BIRDSEYE VIEW POSTS

Since 2012 on the Weather Underground (www.wunderground.com) blogs, I have been posting annotated "birdseye view" charts of the Atlantic basin, with a detailed explanation and forecasting that references the chart. From there you may know me as "NCHurricane2009." While I now do these "birdseye view" posts here, I will continue to do comments via Disqus on Weather Underground at www.wunderground.com/cat6. You can see my Disqus feed at this link for my latest comments. Feel free to reply to me with your disqus account or e-mail at IOHurricanes@outlook.com 

 
 
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MY 2019 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #140

*******Note that forecasts and outlooks in this post are NOT the official forecast from the National Hurricane Center (NHC). They are my own detailed views on the Atlantic tropics based on current observations and latest computer model runs. As such do not make decisions based on my posts...consult news media...watches and warnings from your local weather office...and any evacuation orders issued by local governments to make the most informed and best decisions. Visit the NHC website hurricanes.gov (hurricanes dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.**********


...FRIDAY SEPTEMBER 27 2019 1:50 PM EDT...


See Karen and Lorenzo sections below for all active tropical cyclones in the Atlantic basin. See areas of interest sections below for all other areas being monitored for tropical cyclone formation.


TROPICAL DEPRESSION KAREN...Looks like Karen is being tugged northeastward for a bit longer by the remnant low pressure of Jerry...but soon will take a turn to the west-southwest once the surface ridge moving into the western Atlantic from the eastern US takes over the steering. Water vapor imagery suggests generally dry air just north of Karen caused by upper convergence on the southwest side of an upper trough over eastern Canada/NE US...ejecting from the upper vortex over central Canada...as well as some dry air immediately north of Karen perhaps caused by convergence between the the northeast side of the cell of tropical upper ridging in the area and west side of the central Atlantic upper trough to the east. The thinking from the National Hurricane Center appears to be that the continued northeast track in the short-term will move Karen into enough northerly shear at the northeast corner of the upper ridge such that this dry air is wafted into Karen and kills it into a remnant low in the next 24 hours. My updated forecast track is shifted north and east...which the models also show... given that Karen is still moving northeast. My updated intensity forecast is also notably lowered...but still hangs on to Karen as a tropical cyclone for a longer time as by 48 hours Karen's latest forecast track will place the tropical storm directly below the center of the upper ridge cell where shear will be lower and upper outflow maximum. By 72+ hours...I then show Karen becoming a remnant low as the upper vortex to the west opens into a trough that shifts eastward toward Karen in the mid-latitude westerlies...with the shear from the trough killing the tropical storm. It is now quiet unlikely Karen will produce enough thunderstorm latent heat release to mimimize the effects of the cold core upper trough. The remnants of Karen are likely to degenerate into an elongated north-south surface trough supported by a large area of divergence on the east side of the upper trough...with the broadness of the surface trough making it unlikely that Karen would regenerate later on.

******Infohurricane.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********

0 Hr Position (1200Z Sep 27)...35 mph maximum sustained wind tropical storm centered southeast of Bermuda at 28.8N-59.6W

IOH 24 Hr Forecast (1200Z Sep 28)...35 mph maximum sustained wind tropical depression centered at 28N-59W

IOH 48 Hr Forecast (1200Z Sep 29)...40 mph maximum sustained wind tropical storm centered at 27N-63W

IOH 72 Hr Forecast (1200Z Sep 30)...35 mph maximum sustained wind tropical storm centered at 26N-67W

IOH 96 Hr Forecast (1200Z Oct 1)...Remnant low centered northeast of the Bahamas at 26N-72W


