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 #146

Updated: Oct 13

*******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.**********   ...SUNDAY OCTOBER 11 2020 4:35 PM EDT...

See area of interest sections below for areas being monitored for tropical development. AREA OF INTEREST #1...The vigorous tropical wave of low pressure in the central tropical Atlantic has gradually seen an increase in organized thunderstorm bands around its low pressure spin...with the system supported by the outflow of a tropical upper ridge. In the updated outlook below I have initialized the lowest pressure of this system to be at 11.5N-45.5W as of 1800Z based on the curvature of the thunderstorm bands on satellite pictures. I have raised my odds of tropical cyclone formation to 40% due to the increased organization. Forecast track shows a northward angle in the westward motion from a developing surface ridge weakness to the north as the northwest Atlantic frontal cyclone has sent its main front into the open central Atlantic...and will send another front and its shortwave upper trough from the northeastern US into the central Atlantic as well. The frontal cyclonic system has also left behind an upper trough fragment to the north which will be re-enforced by another fragment from the northeastern US shortwave trough...with southwesterly shear from the upper troughing increasing as soon as 24 hours. Therefore if this tropical wave does indeed go on to develop...it will likely be a weak and sheared system. By 48 hours the shear should be too high for tropical development...so I end the outlook by then with 0% odds of development. ******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook*********** IOH 24 Hr Outlook (1800Z Oct 12)...40% chance of tropical cyclone formation (central tropical Atlantic near 13N-50.5W) IOH 48 Hr Outlook (1800Z Oct 13)...0% chance of tropical cyclone formation (central tropical Atlantic near 15N-55W)

Satellite image over Africa showing area of interest #2 as of 1800Z:

AREA OF INTEREST #2...Based on the latest satellite imagery...a tropical wave of low pressure over interior western Africa is near 10N-3W...and is expected to emerge into the eastern tropical Atlantic in 2 to 3 days where a tropical upper ridge with low shear and upper outflow will persist and may potentially aid in developing this wave. I retain low 20% odds of tropical cyclone formation by day 5 as the development signal from the CMC...GFS...and NAVGEM models remains weak...showing the development of a broad low pressure area instead of explicitly showing tropical cyclone formation. ******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook*********** IOH 24 Hr Outlook (1800Z Oct 12)... 0% chance of tropical cyclone formation (western Africa near 10N-8W) IOH 48 Hr Outlook (1800Z Oct 13)...0% chance of tropical cyclone formation (western Africa near 10N-13W) IOH 72 Hr Outlook (1800Z Oct 14)...5% chance of tropical cyclone formation (eastern tropical Atlantic near 11N-18W) IOH 96 Hr Outlook (1800Z Oct 15)...10% chance of tropical cyclone formation (eastern tropical Atlantic near 11.5N-23W) IOH 120 Hr Outlook (1800Z Oct 16)...20% chance of tropical cyclone formation (eastern tropical Atlantic near 12N-28W)

AREA OF INTEREST #3...An area of disturbed weather with some signs of organization has developed near 7.5N-32.5W over the last 24 hours. When the tropical wave in area of interest #1 emerged from Western Africa a few days ago...a large thunderstorm complex developed east of the wave axis. Perhaps this thunderstorm complex was yet another tropical wave to the east to area of interest #1  that had lost its definition in satellite pictures until today. This disturbance will follow behind area of interest #1 on a west-northwest track toward a surface ridge weakness...and likewise will be in a low shear and upper outflow environment in the near term and then reach a higher shear environment induced by central Atlantic upper troughing in the longer range. My odds of tropical cyclone formation are at a low 15% before the disturbance reaches the higher shear environment. I keep odds on the low side due to lack of computer model support...but will have to increase them further if signs of organization continue. ******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook*********** IOH 24 Hr Outlook (1800Z Oct 12)...5% chance of tropical cyclone formation (eastern tropical Atlantic near 8.5N-37.5W) IOH 48 Hr Outlook (1800Z Oct 13)...15% chance of tropical cyclone formation (central tropical Atlantic near 9.8N-42.5W) IOH 72 Hr Outlook (1800Z Oct 14)...10% chance of tropical cyclone formation (central tropical Atlantic near 11.5N-47.5W) IOH 96 Hr Outlook (1800Z Oct 15)...0% chance of tropical cyclone formation (central tropical Atlantic near 13N-52.5W)

...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. For area of interest #2...tropical wave with broad low pressure spin emerges from western Africa at 48 hours...broad low pressure reaches 30W longitude by 120 hours. For area of interest #3...no tropical cyclone formation shown. 0000Z ECMWF Model Run....For areas of interest #1 to #3...no tropical cyclone formation shown.

1200Z GFS Model Run...For area of interest #1...no tropical cyclone formation shown. For area of interest #2...tropical wave with broad low pressure spin emerges from western Africa at 48 hours...broad low pressure reaches 13N-35W at 120 hours. For area of interest #3...no tropical cyclone formation shown. 0600Z NAVGEM Model Run... For area of interest #1...organizes into a tropical low pressure east of the Lesser Antilles at 15N-57.5W at 72 hours...passes over the northern Lesser Antilles at 102 hours...located over the Virgin Islands at 120 hours. For area of interest #2...tropical wave organizes into a broad low pressure spin offshore of western Africa at 90 hours...broad low pressure reaches 30W longitude at 126 hours. For area of interest #3...no tropical cyclone formation shown.

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