*******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 OCTOBER 21 2022 2:39 AM EDT...
A mid-latitude upper trough and associated surface low with thunderstorm activity is currently located in the open central Atlantic in the vicinity of 30N-40W. Meanwhile the upper ridge currently to the northwest of this system is expected to mature further into a deep-layer ridge to be bolstered by the warm sector of a sprawling Canadian frontal cyclone that is currently forecast to develop over the next 24 hours once the current eastern and central Canadian frontal lows merge. The deep-layered ridge will at first cut-off this system from the mid-latitude westerlies and cause it to evolve into a deep-layered low pressure system... with the deep-layered ridge subsequently accelerating this system west across the open central Atlantic and toward Bermuda over the next few days. The latest model consensus indicates that the westward-accelerating deep-layered low pressure system will be elongated instead of consolidated such that subtropical cyclone formation from this system is unlikely.
Elsewhere and over the next few days... the current upper trough over the eastern United States is expected to pivot offshore and subsequently evolve into a cut-off upper vortex in response to warm core upper ridging that amplifies to the north and northwest (this upper ridging will be associated with the warm sector of the sprwaling Canadian frontal cyclone mentioned in the prior paragraph and also the warm sector of a frontal cyclone forecast to develop over the western US). On the east side of the offshore cut-off upper vortex... wind shear is expected to be low and upper divergence is expected to be sufficiently high to generate a potentially organizing surface subtropical low pressure between the Bahamas and Carolinas. However models currently are not in agreement on whether or not the upper vortex will be circular or elongated... for instance an elongated upper vortex will result in an elongated and less organized surface subtropical disturbance. Therefore I have not declared a new area of interest in assocaition with this system as of this update... should later model runs trend toward a consolidated subtropical system or future observations warrant an area of interest will be added in future updates.
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/). For ECMWF model used Tropical Tidbits (https://www.tropicaltidbits.com/analysis/models/)
1200Z (Oct 20) CMC Model Run...
**Surface low in open central Atlantic accelerates southwest and then west and crosses Bermuda at 102 hours... located west of Bermuda near 32N-68W at 120 hours.
1200Z (Oct 20) ECMWF Model Run...
**Surface low in open central Atlantic moves southwest to 30N-41W at 24 hours... accelerates west as a weaker surface low/trough feature that passes just south of Bermuda at 96 hours and reaches 32N-70W at 120 hours.
0000Z (Oct 21) GFS Model Run...
**South part of eastern Canada upper vortex currently seperating as an eastern US upper trough... upper trough moves offshore of the southeastern US at 30 hours... at 30+ hours the upper trough amplifies into a north-south elongated upper vortex cut-off from the mid-latitude westerlies due to upper ridging to the north and northwest supported by the warm sectors of sprawling Canadian and western US frontal cyclones... eastern divergence zone of elongated upper vortex produces a subtropical surface low near 29.5N-76.5W at 42 hours... the subtropical surface low whirls west beneath the core of the elongated upper vortex where a lack of upper divergence causes it to weaken to a surface trough near 29N-77.5W at 78 hours.
1800Z (Oct 20) NAVGEM Model Run...
**South part of eastern Canada upper vortex currently seperating as an eastern US upper trough... upper trough moves offshore of the southeastern US at 24 hours... at 24+ hours the upper trough amplifies into a north-south elongated upper vortex cut-off from the mid-latitude westerlies due to upper ridging to the north and northwest supported by the warm sectors of sprawling Canadian and western US frontal cyclones... divergence zone on northeast quadrant of upper vortex produces a broad surface low near 26N-71W at 156 hours... broad surface low moves north-northwest and develops a better-defined surface low near 31.5N-71.5W at 168 hours.