Posts

Steven Copertino

Maria and Lee Head Out To Sea, Beautiful Weekend on Tap for the Northeast

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Good Afternoon! 

Today is the first in a series of more Fall-like conditions over the East with mild temperatures, low humidity, and crisp/cool nights. An area of high pressure has moved into the area behind the cold front that passed the area a few days ago, and is providing very clear and calm conditions for the entire Northeast.  Our source region for the air mass overspreading the region is fresh from Canada, so expect these pleasant and drier conditions to last throughout the day and into the evening hours. Winds should be light, but generally out of the northwest for the remainder of the afternoon. With cooler mid level temperature and relatively sunny skies, most of the area should see temperatures get up to the upper 60’s to lower 70’s, with some cooler readings likely farther into New England.

Later on in the day, a weak but compact area of low pressure associated with a mid level trough will begin to push towards the area and bring an increasing chance of clouds by sunset. The mid level system with this area of low pressure is rather impressive for this time of year and would usually be a pretty impressive clipper system for the area if it were deeper into the year, but regardless this system will begin to increase the threat of showers and possibly even a low-topped thunderstorm across the area late this evening. The change in temperature from the ground, into the mid levels of the atmosphere is also rather impressive, and this could become further enhanced as the low nears the warmer coastal regions late this evening and into very early tomorrow morning. At this time we expect any of the heavier activity to be rather isolated, but we would not be surprised to see reports of gusty winds, heavy rainfall, occasional lightning, as well as the potential for some very small hail or graupel. This activity may become more focused over the LI sound and near Connecticut where the increased temperature differential may spark some more feisty showers and thunderstorms. Regardless, we should see overnight lows drop down into the lower to middle 50’s, with some area north and west likely getting down into the 40’s before dawn.

Loop of the current observations over the Northeast this afternoon showing relatively calm and cooler conditions. Also note the energetic low pressure system over the great lakes (CoD Weather)

Loop of the current observations over the Northeast this afternoon showing relatively calm and cooler conditions. Also note the energetic low pressure system over the great lakes (CoD Weather)

As we head into tomorrow and the area of low pressure degrades into a weak trough, we should see another area of high pressure begin to build into the Northeast as well as the Mid-Atlantic states for the remainder of the weekend. For both Saturday and Sunday, skies will be pretty much mostly sunny with some mid level clouds at times. Winds will also be light, but gradually shifting back to a more northerly component on Saturday afternoon, which should reinforce the overall drier weather. Highs will likely remain in the mid to upper 60’s across the entire area, with some locations near the city seeing highs reach into the lower 70’s. Overnight lows will have a much more crisp feel to them as radiational cooling takes over both nights and allows any heating gained during the afternoon hours to quickly radiate back into the atmosphere. Lows will easily drop into the lower to middle 50’s both evenings, with an enhanced potential for areas north and west to see temperatures drop into the 40’s as well. Overall, it should be an excellent weekend for any kind of outdoor activity with clear skies, light winds, and relatively dry weather.

Another area of strong ridging is expected to develop over much of the nation next week, and when looking at a mid level map one may think that we’ll return to the 80 degree highs that we had this week, but due to the juxtaposition of the ridge, we should see an area of high pressure develop to our north and east which will funnel in cooler onshore winds. This will pretty much put a cap on just how warm things can get next week, though we may have to deal with an increase in low level moisture once again and the potential for fog during the evening hours. At this time, it does not appear likely that there will be any heavy rain threats over the next seven days or so, but we will continue to monitor the latest trends and will have a full update on Monday!

ECMWF model showing a large area of ridging forming over the eastern third of the nation next week. Temperatures will likely be back to above-normal next week, but not as warm as this week.

ECMWF model showing a large area of ridging forming over the eastern third of the nation next week. Temperatures will likely be back to above-normal next week, but not as warm as this week.

Maria and Lee Not Long for This World 

Once mighty hurricanes Maria and Lee have been reduced to tropical storms this afternoon after accelerating northeastward into a region of increasing shear and decreasing sea surface temperatures. These system will continue to head off to the east over the next few days, before being absorbed by a larger non-tropical low pressure system that may eventually impact portions of Europe with gusty winds and heavy rainfall.

