*******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.**********
...THURSDAY SEPTEMBER 8 2022 4:08 AM EDT...
The potential for an early to mid September outbreak of Atlantic tropical cyclones is increasing due to Hurricanes Danielle and Earl currently in progress... and a pair of organizing tropical waves in the eastern tropical Atlantic designated as areas of interest #27 and #28 on this blog post. See the respective sections below for an update on each of these systems and the land areas to be affected. In addition to the pair of tropical waves... watching for the possibility of up to three new areas of interest could emerge over the next week as follows:
(1) The upper trough currently over central Canada is expected to interact with Hurricane Earl by this weekend. The northwest side of Earl is expected to pull cool air associated with the trough southward. In addition the sprawling amplified upper ridge over the United States is expected to push toward the Atlantic. Both of these events will cause the upper trough to amplify into a cut-off upper vortex... however the precise position of the upper vortex will depend on how amplified the aforementioned upper ridge will be. A more amplified upper ridge will result in a further south upper vortex that would potentially trigger a subtropical disturbance east of Bermuda. A less amplified upper ridge would result in a further north upper vortex that simply interacts with Earl. Models have trended toward a further north upper vortex... therefore in this update I have not added an area of interest to monitor for the possibility of a subtropical disturbance east of Bermuda.
(2) The cut-off upper vorticity currently over the southern United States is likely to be pushed into the western Gulf of Mexico by Friday and this weekend due to the current sprawling upper ridge building over the United States...where it is expected to coalesce into an upper vortex. The divergent east side of this vortex may trigger a surface low pressure in the north-central Gulf of Mexico over the next 24 hours. However subtropical or tropical development of the surface low is unlikely as the divergence maximum on the east side of the upper vortex and the associated surface low pivot north into the southeastern United States already by 48 hours. Beyond 48 hours... the upper vortex is expected to elongate north-south while gradually merging with an upper trough to approach from western Canada... with the elongated eastern divergence zone of the vortex making it challenging for a focused area of surface low pressure to emerge in the Gulf of Mexico. Given this current outlook on the evolution of the forecast upper vortex... I have not declared a new area of interest for tropical development in the Gulf of Mexico. However the divergent east side of the upper vortex may enhance rainfall across the central United States Gulf coastal region and parts of the southeastern United States in the days ahead.
(3) Model runs suggest that in approximately six days from today... an additional organized tropical wave of low pressure could emerge from the west coast of Africa into the eastern tropical Atlantic. This wave's emergence into the tropical Atlantic waters will be within the 5-day forecasting range by my next update tomorrow... upon which time the wave could be added as yet another area of interest.
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 is designated #27 and #28 as the other twenty-six were mentioned in previous birdseye view posts. 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.
HURRICANE DANIELLE... The upper trough that was west of Hurricane Danielle has been pushed southeastward and away from Danielle's environment by Hurricane Earl's outflow. However Danielle continues moving northeastward in the flow ahead of an approaching upper vortex and new surface frontal low to the west supported by the eastern divergence zone of the vortex. The cool north Atlantic waters are continuing to cause the thunderstorms and associated warm core around Danielle's eye to fade... as evidenced by the southwestern side of the thunderstorm ring dissipating. Danielle will complete its transition into a non-tropical remnant frontal cyclone to be supported by the eastern divergence zone of the incoming upper vortex in the next 24 hours once the warm core fully dissipates.
