BIRDSEYE VIEW POSTS

Since 2012 on the Weather Underground (www.wunderground.com) 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 www.wunderground.com/cat6. 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 IOHurricanes@outlook.com 

 
 
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MY 2020 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #84

*******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 media...watches 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.gov (hurricanes dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.**********


...FRIDAY AUGUST 7 2020 12:37 PM EDT...

See area of interest section below for a tropical wave of low pressure in the central tropical Atlantic being monitored for development.


Elsewhere...a tropical wave in the eastern Caribbean Sea in the vicinity of 65W longitude has seen a notable increase in thunderstorms while interacting with the eastern divergence zone of western Atlantic upper vorticity. Although the upper vorticity is forecast to shrink in size and concentrate over eastern Cuba...it is likely this tropical wave will remain sheared by the upper vorticity and none of the computer models develop it. However some heavy rainfall with flash flooding potential may occurr over Haiti and the Dominican Republic over the next day or so.


And finally...another tropical wave of low pressure in the vicinity of 50W longitude and approaching the Lesser Antilles islands has also seen an increase in shower and thunderstorm squalls due to divergence and outflow supplied by a tropical upper ridge in the region. Even though the wave has no computer model support showing development...will watch for signs of development as the tropical wave will remain in a low shear environment at a distance away from the eastern Cuba upper vorticity mentioned in the previous paragraph while crossing the Lesser Antilles and entering the Caribbean Sea. Will consider adding a statement on the home page bulletins on this site for the Lesser Antilles if the tropical wave shows an increase in vigor later today.


AREA OF INTEREST #1...A tropical wave of low pressure stretched southwest-to-northeast in the central tropical Atlantic has seen an increase in thunderstorms on its southwestern side induced by outflow and divergence of a tropical upper ridge in the region. Satellite imagery suggests a tighter spin may be developing on the east edge of this thunderstorm mass. Meanwhile the northeast part of the tropical wave is defined by an arc of clouds southwest of the Republic of Cabo Verde Islands but contains much less thunderstorm activity while more embedded in the dry saharan air layer...yet curiously the NAVGEM and GFS suggest some short-term development from this norheastern lobe of low pressure..followed by weakening in the long range. Based on current observations however I am more weighted to the more active southwestern lobe...but show an initially slow westward track while assuming the northeastern lobe will have some tug on it...then show a typical 5W longitude per day westward speed after 48 hours assuming that the two lobes will have melted together. I increase the northward angle of the track by 96+ hours as the eastern divergence zone of the south fracture of the eastern North America upper trough will move into the western Atlatnic and somewhat weaken the western part of the surface Atlantic subtropical ridge. I only slowly raise odds of development to low numbers through the forecast period due to the prevalance of the dry saharan air layer and weak model support as the CMC and ECMWF show no development...and NAVGEM and GFS show only a surface low pressuer forming. I stop raising odds of development at 72+ hours as the central Atlantic upper ridge will push upper vorticity currently in the northeast Atlantic toward the Lesser Antilles and in the path of this tropical wave...which may or may not make upper winds less favorable for development by 96 and 120 hours depending on exactly how much of this upper vorticity actually is present by that timeframe.

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

IOH 24 Hr Outlook (1200Z Aug 8)...5% chance of tropical cyclone formation (tropical Atlantic near 10N-42W)

IOH 48 Hr Outlook (1200Z Aug 9)...10% chance of tropical cyclone formation (tropical Atlantic near 10N-45W)

IOH 72 Hr Outlook (1200Z Aug 10)...15% chance of tropical cyclone formation (tropical Atlantic near 11N-50W)

IOH 96 Hr Outlook (1200Z Aug 11)...15% chance of tropical cyclone formation (tropical Atlantic near 12.5N-55W)

IOH 120 Hr Outlook (1200Z Aug 12)...15% chance of tropical cyclone formation (Lesser Antilles near 14N-60W)


...COMPUTER MODEL SUMMARY...

Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)


0000Z CMC Model Run...For area of interest #1...no tropical cyclone formation shown. Elsewhere...tropical wave of low pressure from western Africa shown to become a tropical low pressure near 10.5N-31W in 102 hours...possible tropical cyclone formation near 13N-40W in 162 hours.


0000Z ECMWF Model Run...For area of interest #1...no tropical cyclone formation shown.


0600Z GFS Model Run...For area of interest #1...northeastern and currently inactive portion of the tropical wave organizes into a tropical low pressure spin near 12.5N-39W in 48 hours...opens back to a tropical wave in 72 hours along 45W longitude...crosses the Lesser Antilles as a tropical wave in 120 hours.


0600Z NAVGEM Model Run...For area of interest #1...northeastern and currently inactive portion of the tropical wave organizes into a tropical low pressure spin near 14N-41W in 66 hours...opens back to a tropical wave shortly thereafter...crosses the Lesser Antilles as a tropical wave in 126 hours.

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