Behind these two systems we have a few area to watch, but nothing imminent to develop. There is a surface trough labeled invest 99L near the southern Florida coast that is producing a large area of disorganized showers and thunderstorms, but has not been able to organize significantly due to strong wind shear that will likely persist over the system during the next few days. Farther east, we have another tropical wave producing a large area of showers and thunderstorms just east of the Leeward islands. This system is also being impacted by strong wind shear from an upper level low to its west that should inhibit any significant development in the short term. However, both system will pose a threat for heavy rainfall and potential flash flooding, so please pay attention to your local NWS office for any flood watches or warnings.Lastly, the models have become less-certain regarding the development of a large tropical gyre forecast to form over the western Caribbean in the next week or so. This system would likely be quite large in nature and would take days to organize, but would still pose a significant threat for heavy rains and flooding. We have plenty of time to monitor future trends, but we still expect that this region of the Caribbean will have at least a medium chance for tropical cyclone development over the next 7-12 days.

This afternoons GFS model showing a very large monsoon gyre developing over the Caribbean in around a week or so. Any tropical development would likely be slow to occur due to the large nature of this system (Phillipe Papin)

This afternoons GFS model showing a very large monsoon gyre developing over the Caribbean in around a week or so. Any tropical development would likely be slow to occur due to the large nature of this system (Phillipe Papin)

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Have a great weekend!

Steve Copertino

Steven Copertino

Maria Finally Departs the Caribbean and Jose Fades. Whats Next?

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Good Evening

Back on Monday we highlighted the potential for Maria to become an extremely dangerous Category 4 or even 5 Hurricane before reaching the small island of Dominica in the Lesser Antilles, and unfortunately that is exactly what happened. Maria rapidly intensified into a Category 5 hurricane with 160 mph winds just before making landfall on the small island, and then preceded to head from SE to NW, leaving the entire island in its core for at least three hours. The storm was the second Category 5 land falling hurricane this season, tying the 2007 with Dean a Felix. Details are still very spotty, but the pictures, video, and first-hand accounts of Dominica are heart-breaking. Most, if not all of the homes on the island have suffered severe damage, with some houses being completely destroyed. Due to the topography of the island, devastating mud slides and land slides were common, which swept away homes, roads, and well-built concrete structures. Its hard to believe that we’d have a storm that would rival the total devastation that Hurricane Irma caused just a few weeks ago, but we could be looking at yet another situation  where an entire island community has seen complete devastation. With the peak of the Cape Verde season quickly coming to a climatotlogical end, we should see the frequency of storms impacting this region begin to wind down, but I would not be surprised to see one or two more systems during the month of October given the active state that we are currently in.

Damage from Hurricane Maria when it hit the island of Dominica as a Category 5 hurricane with winds of up to 160 miles per hour (Credit: The Guardian)

Damage from Hurricane Maria when it hit the island of Dominica as a Category 5 hurricane with winds of up to 160 miles per hour (Credit: The Guardian)

Due to the high, mountainous peak of Dominica and the amount of time that Maria spent traversing the island, the inner eyewall of the storm become disrupted and fractured, but not for long. On Tuesday the storm began to rapidly regain strength after dropping to a Category 4 hurricane. Recon missions throughout the day found that the storm had an incredibly compact eye of around 5-8 nautical miles and the winds rose from 155 mph to 175 mph during the course of the day, with the pressure falling to an incredible 908 millibars, making the storm the tenth strongest on record for the Atlantic basin.

Recon also released numerous dropsonde instruments which provide a vertical profile of various locations in the storm, and some of these probes happened to measure extreme winds of around 190-195 mph at the surface, but it is not certain whether these were instantaneous gusts or actually representative of the storms strength. Regardless, the storm began to approach the US Virgin islands late in the day on Tuesday and into the evening. Very deep convection began to develop quite rapidly around the center of the storm, and before long, concentric eye walls began to develop. This marked that the storm was about to attempt an eyewall replacement cycle before hitting Puerto Rico. It was clear that the storm would have issues completing this process and then intensifying once again due to the storms intensity and the size of the outer eyewall, but it also signaled for new dangers to arise. The storms wind field grew quite substantially as it approached Puerto Rico early Wednesday morning, causing the carious weather stations to be blown apart in addition to both weather radars on the island.

The storm raged ashore with winds in the 155 mph range, making Maria a strong Category 4 hurricane on the Saffir-Simpson scale. Maria went on to produce prolific flooding, wind damage, and cut a path of carnage across the island that would send all of its inhabitants into darkness as all of the power facilities went down during the storm. Details are also still rolling in slowly on the extent of the damage to the island, but it may be safe to say that the Puerto Rico that existed before Maria is no longer there. Estimates say that power may not be restored to some portions of the island for possibly up to 4-6 months. Additionally, much of the infrastructure will need to be rebuilt, which will be a daunting task in of itself. The next few weeks and months may be quite rough for the locals, but with resilience and endurance the people of the island will be able to overcome this disaster and restore their home to levels greater than before Maria.

