*******Note that forecast 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.**********
...THURSDAY AUGUST 3 2023 10:50 AM EDT...
The tropical low pressure in the open central Atlantic that was being monitored for signs of development over the last few days has become absorbed by a surface front that has been approaching from the western Atlantic... see area of interest #17 for more information. Elsewhere... the tropical wave of low pressure in the eastern tropical Atlantic that recently emerged from western Africa is showing some signs of organization and has some intermittent model support in recent runs of the CMC and GFS. This marks the nineteenth tropical Atlantic area of interest tracked on this site this year... see area of interest #19 section below for more information on this tropical wave.
AREA OF INTEREST #17... The tropical low pressure in the open central Atlantic that was being monitored for signs of development continued northward in the flow around the west side of the steering Atlantic surface ridge. The associated thunderstorm activity remained disorganized due to ongoing shear associated with the central Atlantic upper vorticity that was slower to dissipate than previously anticipated. The tropical low pressure also was tracking more westward than previous forecasts... placing it closer to the incoming western Atlantic surface front. As such... recently the tropical low has lost its identity to a developing frontal low to its immediate west and this area of interest is now cancelled. Any coastal surf that develops on the shores of Newfoundland by Friday and Saturday will now be associated with an unrelated frontal cyclone that later develops along the absorbing western Atlantic front.
AREA OF INTEREST #19... A tropical wave of low pressure in the eastern tropical Atlantic that recently emerged from western Africa has been producing a persistent region of thundertorms while continuing westward. As of 0600Z the NHC TAFB had the tropical wave positioned just southeast of the Repbulic of Cabo Verde Islands... at 22.5W longitude. However recent satellite imagery has shown that thunderstorm activity has consolidated around a developing tropical low pressure spin just west of the wave axis... or just south-southwest of the islands near 11.2N-25W. The tropical low is expected to continue mainly westward during the 5-day forecast period while steered around the Atlantic surface ridge... albeit some increase in the northward angle of the track is possible in 5+ days as this system reaches the weaker western extent of the surface ridge. Atmospheric conditions are expected to be favorable for development in the 5-day window due to the ongoing regional tropical upper ridge providing low shear and upper outflow. Noting that toward the west an inverted upper trough is embedded in the tropical upper ridge which has gained its identity in between the stronger eastern part of the upper ridge and weaker western part of the upper ridge. As the southern US upper ridge later moves offshore into the western Atlatnic... it will force this inverted upper trough to merge with the southern part of the current western Atlantic upper trough and also a remainder eastern portion of the current central Atlantic upper vorticity string. This merger will result in a lengthy east-west upper vorticity string to the north of the tropical upper ridge... and due to the increasing northward slant in the forecast track it is possible that just after day 5 this system will have to combat increasing westerly shear while moving closer to the upper vorticty string. Another negative factor in the environment of this system is the dry Sahran air layer lurking to the north which it may ingest. For this update I am already starting this new area of interest off with a peak 35% odds of tropical cyclone formation as this system already has signs of organization in satellite pictures and could develop with the help of the regional tropical upper ridge. I have not gone with odds higher than this at this time as the model support remains weak with only the CMC and GFS intermittently suggesting development... and also due to the negative factors mentioned above (potential ingestion of dry Saharan air as well as possible westerly shear just after day 5).
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Aug 4)... 20% chance of tropical cyclone formation (eastern tropical Atlantic near 12N-30W)
IOH 48 Hr Outlook (1200Z Aug 5)... 35% chance of tropical cyclone formation (eastern tropical Atlantic near 12.5N-35W)
IOH 72 Hr Outlook (1200Z Aug 6)... 35% chance of tropical cyclone formation (eastern tropical Atlantic near 13N-40W)
IOH 96 Hr Outlook (1200Z Aug 7)... 35% chance of tropical cyclone formation (central tropical Atlantic near 13.5N-45W)
IOH 120 Hr Outlook (1200Z Aug 8)... 35% chance of tropical cyclone formation (central tropical Atlantic near 14.5N-50W)
******National Hurricane Center (hurricanes.gov) official outlook as of 8 AM EDT*****************************
Not in the official outlook
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
0000Z (Aug 3) CMC Model Run...
**For area of interest #17... no development shown
**For area of interest #19... no development shown
0000Z (Aug 3) ECMWF Model Run...
**For area of interest #17... no development shown
**For area of interest #19... no development shown
0600Z (Aug 3) GFS Model Run...
**For area of interest #17... no development shown
**For area of interest #19... no development shown
0600Z (Aug 3) NAVGEM Model Run...
**For area of interest #17... no development shown
**For area of interest #19... no development shown
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