*******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 AUGUST 9 2020 8:03 PM EDT...
See area of interest section below for the eastern Atlantic tropical wave of low pressure being monitored for development.
The tropical wave of low pressure currently moving into the eastern Caribbean Sea after crossing the Lesser Antilles islands has continued to lose activity despite moving into favorable upper winds beneath a Caribbean upper ridge cell located to the east of western Atlantic upper vorticity. Meanwhile the central Caribbean Sea tropical wave that passed by Haiti...the Dominican Republic...and Jamaica has seen a significant increase in thunderstorms on the southern part of its axis while experiencing upper outflow on the west side of the same Caribbean upper ridge cell...enhanced by an outflow channel streaming northward into the western Atlantic upper vorticity. Although tropical cyclone formation is not expected as the wave makes landfall across Nicaragua...heavy rainfall with flash flooding potential is possible tonight across Honduras...Nicaragua...and Costa Rica.
AREA OF INTEREST #1...The tropical wave of low pressure in the eastern Atlantic continues maintaining organized thunderstorm bands that suggest rotation. Currently the rotation appears to be centered at 10.5N-28W. The thunderstorm activity remains supported by divergence and upper outflow on the south side of a broad tropical upper ridge in the region. Overall I have not raised odds of tropical cyclone formation above 40% as the system has not become better organized. In fact one could argue it has become a little less organized while the strongest thunderstorms have become biased west of the low pressure spin...perhaps easterly shear induced by the strength of the tropical upper ridge. I have raised longer term odds of development from 35% to now 40% as the GFS model has been consistent with the position of cut-off upper vorticity from the northeastern Atlantic that will get pushed southward toward the tropics (by the current central Atlantic upper ridge) in the vicinity of 40W longitude. In other words I believe the upper vorticity will be far north enough to not disrupt this system.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Aug 10)...40% chance of tropical cyclone formation (tropical Atlantic near 10.5N-33W)
IOH 48 Hr Outlook (1800Z Aug 11)...40% chance of tropical cyclone formation (tropical Atlantic near 10.5N-38W)
IOH 72 Hr Outlook (1800Z Aug 12)...40% chance of tropical cyclone formation (tropical Atlantic near 11N-43W)
IOH 96 Hr Outlook (1800Z Aug 13)...40% chance of tropical cyclone formation (tropical Atlantic near 11N-48W)
IOH 120 Hr Outlook (1800Z Aug 14)...40% chance of tropical cyclone formation (tropical Atlantic near 11.5N-53W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z CMC Model Run...For area of interest #1...still intact as a tropical low pressure crossing 12.5N-40W in 66 hours...crosses 19.8N-56W in 144 hours as a possible tropical cyclone
1200Z ECMWF Model Run...For area of interest #1...no tropical cyclone formation shown.
1800Z GFS Model Run...For area of interest #1...still intact as a tropical low pressure crossing 12N-39W in 54 hours...opens back into a tropical wave at 47.5W longitude in 96 hours.
1200Z NAVGEM Model Run...For area of interest #1...no tropical cyclone formation shown.