*******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 28 2022 4:40 AM EDT...
Opportunities for tropical cyclone formation in the Atlantic basin are increasing as we end the month of August due to the following three areas of interest in the tropical latitudes:
(1) See area of interest #20 for more information on a broad but organizing tropical low pressure in the central tropical Atlantic. Note that this system will be near or over the northern Lesser Antilles in approximately five days
(2) See area of interest #22 section below for an update on the surface trough of low pressure continuing westward into the central Caribbean Sea. Over the next few days it has potential to evolve into a tropical low pressure spin as it nears the Cayman Islands... western Cuba... and northeastern Yucatan peninsula of Mexico.
(3) Computer models are in agreement that a large tropical disturbance will emerge from the west coast of Africa in approximately two days... consisting of a pair of tropical waves currently over western Africa. See area of interest #23 section below for more information. Note the large disturbance has potential to bring periods of heavy rain and gusty winds to the Republic of Cabo Verde Islands in the middle of this upcoming week.
In addition... the mid-latitudes of the Atlantic may host tropical development in the days ahead as follows:
(1) A surface low pressure which originated from the decaying tail end of a frontal boundary that was over the northeast Atlantic on August 24 has retrograded westward into the open central Atlantic. This feature shows signs of organization with a well-defined swirl that occasionally features pockets of showers and thunderstorms. See area of interest #24 section below for more information.
(2) The tail end of a large frontal system currently moving across central North America will enter the western Atlantic from the United States east coast in approximately five days. Although some upper westerly flow will likely be over the tail end of the front... any defined surface low pressure feature that develops along the tail end of the front and offshore of the southeastern United States will likely accelerate northeastward toward an additional frontal low to be offshore of Atlantic Canada. This northeastward acceleration would reduce the effect of upper westerly shear... therefore may have to watch for tropical development along the tail end of the front in the days ahead.
New to this site this year... I will be sequentially numbering up areas of interest for possible Atlantic tropical development. In this scheme... will reset back to #1 at the start of next year (January 2023). The current areas of interest in this blog post are designated #20 through #24 as I designated the other nineteen of this year in previous birdseye view posts on the home page. This scheme is to reduce confusion as Atlantic tropical activity increases during the peak of the hurricane season... when multiple simultaneous areas of interest begin and end which previously required shuffling around the area of interest numbers from update to update.
AREA OF INTEREST #20...The pair of closely-spaced vigorous tropical waves of low pressure that were moving into the central tropical Atlantic have finally fused into a singular broad low pressure area. Note the broad low pressure area is denoted as a tropical wave in the NHC TAFB 0000Z surface analysis... indicating the broad low pressure area did not have a well-defined center of spin during that time. However based on the latest satellite imagery... a center of rotation appears to be consolidating near the southern edge of a circular thunderstorm cluster... in the vicinity of 15N-41W. This center of rotation is north and west of my previous forecast... and my updated one in the outlook below is adjusted accordingly. The track is also expected to slow down and bend slightly north in 4+ days as this system reaches the weaker western side of the Atlantic surface ridge. Favoring this system in the short-term is the ongoing tropical upper ridge in the region featuring low shear and upper outflow. Due to the north and west adjusted forecast track... this system is at increased risk for exposure to westerly shear in the longer range to be induced by the current central Atlantic upper vorticity... particularly as the vorticity retrogrades south and west into the path of this system. Therefore in this update my peak 5-day odds of tropical cyclone formation are lowered to 40%... with odds trimmed back down to 30% by day 5 as this system potentially moves closer to the upper vorticity and its associated shear (meanwhile the NHC has raised odds of tropical cyclone formation to 60% as this system has continued to become gradually more organized).
