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Since 2012 on the now retired 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 at Yale Climate Connections via Disqus where the former Weather Underground community has moved to. Feel free to reply to me there, at my Disqus feed at this link, or via e-mail at 

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*******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.**********

...FRIDAY NOVEMBER 20 2020 9:54 AM EDT...

See area of interest section below for an update on the tail end of the current central Atlantic cold front currently being monitored for tropical development.

AREA OF INTEREST #1...The tail end of the cold front that lies across the central Atlantic remains located east of the Bahamas and north of the eastern Caribbean Islands. The upper trough associated with this front is leaving behind a cold core string of upper vorticity that will soon become an east-west oriented cut-off upper vortex in response to an adjacent amplified warm eastern US upper ridge to build ahead of another cold front that will pivot southeast across central Canada. As the upper vortex forms in the next 24 hours...upper divergence will increase and wind shear will reduce on the east side of the upper vortex...which could result in the formation of a tropical disturbance along the tail end of the current central Atalntic cold front. The forecast positions in the outlook below are based on the location of the upper divergence maximum on the east side of the forecast upper vortex in the 0600Z GFS model run from this morning. By 48+ hours...the upper ridge over the eastern US will erode as the cold front and upper trough over from central Canada approaches...which will cause the upper vortex to de-amplify as it merges with incoming upper trough...resulting in an increase in wind shear. Thus by 72 hours I drop odds of development to 0%. I forecast a very low 5% chance of tropical cyclone formation by 48 hours as there are no current signs of an organizing tropical disturbace along the tail end of the front such that development in the short term is not expected. The odds are kept low as their continues to be a lack of computer model support...with any of the models that show a closed surface circulation developing being too late in the window of time where shear increases...with absorption into the cold front arriving from central Canada not long after once the front moves into the Atlantic which would transition this system to non-tropical (see 0000Z ECMWF in the model summary below for example).

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

IOH 24 Hr Outlook (1200Z Nov 21)...0% chance of tropical cyclone formation (western Atlantic near 26N-64W)

IOH 48 Hr Outlook (1200Z Nov 22)...5% chance of tropical cyclone formation (western Atlantic near 27N-64W)

IOH 72 Hr Outlook (1200Z Nov 23)...0% chance of tropical cyclone formation (south of Bermuda near 30N-64W)


Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (

0000Z CMC Model Run... For area of interest tropical cyclone formation shown.

0000Z ECMWF Model Run...For area of interest #1...surface low consolidates at 26.5N-71.5W at 72 hours...quickly transitions to a non-tropical low along an incoming front to the northwest by 96 hours.

0600Z GFS Model Run...For areas of interest tropical cyclone formation shown.

0600Z NAVGEM Model Run...For areas of interest tropical cyclone formation shown.

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