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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 #27H (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.**********


...TUESDAY JUNE 27 2023 1:45 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 1600Z June 27 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)… The remnants of Cindy continue on as a surface low/trough in the western Atlantic waters midway between the Lesser Antilles and Bermuda. As of 1200Z the NHC TAFB surface analysis and the CIMSS 850 mb vorticity product suggested the low-level center was near 24N-63.5W… however satellite imagery suggested a cloud swirl center near 25N-64.5W at the western edge of a thunderstorm burst which is also the center chosen for the NHC Tropical Weather Outlook. Westerly shear that has been plaguing Cindy has been reducing as the shearing cold core upper vorticity in the region has been weakening from prolonged isolation from high-latitude cold air. The reduction in shear is evidenced by increasing thunderstorm activity once again being able to fire near the low-level low pressure center… and I am continuing track and intensity forecasting for Cindy assuming that it will regenerate into a tropical cyclone. During the forecast period Cindy will be accelerating northward in strong deep-layer southerly flow between the west extent of the Atlantic surface ridge and approaching upper trough/surface frontal system nearing from the northeastern US. The upper trough will be amplified as to avoid excess westerly shear… instead potentially helping Cindy with its eastern divergence zone.


My updated forecast track is adjusted southwestward based on Cindy’s current position relative to the previous forecast. I have also continued with a slow intensification rate as the sea-surface temperature profile that lies ahead is not conventionally conducive for tropical development. Between Cindy’s current position and 31N latitude water temps are at the 26+ deg C threshold needed for tropical development… and a rather narrow band of 26 deg C at 38N latitude has recently developed in association with the Gulf Stream (https://www.nhc.noaa.gov/sst/). However between 31N and 38N water temps are at a lukewarm 22 to 24 deg C which makes tropical development more questionable… but it may still happen with the help of the divergence on the east side of the incoming upper trough as noted above. I transition Cindy to non-tropical as it closes in on Nova Scotia at 40+ north latitude where water temps rapidly drop into the teens of deg C. Noting the recent global model guidance has trended much more to the southeast and away from Nova Scotia for the longer range… this could be the models reacting to Cindy currently being further south of previous forecasts and thus the models now want to transition Cindy into a feature supported by the southern divergence region of the incoming upper trough instead of the northern regions of the upper trough. If the global model consensus remains this way or if future observations warrant… may have to make a shift to the long-range track forecast in future updates.


Regarding impacts:

(1) Interests in Bermuda should be aware of Cindy as it is expected to pass over the island. Timing for potential impacts (coastal surf… rain… wind) would be late tomorrow and into Thursday.

(2) Interests in Nova Scotia and New Brunswick should also be aware of Cindy as it could make landfall as a vigorous frontal cyclone in about four days. In this scenario surf could also spread to the northeastern US coast during this timeframe.

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

0 Hr Position (1200Z Jun 27)… Remnant low located at 25N-64.5W

IOH 24 Hr Forecast (1200Z Jun 28)… 40 mph maximum sustained wind tropical storm centered at 27.5N-66.5W

IOH 48 Hr Forecast (1200Z Jun 29)… 50 mph maximum sustained wind tropical storm centered just southwest of Bermuda at 32N-64W

IOH 72 Hr Forecast (1200Z Jun 30)… 60 mph maximum sustained wind tropical storm centered at 38N-65W

IOH 96 Hr Forecast (1200Z Jul 1)… Remnant frontal cyclone over Nova Scotia centered at 44.8N-63.5W

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

Formation chance through 48 hours...10%

Formation chance through 7 days (168 hours)...30%


AREA OF INTEREST #11 The tropical wave of low pressure currently moving westward into the Lesser Antilles island chain did not develop further in the last 24 hours… but will continue to bring squalls of heavy rains and possibly gusty winds over the next day or so. Tropical cyclone formation for this wave is not anticipated as it moves into westerly shear associated with the ongoing upper vorticity in the Caribbean and western Atlantic. This is my final statement on this system on this blog.

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

IOH 24 Hr Outlook (1200Z Jun 28)… 0% chance of tropical cyclone formation (eastern Caribbean Sea near 14.5N-63.5W)

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

Not in the official outlook


...COMPUTER MODEL SUMMARY...

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


0000Z (Jun 27) CMC Model Run...

**For Area of Interest #10… makes landfall over Nova Scotia as a weak frontal low at 114 hours

**For Area of Interest #11… no development shown


0000Z (Jun 27) ECMWF Model Run...

**For Area of Interest #10… remnant trough of Cindy redevelops into a surface low over Bermuda at 72 hours… subsequently accelerates north-northeast toward Nova Scotia while transitioning into a non-tropical frontal low and becomes absorbed by additional frontal low to the west while just offshore of Nova Scotia at 150+ hours

**For Area of Interest #11… no development shown


0600Z (Jun 27) GFS Model Run...

**For Area of Interest #10… remnant trough of Cindy redevelops into a surface low just southeast of Bermuda at 78 hours… evolves into weak frontal low northeast of Bermuda through 120 hours

**For Area of Interest #11… no development shown


0600Z (Jun 27) NAVGEM Model Run...

**For Area of Interest #10… evolves into weak frontal low east of Bermuda through 102 hours… frontal low turns east to 32.5N-57.5W through 120 hours

**For Area of Interest #11… no development shown

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