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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.**********

...SATURDAY NOVEMBER 23 2019 1:47 PM EDT...

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

TROPICAL STORM SEBASTIEN...Even though the thunderstorm intensity of Sebastien has lessened on colorized infrared satellite as the tropical storm accelerates northeastward into cooler central Atlantic waters...ASCAT pass data from late last night have forced the National Hurricane Center to slightly increase the intensity of Sebastien. Sebastien remains on the east side of a western Atlantic frontal upper trough which has recently split in half...and from this information it is likely that Sebastien's current strength has more to do with the supportive divergence zone of the upper trough. The southern split of this upper trough is expected to merge with the upper trough/surface frontal cyclone approaching from eastern Canada...with the combined system sending Sebastien northeastward over or very close to the Azores by Monday morning. With Sebastien expected to remain in the supportive eastern upper divergence zone of the combined system...and with the current intensity of Sebastien...I have raised my intensity forecast to show even slower weakening. I also expect the thunderstorm intensity to further reduce as the tropical storm moves into even cooler I forecast transition to a non-tropical frontal cyclone by tomorrow. Regarding track...we in the forecasting world have been caught off-guard as Sebastien's cloud swirl center was found to be northeast of previous estimates once the sun rose over the tropical storm this morning and visible satellite became available...thus all updated forecast tracks have been adjusted northeastward. Even the initiation of the 1200Z GFS model had Sebastien too far southwest. Hoever my updated forecast track is only a northward adjustment of the GFS as Sebastien is also moving more north and less east in recent satellite animation. Although the recent more northward jog suggests Sebastien may pass just north of the Azores by Monday morning...Sebastien has been full of surprises so the Azores should assume that the remnant frontal cyclone of Sebastien could pass over the islands on Monday with damaging gusty winds. Sea swells will also occurr on the islands regardless of whether Sebastien's center passes over or just north of the islands.

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

0 Hr Position (1200Z Nov 23)...65 mph maximum sustained wind tropical storm centered at 30.4N-47.7W

IOH 24 Hr Forecast (1200Z Nov 24)...60 mph maximum sustained wind frontal cyclone centered at 36.5N-40W

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