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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 2023 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #3

*******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.**********


...WEDNESDAY JANUARY 25 2023 12:00 AM EDT...

Eastern Atlantic surface low pressure maintaining a well-defined center... monitoring this feature for acquisition of tropical characteristics within the next 48 hours. See area of interest #1 section below for more details.


As done on this site starting last year... I will be sequentially numbering up areas of interest for possible Atlantic tropical development throughout the year... resetting back to #1 at the start of each year. This scheme is so that each area of interest retains a numeric identity from update to update... which reduces confusion when simultaneous areas of interest begin and end when tropical activity increases particularly during the Atlanitc Hurricane Season. I have not counted the short-lived northwest Atlantic tropical event on January 16 as #1 as that system was expected to quickly shed its tropical characteristics and not become identified as a subtropical or tropical cyclone by the National Hurricane Center... instead I am identifying the area of interest discussed below as #1 for this year (refer to special update #0A available on the home page of this site for a report on the January 16th event).


AREA OF INTEREST #1... The eastern Atlantic surface low pressure that materialized yesterday with the support of a forming upper vortex in the region has whirled into a positioned directly below the vortex... and as of 0000Z its well-defined center was located at 28N-37W. Water temps in the region are in the low-20s of deg C while upper air temps associated with the vortex are rather cold and potentially de-stabilizing (overhead 200 mb heights are below 1200 dekameters... currently near 1180 dekameters). Therefore watching for the potential formation of core shower and thunderstorm activity which would indicate an increase in tropical characteristics of this system. So far the well-defined center of the surface low pressure has shown attempts at developing nearby activity... however the activity thus far has failed to wrap around the center while remaining lopsided to the southeast of the center. Off to the northwest... the cold northerly flow on the west side of a frontal cyclone that is now departing from Atlantic Canada is amplifying an upper trough over eastern Canada southward into the northwestern Atlantic and has de-amplified the warm core western Atlantic upper ridge... meanwhile the warm southerly flow on the east side of this frontal cyclone is re-enforcing the current warm core northeast Atlantic deep-layer ridge. Over the next 24 hours... southerly warm flow ahead of the currently developing winter storm over the eastern US is expected to re-amplify the western Atlantic upper ridge... which will in turn cause the aforementioned northwest Atlantic upper trough to further amplify further into a second upper vortex to approach the eastern Atlantic surface low pressure system from the northwest. The interaction with the second upper vortex will play a large role in the remaining lifespan of the eastern Atlantic surface low pressure of interest.


In regards to the track of this system... so far the well-defined surface low pressure center has accelerated southward. This is due to the overhead upper vortex's southeastern divergence zone dropping surface pressures to the southeast... with the well-defined center now being pulled around the larger adjacent area of dropping pressures. The forecast track in the outlook below is adjusted southward accordingly and suggests a counter-clockwise loop turn while the well-defined center first gets pulled southeastward toward the aforementioned area of dropping surface pressures in that direction... followed by the well-defined center taking a turn toward the west while then gravitated toward another area of dropping surface pressures to be associated with the southeastern divergence zone of the second upper vortex to approach from the northwest. The westward turn will also be aided by the merger between the re-amplifying western Atlantic upper ridge and current northeast Atlantic deep-layer ridge... resulting in a singular sprawling deep-layer ridge to the north that also steers this system westward. I suggest low 10% odds of subtropical cyclone formation as the current well-defined center could soon lose its identity to the aforementioned adjacent areas of dropping surface pressures... resulting in a remnant broad low pressure area that lacks a defined center needed for subtropical cyclone formation sooner rather than later. The upper layer of the steering deep-layer ridge is forecast to be southwest of the surface layer... resulting in a faster westward track of the surface low pressure system while the overhead upper vorticity in the region lags behind toward the east. By 72+ hours this will place the surface low pressure system underneath suppressive upper convergence on the west side of the upper vorticity... ultimately weakening what remains of the surface low pressure system by that time. As a result the I drop odds of subtropical development to 0% by 72 hours.

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

IOH 24 Hr Outlook (0000Z Jan 26)... 10% chance of subtropical cyclone formation (eastern Atlantic near 26N-35W)

IOH 48 Hr Outlook (0000Z Jan 27)... 10% chance of subtropical cyclone formation (eastern Atlantic near 26N-38W)

IOH 72 Hr Outlook (0000Z Jan 28)... 0% chance of subtropical cyclone formation (central Atlantic near 26N-43W)


...COMPUTER MODEL SUMMARY...

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


1200Z (Jan 24) CMC Model Run...

**For area of interest #1... current eastern Atlantic surface low pressure loses its current well-defined center and becomes broad while passing near 26N-35W by 18 hours... surface low subsequently accelerates westward and weakens to a surface trough while passing near 21.5N-44W by 102 hours.


1200Z (Jan 24) ECMWF Model Run...

**For area of interest #1... current eastern Atlantic surface low pressure loses its current well-defined center and becomes broad while passing near 23.8N-37W by 36 hours... surface low subsequently accelerates westward and weakens to a surface trough while passing near 25N-45W by 102 hours.


1800Z (Jan 24) GFS Model Run...

**For area of interest #1... current eastern Atlantic surface low pressure loses its current well-defined center and becomes broad while passing near 23N-37W by 30 hours... surface low subsequently accelerates westward and weakens to a surface trough while passing near 25N-45W by 111 hours.


1800Z (Jan 24) NAVGEM Model Run...

**For area of interest #1... current eastern Atlantic surface low pressure loses its current well-defined center and becomes broad while passing near 23N-35W by 36 hours... surface low subsequently accelerates westward and weakens to a surface trough while passing near 24N-44W by 72 hours


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