Regardless of tropical cyclone formation or not... this broad tropical low pressure system has potential to bring heavy rain and gusty winds to the northern Lesser Antilles on Thursday.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Aug 29)...15% chance of tropical cyclone formation (central tropical Atlantic near 15.5N-46W)
IOH 48 Hr Outlook (0000Z Aug 30)...35% chance of tropical cyclone formation (central tropical Atlantic near 15.5N-51W)
IOH 72 Hr Outlook (0000Z Aug 31)...40% chance of tropical cyclone formation (central tropical Atlantic near 15.5N-55W)
IOH 96 Hr Outlook (0000Z Sep 1)...40% chance of tropical cyclone formation (east of the northern Lesser Antilles near 16.5N-59W)
IOH 120 Hr Outlook (0000Z Sep 2)...30% chance of tropical cyclone formation (over the northern Lesser Antilles near 17.5N-62.5W)
AREA OF INTEREST #22...A Caribbean surface trough of low pressure continues to make its way westward and is now in the central Caribbean waters due south of Haiti. The trough has become better defined on satellite imagery within the last 24 hours and featured scattered showers and thunderstorms that extended as far north as the Dominican Republic and Haiti on Saturday. As of 0000Z the NHC TAFB has upgraded the surface trough to a tropical wave in their surface analysis. The GFS model insists on reviving this feature as it later reaches the western Caribbean Sea. The trigger for the revival appears to be interaction with the upper vortex currently located just north of the Dominican Republic as the vortex retrogrades southwest into the path of the surface trough. This will allow the surface trough to interact with upper divergence on the southeastern side of the upper vortex. And after the divergence zone of the upper vortex potentially enhances the surface trough... wind shear is expected to relax by days 4 and 5 as the cold core upper vortex dissipates while it remains cut-off from high-latitude cold air. Due to the increased definition of the surface trough in satellite pictures... I have slightly raised peak 5-day odds of tropical cyclone formation to 10%. Despite increased definition...the surface trough remains a weak feature and therefore waiting for the trough to become even more defined before raising odds of tropical cyclone formation further. Additional support from other models besides the GFS would also warrant raising development odds further in future updates.
Regarding the forecast track of the surface trough... an increase in the northward angle is anticipated as it rounds the southwest side of the Atlantic surface ridge... eventually taking it toward western Cuba and the northeastern Yucatan peninsula of Mexico. Regardless of tropical cyclone formation or not... these land areas on Thursday could see heavy rains and gusty winds from this system should it in fact become invogorated as the GFS model has been forecasting. The Cayman Islands may also see similar impacts from this system in the middle of this upcoming week.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Aug 29)...0% chance of tropical cyclone formation (south of Jamaica near 16N-77.5W)
IOH 48 Hr Outlook (0000Z Aug 30)...0% chance of tropical cyclone formation (south of the Cayman Islands near 17N-80W)
IOH 72 Hr Outlook (0000Z Aug 31)...0% chance of tropical cyclone formation (just southwest of the Cayman Islands near 18N-82W)
IOH 96 Hr Outlook (0000Z Sep 1)...10% chance of tropical cyclone formation (west of the Cayman Islands near 19.5N-84W)
IOH 120 Hr Outlook (0000Z Sep 2)...10% chance of tropical cyclone formation (between the western tip of Cuba and northeastern corner of Yucatan peninsula near 22N-86W)
AERA OF INTEREST #23...Satellite imagery of Africa as of 0300Z earlier today. Red dashed lines indicate the location of a pair of inland western Africa tropical waves. A red "L" on the western wave marks the estimated center of its spin. The pair of waves are likely to combine to make a large tropical disturbance that enters the eastern tropical Atlantic in approximately two days:
Over western Africa are a pair of closely spaced and vigorous tropical waves of low pressure. The western wave appears to have a broad center of rotation near 12.5N-13W...and is a rather large feature while producing western curved thunderstorm bands that already reach well offshore of the west coast of Africa. The eastern wave appears to be located in the vicinity of 2E longitude. Models agree the pair of waves will merge into a rather large tropical disturbance that exits the west coast of Africa over the next 48 hours. Odds of tropical cyclone formation by day 5 are set at a low 20% as the large disturbance will need some time... likely more than 5 days... to consolidate enough to support tropical cyclone formation. However even if this system does not become a tropical cyclone within the next five days... it certainly has the potential to bring periods of heavy rain and gusty winds to the Republic of Cabo Verde Islands during the middle of this upcoming week.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Aug 29)...0% chance of tropical cyclone formation (western Africa near 12.8N-9W)
