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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 #27I (Special Update)

*******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 JUNE 28 2023 10:45 PM EDT...

The following is a special update on recent tropical activity in the Atlantic as I am currently on vacation. While on vacation I will continue to issue special updates on active disturbances or tropical cyclones when possible... meanwhile refer to the National Hurricane Center website hurricanes.gov (hurricanes dot gov) for up to the minute latest information on the Atlantic tropics.


Satellite image as of 2230Z June 28 showing current areas of interest (AOIs)… along with a simplified surface analysis of surface low pressures (Ls)… high pressure ridges (Hs)… and fronts (red lines) based on the NHC TAFB surface analysis at the time. Blue-dashed lines and Ls are used to mark the location of upper vorticity:


AREA OF INTEREST #10 (REMNANTS OF CINDY)… Over the last 36 hours… the remnant surface trough of Cindy located in the open western Atlantic drifted further westward than previous projections… perhaps as it became a shallow feature pushed by the strong Atlantic surface ridge. In the upper levels the weakening upper vorticity axis in the region has recently merged with the upper trough pushing into the western Atlantic from the eastern US. The further west position of Cindy’s remnants now places it directly below the upper vorticity axis where there is a lack of supporting divergence… and the remnants of Cindy are no longer expected to re-develop (ex-Cindy was dropped from the NHC tropical weather outlook earlier on Wednesday). The risk of tropical development in the region has now transferred to new area of interest #12 discussed below… which is a new surface trough being generated by the eastern divergence zone of the upper vorticity axis. The dissipating remnant surface trough of Cindy meanwhile should continue north around the west extent of the Atlantic surface ridge… and this is my final statement on ex-Cindy on this blog.


For Bermuda… refer to area of interest #12 section below for potential impacts.


Interests in Nova Scotia are no longer expected to see impacts from a tropical system in the days ahead.

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

IOH 24 Hr Outlook (1800Z Jun 29)… 0% chance of tropical cyclone formation (western Atlantic near 29N-70W)

******National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT***************************

Not in the official outlook


AREA OF INTEREST #12… Over the western Atlantic the upper trough emerging from the eastern US is merging with upper vorticity that has been lingering in the region… resulting in a lengthier upper trough. The eastern divergence  zone of the upper trough is producing a new surface trough near 27.5N-62W now being monitored for tropical development as the upper trough itself is amplified… which is keeping westerly wind shear levels low while at the same time the eastern divergence zone of the upper trough may aid in thunderstorms and tropical development.


This system is expected to be steered by the southerly flow on the east side of the upper trough and west side of the Atlantic surface ridge… with the upper trough also advancing slowly east with time… which will result in a net north-northeast track of this system. At present the strongest thunderstorms in the region are just south of the surface trough. However the surface trough is beginning to have a well-defined low-level circulation as seen by the CIMSS 850 mb vorticity product… therefore I have assigned higher peak odds of tropical cyclone formation (40%) than the NHC as of this writing. I drop tropical development odds to 0% once this system reaches water temps below 26 deg C at 72+ hours… which combined with the ongoing interaction with the upper trough should cause this system to transition into a surface non-tropical frontal low.


Should a tropical cyclone form within the next 48 hours… Bermuda may see coastal surf as this system passes just east of the island.

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

IOH 24 Hr Outlook (1800Z Jun 29)… 30% chance of tropical cyclone formation (southeast of Bermuda near 29N-62W)

IOH 48 Hr Outlook (1800Z Jun 30)… 40% chance of tropical cyclone formation (east of Bermuda near 32.5N-61W)

IOH 72 Hr Outlook (1800Z Jul 1)… 0% chance of tropical cyclone formation (western Atlantic near 35N-60W)

******National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT***************************

Formation chance through 48 hours...10%

Formation chance through 7 days (168 hours)...20%


...COMPUTER MODEL SUMMARY...

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


1200Z (Jun 28) CMC Model Run...

**For Area of Interest #10… no development shown

**For Area of Interest #12… evolves into a surface low east-southeast of Bermuda at 48 hours… evolves into a frontal low that curves east to 32.5N-57.5W through 120 hours


1200Z (Jun 28) ECMWF Model Run...

**Not available at above-mentioned source


1200Z (Jun 28) GFS Model Run...

**For Area of Interest #10… no development shown

**For Area of Interest #12… evolves into a surface low east-southeast of Bermuda at 39 hours and possible tropical cyclone just east of Bermuda at 51 hours… turns north-northeast to 40N-60.5W through 120 hours while transitioning into a non-tropical frontal low


1200Z (Jun 28) NAVGEM Model Run...

**For Area of Interest #10… no development shown

**For Area of Interest #12… evolves into a surface low just north of Bermuda at 54 hours… through 120 hours evolves into frontal low that moves north-northeast to 42.5N-57W

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