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BIRDSEYE VIEW POSTS

Since 2012 on the now retired Weather Underground 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 at Yale Climate Connections via Disqus where the former Weather Underground community has moved to. Feel free to reply to me there, at my Disqus feed at this link, or via e-mail at IOHurricanes@outlook.com 

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MY 2022 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #164

Updated: Dec 5, 2022

*******Note that forecast 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.**********


...SATURDAY DECEMBER 3 2022 11:17 PM EDT...

Potential for a long-duration central Atlantic cyclonic storm is increasing... with the core of this system also potentially gaining tropical characteristics... therefore resuming daily birdseye view posts on this site. See area of interest #48 section below for more informtion on the forecast central Atlantic storm system.


New to this site this year... I will be sequentially numbering up areas of interest for possible Atlantic tropical development. In this scheme... will reset back to #1 at the start of next year (January 2023). The current area of interest in this blog post is designated #48 as the other numbers were used in previous birdseye view posts. This scheme is to reduce confusion as Atlantic tropical activity increases during the peak of the hurricane season... when multiple simultaneous areas of interest begin and end which previously required shuffling around the area of interest numbers from update to update.


AREA OF INTEREST #48...Over the last several days an amplified upper trough pattern has persisted over North America and northeast Atlantic. The warm sectors of surface frontal systems generated by the North American upper trough regime have been supporting a warm upper ridge pattern over the Gulf of Mexico and western Atlantic. Meanwhile some of the upper trough energy that ejected from North America this past week has become cut-off from the mid-latitude westerlies and in the central subtropical Atlantic thanks to the upper ridge. The eastern divergence zone of this cut-off energy has been generating a broad surface low with some shower activity in the vicnity of 25N-50W over the last few days. Elsewhere... the current north Atlantic upper trough which has also ejected from North America is also seeing its south side becoming cut-off by the upper ridge... in the western Atlantic to the southeast of Bermuda (the current batch of showers and thunderstorms southeast of Bermuda used to define this area of interest in the above birdseye view chart is being generated by the eastern divergence zone of the western Atlantic cut-off energy). The cut-off western and central Atlantic upper energy is expected to merge over the next 24 hours... however in previous days the models had been mixed on how to handle this energy:

(1) Some model runs suggested the aforementioned warm upper ridge (off to the west of the energy) would be less amplified... allowing the energy to simply become less cut-off from and more entangled with the current upper trough approaching from eastern Canada and current northeast Atlantic upper trough... with the entanglement between all of these features resulting in a series of upper divergence maximums/broad surface lows.

(2) Other models runs suggested the warm upper ridge being amplified enough to send a chunk of the current eastern Canada upper trough southeastward into the central Atlantic cut-off energy... further re-enforcing the cut-off energy. The more amplified upper ridge also keeps the cut-off energy isolated from the mid-latitude westerlies and keeps the energy itself also more amplified... resulting in a stronger and more focused divergence zone on the east side of the energy that spawns a central Atlantic surface cyclonic storm.

Recently the GFS... NAVGEM... CMC... and ECMWF models have converged on the latter solution which results in a central Atlantic cyclonic storm. Conditions in this scenario will be potentially conducive to the formation of a tropical core within the cyclonic storm... therefore with the recent model agreement I have declared the aforementioned upper-level energy as an area of interest for tropical development in the days ahead. This marks the forty-eighth tropical Atlantic area of interest I have tracked on this site this year.


Because the central Atlantic cyclonic storm has potential to form near 25N latitude where water temps are currently running at 26 deg C... thermodynamic conditions could be conducive for thunderstorm activity and acquisition of tropical characteristics. Once the storm drifts northeastward toward water temps below 26 deg C... the upper-level energy is forecast to be cold enough to maintain the potential for thunderstorm activity (200 mb heights forecast to be below 1200 dekameters). As is typically seen with a surface cyclonic storm supported by upper-level energy... the storm is forecast to whirl beneath the energy which will result in deep-layer cyclonic flow keeping wind shear levels also low enough for potential tropical development. Should the thunderstorms of the tropical core release enough latent heat to generate warm core outflow... the outflow could result in the intensification of this system's core into a fully tropical storm or hurricane (similar to Hurricane Martin which formed at the beginning of November). Due to the strong model consensus mentioned in the previous paragraph... in the outlook below I have already assigned a peak 50% chance that this system acquires tropical characteristics. Should the model consensus persist... I will be raising odds of tropical development further in future updates.


