Since 2012 on the 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 via Disqus on Weather Underground at You can see my Disqus feed at this link for my latest comments. Feel free to reply to me with your disqus account or e-mail at 

  • NCHurricane2009


Updated: Jul 2

*******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.**********

...TUESDAY JUNE 30 2020 4:29 PM EDT...

See area of interest sections below for areas in the tropical Atlantic being monitored for tropical cyclone development. Elsewhere...the models have grown into increasing disagreement about the possiblity of a surface low pressure to form in the western Atalntic in a couple of days to the southwest of area of interest be induced by the eastern divergence zone of the upper vortex currently over the northeastern United States. The CMC is the southern outlier with such a surface low pressure and the ECMWF is a northern outlier while showing it quickly transition into a non-tropical low pressure along the front tied to the upper vortex. Meanwhile the GFS and NAVGEM do not show such a low pressure forming...with the GFS instead showing the upper vortex shifting eastward fast enough to energize area of interest #2 with the vortex's eastern divergence zone. Therefore I do not plan on marking another area of interest to the west of area of interest #2 at this time.

Computer models also suggest by next week...another subtropical or tropical disturbance could emerge with the support of the upper vortex that has recently moves into the central United States from the southwestern United States. However the latest model trends suggest the disturbance will stay inland over the southeastern United States...with only the GFS showing tropical cyclone formation in the western Atlantic offshore of the southeastern United States. Due to current model inconsistency...not considering this upper vortex an area of interest for tropical development at this time.

AREA OF INTEREST #1...The vigorous tropical wave of low pressure in the central tropical Atlantic has finally succumbed to the dry saharan air in the region while losing thunderstorm activity over the last 24 hours. Atmospheric conditions will also become hostile for tropical development as the wave moves into westerly wind shear being generated by central Atlantic upper vorticity. Because the wave has been removed from the National Hurricane Center tropical weather outlook and has hostile conditions ahead...this is my final statement on this feature on this blog.

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

IOH 24 Hr Outlook (1800Z Jul 1)...0% chance of tropical cyclone formation (Lesser Antilles near 15N-60W)

AREA OF INTEREST #2...Visible satellite animation suggests a broad surface low pressure spin centered at 32N-72W has formed either along or just ahead of the cold front being driven into the western Atlantic from the northeastern United States. This is due to ongoing upper outflow support induced by the upper ridging out ahead of the front. However the intensity of the thunderstorm activity is limited and appears to be sheared to the southeast of the center due to upper-level winds around the periphery of the upper vortex driving the aforementioned front. The evolution of this surface low pressure will largely depend on how the upper vortex evolves...and the models still disagree on exactly how this will happen. But altogether it appears the models show this surface low becoming better defined in the open northwestern Atlantic at the northeastern extent of the warm Gulf stream waters in the vicinity of 38N-65W in 48 hours. Therefore I have slowed the northeastward speed of the surface low pressure in my updated outlook below to come into aligment with those coordinates at 48 hours. When studying the 1200Z GFS upper-level wind animation...the increased definition of the surface low in 48 hours maybe due to the upper vortex shifting offshore closer to the surface low where it could energize it with its eastern divergence zone. I have peak odds of tropical cyclone development at 15% in 72 hours when the shear around the upper vortex may drop if the upper vortex becomes less elongated and more circular as the 1200Z GFS model run suggested. I drop odds of development to 0% by 96 hours as the surface low moves northeastward into cooler waters and has a higher likelihood of losing tropical characteristics while merging with the front driven by the upper vortex and also by that time a high-latitude upper trough that moves around the central North American upper ridge while diving southward into southeastern Canada.

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

IOH 24 Hr Outlook (1800Z Jul 1)...5% chance of tropical cyclone formation (northwest of Bermuda near 35N-68W)

IOH 48 Hr Outlook (1800Z Jul 2)...5% chance of tropical cyclone formation (northwestern Atlantic near 38N-65W)

IOH 72 Hr Outlook (1800Z Jul 3)...15% chance of tropical cyclone formation (northwestern Atlantic near 39N-61W)

IOH 96 Hr Outlook (1800Z Jul 4)...0% chance of tropical cyclone formation (northwestern Atlantic near 41N-57.5W)


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

1200Z CMC Model Run...For area of interest tropical cyclone formation shown. For area of interest #2...low pressure forms near 38.5N-67W in 36 hours...loses its identity near 41N-61W in 48 hours. Elsewhere...broad surface low pressure forms offshore of the Carolinas in 48 hours...drifts east-southeastward and develops a weak but tighter center near 30.5N-73W in 96 hours...loses its identity west of Bermuda by 138 hours.

0000Z ECMWF Model Run...For area of interest tropical cyclone formation shown. For area of interest #2...low pressure forms near 38N-66W in 48 hours...transitions to non-tropical low pressure along southeastern Canadian front (currently the front just offshore of the northeastern US) while located just southeast of Newfoundland at 72 hours. Elsewhere...broad low pressure area forms offshore of the United States mid-Atlantic coast by 96 hours...consolidates into strengthening frontal cyclone at 40N-60W by 120 hours as front from southeastern Canada shifts southward into the broad low pressure area.

1200Z GFS Model Run...For area of interest tropical cyclone formation shown. For area of interest #2...tropical cyclone formation suggested near 39N-61W by 78 hours...drifts east-northeastward while a non-tropical frontal low pressure along southeastern Canada front (currently the front just offshore of northeastern US) forms to the northeast at 120 hours...the frontal low pushes frontal zone southward into potential tropical cyclone as both features moves east-northeastward into the open north Atlantic in the long range.

1200Z NAVGEM Model Run...For area of interest tropical cyclone formation shown. For area of interest #2...weak low pressure center shown forming near 40N-65W by 36 hours...loses its identity near 42N-60W by 48 hours.


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