GOES 16 imagery of Hurricane Maria making landfall on the island of Puerto Rico with winds of up to 155 miles per hour

GOES 16 imagery of Hurricane Maria making landfall on the island of Puerto Rico with winds of up to 155 miles per hour

Maria has since left the Caribbean, and land interaction along with an increase in vertical wind shear have been affecting the system. The storm weakened down to a Category 2 on Thursday, but has since regained some strength and is now a 125 mph Category 3 hurricane. The storm is currently located very close to the Turks and Caicos, producing winds up to tropical storm force on the islands along with torrential rainfall as it slowly heads NNW at around nine miles per hour. Maria should keep this heading over the weekend and into the early portion of next week, but some key aspects of this forecast remain in question. While it is quite likely Maria misses the United States, the American model has been trending strong with the riding out ahead of Maria in the past few runs, bringing the storm precariously close to the Outer Banks of North Carolina. Again, such a solution looks unlikely right now, but with the remnants of Jose still meandering around, we truly will not know just how close the storm passes to the east coast before it makes its famed passage out to sea.

Trend loop of the GFS model showing the westward trend over the past 5 runs (Courtesy of TropicalTidbits)

Trend loop of the GFS model showing the westward trend over the past 5 runs (Courtesy of TropicalTidbits)

So What Else? 

Well, we have the remnants of tropical storm Jose which has finally become post-tropical after 70 advisories by the National Hurricane Center. For reference, this storm has been ongoing since Hurricane Irma was north of Hispaniola! The remnants of this storm should gradually dissipate over the next few days and really should not be much of a threat besides increased wave action and showers. Elsewhere, Tropical Storm Lee has come back to life after shedding about three different low level circulations over the past three days and is located well out in the open Atlantic, just east of a large upper level low. Lee is an extraordinarily small system and is reminiscent of Hurricane Michael from 2012 in that of it is relying heavily on baroclinic process to form convection and strengthen. Given its size and the upper level conditions, I would give the storm a higher than normal odds of becoming a small hurricane over the next few days.

Lastly, our eyes turn to the western Caribbean as the month of September begins to fade. Medium and long range models are showing that this area of the Atlantic basin may become much more active during the next few weeks as a large area of upper level divergence sets up right over extremely warm sea surface temperatures of around 31-32 Celsius. This upper level divergence over very warm waters would promote a large amount of deep convection to form, which could eventually lower pressures in the Caribbean and cause a tropical system to form. This is all at least 8-12 days out at this point, but the signals are there that we should begin to monitor this region for potential tropical cyclone development as we near the beginning of October.

I will have a full update on Maria and any other threat that may pop up on Monday!

ECMWF model showing large scale rising over the western Caribbean in about 10 days. Conditions could become quite favorable for tropical cyclone genesis by this time.

ECMWF model showing large scale rising over the western Caribbean in about 10 days. Conditions could become quite favorable for tropical cyclone genesis by this time.

Have an excellent weekend!

Steven Copertino

Steven Copertino

Showers and Thunderstorms Possible, Hurricane Jose Still Meandering Over the Open Atlantic

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Good evening! 

Today was a transitional day for much of the area, as the remnants of Hurricane Irma and another mid level system congealed over the Ohio Valley, and worked to produce widespread cloudiness and isolated showers today. While this area of showers is mainly concentrated with the main mid-level system over the Ohio Valley, a warm front will be pushing in from west to east as we talked about last time, but looks to significantly slow once it crosses the Pennsylvania/New Jersey area as it feels the leftover high pressure just off the mid Atlantic coast. This warm front will have some small amounts of lift associated with it still, so showers will be possible for the remainder of the evening, with some showers having locally heavy downpours. The overall threat for heavy rain should be mitigated somewhat by residual subsidence and dry air, but any areas that experience these showers should expect a quick 20-30 minute period of at least steady rain. The combined factors look quite poor for any kind of flooding conditions, except for some very isolated ponding on roadways in the absolute heaviest showers.

Regardless, temperatures were able to get into the upper 70’s to lower 80’s across the area, despite some cloud cover in spots. One thing that was quite noticeable this afternoon and into the early evening hours, was the marked increase in low level humidties over the region. This due partly to the large breadth of leftover tropical air that has since collapsed outwards from the remnants of Irma and has since become entangled with the warm front. As we head into the overnight hours, the threat for showers will gradually diminish with time, and it appears the vast majority of the area should remain dry. Due to the increased low level moisture, it appears that overcast conditions and even some patchy fog will be possible, especially inland. Tonight’s conditions will be quite poor for radiational cooling to take place, so expect temperatures to stay in the low to middle 60’s for lows this evening.

