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

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

Atlantic Becomes Hyperactive, Irma Still a Potentially Catastrophic Category 5 Hurricane

Good Evening! 

The Atlantic has grown quite a bit from the past few months, from only being able to produce short-lived storms, to producing a record-shattering Category 5 and two more hurricanes simultaneously! The last time that there were three active hurricanes in the Atlantic was back in 2010. Depending on the timing of each system, we may even have a slight chancre at seeing two or even three major hurricanes at once, a sign that conditions have really changed across the basin.

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Starting from the right, we have Hurricane Jose, which formed yesterday from an elongated area of low pressure associated with a tropical wave a couple days after Irma formed. Since yesterday, Jose has very steadily become more organized, with expanding upper level outflow, deep convection, and even a small eye popping out every once in a while. The system is currently in a pocket of light wind shear of around 10-15 mph, but there are some indication that the extremely large upper level outflow from Irma is blowing some of the thunderstorms to the east of the center, which may keep further intensification at a more gradual pace for the next 24 hours. Jose is in a weak area of steering relative to its position, so the movement of the next few days is expected to be generally west northwest before an upper level trough to the north of the system causes the storm to speed up a bit and even back away to the east by the weekend. This timing with the trough will be very important, since the hurricane is expected to be rather close to the same islands that Hurricane Irma devastated, and any deviation west in the track would result in the storm potentially affecting the islands. Environmental conditions around 15N look quite favorable for the storm to intensify into the seasons third major hurricane of the year, with the ECMWF, GFS, and HWRF all showing the storm becoming a strong hurricane in about 5 days.

This afternoons HWRF model showing Jose very close to the islands that were just affected by Irma (Courtesy of Weatherbell)

This afternoons HWRF model showing Jose very close to the islands that were just affected by Irma (Courtesy of Weatherbell)

By Monday, the storm should be well north of Puerto Rico and Hispaniola and over the open ocean. At this time, most of the reliable model guidance has steering once again breaking down, and we could see the storm once again drift to the east, but this time for a more prolonged period of time. If Jose were to drift underneath the subtropical ridge as it moves eastward, it would likely stick around for quite some time as it would have to wait for another trough to pick it up and drag it north. Land impacts for this system are low, but the Lesser Antilles should monitor the progress of this system due to the impacts of Irma. Overall, it looks like Jose will be a storm that should generally head out to sea over the next five days or so, then meander for at least another five days.

Infrared Satellite Imagery of recently upgraded Hurricane Jose over the Central Atlantic. Note the lack of upper level cirrus clouds on the western half of the storm due to the outflow from Hurricane Irma (Courtesy of Navy NRL)

Infrared Satellite Imagery of recently upgraded Hurricane Jose over the Central Atlantic. Note the lack of upper level cirrus clouds on the western half of the storm due to the outflow from Hurricane Irma (Courtesy of Navy NRL)

We now move on to Katia, which was designated as a tropical storm early this morning (around 5am) and has since rapidly intensified throughout the day, becoming a 75mph hurricane over the Bay of Campeche. Katia seems to have formed from a tropical wave interacting with the tail-end of a cold front draped across the southern Gulf of Mexico and into the Bay of Campeche. Given the time of year, how warm the ocean is, and the concave geography of the area, it really is no surprise that the system has taken off like it has.  The system is attempting to establish a southern outflow channel which is helping to ventilate the system, but the same cold front that spawned Katia is also producing a very high amount of wind shear on the northern side of the system. This shear should keep Katia from organizing too rapidly, but again with very warm waters and the southern outflow channel, it seems that the system should be able to organize gradually for the next 24 hours. After that, the system to begin to sink to the south and west, where shear may be substantially lower than it is right now. This could allow the system to organize more rapidly as it nears landfall late Friday and into the early morning hours of Saturday. With resources limited due to near-constant surveillance of Hurricane Irma, we may have to rely on satellite estimated for intensity, but regardless, I feel that the system has a medium potential to reach Major Hurricane status before making landfall on the Mexican coastline.

This afternoons rainfall projection from the HWRF model showing very heavy rainfall amounts just off the Mexican coastline. Katia will need to be monitored closely for a potentially deadly mudslide event (Courtesy of NOAA HRD/HWRF)

This afternoons rainfall projection from the HWRF model showing very heavy rainfall amounts just off the Mexican coastline. Katia will need to be monitored closely for a potentially deadly mudslide event (Courtesy of NOAA HRD/HWRF)

The primary threats from Katia will be extremely heavy rainfall capable of triggering deadly mudslides. Winds will also be a secondary concern depending on just how strong Katia can get, but due to the history of the region, the rainfall threat supersedes this.