After 24 hours... Danielle's remnant frontal cyclone is expected to undergo a counter-clockwise loop turn in a fujiwhara interaction with the frontal low to the west (ex-Danielle is also expected to absorb the frontal low in the interaction). The counter-clockwise loop will also be induced by the steering flow around the upper vortex. Once the upper ridge currently over eastern Canada shifts into the far north Atlantic... the ridge is expected to push the upper vortex and ex-Danielle east-southeastward into the northeast Atlantic waters north of the Azores and offshore of Portugal and Spain's west coast by day 5. The erratic counter-clockwise loop turn followed by the east-southeast turn will prolong coastal sea swells for the Azores to a few days. By day 5 ex-Danielle will be weakening while having whirled beneath the center of the overhead upper vortex where there is a lack of supporting upper divergence... however ex-Danielle will need time to spin down from its current strength. As such... some model runs suggest that ex-Danielle will still be strong enough to push coastal sea swells into the west coast of Portugal and Spain by day 5.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0000Z Sep 8)...75 mph maximum sustained wind hurricane transitioning into a non-tropical frontal cyclone while centered at 45.6N-32.9W
IOH 24 Hr Forecast (0000Z Sep 9)...Non-tropical remnant frontal cyclone centered at 49.5N-31W
HURRICANE EARL... The second hurricane of the 2022 Atlantic Hurricane Season continues to drift northward in the direction of Bermuda while steered by the lingering upper vorticity to the west. The upper vorticity has continued to fade while remaining cut-off from high-latitude cold air... which has allowed the shear in Earl's environment to relax such that Earl has been able to strengthen into the strongest hurricane of the 2022 Atlantic season thus far... while now rated as a category 2 with 100 mph maximum sustained winds. However their remains some evidence of lingering shear as thunderstorms and outflow immediately southwest of Earl's core are absent. Despite true color visible satellite imagery suggesting improved organization with a faint eye appearing in Earl's core... the core has struggled to organize on colorized infrared satellite pictures while the eye appears to be large and ragged. The northward travel of Earl has been slow due to the weakening of the steering upper vorticity to the west... however at 48+ hours the upper trough currently over central Canada is expected to be far south enough by the time it approaches the hurricane to finally jettison Earl northeastward. Yesterday the usually more reliable GFS and ECMWF models were in agreement that the sprawling upper ridge currently over the United States would be amplified enough to cut-off most of the upper trough into an upper vortex southwest of Earl... with this vortex producing a subtropical system east of Bermuda. In that solution Earl would curve more eastward in track by day 4 in an upper-level westerly jet to setup between this upper vortex and south side of what will be ex-Danielle's upper vortex. While the ECMWF clings to this solution... the GFS has abandoned that idea and has joined the remaining global models in showing a less amplified United States upper ridge... allowing the upper trough to cut-off into an upper vortex further north such that Earl becomes entangled with the vortex and whirls more north in track and much closer to Newfoundland instead of curving eastward out to sea in the long range. When comparing the ECMWF versus the rest of the models... we have an unusally large spread in possible tracks in the long range... so what to do? Initially I had gone with the GFS-ECMWF consensus yesterday... however in this update I have begun to shift the longer range track westward in case Earl indeed ends up not curving out to sea and instead hangs out close to Newfoundland.
Regarding intensity... the intensity of the wind shear in Earl's environment may increase a little in the next 24 hours as the current central Canadian upper trough approaches Earl... and the intensification rate in my forecast for the next 24 hours is less than what we have seen in the prior 24 hours. On day 2 the shear is expected to relax as northerly flow on Earl's northwest quadrant will pull cool air associated with the trough southward... helping the trough amplify into an upper vortex featuring less shear and more upper divergence on its east side. This divergence could also aid Earl while the hurricane is still over warm water... therefore my forecast rate of intensification is ramped up between 24 and 48 hours. Although the favorable interaction with the amplifying upper trough/vortex persists through day 3... the hurricane will be fast approaching cooler waters on its accelerating northeast track and therefore a gradual weakening rate is shown from day 2 to 3. By day 4 transition to a still strong non-tropical frontal cyclone is expected to be completed while the storm moves across waters below 26 deg C. While the NHC has ramped up the forecast peak intensity of Earl to 130 mph maximum sustained category 4 winds... I have chosen to move away from that forecast intensity and instead trim down the peak to 125 mph category 3 as Earl strengthened a little slower than I previously thought and the core has struggled with a ragged instead of sharply-defined eye.
Regarding impact to land areas:
(1) For Bermuda... coastal sea swells are expected to increase to strong levels throughout today... afterwards decreasing on Friday as the hurricane accelerates northeastward and away. The latest forecast track suggests the northwest quadrant of the hurricane could overspread the island with tropical storm force winds and heavy rainfall by tonight. Preparations for tropical storm conditions should have been completed by now.
(2) The long range track for Earl and its remnant frontal cyclone has become unusually uncertain. A more eastward track could allow Earl to add to ex-Danielle's northeast Atlanitc and Azores coastal sea swells by this weekend. Or a more westward track could cause Earl to bring coastal sea swells to Newfoundland this weekend. If the long-range track curves westward enough... southeastern Nefoundland this weekend could also be subject to gale force winds on the northwest quadrant of Earl's remnant frontal cyclone. Interests in Newfoundland should monitor the progress of shifts in Earl's long range forecast track.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0000Z Sep 8)... 100 mph maximum sustained wind hurricane centered south of Bermuda at 27.2N-65.5W
IOH 24 Hr Forecast (0000Z Sep 9)... 110 mph maximum sustained wind hurricane centered just south- southeast of Bermuda at 30N-64W
IOH 48 Hr Forecast (0000Z Sep 10)... 125 mph maximum sustained wind major hurricane centered in the open central Atlantic at 35N-58W
IOH 72 Hr Forecast (0000Z Sep 11)... 105 mph maximum sustained wind hurricane centered in the open north Atlantic near 41N-51W
IOH 96 Hr Forecast (0000Z Sep 12)... Non-tropical remnant frontal cyclone centered at 49N-42.5W
AREA OF INTEREST #27...The organized tropical wave of low pressure that has been moving west-northwest across the eastern tropical Atlantic is now heading into the central tropical Atlantic. The wave continues to feature a low pressure center... however the broad center appears to be coalescing further to the northwest than I previously thought while located near 17.5N-37.5W instead of the 15N-35W shown in my forecast yesterday. The west-northwest track is expected to continue while this system angles toward the surface ridge weakness currently being produced by Hurricane Earl. This weakness will remain open as the upper trough to interact with Earl will have a large eastern divergence zone that will keep surface pressures low to the south of Earl. As such by the later part of the 5-day forecast period... a complete north turn into the ridge weakness is expected.
