MY 2023 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #27J (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.**********

...FRIDAY JUNE 30 2023 12:45 AM EDT...

The following is a special update on recent tropical activity in the Atlantic as I am currently on vacation. Note the forecasting below was completed on 1200Z Thursday… however I could not release this update until now due to vacation activities. Since 1200Z Thursday the thunderstorm activity associated with area of interest #12 has decreased… and its potential for tropical cyclone formation is reducing. 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 1630Z June 29 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 #12… A surface trough of low pressure in the western Atlantic… in the vicinity of 28.5N-62W as of 1200Z… continues to be supported by the eastern divergence zone of a lengthy upper trough. This feature continues to be monitored for tropical development as the supporting upper trough is amplified… which is keeping westerly wind shear levels low while at the same time the eastern divergence zone of the upper trough is aiding in thunderstorm generation. This system is being steered in 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. The surface trough continues to have a well-defined low-level circulation as seen by the CIMSS 850 mb vorticity product… while it also has seen an increase in thunderstorms… therefore I continue to assign higher peak odds of tropical cyclone formation (40%) than the NHC as of third writing. I drop tropical development odds to 0% once this system reaches water temps below 26 deg C at 48+ 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 24 hours… Bermuda may see coastal surf as this system passes just east of the island.

Update as of 12:45 AM EDT Friday… Since 1200Z Thursday the thunderstorm activity associated with area of interest #12 has decreased… and its potential for tropical cyclone formation is reducing. I now drop my peak odds of tropical cyclone formation to 25%.

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

IOH 24 Hr Outlook (1200Z Jun 30)… 40% chance of tropical cyclone formation (east of Bermuda near 32N-61.2W)

IOH 48 Hr Outlook (1200Z Jul 1)… 0% chance of tropical cyclone formation (western Atlantic near 34.5N-60.2W)

******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)...10%

...COMPUTER MODEL SUMMARY...

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

0000Z (Jun 29) CMC Model Run...

**For Area of Interest #12… evolves into a surface low southeast of Bermuda at 42 hours… evolves into a frontal low that curves northeast to 34N-60W through 120 hours

0000Z (Jun 29) ECMWF Model Run...

**Not available at above-mentioned source

0600Z (Jun 29) GFS Model Run...

**For Area of Interest #12… evolves into a surface low southeast of Bermuda at 18 hours and evolves into a possible tropical cyclone east of Bermuda through 45 hours… turns north-northeast to 36.5N-59W through 96 hours while transitioning into a non-tropical frontal low… becomes absorbed by additional frontal low approaching from the west through 120 hours

0600Z (Jun 29) NAVGEM Model Run...

**For Area of Interest #12… evolves into a surface low just south of Bermuda at 30 hours… turns north-northeast to 40N-58.5W through 96 hours while transitioning into a non-tropical frontal low… frontal low moves into southeastern Newfoundland at 132 hours