This evenings latest high resolution visible satellite imagery, regional radar mosaic, and surface observations, showing only a few areas of showers lingering over the area (Courtesy of College of DuPage)

This evenings latest high resolution visible satellite imagery, regional radar mosaic, and surface observations, showing only a few areas of showers lingering over the area (Courtesy of College of DuPage)

Thursday Into Saturday

After meandering and festering over the Ohio valley for over two days, the large mid level trough associated with the remnants of Hurricane Irma will finally begin to lumber on east. This mid level system should continue to increase mid level moisture over the area, with PWATS nearing the 1.5 to 1.8″ range.  Depending on how much sunshine the area can get tomorrow, it is possible that the area can destabilize a bit, with 500-1500 joules/kg of SBCAPE possible. With the increased moisture, surface instability, and small amounts of enhanced lift from the mid level system, widespread shower and thunderstorm development may be possible as we head into the early to mid afternoon hours tomorrow. This activity would mainly be focused in a corridor from eastern Pennsylvania, southern New York, and fading into the NYC and Long Island area.  Shear will be quite meager with this decaying mid level system, so no severe thunderstorms are likely tomorrow. We may however see some isolated strong showers and thunderstorms capable of producing gusty winds, heavy rainfall, and very small hail. Additionally, these storms are expected to have a low threat of flash flooding due to their modest forward speed and PWATS being on the lower side of what we would want to see for any kind of flash flooding. Storms should reach their peak for the western areas around mid to late afternoon, with the activity translating to the NYC metro by late afternoon and into the evening. By this time, any stronger storms should have begun to weaken considerably at this point. Highs during the day will be in the upper 70’s to lower 80’s once again, with a muggy feel to the day.

Friday looks to be quite similar as the decaying mid level system pushes the last of its energy over the region. This should allow the slow-moving frontal boundary to move directly over the region during the afternoon hours on Friday, leading to more possible shower and thunderstorm development. Daytime heating and instability should pool up to the point where the meager amounts of lift should be able to trigger showers and an isolated thunderstorm to form over the area during the late afternoon hours, into the early evening. At this time, it appears that the greatest coverage for any showers and thunderstorms will be just to the north of the NYC metro area. Highs should once again reach into the upper 70’s to lower 80’s over much of the area, with lows ranging from the lower to middle 60’s.

By Saturday, a weak area of high pressure is expected to form over the area, providing an opportunity for warmer and drier conditions to take hold. Most of the Northeast should remain mostly sunny with light winds and high clouds during the weekend, possibly lasting into the early portions of next week.

NAM model showing the decaying mid level trough moving over the area, potentially sparking a few round of showers and thunderstorms

NAM model showing the decaying mid level trough moving over the area, potentially sparking a few round of showers and thunderstorms

Hurricane Jose

Jose is still meandering over an area between Bermuda and the southern Bahamas. Jose currently has winds of around 75 mph, just barely making it a hurricane. The system is still experiencing some strong vertical wind shear, separating the mid level center from the low level center, which is inhibiting any kind of strengthening, and should continue to do so until it can find a more favorable environment, if it ever does. Jose has completed a cyclonic loop and should begin to head off to the North starting tomorrow. The vast majority of the models take Jose well out to sea, but there have been some model runs showing an area of high pressure developing over Jose as it tries to escape out to sea. Instead of continuing north, the system slows down and begins to head westward towards the east coast. This is occurring in the Day 6-8 period on the models, so continuity and reliability is very low, and not much stock is being put into these operational runs. Only a minority of the EPS members show Jose making it to the US east coast, and such a scenario is extremely unlikely. Regardless, we will monitor the progress of Jose over the next few days. We will have an update on the system by Friday afternoon!

This evenings latest GOES 16 infrared imagery of Hurricane Jose, showing the storm located north of Puerto Rico with very cold cloud tops and a sheared appearance to the system. Jose should track generally north over the next five days or so.

This evenings latest GOES 16 infrared imagery of Hurricane Jose, showing the storm located north of Puerto Rico with very cold cloud tops and a sheared appearance to the system. Jose should track generally north over the next five days or so.

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Have a great evening!

Steve Copertino

Steven Copertino

Watching the Remnants of Hurricane Irma Over Georgia

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Good Evening! 

