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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 forecast 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 MAY 24 2024 2:50 AM EDT...

Even though the 2024 Atlantic Hurricane Season does not officially start until June 1... resuming daily birdseye view posts on the Atlantic tropics while the National Hurriane Center is monitoring a surface trough of low pressure in the vicinity of eastern Cuba and eastern Bahamas for signs of tropical development. See area of interest #2 section below for more information.

AREA OF INTEREST #2... The surface trough of low pressure currently in the vicinity of the eastern Bahamas and eastern Cuba originated from a supporting upper trough that was over the southwestern United States on May 16. By May 20 the upper trough had pivoted offshore into the western Atlantic from the southeastern United States with its eastern divergence zone producing a broad area of low surface pressures in the vicinity of the northwestern Bahamas... however regional westerly shear at the time was excessive as the upper trough was of low enough amplitude resulting in excess upper westerlies across the trough's east side. This resulted in the showers and thunderstorms being displaced southeastward away from the lowest surface pressures. After that time the upper trough began to amplify southward into the central Caribbean which resulted in a southeastward shift in the area of disturbed weather away from the Bahamas and into the central Caribbean... overspreading Hispaniola (Haiti and the Dominican Republic) and adjacent land areas. The amplification of the upper trough was in response to adjacent amplification of warm core upper ridging to the west within the warm sector of the North American frontal systems that are currently over eastern Canada (previously over the central US) and next frontal system that is currently heading into the central US. The amplification of the upper trough resulted in a reduction in westerly shear... allowing the disturbance to become better organized into a sprawling comma-shaped cloud mass through Wednesday May 22 and Thursday. The lowest surface pressures... now a southwest-northeast tilted surface trough axis in the vicnity of eastern Cuba and the eastern Bahamas... has become more collocated with the head of the comma-shaped system under the reduced shear and by 8 AM EDT Thursday the NHC has begun to mention this system in their tropical weather outlook. This marks the second tropical Atlantic area of interest tracked on this site this year.

Going forward this system is expected to accelerate northeast into the waters southeast of Bermuda and into the open central Atlantic as the north half of its supporting upper trough pivots in that direction ahead of the upstream upper troughs currently approaching from eastern Canada and central North America... a piece of energy from the central North America upper trough in fact will soon seperate and chase this system. Over the next 48 hours westerly shear over this system will be increasing due to the upper westerlies ahead of the approaching upstream upper troughs/energy. During this timeframe I agree with the NHC in showing a low 10% odds of tropical cyclone formation due to the increasing shear. In addition the GFS model which has been the most aggressive in developing the surface low pressure area has recently backed off... and the recent ECMWF which hardly shows development while depicting an elongated surface low pressure area may have the right idea as the CIMSS 850 mb vorticity product ( shows this system is elongated toward the surface (instead of a well-defined center needed for tropical cyclone formation) in response to the elongated divergence zone of the parent upper trough... and the forecast upper wind fields shows the parent upper trough continuing to have an elongated divergence zone over the next 48 hours while its north half ejects northeastward. I end my outlook by 48 hours (bring odds of development to 0%) when this system reaches waters below 26 deg C... as the parent upper trough is too warm (200 mb heights well above 1200 dekameters) to support instability and tropical development over water temps below 26 deg C.

It is worth noting that over the next week (through May 31) this area of interest may make a comeback as a tropical entity in the open central Atlantic. Initially this area of interest will transition into a non-tropical frontal system supported by the approaching eastern Canada upper trough. Through 7 days models indicate this upper trough and its associated cold air will amplify southward into the central Atlantic in response to upstream amplification of warm core upper ridging to the west in the warm sector of what is currently the vigorous central North America upper trough and associated surface frontal systems. The low shear nature of the forecast high-amplitude central Atlantic upper trough... combined with its de-stabilizing cold upper air temps... may allow this area of interest to transition back into a tropical system while over water temps below 26 deg C. The recent 1800Z GFS model run was explicit in showing this idea... therefore we may not be done with this area of interest after the short-term 48-hour window passes... stay tuned.

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

IOH 24 Hr Outlook (0000Z May 25)... 10% chance of tropical cyclone formation (western Atlantic near 26N-70W)

IOH 48 Hr Outlook (0000Z May 26)... 0% chance of tropical cyclone formation (east-southeast of Bermuda near 31N-60W)

*****National Hurricane Center ( official outlook as of 2 AM EDT***************************

Formation chance through 48 hours... 10%

Formation chance through 7 days... 10%


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

1200Z (May 23) CMC Model Run...

**For area of interest #2... surface low becomes established south of Bermuda near 28N-66W at 36 hours... subsequently moves northeast while transitioning into a non-tropical frontal low then cyclone located at 41N-40W by 168 hours.

1200Z (May 23) ECMWF Model Run...

**For area of interest #2... passes southeast of Bermuda as an elongated surface low through 60 hours... in long range (through 168 hours) the southwest part of the elongated circulation becomes a frontal cyclone near 39N-41W

1800Z (May 23) GFS Model Run...

**For area of interest #2... surface low becomes established south of Bermuda near 29N-65W at 33 hours... subsequently accelerates east-northeast while transitioning into a non-tropical frontal low then cyclone located west-southwest of the Azores... or near 36.5N-36W... at 168 hours

1800Z (May 23) NAVGEM Model Run...

**For area of interest #2... surface low becomes established south-southwest of Bermuda near 27N-68.5W at 24 hours... subsequently moves northeast while transitioning into a non-tropical frontal low then cyclone located at 41N-45W by 168 hours.

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