IR shot of recently upgraded Hurricane Katia in the Bay of Campeche. Katia is likely to strengthen as it heads southwest over the next few days

IR shot of recently upgraded Hurricane Katia in the Bay of Campeche. Katia is likely to strengthen as it heads southwest over the next few days

Now for the main-ticket item…

Hurricane Irma has blown past all expectation over the past 24 hours after it rapidly intensified into a 185 mph Category Five storm just east of the northern Lesser Antilles. This is the strongest ever recorded hurricane outside of the Caribbean and Gulf of Mexico, and the eye of Irma went over the northern Leeward Islands last evening with devastating impacts. At the time of this article, there are no reliable fatality reports, but images and ground reports indicate that at least 90% of all infrastructure in Barbuda has been destroyed. An automated weather station reported wind gusts up to 155 mph shortly before being destroyed. Other islands have not reported much over the past 12 hours, likely due to the fact cell towers have quite literally been bent in half and destroyed.

Since moving through the islands, Irma has battled with some westerly shear in the mid levels of the atmosphere and even some dry air, but this did not halt the beast from once again dropping pressure back down to the 916mb level (down from the 920’s). Irma once again has good to excellent outflow in all quadrants, and very cold convection surrounding the eye. There are some indications on radar that the storm may be about to go through another eyewall replacement cycle, which may temporarily weaken the system. While the system may temporarily weaken, once the new eyewall forms, the windfield in the hurricane will likely expand quite a bit, which is what we have seen happen ever since this system left Africa.

Water Vapor imagery of Hurricane Irma with winds up to 185 mph winds. Notice the wispy blue clouds expanding from the north and south, indicative of a very favorable environment.

Water Vapor imagery of Hurricane Irma with winds up to 185 mph winds. Notice the wispy blue clouds expanding from the north and south, indicative of a very favorable environment.

Irma is located just to the north of Puerto Rico this evening and should continue heading west-northwest over the next 36 hours, near the coast of Hispaniola. This is an interesting position and situation, because the very large circulation of the hurricane will be interacting with the very tall mountains of the island. Depending on how close the center gets to the coast of Hispaniola, there may be some downsloping winds, which are cool winds coming down from the mountains and into the circulation of the storm. This is a topic that is not well modeled or talked about by the National Hurricane Center, but has the potential to weaken the storm for a small period of time. After the storm pulls away from Hispaniola, it should be nearing the southern Bahamas early Friday morning and into Saturday.

Conditions will be extremely favorable for the hurricane, with very warm waters of 30-32C, low shear, and a very moist environment. Even if Irma does weaken down to a Category 3, I see no reason why the storm would not be able to restrengthen into at least a Category 4 by Saturday. It is looking like Saturday also will be the critical point for the storm regarding whether or not it will directly impact Florida. The old solutions of the storm interacting with Cuba, and then potentially heading up the west coast of the state are now unlikely, and we now have a rough consensus that the storm will likely affect the eastern half of the state in some shape or form.

This afternoons model guidance suggests that once Irma is just north of the Cuban coast, a mid level disturbance in the central Plains will begin to rapidly drop south and into the Ozarks. This mid level system will begin to interact with Irma, bringing it northward by late Saturday. The key point in this forecast is just how far west Irma can get before it begins to interact with the mid level system. IF it is farther west than forecast, then the western half of Florida will likely feel the brunt of Irma. IF the storm is east, then it may scrape the east coast of Florida and eventually impact the east coast. This will be the crucial point in the forecast to focus on, and we likely wont know the exact details for a bit of time. However, the threat of Irma impacting south Florida is significant enough that those in the path should begin preparations by going over their hurricane plans, or potentially beginning to evacuate if you feel you need to do so or are told to do so. At this time, it seems that the chance of Irma impacting the US is almost unavoidable, and those from the Florida Keys to all the way up to North Carolina need to closely follow the progress of this system!

****When making decisions, always consult the National Hurricane Center, your local National Weather Service, government officials, and local Emergency Managers.****

This afternoons European Ensembles showing a variety of tracks, but with the vast majority of the members impacting Florida, as well as other states along the East coast (Courtesy of Weathernerds.org)

This afternoons European Ensembles showing a variety of tracks, but with the vast majority of the members impacting Florida, as well as other states along the East coast (Courtesy of Weathernerds.org)

We will have another update on all three storms on Friday! If you are in the path of the storm, please remain alert and be prepared!

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

Wednesday to bring another gem, another launch

The weather on Tuesday was amazingly comfortable, with plenty of sun and a light breeze. When we said earlier this week that the weather would be incredible this entire work week, we weren’t kidding. Another gem of a day is expected on Wednesday, as highs will moderate only a few degrees towards the lower to mid 70’s. A Canadian high pressure system will remain in control through Friday, and highs will rise a little bit each day as the airmass modifies. But clear skies and light winds are expected once again on Wednesday — making the midweek day especially pleasant. A chilly start can be expected once again for the morning commute on Wednesday, as lows will dip into the upper 30’s and 40’s in the suburbs for the second straight morning.

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