IOH 48 Hr Outlook (0000Z Aug 30)...0% chance of tropical cyclone formation (western Africa near the eastern tropical Atlantic coast near 13.2N-14W)
IOH 72 Hr Outlook (0000Z Aug 31)...0% chance of tropical cyclone formation (just offshore of western Africa near 13.8N-19W)
IOH 96 Hr Outlook (0000Z Sep 1)...10% chance of tropical cyclone formation (just south of the Republic of Cabo Verde Islands near 14.2N-24W)
IOH 120 Hr Outlook (0000Z Sep 2)...20% chance of tropical cyclone formation (eastern tropical Atlantic near 15N-29W)
AREA OF INTEREST #24...A swirl of low surface pressure is currently centered in the open central Atlantic at 32.4N-54.5W and occasionally fires pockets of showers and thunderstorms. As a result we now have yet another area of interest for tropical development in the Atlantic basin... the twenty-fourth I have tracked on this blog this year. This feature traces its origins to a northeastern Atlantic upper trough and associated surface front that was over the northeastern Atlantic Ocean on August 24. Since then... the tail end of the front decayed into multiple swirls of low pressure retrograding westward toward the central Atlantic while steered around the south side of the Atlantic surface ridge. Most of the swirls became stomped out by the high surface pressures of the ridge being generated by the upper convergence zone between the northeast side of the current central Atlantic upper vorticity and southeast side of the current central Atlantic upper ridge. The exception has been the remaining swirl that is now our area of interest... which appears supported by an area of upper divergence between the northwest side of the upper vorticity and south side of the upper ridge as illustrated in the above birdseye view chart.
The current surface ridge over the northeastern United States will soon merge with the Atlantic surface ridge... leaving the swirl of low pressure trapped stationary inside the ridge over the next 48 hours. After that time... the frontal system currently approaching from central North America will erode the northwest side of the surface ridge... allowing this system to make an escape to the north-northwest and then toward the north. Upper-level winds are expected to become increasingly conducive for tropical development as the current central Atlantic upper ridge axis with its low shear and upper outflow gets knocked southeastward over the surface swirl of low pressure due to the push of the current upper trough entering the western Atlantic from eastern North America. Therefore I have already raised odds of tropical cyclone formation to 30%. These odds however are still toward the low side as the surface low pressure swirl is surrounded by the Atlantic surface ridge and its associated sinking dry air environment caused by the upper convergence supporting the ridge. The subtropical designation is used at 72 and 96 hours as this system will align with the divergent east side of a cold core upper vortex to be left behind by the upper trough currently entering the western Atlantic. Thus this system could resemble a hybrid supported in a non-tropical fashion by the divergence zone of the upper vortex... and supported in a tropical fashion by thunderstorm-generated warm core upper outflow that could be established just east of the upper vortex. A tropical desingation is returned at 120 hours as the northward track of the surface low pressure swirl pulls it away from the upper vortex.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Aug 29)...30% chance of tropical cyclone formation (central Atlantic near 32.5N-55W)
IOH 48 Hr Outlook (0000Z Aug 30)...30% chance of tropical cyclone formation (central Atlantic near 32.5N-55W)
IOH 72 Hr Outlook (0000Z Aug 31)...30% chance of subtropical cyclone formation (central Atlantic near 34N-55W)
IOH 96 Hr Outlook (0000Z Sep 1)...30% chance of subtropical cyclone formation (central Atlantic near 35N-56W)
IOH 120 Hr Outlook (0000Z Sep 2)...30% chance of tropical cyclone formation (northwestern Atlantic near 39N-56.5W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z (Aug 27) CMC Model Run...
