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 #54

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


...MONDAY JULY 6 2020 1:17 PM EDT...

See Tropical Storm Edouard section below for the only active tropical cyclone in the Atlantic basin. See area of interest sections below for other areas being monitored for tropical cyclone development.


TROPICAL STORM EDOUARD...Edouard continues to remain an interesting specimen of a tropical storm while accelerating rapidly east-northeast across cooler 22 deg C waters and still having an impressive circular canopy of thunderstorms that covers the center and northeast half of the circulation. As of 11 AM EDT...the National Hurricane Center estimated maximum sustained winds have increased to 45 mph. Given the cooler waters...Edouard's support is likely coming from the eastern divergence zone of an upper trough materializing off to the west as two shortwave upper troughs (one over eastern Canada and the other over the west Atlantic) merge. Because of the tropical storm is moving rapidly east-northeast...this appears to be reducing...but not entirely eliminating...the shear from the upper trough that would otherwise normally tear apart the tropical storm. Edouard is moving faster to the east-northeast than the 0600Z GFS showed...so my 24-hour forecast point is a bit east of that model run. This forecast point would place Edouard over even cooler 18 deg C waters. Will assume that these water temperatures will finally cause Edouard's thunderstorm canopy and tropical characteristics to fizzle out...thus my 24 hour forecast point calls for Edouard to be a non-tropical frontal low pressure. Given that the ECMWF...GFS...and NAVGEM show strengthening...probably from the aforementioned support of the upper trough...I forecast additional strengthening to 50 mph maximum sustained winds by 24 hours. The ECMWF had a curiously strange solution of showing Edouard exploding into an intense tropical cyclone at 24 hours and then transitioning to a non-tropical system by 48 hours. Maybe this is due to the ECMWF severely over considering Edouard's thunderstorm canopy? Will ignore that model solution.

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

0 Hr Position (1200Z Jul 6)...45 mph maximum sustained wind tropical storm centered at 40.8N-50W

IOH 24 Hr Forecast (1200Z Jul 7)...50 mph maximum sustained wind non-tropical remnant frontal low centered at 47N-33W


AREA OF INTEREST #1...The broad surface low pressure in the northeastern Gulf of Mexico appearas to be advancing inland into the southeastern United States as its tighter circulation that was near Louisiana over the past couple of days is now seen moving northeastward into southwestern Georgia as a well-defined cloud swirl. This track is expected to generally continue from the steering influence of the western periphery of the Atlantic surface subtropical ridge. Based on the current northward angle of the track seen in satellite animation...I have adjusted the track to be further inland across the southeastern United States...then emerging over the western Atlantic waters offshore of the mid-Atlantic and northeastern United States where water temperatures are cooler. The more north track also increases the chances that this system transitions into a less tropical feature supported by the eastern divergence zone of the central Untied States upper vorticity...later on to be supported by the eastern divergence zone of a large shortwave upper trough to eject from the northwestern Canada upper vortex as this system paralles the northeastern United States coast in 96 hours. Therefore I have reduced my odds of tropical cyclone formation to 10%...and due to the more north angle in track have removed coastal Georgia from seeing possible impacts from this system on the home page bulletins of this site. There is one caveat though...that the current tight center seen moving into southwestern Georgia dissipates and the broad low pressure redevelops a tight center further south in more favorable upper-level winds for tropical development in between the central United States upper vorticity and Gulf of Mexico upper vorticity. If this were to occurr...I would begin to show higher odds of development once again.

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

IOH 24 Hr Outlook (1200Z Jul 7)...0% chance of tropical cyclone formation (northeastern Georgia near 33.5N-82.5W)

IOH 48 Hr Outlook (1200Z Jul 8)...0% chance of tropical cyclone formation (eastern North Carolina/South Carolina border near 34.5N-79W)

IOH 72 Hr Outlook (1200Z Jul 9)...10% chance of tropical cyclone formation (northern Outer Banks of North Carolina near 36N-76W)

IOH 96 Hr Outlook (1200Z Jul 10)...0% chance of tropical cyclone formation (just southeast of New Jersey near 38.5N-74W)


AREA OF INTEREST #2...The vigorous tropical wave of low pressure in the central tropical Atlantic currently en route to the southern Lesser Antilles apperas to be succubming to the dry saharan air to the north...while losing its northern outer band of thunderstorms and as the circular canopy of thunderstorms further south begins to weaken. Therefore despite being in an otherwise favorable environment of low shear and upper outflow beneath tropical upper ridging...I have dropped my peak odds of tropical cyclone formation to 20%. I gradually increase the northward angle in the forecast track of the tropical wave as it moves across the Caribean Sea as it reaches the western extent of the steering Atlantic surface subtropical ridge. I start tapering the odds of development down to 0% by 72 hours as the upper vorticity over the eastern Bahamas is forecast to shift southward over the tropical wave which would suppress its upper outflow.

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

IOH 24 Hr Outlook (1200Z Jul 7)...20% chance of tropical cyclone formation (over the southern Lesser Antilles near 13N-60W)

IOH 48 Hr Outlook (1200Z Jul 8)...10% chance of tropical cyclone formation (eastern Caribbean Sea near 15N-65W)

IOH 72 Hr Outlook (1200Z Jul 9)...0% chance of tropical cyclone formation (south of the Dominican Republic near 17N-70W)


...COMPUTER MODEL SUMMARY...

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


0000Z CMC Model Run...Tropical Storm Edouard not initialized within the adjacent broad frontal low in model run. For area of interest #1...consolidated low pressure center forms over the Georgia/South Carolina border in 54 hours...reaches the United States east coast at the North Carolina/Virginia border in 78 hours...reaches New Jersey in 120 hours. For area of interest #2...no tropical cyclone formation shown.


0000Z ECMWF Model Run...For Tropical Storm Edouard...shows it as an intense tropical cyclone in 24 hours at 42N-46W...reaches the northeast Atlantic as a much weaker non-tropical frontal low in 48 hours. For area of interest #1...surface low pressure center becomes defined on carolina coast in 72 to 96 hours...positioned just offshore of southeastern Maryland in 120 hours. For area of interest #2...no tropical cyclone formation shown.


0600Z GFS Model Run...For Tropical Storm Edouard...shows circulation strengthen in next 24 hours while reaching 44N-40W (will assume its non-tropical by this point)...reaches the northeastern Atlantic by 48 hours. For area of interest #1...surface low pressure center becomes defined on carolina coast in 72 hours...reaches Massachusetts by 120 hours. For area of interest #2...no tropical cyclone formation shown.


0600Z NAVGEM Model Run...For Tropical Storm Edouard...shows circulation strengthen in next 24 hours while reaching 44.5N-41.5W (will assume its non-tropical by this point)...reaches the northeastern Atlantic by 48 hours. For area of interest #1...surface low pressure becomes defined at the northern Georgia/South Carolina border in 66 hours...reaches United States east coast at North Carolina/Virginia border in 114 hours...shown strengthening while moving north-northeastward into Cape Cod Massachusetts by 138 hours (possibly as a non-tropical cyclone supported by the eatern divergence zone of an approaching shortwave upper trough). For area of interest #2...no tropical cyclone formation shown.

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