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 2020 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #151

*******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 OCTOBER 16 2020 2:17 PM EDT...

See area of interest sections below for multiple areas being monitored for tropical development.


Elsewhere...the current northeast Atlantic upper trough has amplified into an impressive and large upper vortex...with the amplification of the upper trough caused by the amplification of north Atlantic upper ridging in the warm sector of multiple frontal systems/upper troughs pivoting around the central North America upper vortex. While the northeastern Atlantic upper vortex will be cold enough to support thunderstorms over mild water temps...the latest model runs suggest the upper vortex will become elongated such that the surface frontal cyclone to be supported by the vortex will be elongated without a singular center needed for subtropical development. Therefore not adding another area of interest in the northeast Atlantic.


AREA OF INTEREST #1...The tropical wave of low pressure in the eastern tropical Atlantic has lost its defined spin...and the thunderstorm activity has become displaced to the northeast of the wave axis as southwesterly wind shear already begins to increase thanks to the arrival of the central Atlantic upper trough pushed toward this tropical wave by the upper trough tied to area of interest #2. Therefore tropical cyclone formation is becoming unlikely...and I have dropped my odds of development to 0%. This is my final statement on this tropical wave on this blog.

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

IOH 24 Hr Outlook (1200Z Oct 17)...0% chance of tropical cyclone formation (eastern tropical Atlantic near 13N-36W)


AREA OF INTEREST #2...The current western Atlantic upper trough is amplifying due to adjacent amplification of the current western Atlantic upper ridge and developing north Atlantic upper ridge in the warm sector of frontal systems supported by upper troughs pivoting around the central North America upper vortex. A fragment of the current northeast Atlantic upper vortex is also expected to retrograde southwestward into the western Atlantic upper trough which will re-enforce it. The amplifying upper trough is triggering the formation of a surface low pressure near 31N-55W with its increasing eastern divergence zone...with the new surface low aleady appearing consolidated with a comma shaped shower and thunderstorm mass on its north and east sides as we typically see in subtropical cyclone formations triggered by upper troughs. Therefore any idea that this surface low may be broad without a consolidated center because the upper trough was forecast to broaden with the arrival of the energy from the northeast Atlantic upper vortex is being tossed out...and I have significantly raised odds of subtropical cyclone formation to 70%.


Most of the model suite indicates that the surface low pressure will drift southwestward as the current north Atlantic surface ridge intensifies under the convergence zone of the developing north Atlantic upper ridge...and from surface ridges over eastern North America that will be supported by the western convergence zones of the other upper troughs to pivot northeastward around the central North America upper vortex. However the ECMWF shows a more east-weighted surface low in response to the chunk of energy to arrive from the northeast Atlantic upper trough...thus in my track forecast I am not as far west as the GFS-NAVGEM-CMC camp. Regardless of which camp of models is believed...this surface low pressure system over the next few days will be over open water between Bermuda and the northern Caribbean islands...and if the ECMWF is to be believed then this system could be even further from these land areas. Therefore I have not added any home page bulletins regaring land area impacts from this system.

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

IOH 24 Hr Outlook (1200Z Oct 17)...70% chance of subtropical cyclone formation (central Atlantic near 30N-55W)

IOH 48 Hr Outlook (1200Z Oct 18)...70% chance of subtropical cyclone formation (central Atlantic near 28N-56W)

IOH 72 Hr Outlook (1200Z Oct 19)...70% chance of subtropical cyclone formation (central Atlantic near 26N-57W)

IOH 96 Hr Outlook (1200Z Oct 20)...70% chance of subtropical cyclone formation (central Atlantic near 25N-58W)

IOH 120 Hr Outlook (1200Z Oct 21)...70% chance of subtropical cyclone formation (western Atlantic near 24N-61W)


AREA OF INTEREST #3...The current area of showers and thunderstorms in the western Caribbean Sea to the northeast of Nicaragua is supported by the divergence zone of a small upper vortex that has over the last few days broken away from the central Atlantic upper trough...thanks to the strength of the current western Atlantic upper ridge. This thunderstorm activity is expected to increase over the next few days once the small upper vortex dissipates...and as a part of the aforementioned upper ridge shifts southward into the western Caribbean Sea in response to the series of strong upper troughs to pivot around the central North America upper vortex...increasing the upper outflow needed for thunderstorms and low surface pressure. This could result in the formation of a tropical cyclone in the western Caribbean region in the long range. I only have low 10% odds of tropical cyclone formation and by day 5 as the models that do show development continue to gradually delay the formation of a defined surface low pressure...and two of the major global models...the ECMWF and NAVGEM...continue to not show development perhaps as they forecast the inflow of the low pressure system in area of interest #2 to interfere with the ability for inflow and thunderstorms to accumulate in the western Caribbean. Given that area of interest #2 is already developing quiet nicely on satellite pictures...there is a possiblity that this could be what actually happens. Since its not clear that a tropical cyclone will form in this region...I continue to withold putting statements for land areas in regards to this area of interest on the home page bulletins of this site.

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

IOH 24 Hr Outlook (1200Z Oct 17)...0% chance of tropical cyclone formation (western Caribbean Sea near 13N-80W)

IOH 48 Hr Outlook (1200Z Oct 18)... 0% chance of tropical cyclone formation (western Caribbean Sea near 13N-80W)

IOH 72 Hr Outlook (1200Z Oct 19)...0% chance of tropical cyclone formation (western Caribbean Sea near 13N-80W)

IOH 96 Hr Outlook (1200Z Oct 20)...0% chance of tropical cyclone formation (western Caribbean Sea near 13N-80W)

IOH 120 Hr Outlook (1200Z Oct 21)...10% chance of tropical cyclone formation (western Caribbean Sea near 13N-80W)


...COMPUTER MODEL SUMMARY...

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


0000Z CMC Model Run...For area of interest #1...no tropical cyclone formation shown. For area of interest #2...weak broad surface low forms near 30.5N-55W at 12 hours...drifts southwestward to 24.5N-65W by 120 hours while undergoing some strengthening. For area of interest #3...weak surface low forms in the western Caribbean Sea west of Jamaica at 162 hours...possible tropical cyclone formation suggested in long range. Elsewhere...tropical wave organizes into a tropical low pressure near 9N-40W at 150 hours.


0000Z ECMWF Model Run...For area of interest #1...no tropical cyclone formation shown. For area of interest #2...weak broad surface low forms near 31.5N-56W at 24 hours...drifts southwest and then northeast while undergoing some strengthening...reaching 29N-55W by 120 hours. For area of interest #3...no tropical cyclone formation shown.


1200Z GFS Model Run...For area of interest #1...no tropical cyclone formation shown. For area of interest #2...surface low drifts southwest while undergoing some strengthening...reaching 24N-63W by 120 hours. For area of interest #3...weak surface low forms in the western Caribbean Sea near 14N-80W by 120 hours...possible strong tropical cyclone forms while disturbance generally stationary by 168 hours.


0600Z NAVGEM Model Run... For area of interest #1...no tropical cyclone formation shown. For area of interest #2...surface low drifts southwest while undergoing some strengthening...reaching 25N-61W by 120 hours. For area of interest #3...no tropical cyclone formation shown.

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