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 

  • 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.**********


Satellite image of quickly organizing tropical wave of low pressure (now tagged as Invest 92L) to the east of Hurricane Larry and southeast of the Republic of Cabo Verde Islands...taken at 1820Z:

The tropical wave of low pressure that has moved into the eastern tropical Atlantic from western Africa and behind Hurricane Larry has made a notable recovery while generating a concentrated thunderstorm mass with signs of rotation near 13.8N-20.2W. This could be due to the westward acceleration of Larry out of the region which has allowed this wave to have room to accumulate surface inflow needed for moisture and thunderstorms instead of competing with Larry. This wave has been introduced in earnest in the NHC tropical weather outlook as of 11 AM EDT due to its close proximity to the Republic of Cabo Verde Islands. This tropical wave will likely slow down and turn more west-northwest in track while caught in a developing surface ridge weakness to the north and northeast to be induced by the divergence zone of upper vorticity to be deposited by the current north Atlantic upper trough. While pushed around by mid-latitude upper ridging...this upper vorticity by 48+ hours is also expected to retrograde southwest toward this tropical wave which will likely increase the shear and also suppress the upper outflow of the wave as the upper vorticity shifts directly over the wave. However for the next 24 hours and before the upper vorticity arrives...I have already assigned 50% odds of development due to the current organized structure of the wave and current low shear and upper outflow induced by the tropical Atlantic upper ridge. This is higher than the NHC outlook product as of this writing which has 30% odds. Interests in the Republic of Cabo Verde Islands may see gusty winds and heavy rains over the next 24 particular toward the southern islands. After 24 hours...odds of development are trimmed down to 0% by 72 hours to reflect the approach of the unfavorable upper vorticity.

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

IOH 24 Hr Outlook (1800Z Sep 3)...50% chance of tropical cyclone formation (just south of the southwestern Republic of Cabo Verde Islands near 14.5N-25W)

IOH 48 Hr Outlook (1800Z Sep 4)...10% chance of tropical cyclone formation (west of the Republic of Cabo Verde Islands near 16N-27.5W)

IOH 72 Hr Outlook (1800Z Sep 5)...0% chance of tropical cyclone formation (eastern tropical Atlantic near 18N-30W)

For information on Hurricane Larry and the rest of the Atlantic tropics... refer to post #98 available on the home page of this site.

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