Hurricane Irma battered the Florida peninsula yesterday, first making landfall on the Florida Keys as a Category 4, then again later in the day near Naples as a Category 3. Though information is still rolling in on the extent of the damage in the state, it is pretty obvious that the entire state of Florida has been affected to some degree. After its final landfall in Florida, the storm began to expand its radius of tropical storm force winds quite a bit as the mid level system from Canada began to interact with the hurricane and started some extra-tropical processes. This only worsened the already massive storm surge that the hurricane carried with it during its long trek across the Atlantic. Places as far north as Charleston experienced storm-surge related damage, as well as power outages from Irma’s massive circulation. As is common with many intense hurricanes when they hit land, the amount of momentum that the storm had built up over the past two weeks will take some time to spin down, and that has been very evident today on radar and satellite.  If we look at radar images from the south, we can see a large area of rotation associated with the decaying low level circulation of Irma, as well as the more pronounced mid level circulation. This mid level circulation has been responsible for mixing down strong wind gusts to hurricane-force today across portions of the southeast, causing tree damage and numerous power outages.

Irma will continue to weaken over the next day or so, as it makes its way into the Tennessee River valley by Tuesday afternoon. The storm will be fully-extra-tropical (meaning that other process are sustaining the wind and convection and the storm in no longer fed by its warm-core) and quite large in nature. Showers and thunderstorms should extend all the way from Arkansas to portions of the southern Mid-Atlantic states like Virginia and Maryland. Some of the stronger showers and storms may be able to mix down some residual tropical storm strength gusts, and will also be capable of producing tropical downpours which may caused localized flooding of poor drainage areas and perhaps on roads. There is also a risk of tornadoes with any cells coming in from the feeder bands over the Atlantic. There have been some strong signatures observed over water during the past 24 hours, and a tornado watch has been issued for portions of the Southeast.

Please check with your local NWS office to stay on top of any watches or warnings that may be issued once the NHC declares the storm “post-tropical” and hands over the tracking to the folks at the Weather Prediction Center.

Hi-res Base Reflectivity imagery of the remnants of Hurricane Irma over the Southeast US

Hi-res Base Reflectivity imagery of the remnants of Hurricane Irma over the Southeast US

As Irma winds down late Tuesday and into Wednesday as the low begins to fully occlude and fill in, a warm front will progress from west to east over the Mid Atlantic states, and eventually into the Northeast. This front will begin to slow as it moves through Pennsylvania on Wednesday, due to the residual high pressure system just off the coast of the Mid Atlantic. This will cause numerous showers to form over the area, but as tropical moisture begins to fade, these showers should be on the more typical side, with steady rain and generally cloudy conditions expected.

As of right now, the most unsettled day across the eastern half of the nation appears to be on Thursday, when a little more surface heating may take place just ahead of the main area of mid level energy, and this could create a marginally unstable air mass supportive of weak thunderstorms and isolated downpours. Friday may feature more showers and possibly some thunderstorms over much of the Mid Atlantic and Northeastern states, but the overall area of coverage will depend on just how strong the mid level energy remains as it meanders over the next few days. Dry conditions may return this weekend, as an area of high pressure begins to build in from the west, which should kick the remnants of Irma out of the area and allow for more stable and clear conditions.

Evolution of the mid level remnants of Hurricane Irma over the next few days as it meanders across the eastern third of the country

Evolution of the mid level remnants of Hurricane Irma over the next few days as it meanders across the eastern third of the country

Hurricane Jose Wandering Over the Open Atlantic

Hurricane Jose is still out and about over the Atlantic, located to the north of Hispaniola and Puerto Rico. Jose has been experiencing significant wind shear due to the very rapid expansion of Irma’s outflow once it began to undergo an extra-tropical transition. Even in the face of this shear, the storm has been able to maintain hurricane intensity, and currently has winds of around 100 mph. The storm may continue to weaken as it begins to execute a very complex loop over the next few days due to a break-down of the steering currents from the remnants of Irma. This pattern is forecast to last until Friday or so, when the hurricane will once again be located just north of the Bahamas. It is at this point that the models begin to diverge significantly. Some models have the storm taking a hard right and heading out to sea, and others have Jose maintaining a more westerly motion by this weekends, which would put it uncomfortably close to the southeast US. This scenario would result in the storm also encountering more favorable conditions for re-intensification as an upper level high would be allowed to rebuild overhead.

While it is much too early to say what the overall outcome will be, there is plenty of time to watch this storm as it churns over the open waters of the Atlantic, with the only concerns being increased wave action and rip-tides. We will have more on this storm regardless if it becomes a legitimate threat to the east coast over the next few days!

Latest GOES 16 IR imagery showing Jose getting beaten up by shear from now Tropical Storm Irma's outflow (courtesy of weather.us)

Latest GOES 16 IR imagery showing Jose getting beaten up by shear from now Tropical Storm Irma’s outflow (courtesy of weather.us)

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