle lift manifest itself over Pennsylvania around noon today, which allowed for some showers to move eastward through eastern Pennsylvania, New Jersey, and New York. Occasional breaks in the clouds and very warm temperatures a few thousand feet off the ground allowed temperatures to spike back into the low to middle 80’s across the entire region, despite sudden temperature drops with any gusty showers that passed through some locations.

As of 630pm, a convective complex was evolving over the eastern half of Pennsylvania, and this complex will continue to head eastward through the evening. With adequate amounts of wind shear, instability, and an extremely moist air mass in place, torrential downpours, frequent lightning, and some gusty winds seem quite likely for those in the path of these showers and storms. Synoptic winds (winds not associated with small scale features) have already been quite impressive this afternoon, so we are quite confident that the probability for tropical-like downpours and gusty winds could cause some localized flooding with debris from trees likely clogging sewers. In lieu of this slight risk for severe thunderstorms, the Storm Prediction Center in Norman Oklahoma has issued a severe Thunderstorm Watch until 10pm this evening. The rest of the evening should remain quite unsettled, with the potential for more showers and thunderstorms behind this complex, so make sure to pay attention to your local NWS office for any potential warnings!

Animated regional radar mosaic, showing the evolution of a complex of showers and thunderstorms approaching the area. The main threats appear to be heavy downpours and gusty winds (Courtesy of College of DuPage)

Animated regional radar mosaic, showing the evolution of a complex of showers and thunderstorms approaching the area. The main threats appear to be heavy downpours and gusty winds (Courtesy of College of DuPage)

Saturday Morning to Evening

As we head into tomorrow morning, things look to remain quite unstable as the energy from the remnants of Cindy approaches the area while the cold front to our east compresses all of the rich tropical moisture into a focal point, located right over our area. During the day today, the high resolution models have been keying in on a very heavy band of rain moving over portions of Pennsylvania, New Jersey, New York, and Connecticut by 7-10 am tomorrow. This band of heavy rain is directly associated with a mid level piece of energy currently located over portions of Kentucky, which will likely continue NE throughout the evening hours. A crucial point here is that since the energy already exists and is well sampled, the models likely have a decent grasp on the situation over the next 12-18 hours. Regardless, as this piece of energy nears our area tomorrow morning, we will have to monitor the situation very closely since any rainfall with this system will likely be quite intense, which could produce localized flash-flooding, and exacerbate and potential flooding issues caused by tonight’s storms.

Thankfully, the rain threat looks to quickly diminish later tomorrow morning, into the early afternoon hours. Any residual showers and thunderstorms look to press off to the east and offshore, leaving much drier conditions in their wake. With clearing skies, westerly winds, and warm low to mid level temperatures, temperatures should be able to climb into the middle 80’s with ease by late tomorrow afternoon, making for a nice rebound. Weak high pressure will be over the region Saturday night. Clear to partly cloudy skies are expect with lows in the 60s in many of the suburbs to lower 70s in NYC and urban areas.

Rapid Precision Models deception of this evening and tomorrow mornings heavy rain threats (Courtesy of WSI)

Rapid Precision Models deception of the possible heavy rain threats this evening, lasting into tomorrow morning (Courtesy of WSI)

Sunday and Beyond 

Sunday looks to be quite beautiful early on, with increasing sunshine during the early morning and afternoon hours and light winds from the west/southwest due to high pressure exiting off the Mid Atlantic coast. With the mid/upper level trough moving over the region during the day, slightly cooler temperatures aloft will limit just how warm temperatures can get, with highs likely reaching into the lower to middle 80s over much of the area. There is some potential for sea-breeze activity to knock temperatures down into the 70’s during the afternoon hours, but this will likely happen on a very small scale. Later in the day, a weak cold front looks to move through the area, and bring at least an increase in cloudiness, with an outside chance at a shower or weak thunderstorm towards the evening hours.

By Monday, troughiness will increase once again over the northern section of the Great Lakes region, which will likely usher in a cooler and much direr air mass compared to what we have been experiencing over the past few days. This area of below normal temperatures looks to continue into at least Tuesday, before we have to watch for the potential of a ridge building over the east, possibly by Wednesday. Mid level ridging may continue to build into the Northeast and Mid-Atlantic through end of the week, with more heat and humidity possible over the east.  As of right now, no significant precipitation or convection is expected, until the trough over Rockies finally shifts east into Northeast/Mid-Atlantic region by next weekend.

This afternoons European Ensembles showing a rather high likelihood of below normal temperatures for the first half of next week.