**For area of interest #20...tropical low passes just north of the Lesser Antilles at 156 hours... tropical cyclone formation just north of the Virgin Islands at 168 hours.
**For area of interest #22...no development shown
**For area of interest #23...vigorous tropical wave emerges from the west coast of Africa at 42 hours... organizes into a large broad tropical low centered over the northern Republic of Cabo Verde Islands through 108 hours... center of broad tropical low reaches 17.8N-35.5W at 168 hours
**For area of interest #24...small surface low dissipates near 32.2N-54.5W at 54 hours.
**Surface low along a cold front becomes defined just offshore of North Carolina at 114 hours... moves east-northeast and evolves into a compact tropical cyclone near 35N-70W at 132 hours... at 156 hours reaches 40.2N-60.5W where it begins to become entangled with a large non-tropical low developing on the north end of the cold front... moves north-northeast into the core of the non-tropical low and toward southeastern Newfoundland while it transitions into a non-tropical frontal cyclone just after 168 hours.
1200Z (Aug 27) ECMWF Model Run...
**For area of interest #20...tropical cyclone formation suggested just northeast of the northern Lesser Antilles near 19N-60W at 144 hours... strengthens into a strong tropical storm while passing north of the Virgin Islands and Puerto Rico and reaches 20.8N-65.2W at 168 hours
**For area of interest #22...no development shown
**For area of interest #23...vigorous tropical wave emerges from west coast of Africa at 48 hours... organizes into a large broad tropical low centered over the northern Republic of Cabo Verde Islands through 96 hours... center of broad tropical low reaches 20.2N-40W at 168 hours
**For area of interest #24...no development shown
**Tropical wave emerges from west coast of Africa at 144 hours... organizes into a tropical low near 13N-20W at 168 hours.
1800Z (Aug 27) GFS Model Run...
**For area of interest #20...tropical low passes just northeast of the Lesser Antilles near 20N-59W at 141 hours... coalesces into a compact tropical depression near 24N-65.2W at 168 hours
**For area of interest #22...surface trough develops a surface low near 16N-81W at 81 hours... makes landfall on east coast of the Yucatan peninsula just north of Belize at 120 hours... becomes a tropical depression in the northeastern Bay of Campeche and just offshore of the northwestern Yucatan peninsula at 156 hours... becomes a tropical storm in the southwestern Gulf of Mexico near 22N-92.5W at 168 hours.
**For area of interest #23...vigorous tropical wave emerges from west coast of Africa at 48 hours...east side of broad tropical wave establishes a consolidated low pressure center just offshore of Senegal at 63 hours... consolidated low pressure swings west-northwest around remainder of the tropical wave and passes just north of the Republic of Cabo Verde Islands at 90 hours while strengthening into a tropical cyclone... tropical cyclone located at 18N-40W at 168 hours.
**For area of interest #24...slowly drifts north while trapped in Atlantic surface ridge and becomes a tropical cyclone near 35N-56W at 108 hours... northward forward speed increases as approach of strong eastern North America frontal system erodes west side of Atlantic surface ridge with system weakening to a remnant low near 40N-56W at 126 hours... remnant low reaches 50N-48W at 168 hours
**Tropical wave emerges from west coast of Africa at 150 hours... begins to organize into a tropical low near 15N-20W at 168 hours
1800Z (Aug 27) NAVGEM Model Run...
**For area of interest #20...tropical cyclone formation suggested near 15.5N-48.5W at 96 hours... passes just north of the Lesser Antilles... Virgin Islands... and Puerto Rico from 156 to 168 hours while gradually strengthening into a hurricane.
**For area of interest #22...no development shown
**For area of interest #23...vigorous tropical wave emerges from west coast of Africa at 54 hours... as a broad low pressure area containing two centers the wave passes through the Republic of Cabo Verde Islands through 120 hours... the two centers merge resulting in a rather large oblong low pressure area west of the islands by 168 hours.
**For area of interest #24...no development shown