Regarding the favorability for tropical cyclone formation of this disturbance... that picture has become more murky as an upper trough that was formerly interacting with Hurricane Danielle has been pushed southeastward toward this system by the outflow of Hurricane Earl. The more northwest position of the tropical low pressure spin has placed this system closer to the upper trough and its associated shear... which is why this system has already obtained a sheared appearance with the thunderstorm actiivty lopsided to the north side of the circulation. As a result in this update I have kept my peak odds of tropical cyclone formation at 60% instead of raising them to 70% as the NHC has recently done in their tropical weather outlook. Even though the upper trough will likely be amplified into a cut-off upper vortex by Earl's outflow... and even though the upper vortex will later retrograde northwestward and away toward the upper trough to interact with Earl... the updated forecast track which is shifted northwestward (owing to the current position of the low pressure spin) still keeps this system too close to the upper vortex such that some shear will still be a problem for this system. Odds of development are gradually trimmed down at 72+ hours as the updated forecast track brings this system even closer to the shearing upper southwesterlies associated with the upper vortex... with the southwesterlies then maintained by the south side of the upper trough interacting with Earl which will absorb the upper vortex.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Sep 9)...60% chance of tropical cyclone formation (central tropical Atlantic near 18.5N-42.5W)
IOH 48 Hr Outlook (0000Z Sep 10)...60% chance of tropical cyclone formation (central tropical Atlantic near 20N-47.5W)
IOH 72 Hr Outlook (0000Z Sep 11)...50% chance of tropical cyclone formation (central tropical Atlantic near 21.5N-52W)
IOH 96 Hr Outlook (0000Z Sep 12)...40% chance of tropical cyclone formation (central Atlantic near 25.5N-52W)
IOH 120 Hr Outlook (0000Z Sep 13)...20% chance of tropical cyclone formation (central Atlantic near 30.5N-51W)
AREA OF INTEREST #28...The broad center of rotation of the tropical wave of low pressure that has recently departed the west coast of Africa appears to have coalesced further to the southwest near 8N-19.5W where a small area of concentrated thunderstorms with banding features is currently in progress. This disturbance is expected to continue steadily westward across the eastern tropical Atlantic and around the south side of the current eastern Atlantic surface ridge. The forecast track points are adjusted south and west to account for the current estimated center of rotation. Regarding development potential...this disturbance will be in an environment of low shear and upper outflow beneath the tropical upper ridge in the region. In combination with the disturbance's attempts at esbalishing a low pressure center... and with the latest center being further south away from the dry Saharan air layer... I maintain 50% peak odds of tropical cyclone formation which remains higher than the NHC's outlook on this system as of this writing. However I have lowered shorter term odds of tropical cyclone formation as this system has simply shifted its location of its rotation center instead of making progress on the previous one.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Sep 9)...25% chance of tropical cyclone formation (eastern tropical Atlantic near 8.5N-22.5W)
IOH 48 Hr Outlook (0000Z Sep 10)...35% chance of tropical cyclone formation (eastern tropical Atlantic near 9.5N-26.5W)
IOH 72 Hr Outlook (0000Z Sep 11)...45% chance of tropical cyclone formation (eastern tropical Atlantic near 10N-31.5W)
IOH 96 Hr Outlook (0000Z Sep 12)...50% chance of tropical cyclone formation (eastern tropical Atlantic near 10.5N-36.5W)
IOH 120 Hr Outlook (0000Z Sep 13)...50% chance of tropical cyclone formation (central tropical Atlantic near 11N-41.5W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z (Sep 7) CMC Model Run...
**For Hurricane Danielle... moves northeast with remnant frontal cyclone reaching 48.5N-31W at 30 hours... while undergoing a fujiwhara interaction with and absorbing adjacent frontal low to the west the remnant frontal cyclone undergoes a counter-clockwise loop... at end of the interaction the remnant frontal cyclone weakens to a frontal low and moves east-southeast with the frontal low dissipating near 41N-17W at 108 hours.