This afternoons European Ensembles showing a rather high likelihood of below normal temperatures for the first half of next week.

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: Unsettled Conditions Continue, Keeping An Eye on Tropical Storm Cindy

/1 Comment/by

Good Evening! 

As discussed back on Monday, some residual moisture and weak instability worked its way into the area during the morning and afternoon hours, and when coupled with some forcing just to our northeast, we saw scattered showers and thunderstorms develop across much of the region. These showers and thunderstorms had some decent dynamics to work with, with wind shear being high, lapse rates being quite steep, and the upper level jet streak being located in a favorable position for divergence aloft. Since these conditions came together just at the right time, we actually saw some strong to locally severe thunderstorms develop over New Jersey, Pennsylvania, and portions of Connecticut. A segment developed in Pennsylvania and went on to track east, leaving numerous wind damage reports in its wake. Further north, isolated cells developed over southern New York and went on to track into Connecticut, which brought a few small hail reports and isolated wind damage reports.

As of right now, these storms have begun to weaken and are moving off the coast as the best dynamics and instability begin to fade away. Despite the storms and occasional cloudiness, temperatures were able to rise into the low to middle 80’s across much of the area. The cold front which acted as the lifting mechanism for today’s storms will begin to move through the region and bring a drier airmass in its wake later this evening. Clouds should begin to diminish by sunset, which should allow temperatures to fall back down into the 60’s tonight, with lows in the 50’s possible farther north and east of the city.

This evenings latest high resolution visible satellite imagery, regional radar mosaic, and surface station plots, showing the bulk of the shower and thunderstorm activity pushing to the east.

This evenings latest high resolution visible satellite imagery, regional radar mosaic, and surface station plots, showing the bulk of the shower and thunderstorm activity pushing to the east.

Thursday into Friday 

Thursday should start off as a rather beautiful day with low humidity, clear skies, and light winds from the west. Weak high pressure at the surface and aloft will allow the area to stay mostly-sunny during the day tomorrow, with just some upper level cirrus clouds likely approaching the area. Temperatures aloft will be rather mild thanks to the ridging overhead, so expect to see highs in the low to middle 80’s once again tomorrow, except this time it will feel more pleasant due to the lower dew points. Later in the evening tomorrow, low level moisture advection will begin to overspread the area due to a weak warm front aloft. This moisture will be quite rich in nature, as the majority of it is being fed from the deep south and portions of the Gulf of Mexico thanks to Tropical Storm Cindy. Some elevated showers and thunderstorms may try to develop late tomorrow evening as the moisture feed begins to overspread the region, but at the very least it seems likely that clouds will increase in earnest tomorrow night. The increased cloudy skies and rich moisture feed will lead to low temperatures not really being able to fall all that much, with temperatures in the low 70’s likely across most of the area.

This afternoons Rapid Precision model, showing the potential for heavy rains associated with the remnants of Tropical Storm Cindy to affect the region on Friday and into Saturday (Credit: WSI)

This afternoons Rapid Precision model, showing the potential for heavy rains associated with the remnants of Tropical Storm Cindy to affect the region on Friday and into Saturday (Credit: WSI)

The forecast on Friday becomes quite complex as a strong northern stream disturbance begins to interact with the remnants of Tropical Storm Cindy, which will likely be situated over the Ozarks by Friday morning. The aforementioned warm front that we talked about for Thursday evening should be through the area by Friday afternoon, leaving most of the area with partly cloudy skies and warm temperatures once again.

Highs will likely be able to climb into the middle 80’s with ease, but the increasing moisture from the south will also raise the dewpoints over the area, possibly making for a very muggy afternoon. With sunshine likely during the afternoon hours and an abundance of moisture also in place, instability will build over the area, and will be accompanied by some modest wind shear over the area. The pieces will be in place for heavy showers and thunderstorms to go up over the area during the afternoon hours, but the item in question will be whether or not we have a direct trigger to set off any storms. At this time, it appears likely that an adequate amount of mid level energy will be in place to set off the development of some isolated showers and thunderstorms capable of producing gusty winds and very heavy rainfall rates, possibly causing some localized flooding.

As we head into the late afternoon and evening, the threat for more showers and thunderstorms will increase markedly as the direct remnant moisture from Tropical Storm Cindy begin to crash into a cold front located to our west. Again, the main question that will be determining whether or not we see widespread heavy rainfall comes down the need for a “trigger” mechanism. One possible outcome is that Cindy deteriorates after making landfall to the point that the systems energy is dissipated, and all that is left is just some moisture. This outcome would lead to showers and thunderstorms being more scattered during the later portion of Friday, but still have the potential for heavy, tropical downpours.