In the long range (120+ hours)... the warm upper ridge mentioned in the first paragraph of this discussion is currently forecast to force the current northeast Atlantic upper trough energy southwestward toward the energy of the foreast central Atlantic storm. Moreover the northwest side of the large outer surface circulation of the storm would also help pull the cold air associated with the approaching northeastern Atlantic cold-core energy southward. Should the upper-level energy of the storm and northeast Atlantic upper-level energy in fact merge in such a scenario... this will result in a strong upper trough that sends the central Atlantic storm toward the northeast Atlantic while the eastern divergence zone of the upper trough gives extended intensity and life to the surface storm. I drop odds of tropical development to 40% by the 120 hour mark as it is not clear yet if the upper trough will have a focused or elongated upper divergence maximum... with an elongated maximum resulting in an elongated circulation to the storm that would not allow it to qualify as a tropical system. Regardless of whether or not this system becomes classified as tropical or not... a strong and long duration cyclonic storm is anticipated for the central to northeast Atlantic in 3+ days which will be a concern for marine interests.

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

IOH 24 Hr Outlook (0000Z Dec 5)... 0% chance of subtropical cyclone formation (central Atlantic near 24N-54.5W)

IOH 48 Hr Outlook (0000Z Dec 6)... 0% chance of subtropical cyclone formation (central Atlantic near 25N-52.5W)

IOH 72 Hr Outlook (0000Z Dec 7)... 25% chance of subtropical cyclone formation (central Atlantic near 26N-52.5W)

IOH 96 Hr Outlook (0000Z Dec 8)... 50% chance of subtropical cyclone formation (central Atlantic near 27.5N-52.5W)

IOH 120 Hr Outlook (0000Z Dec 9)... 40% chance of subtropical cyclone formation (central Atlantic near 30N-47.5W)


...COMPUTER MODEL SUMMARY...

Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)


1200Z (Dec 3) CMC Model Run...

**For area of interest #48... consolidated surface low develops near 26N-54.5W at 60 hours... potential subtropical cyclone suggested near 27.8N-51W at 84 hours... potential hurricane suggested near 28.5N-52W at 102 hours... hurricane located near 28.8N-48.5W at 120 hours.


1200Z (Dec 3) ECMWF Model Run...

**For area of interest #48... conolidated surface low develops near 25.5N-54W at 60 hours... potential subtropical cyclone suggested near 28N-51.5W at 84 hours... subtropical cyclone strengthens further while reaching 29N-53W through 102 hours... subtropical cyclone shifts east to 27.5N-51.5W through 120 hours.


1800Z (Dec 3) GFS Model Run...

**For area of interest #48... eastern divergence zone of current western Atlantic cut-off upper trough causes current central Atlantic broad surface low to reform further west near 25.5N-56.5W through 42 hours... surface low gradually consolidates and strengthens to a potential subtropical cyclone located near 30N-53.5W through 84 hours... subtropical cyclone shifts east to 29N-48W through 120 hours.


1200Z (Dec 3) NAVGEM Model Run...

**For area of interest #48... current central and western Atlantic cut-off upper troughs merge with the eastern divergence zone of the merger intensifying the current central Atlantic surface low (near 50W longitude) and developing an additional surface low to the southwest near 24.5N-55W through 66 hours... the eastern of the two surface lows becomes the dominant while strengthening into a potential subtropical cyclone near 30N-50.5W through 96 hours... transition to potential hurricane suggested through 120 hours while system undergoes a cyclonic loop at this general location.

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