*******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 SEPTEMBER 16 2022 4:47 PM EDT...
The tropical wave of low pressure located well east of Tropical Storm Fiona... designated area of interest #29 in full update #102 from this morning... is developing a tropical low pressure spin at the north end of its axis. Odds are increasing that this tropical low pressure will develop in the open central Atlantic in the days ahead. Meanwhile refer to full update #102 available on the home page of this site for more information on tropical activity elsewhere in the Atlantic... including on Tropical Storm Fiona which is currently closing in on the northern Caribbean islands.
AREA OF INTEREST #29...True color visible satellite image of a tropical disturbance that has become well-defined on the north side of a tropical wave of low pressure and well to the east of Tropical Storm Fiona. Image taken at 1640Z:
The tropical wave of low pressure located well east of Tropical Storm Fiona... designated area of interest #29 in full update #102 from this morning... is developing a tropical low pressure spin at the north end of its axis. As a result I am using this special update to ramp up tropical cyclone formation odds for this new feature. A portion of the upper trough that has been interacting with ex-Earl has become cut-off into an upper vortex just northwest of the tropical wave due to a building western Atlantic upper ridge. It is probable the upper divergence on the southeast side of the cut-off upper vortex has helped to trigger the now-observed tropical low pressure spin on the north side of the wave. While transitioning into a feature supported by the divergent east side of the upper vortex... the tropical low is likely to turn north over the next 72 hours. I have low 10% odds of tropical cyclone formation during this timeframe as the modeling depicts an upper vortex elongated north-south... potentially resulting in an elongated upper divergence zone on the east side of the vortex that potentially elongates the tropical low itself such that the establishment of a tight center needed for tropical development becomes challenging.
By 96 hours... the major upper trough currently approaching from eastern Canada will have lodged a cell of western Atlantic upper ridging into the eastern Atlantic. A more focused area of upper divergence between the northeast corner of the upper vortex and northwest side of this eastern Atlantic upper ridge cell may allow for a more focused surface spin to develop within the tropical low pressure...and this is when I increase development odds to 20%. Once the major upper trough shifts northeastward and away into the northeast corner of the Atlantic at 120 hours... the eastern Atlantic upper ridge cell and remainder of the western Atlantic upper ridge have potential to bridge over this disturbance... providing a better upper outflow and lower shear environment needed for tropical development. This is when I raise odds of tropical cyclone formation further to 30% in this update. An increasing turn to the west is depicted at 96 and 120 hours as this disturbance rounds the north side of the upper vortex and responds to a building surface ridge to the north supported by the western convergence zone of the departing major upper trough.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Sep 17)...10% chance of tropical cyclone formation (central tropical Atlantic near 18.5N-45W)
IOH 48 Hr Outlook (1200Z Sep 18)...10% chance of tropical cyclone formation (central Atlantic near 22N-45W)
IOH 72 Hr Outlook (1200Z Sep 19)...10% chance of tropical cyclone formation (central Atlantic near 25.5N-45W)
IOH 96 Hr Outlook (1200Z Sep 20)...20% chance of tropical cyclone formation (central Atlantic near 27.5N-46W)
IOH 120 Hr Outlook (1200Z Sep 21)...30% chance of tropical cyclone formation (central Atalntic near 28N-49W)