**For Hurricane Earl... passes just southeast of Bermuda at 42 hours... afterwards accelerates northeast and reaches 44N-48.5W (east-southeast of Newfoundland) at 120 hours as a remnant frontal cyclone
**For area of interest #27... tropical low moves northwest toward Earl and dissipates near 26N-50W at 78 hours
**For area of interest #28... tropical wave organizes into a tropical low near 11N-22W at 42 hours... tropical low located near 15N-34W at 120 hours.
**Tropical wave emerges from west coast of Africa at 120 hours... organizes into a tropical low near 11.2N-21W at 138 hours... tropical cyclone formation suggested south of the Republic of Cabo Verde Islands at 156 hours... tropical cyclone located at 12N-27.5W at 168 hours.
1200Z (Sep 7) ECMWF Model Run...
**For Hurricane Danielle... moves northeast with remnant frontal cyclone reaching 47.5N-31W at 24 hours... while undergoing a fujiwhara interaction with and absorbing adjacent frontal low to the west the remnant frontal cyclone undergoes a counter-clockwise loop... at end of the interaction the remnant frontal cyclone weakens to a frontal low and moves east-southeast with the frontal low located just offshore of the Portugal/Spain border at 120 hours.
**For Hurricane Earl... passes just southeast of Bermuda between 24 and 48 hours...afterwards accelerates northeast and reaches 43.8N-40.8W at 120 hours as a remnant frontal cyclone
**For area of interest #27... becomes a tropical depression near 18.8N-40.2W at 24 hours... weakens to a remnant low near 21N-46W at 48 hours... remnant low curves northward toward Earl and dissipates near 32N-50W shortly after 96 hours.
**For area of interest #28... tropical wave gradually consolidates into a tropical low which reaches 15.5N-39.5W at 120 hours.
**Tropical wave emerges from west coast of Africa just after 96 hours... organizes into a tropical low near 13N-19.8W at 120 hours... tropical cyclone formation suggested just south of the Republic of Cabo Verde Islands at 144 hours... potentially strengthens into a hurricane near 14N-31W at 168 hours.
**Upper trough that interacts with Earl at 48 hours deposits a cut-off upper vortex and associated surface frontal cyclone southwest of Earl and near 35N-61.5W at 72 hours... frontal cyclone drifts south and transitions into a subtropical storm near 33N-61W at 96 hours... subtropical storm begins to weaken while drifitng southwest to the waters just southeast of Bermuda through 144 hours... subtropical storm turns on a north-northeast drift and weakens further to a remnant low near 33N-61.5W at 168 hours.
1800Z (Sep 7) GFS Model Run...
**For Hurricane Danielle... moves northeast with remnant frontal cyclone reaching 47.5N-31W at 18 hours... while undergoing a fujiwhara interaction with and absorbing adjacent frontal low to the west the remnant frontal cyclone undergoes a counter-clockwise loop... at end of the interaction the remnant frontal cyclone moves east-southeast with the frontal cyclone located just offshore of the Portugal/Spain border at 120 hours.
**For Hurricane Earl... passes just southeast of Bermuda at 33 hours... afterwards accelerates north-northeast where it reaches waters just offshore of southeast Newfoundland by 120 hours as a remnant frontal cyclone
**For area of interest #27... becomes a tropical depression near 17.8N-40W at 18 hours... weakens to a remnant low near 20N-48W at 51 hours... remnant low becomes elongated north-south and dissipates near 27.5N-52.5W at 81 hours.
**For area of interest #28... no development shown
1800Z (Sep 7) NAVGEM Model Run...
**For Hurricane Danielle... moves northeast with remnant frontal cyclone reaching 47.5N-32.5W at 18 hours... while undergoing a fujiwhara interaction with and absorbing adjacent frontal low to the west the remnant frontal cyclone undergoes a counter-clockwise loop... at end of the interaction the remnant frontal cyclone moves east-southeast with the frontal cyclone located just offshore of the Portugal/Spain border at 120 hours.
**For Hurricane Earl... passes just southeast of Bermuda at 36 hours... afterwards accelerates northeast where it reaches 45N-44W at 120 hours as a remnant frontal cyclone
**For area of interest #27... becomes a tropical depression at 12 hours while located near 18N-39.5W... turns northwest toward Earl and weakens to a remnant low near 25N-50W at 72 hours... remnant low dissipates near 30.5N-48.5W at 90 hours
**For area of interest #28... tropical wave gradually consolidates into a tropical low which reaches 15.5N-42W at 120 hours.
**Tropical wave emerges from west coast of Africa at 120 hours and organizes into a tropical low just offshore of Senegal shortly thereafter... develops into a tropical depression while moving into the southeastern Republic of Cabo Verde Islands at 168 hours.
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