*******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.**********
...TUESDAY OCTOBER 29 2019 5:37 PM EDT...
See area of interest section below for details on the strong non-tropical cyclone in the northwest Atlantic currently being monitored for acquisition of tropical characteristics. Elsewhere...the surface trough over the Gulf of Mexico is becoming supported by a vast region of upper divergence on the west side of the upper ridge axis in the region and out ahead of a large upper vortex over central Canada as it approaches landfall in Louisiana. With the expected landfall...tropical cyclone formation here is not possible...and this system in the next 48 hours will become assimilated into a rapidly strengthening frontal cyclone over the central United States(this frontal cyclone is forecast to form with the support of a lobe of vorticity swinging around the south side of the larger central Canadian upper vortex).
AREA OF INTEREST #1...The impressive frontal cyclone in the northwestern Atlantic has begun to weaken while under a lack of divergence beneath the central region of its parent upper vortex. The question remains as to whether or not the core of the decaying frontal cyclone will acquire tropical characteristics over the next couple of days. In the last 24 hours cold upper air temperatures of the upper vortex have allowed for pockets of thunderstorms to fire near the frontal cyclone's core despite being over mild water temperatures of 18 to 20 deg C...thus I have bumped up my odds of subtropical cyclone formation from 50% to 60%. To the west...there is enough upper ridging in the higher (more northern) latitudes within the eastern warm sector of a central Canada frontal cyclone such that the cold core upper vortex is beginning to split into southwestern and northeastern halves...and the frontal cyclone is observed beginning to dive southwestward from 42.5N-39W while whirling into the southwestern split of the upper vortex. Therefore my updated forecast track in the outlook below is nudged southward...with an eastward acceleration later on as models continue to agree that the split halves of the upper vortex will accelerate eastward while kicked by the nearing upper vorticity of the central Canadian frontal system. I drop the odds of subtropical cyclone formation to 0% by 72 hours as this frontal cyclone will likely be rapidly weakening while falling behind the eastward-accelerating upper vorticity...leaving the storm in unfavorable western convergence on the west side of the upper vorticity. Interests in the Azores can expect a round of coastal sea swells and possible gusty winds from now till Thursday. The gusty winds in the near-term would be from the large size of the strong frontal cyclone circulation despite being centered well west of the islands...and in the longer range would be from the circulation nearing the islands despite the storm circulation gradually weakening and shrinking.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Oct 30)...60% chance of subtropical cyclone formation (central Atlantic near 40N-40W)
IOH 48 Hr Outlook (1800Z Oct 31)...60% chance of subtropical cyclone formation (central Atlantic near 41N-35W)
IOH 72 Hr Outlook (1800Z Nov 1)...0% chance of subtropical cyclone formation (just north of the Azores near 42N-27W)