The second option would be that Cindy does maintain itself as a coherent and trackable system in at least the mid levels of the atmosphere. This would allow the residual lift from the decaying tropical storm to spark numerous showers and thunderstorms during the afternoon hours of Friday, and would carry a much greater threat of torrential downpours and localized flooding concerns. At this time, it is looking likely that what will happen will be a healthy blend of both scenarios, with Cindy retaining some mid level energy that will set off heavy showers and storms just to the west of the NYC area, which will have the potential to track eastward and put down some impressive rainfall totals in a short period of time. This solution is baked up by this afternoons European model and the American model. Since Cindy has not yet made landfall, this solution may still change, so be sure to stay up to date and check back again over the coming days! Also, please keep an eye on the latest NWS products in the event that Flood Watches are issued down the line.

Image showing very impressive amounts of water vapor being advected north over our area, which will greatly increase the threat of heavy showers and thunderstorms.

Image showing very impressive amounts of water vapor being advected north over our area, which will greatly increase the threat of heavy showers and thunderstorms.

Saturday and Beyond

Heavy showers and storms may continue into the early morning hours of Saturday and possibly even the afternoon as the cold front pushes through the area, dragging the rest of the deep tropical moisture with it. There are still some model difference on fast the cold front with tropical moisture moves offshore Saturday afternoon. If the front is slower, a more showers and thunderstorms could linger into Saturday afternoon. But latest model trends have been faster, so we are still leaning to more clearing skies by Saturday afternoon. More sunshine will help temperatures rise into middle 80s on Saturday afternoon.

The cold front and its associated moisture should then begin to shift well offshore, leaving an area of weak high pressure in its wake. Sunday should be quite pleasant, with clearing skies and highs in the lower 80’s, also accompanied by a much more comfortable airmass.

An active northern stream will keep conditions relatively unsettled for the foreseeable future, with a chance at a cool-down later in the week as well.

This afternoons European ensemble mean showing a shot at some cooler weather into the middle portion of next week (Courtesy of WeatherBell)

This afternoons European ensemble mean showing a shot at some cooler weather into the middle portion of next week (Courtesy of WeatherBell)

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

John Homenuk

PM Premium Update: Unsettled weather lies ahead

/by

It so often works this way, but it never gets old: Torrential rain and heavy thunderstorms one day give way to beautiful blue skies and drier air the next. Today was the latter in the sequence of days, but there is a flaw in the design of appreciating such a thing; the repetitiveness that lies ahead signals an unsettled pattern will continue. Yes, stormy days again appear on the horizon in the not-so-distant future, and the atmospheric pattern doesn’t look to let up.

Forecast models are in rather good agreement regarding the overall evolution of the pattern, suggestive that multiple disturbances will swing through the Mississippi Valley and Northeast States over the next several days. And while that my not necessarily mean a washout for the area, it will mean continued opportunities at precipitation and a lack of steady warmth. This comes as bad news for those who have been longing for summer’s heat to arrive.

Read more

Steven Copertino

Public Analysis: Severe Thunderstorms Ending This Evening, More Unsettled Weather Possible

/by

Good Evening! 

Over the past few hours or so we have seen the development of multiple rounds of strong to locally severe thunderstorms over much of the Northeast. These storms formed just ahead of a cold front located over portions of central Pennsylvania, with moderate to strong instability ahead of this front as well as some sufficient upper level dynamics superimposed over the Northeast. Some early morning storms were noted over portions of Northeast Pennsylvania, Northern New Jersey, and Southern Connecticut, but these storms were mainly heavy rain producers as the environment was not sufficiently destabilized from daytime heating yet.

At the time of this article, the last batch of strong thunderstorms were winding down over much of the area as the loss of surface heating in addition to the storms interacting with the marine air closer to the coast caused them to weaken quite a bit. From what we can tell as of right now, the vast majority of the storm reports from this afternoon were in the form of wind damage, although there have been very isolated reports that a tornado may have touched down in Berks County, Pennsylvania. This report will likely have to be confirmed by the NWS in the coming day. Otherwise, most of the wind damage was restricted to trees, which is quite common this time of year as saturated grounds and a full canopy of leaves can often lead to trees getting knocked onto property, or limbs being blow into power lines.

