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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.**********

...WEDNESDAY NOVEMBER 20 2019 1:54 PM EDT...

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

TROPICAL STORM SEBASTIEN...Tropical Storm Sebastien northeast of the Lesser Antilles has continued drifting more westward and less northward...and is now north of the Lesser Antilles and northeast of the Virgin Islands. This seems to indicate the Atlantic subtropical ridge to the northeast has had more influence in steering Sebastien...but the latest satellite animations suggest that Sebastien is now pausing its westward track and is beginning to turn northward as the latest frontal low in the western Atlantic has finally captured the tropical storm. I have adjusted my forecast track southward due to the delay in the northward turn. The tropical storm remains under westerly shear that is keeping thunderstorms east of the center as the upper southwesterly winds ahead of the frontal low's upper trough are impinging from the west. However some strengthening of the tropical storm has occurred as the shear levels are somewhat reduced from the anticyclonic flow of the upper ridge axis the tropical storm is under...supported by the warm air advection ahead of the frontal low. In addition the eastern and southern outflow of the tropical storm is enhanced by upper vorticity lingering to the south and east. I continue to forecast a peak strength of 60 mph maximum sustained winds to occurr in the next 24 hours and just before Sebastien merges with the cold front driven by the frontal low as the increasingly north and then northeast forecast track will be moreso in alignment with the upper southwesterly winds which may help in reducing the shear...and the divergence zone on the east side of the frontal low's large upper trough may also aid Sebastien during this time. Some sea swells generated by Sebasiten may reach the shores of the Virgin Islands and northern Lesser Antilles in the next 24 hours...after which time this potential should diminish as Sebastien finally moves northward and away.

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

0 Hr Position (1200Z Nov 20)...50 mph maximum sustained wind tropical storm centered at 21.1N-61.7W

IOH 24 Hr Forecast (1200Z Nov 21)...60 mph maximum sustained wind tropical storm merging with cold front at 25N-60W

IOH 48 Hr Forecast (1200Z Nov 22)...Remnant frontal low centered at 30N-54W

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