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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 22 2019 5:24 PM EDT...

See Tropical Storm Sebastien section below for details on the only active tropical cyclone in the Atlantic basin.

TROPICAL STORM SEBASTIEN...Despite the approach of a frontal zone to the west and its upper trough...Tropical Storm Sebastien's track has turned more eastward and less northward. This indicates that the surface ridge building behind the front appears to be influencing the steering as well. Therefore yet again the NHC official forecast and also my updated forecast track are adjusted southward. My updated track is based on the current angle of the tropical storm's track currently seen in satellite animation which suggests arrival to 28N-50W by 24 hours. Although the south part of the incoming front and upper trough is expected to fracture from its parent frontal low currently passing by southeastern Newfoundland while becoming jammed by both surface and upper-level ridges to the west and east...the south fragments of the front and upper trough are expected to continue eastward out ahead of the upper trough and surface frontal low currently over eastern Canada...therefore the current east-northeast track of Sebastien is generally expected to continue during the forecast period. The tropical storm has not been able to acquire additional strength while the southwesterly shear induced by the frontal upper trough increases as the frontal zone has moved even closer to Sebastien. It is curious that the maximum sustained winds and the thunderstorms have not weakened as the tropical storm crosses the 26 deg C isotherm into cooler waters. This is likely from the supportive divergence also induced by the frontal upper trough. Thus in my updated forecast track I hold onto Sebastien's tropical status for 24 more hours while also showing only gradual weakening. Even though Sebastien's track has been further south than previously thought...there still appears to be enough surface ridging to the east during the forecast period to drive Sebastien northeastward into the Azores on depending on the strength of what should be the remnant cyclone of Sebastien gusty winds and sea swells could be possible over the islands by then.

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

0 Hr Position (1200Z Nov 22)...60 mph maximum sustained wind tropical storm centered at 25.2N-55.3W

IOH 24 Hr Forecast (1200Z Nov 23)...50 mph maximum sustained wind tropical storm centered at 28N-50W

IOH 48 Hr Forecast (1200Z Nov 24)...40 mph maximum sustained wind non-tropical remnant low centered at 31N-45W

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