*******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.**********
...MONDAY SEPTEMBER 12 2022 12:20 AM EDT...
See the remnants of Earl section below for an update on the hurricane that has spent this weekend transitioning into a strong non-tropical remnant frontal cyclone positioned just offshore of southeastern Newfoundland. Elsewhere in the low-latitudes... continuing to monitor tropical waves of low pressure for signs of development... see area of interest #28 and #29 sections below for more information.
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 #28 and #29 as the other twenty-seven 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.
REMNANTS OF EARL... Special update #97A on the home page of this site chronicles this weekend's transition of Hurricane Earl into a non-tropical frontal cyclone offshore of southeastern Newfoundland. The northwest quadrant of the still-strong remnant frontal cyclone has been lashing southeastern Newfoundland with gusts exceeding 40 mph since Saturday late afternoon/evening. Gusty winds over southeastern Newfoundland... as well as sea swells along much of the Newfoundland coastline... will linger into Monday as the remnant frontal cyclone continues to meander beneath the upper vortex it is interacting with. Afterwards... the upper vortex is expected to finally shift east as a typical mid-latitude feature with the remnant frontal cyclone following suit which will help improve weather conditions for Newfoundland. The remnant frontal cyclone is now undergoing a typical post-mature weakening phase while trapped beneath the center of the upper vortex where there is a lack of upper divergence. However the remnant cyclone will take time to spin down from its current strength... and the latest model runs suggest that in about 4 days the remnant cyclone may still be strong enough to push sea swells onto the shores of the Azores. This is my final statement on Earl on this blog as it is no longer a tropical system. Statements regarding the impacts of the remnant cyclone in the days ahead will be carried on the home page bulletins of this site.
AREA OF INTEREST #28...The tropical wave of low pressure that was previously in the eastern tropical Atlantic is now entering the central tropical Atlantic. Its area of rotation has become increasingly broad without a well-defined center... however at the same time the tropical wave has seen an increase in thunderstorm activity and over a wide area. This system is expected to continue steadily westward across the tropical Atlantic and around the south side of the current Atlantic surface ridge. The updated forecast track below has a minor adjustment based on the current area of rotation's location... which I estimated to be near 10.5N-40W as of 0000Z earlier this evening. The remnant frontal cyclone of Earl going forward will be weakening... causing the associated surface ridge weakness to close which in turn will allow this system to continue westward through 5 days.
Given the above-noted increase in the tropical wave's thunderstorms while simultaneously maintaining rotation on satellite animation... I continue to maintain this tropical wave as an area of interest and raise peak odds of tropical cyclone formation to 20%. Over the next four days the atmospheric conditions support development potential due to low shear and upper outflow beneath the tropical upper ridge in the region... and this tropical wave has potential to bring heavy rainfall and gusty winds to the Lesser Antilles by day 4 should it maintain its current setup or indeed attempt to develop further. By day 5... forecast changes in the upper atmospheric pattern could make conditions less favorable for tropical development as this system moves into the eastern Caribbean. Upper vorticity that has been trapped in the central Caribbean has recently been dragged into the eastern Caribbean by the large upper vortex associated with Earl's remnant frontal cyclone. Meanwhile the current upper vorticity over western Canada is expected to produce a vigorous frontal system over the east coast of Canada and northwest Atlantic by days 4 and 5... with the warm sector of this frontal system building an upper ridge over the western Atlantic that cuts-off some of the upper vorticity tied to Earl's remnant system. This cut-off upper vorticity will then be pushed toward the eastern Caribbean by the forecast western Atlantic upper ridge... which will only re-enforce the current lingering upper vorticity in the area. By day 5 I drop odds of tropical cyclone formation to 10% due to potential for southwesterly shear to be induced by this axis of upper vorticity. Beyond day 5... if the current upper wind forecast holds... tropical development will become quiet difficult as the tropical wave moves directly below the upper vorticity axis where upper outflow would be suppressed.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Sep 13)...0% chance of tropical cyclone formation (central tropical Atlantic near 11N-45W)