The main reason that today really lacked the “punch” of some of the more impressive severe weather events can be linked to two main things. First off, the amount of precipitatable water in the atmosphere was extremely high (on the order of 2″ in some places) and the lapse rates were quite low (the change of temperature as you get higher in altitude, which creates more substantial thunderstorm updrafts). This combination allowed the area to experience more tropical downpours than anything, as all the water would gather in the atmosphere, and due to the lack of strong updrafts, would quickly collapse to the surface, bringing very heavy rain and strong wind gusts. Another element that seems to have caused a rather lackluster event was the fact that we saw clouds develop early in the afternoon hours, which really limited the amount of surface heating that could occur before thunderstorms started to blossom over the area. Had there been more distinct clearing ahead of the main line, this event would have likely produces numerous/widespread wind damage reports over the region.

This evenings latest radar satellite and surface observations showing some heavy thunderstorms still over the region. These storms will likely be capable of producing torrential downpours and some gusty winds.

This evenings latest radar satellite and surface observations showing some heavy thunderstorms still over the region. These storms will likely be capable of producing torrential downpours and some gusty winds.

Storms will likely continue through the overnight hours for some southern and eastern locations as strong upper level divergence allows the strong tropical moisture to form heavy showers along any remaining convergence boundaries that are left over the region. The main threat from these showers and thunderstorms will likely be limited to very heavy rain and frequent lightning, though some strong winds cannot be completely ruled out just yet. Any lingering showers and thunderstorms should begin to gradually fade and shift eastward late this evening and into the very early morning hours as a cold front continues to press over the area.

Tuesday morning should start off relatively dry as stout westerly winds usher in a much drier air-mass than what we have been dealing with over the past few days. With this direr air aloft in place, much of the area should experience mostly sunny conditions, with some gusty winds developing by the late morning and afternoon hours in response to a vertical temperature gradient brought about by a mid level trough passing to our north. Despite the gusty winds, tomorrow will still have some degree of humidity left to it, though it won’t be able to rise to levels even close to the past few days. These combined condition’s should allow temperatures to rise into the low to middle 80’s across the entire region.

Wednesday will feature much of the same as the previous day, with early morning clear skies, giving way to some cumulus clouds likely developing by the mid afternoon hours. With some weak instability and moisture in place and a trigger to the north, we may see some scattered shower and thunderstorm development over the Northwestern portions of the region during the afternoon hours. The main threats from these showers and potential storms looks to be heavy rainfall and gusty winds. Highs on Wednesday will likely be able to climb at least into the upper 70’s, with lower to middle 80’s quite likely for inland locations.

This evenings latest Rapid Precision Model showing scattered showers, and possibly even a shallow thunderstorm or two developing during the afternoon hours on Wednesday (Courtesy of WSI)

This evenings latest Rapid Precision Model showing scattered showers, and possibly even a shallow thunderstorm or two developing during the afternoon hours on Wednesday (Courtesy of WSI)

Thursday and Beyond

An area of mid level ridging is likely to build over the region into Thursday and Friday, which should allow more sunny weather and warm temperatures to persist. Temperatures should easily be able to rise into the lower to middle 80’s for both days, with a chance at some afternoon showers and thunderstorms possible as moisture from down south begins to head towards our region.

This moisture is associated with what is currently “Potential Tropical Cyclone 3”-or the precursor to a tropical storm. This system was located over the central Gulf of Mexico as of 5pm EST with winds of 40 mph. This system is very large in nature and still lacks an organized low level circulation-though there are some indication that the system is trying to get its act together. This system will likely move north, and then west north west over the next 36-48 hours while lashing the Gulf Coast with copious amounts of heavy rain and gusty winds. By Wednesday or so, the system should be close to landfall along the Gulf Coast as a mid range tropical storm with winds likely around 50-60 mph.

After this system makes landfall along the Gulf Coast, the abundant moisture from this system will likely linger around the southeast for a day before a storm system moving through the Great Lakes drags a cold front through that area and potentially funnels that moisture towards our area in time for the weekend. Such a scenario could bring heavy tropical downpours on Saturday and Sunday, but at this time confidence is very low in such a scenario. We will continue to monitor this situation over the next few days and provide updates as needed!

This afternoons European model showing the potential tropical cyclones residual moisture being entrained along a cold front. There is a possibility that this moisture could eventually wind up over the Northeast later this weekend

This afternoons European model showing the potential tropical cyclones residual moisture being entrained along a cold front. There is a possibility that this moisture could eventually wind up over the Northeast later this weekend

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