MAJOR HURRICANE LORENZO...Lorenzo appears to have peaked as a category 4 hurricane while flattening out at 145 mph maximum sustained winds overnight...with the satellite appearance degrading a bit as the hurricane battles with the upper trough in the central Atlantic. In fact the hurricane was recently downgraded a smidge to 140 mph maximum sustained winds. However I forecast Lorenzo to generally maintain its current strength in the next 24 hours as its tremendous thunderstorm latent heat release splits the upper trough in half...with Lorenzo potentially finding a spot of lower shear in between the split halves. Lorenzo's thunderstorm latent heat release looks like it will also keep the upper trough currently ejecting from the central Canada upper vortex...currently over the northeatern US/eastern Canada...at bay to the west. The gradual weakening I show after 24 hours has a little to do with some light shear out ahead of the aforementioned upper trough ejecting from eastern Canada/northeastern US when it moves toward Lorenzo...but really has more to do with increasingly cooler water temps along the forecast track as the upper trough is kept at bay by Lorenzo's thunderstorm latent heat release. The shearing upper southwesterly flow ahead of the aforementioed upper trough will try to nudge Lorenzo eastward...but the Atlantic subtropical surface ridge will prevent an eastward turn for the middle part of the forecast. Once Lorenzo moves past the surface ridge by 96+ hours...it will finally turn increasingly eastward toward the Azores. As it does so...a second a more vigoorous upper trough ejecting from the central Canada upper vortex will keep Lorenzo energized with tremendous upper divergence on its east side...thus transitioning Lorenzo into a formidable non-tropical remnant gale still packing hurricane-force winds. Therefore it appears damaging winds will overspread the Azores on Tuesdsay evening...interests here should continue to monitor the progress of Lorenzo carefully! My updated forecast track is nudged westward given Lorenzo's current position...and it appears the most significant effects from Lorenzo in the Azores will be towards the western islands.

******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********

0 Hr Position (1200Z Sep 27)...140 mph maximum sustained wind major hurricane centered at 19.4N-42.9W

IOH 24 Hr Forecast (1200Z Sep 28)...140 mph maximum sustained wind major hurricane centered at 22.5N-43W

IOH 48 Hr Forecast (1200Z Sep 29)...130 mph maximum sustained wind major hurricane centered at 27N-42.5W

IOH 72 Hr Forecast (1200Z Sep 30)...120 mph maximum sustained wind major hurricane centered at 31N-41W

IOH 96 Hr Forecast (1200Z Oct 1)...105 mph maximum sustained wind hurricane transitioning to non-tropical centered southwest of the Azores at 35N-36.5W

IOH 120 Hr Forecast (1200Z Oct 2)...95 mph maximum sustained wind non-tropical remnant gale centered north of the Azores at 46.5N-25W


AREA OF INTEREST #1...The surface trough of low pressure in the southwestern Gulf of Mexico continues to lack thunderstorms...albeit it briefly had a flare up of activity over the Yucatan last evening which has long since died down. It appears that this disturbance is tracking further south more toward Veracruz instead of Tamualipas...perhaps while gravitated toward a stronger tropical disturbance seen on satellite in the eastern Pacific offshore of Mexico's south coast. Although upper winds could become more conducive for the Gulf disturbance to develop as an upper ridge over Mexico overspreads the disturbance in the wake of the upper trough departing the Gulf of Mexico...tropical cyclone formation appears unlikely at this point as it will soon be approaching landfall. This is my planned final statement on this disturbance as an area of interest on this blog.

******Infohurricanes.com Outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********

IOH 24 Hr Outlook (1200Z Sep 28)...0% chance of tropical cyclone formation (just offshore of the east-central Mexico coast near 22N-96W)


AREA OF INTEREST #2...The thunderstorm activity of the tropical wave southeast of Hurricane Lorenzo has diminished in the last 24 hours...but could soon reach more favorable conditions beneath the cell of persistent tropical upper ridging in the eastern Atlantic. In the longer range...the current central Atlantic upper trough and perhaps a portion of the upper trough currently emerging from the northeastern US/eastern Canada could be pushed southward toward the Atlantic tropics by the strong upper anticyclone of Hurricane Lorenzo...although today's 0600Z GFS model run suggested less of this upper troughing reaching the tropics. However this will be my planned final statement on this tropical wave as an area of interest unless it later develops persistent thunderstorm activity under the cell of tropical upper ridging...especially if it also appears the aforementioned upper troughing will not negatively affect this tropical wave in the longer range.

******Infohurricanes.com Outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********

IOH 24 Hr Outlook (1200Z Sep 28)...0% chance of tropical cyclone formation (tropical Atlantic near 32.5W)

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