Since 2012 on the 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 via Disqus on Weather Underground at You can see my Disqus feed at this link for my latest comments. Feel free to reply to me with your disqus account or e-mail at 

  • NCHurricane2009


*******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 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 dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.**********

...WEDNESDAY MAY 19 2021 8:55 PM EDT...

A surface frontal low that has recently ejected southward from southeastern Canada and western Atlantic surface trough...features within the yellow-circled region in the above satellite image...are expected to coalesce into a surface cyclone to be initially supported by the eastern divergence zone of a cold core upper vortex...with the surface cyclone by 48 hours whirling westward into a position directly below the upper vortex. The upper vortex is expected to be cold enough for instability and thunderstorms...and in this environment subtropical cyclone formation east of Bermuda is likely...see birdseye view post #1 on the home page of this site for more details.

Meanwhile...this special update is to:

**Increase my odds of subtropical cyclone formation to 80% due to global model consensus (CMC...GFS....NAVGEM...ECMWF) showing the formation of a subtropical cyclone as of the 1200Z and 1800Z model cycle.

**Shift the forecast track westward closer to Bermuda per the latest 1200Z and 1800Z global model consensus (CMC...GFS....NAVGEM...ECMWF)

**Bermuda is more likely to sea coastal sea swells from this system Friday and Saturday...possibly lasting through Sunday

**If these trends next update will replace the outlook below with a subtropical cyclone formation forecast containing an intensity forecast instead of probabilities of formation

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

IOH 24 Hr Outlook (1800Z May 20)...0% chance of subtropical cyclone formation (western Atlantic near 32.5N-55W)

IOH 48 Hr Outlook (1800Z May 21)...70% chance of subtropical cyclone formation (western Atlantic near 33N-60W)

IOH 72 Hr Outlook (1800Z May 22)...80% chance of subtropical cyclone formation (east of Bermuda near 33N-61.5W)

IOH 96 Hr Outlook (1800Z May 23)...80% chance of subtropical cyclone formation (northeast of Bermuda near 35N-61.5W)

IOH 120 Hr Outlook (1800Z May 24)...0% chance of subtropical cyclone formation (absorbed by front moving into the northwest Atlantic near 39N-59W)

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