IOH 48 Hr Outlook (0000Z Sep 14)...10% chance of tropical cyclone formation (central tropical Atlantic near 12N-50W)
IOH 72 Hr Outlook (0000Z Sep 15)...15% chance of tropical cyclone formation (central tropical Atlantic near 12.5N-55W)
IOH 96 Hr Outlook (0000Z Sep 16)...20% chance of tropical cyclone formation (in vicinity of Barbados near 13N-60W)
IOH 120 Hr OUtlook (0000Z Sep 17)...10% chance of tropical cyclone formation (eastern Caribbean Sea near 14N-65W)
AREA OF INTEREST #29...Computer models have insisted that a tropical disturbance will materialize offshore of western Africa in the near-term... and we have been tracking a pair of tropical waves over Africa in an attempt to discern which one(s) will contribute to the disturbance. The western of the two waves is nearing the west coast of Africa while featuring an area of rotation near 12N-15W with somewhat organized thunderstorm activity on the west side of the circulation. It appears the this western wave will be the singular feature to contribute to the expected offshore disturbance while the the eastern wave... currently in the vicinity of 0W longitude... lags behind to the east. The updated forecast track in the outlook below has a minor adjustment based on the current position of the above-mentioned western tropical wave. Atmospheric conditions offshore of Africa and in the eastern/central tropical Atlantic are expected to be favorable for development over the next five days due to the ongoing presence of a tropical upper ridge in the region with low shear and upper outflow. And given that the expected disturbance has better potential to start off consolidated while being focused with one wave instead of two waves entangling with each other... I have raised peak odds of tropical cyclone formation to 20%. Meanwhile the NHC has recently lowered their odds of tropical cyclone formation to 20% from 30% while many of the recent computer model runs continue to back off in showing development. Considering that the thermodynamic conditions offshore of Africa this hurricane season have been hostile over the last several days with air that has been too dry... low odds of tropical cyclone formation seem reasonable and I reserve the 20% odds to the end of the 5-day forecast period... when this disturbance will be further away from Africa.
Noting that this disturbance's lowest pressure is now on track to pass just south of the Republic of Cabo Verde Islands on Tuesday. This disturbance could bring heavy rainfall and gusty winds to the islands during that time... albeit the odds of this occuring appear slim due to the aforementioned ongoing dry air mass that has prevalent offshore of Africa.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Sep 13)...0% chance of tropical cyclone formation (offshore of western Africa near 12.5N-20W)
IOH 48 Hr Outlook (0000Z Sep 14)...10% chance of tropical cyclone formtion (just southwest of the Republic of Cabo Verde Islands near 13N-25W)
IOH 72 Hr Outlook (0000Z Sep 15)...10% chance of tropical cyclone formtion (eastern tropical Atlantic near 13.5N-30W)
IOH 96 Hr Outlook (0000Z Sep 16)...10% chance of tropical cyclone formation (eastern tropical Atlantic near 14N-35W)
IOH 120 Hr Outlook (0000Z Sep 17)...20% chance of tropical cyclone formation (central tropical Atlantic near 14.5N-40W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z (Sep 11) CMC Model Run...
**For area of interest #29... tropical wave emerges from west coast of Africa at 12 hours... organizes into a broad tropical low near 14N-21W at 42 hours... tropical low passes just south of the Republic of Cabo Verde Islands through 60 hours... tropical cyclone formation suggested near 19.5N-39.5W at 126 hours.
1200Z (Sep 11) ECMWF Model Run...
**For area of interest #29... tropical wave emerges from west coast of Africa in next 24 hours while organizing into a broad tropical low near 14N-20W... tropical low passes just south of the Republic of Cabo Verde Islands through 48 hours... tropical low opens to a wave near 40W longitude at 120 hours
1800Z (Sep 11) GFS Model Run...
**For area of interest #29... tropical wave emerges from west coast of Africa at 9 hours... organizes into a broad tropical low just southeast of the Republic of Cabo Verde Islands at 33 hours which passes just south of the islands through 57 hours... tropical low opens to a wave near 32W longitude at 84 hours
1200Z (Sep 11) NAVGEM Model Run...
**For area of interest #28... tropical wave organizes into a tropical low in the next 24 hours near 14N-39.5W... tropical cyclone formation suggested near 17.5N-55W at 156 hours.
**For area of interest #29... tropical wave emerges from west coast of Africa at 18 hours... organizes into a broad tropical low southeast of the Republic of Cabo Verde Islands at 42 hours... tropical low opens to a wave near 35W longitude at 126 hours.
**Tropical wave emerges from west coast of Africa at 108 hours... becomes well-organized tropical low while passing south of the Republic of Cabo Verde Islands at 144 hours... becomes a tropical depression near 13.5N-28W at 168 hours