*******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 1 2022 5:33 PM EDT...
The quiet July-August spell of no tropical cyclones in the Atlantic comes to an abrupt ending as Tropical Storm Danielle quickly forms in the open north-central Atlantic... and has potential to become a category 1 or 2 hurricane within the next few days. See Danielle section below for more information.
Elsewhere...monitoring the following areas of interest for tropical development in the days ahead:
(1) See area of interest #20 section below for more information on an organizing tropical low pressure in the central tropical Atlantic. Note that this system will pass near the northern Lesser Antilles tomorrow and into Saturday... and near Bermuda by early next week.
(2) See area of interest #22 section below for an update on the disturbance in the western Caribbean Sea now moving into Belize and the Yucatan peninsula of Mexico.
(3) See area of interest #23 section below for more information on the tropical low pressure in the far eastern Atlantic passing just north of the Republic of Cabo Verde Islands.
(4) Satellite imagery shows a tropical wave of low pressure with concentrated thunderstorms over western Africa passing 7.5W longitude. The latest model runs do not develop this feature... however should it show signs of organization will add it as an area of interest in future updates as conditions for development in the offshore eastern tropical Atlantic waters remain favorable with a persistent tropical upper ridge featuring low shear and upper outflow.
(5) Satellite imagery shows a tropical wave of low pressure with curved bands of thunderstorms over central Africa passing 4E longitude. This tropical wave has some model support showing development when it reaches the eastern tropical Atlantic in approximately 5+ days. This wave may need to be added as an area of interest for tropical development in future updates.
(6) A frontal cyclone over eastern Canada has driven a cold front into the western Atlantic waters offshore of the United States east coast. There are no signs of tropical development along the tail end of this front offshore of the southeast United States coast. However satellite imagery and the CIMSS 850 mb vorticity product (http://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=) show that the front has developed a new low pressure spin just northeast of Bermuda. The new surface low is supported by split flow upper divergence between southwesterlies out ahead of the eastern Canada upper trough and northwesterlies streaming into a nearby upper vortex to the southeast. Due to the surface ridge building behind the front... this surface low will head generally east across the open central Atlantic and toward Daneille... and wind shear levels are expected to remain low as the upper trough over eastern Canada will be slow to push into the western Atlantic due to resistance caused by the current upper anticyclonic ridge just offhsore of Newfoundland. It is possible this surface low gets upgraded to an area of interest to the west of Danielle in the next 48 hours. After that tropical development of this feature will be difficult as it nears Daneille which is expected to dominate the region as a hurricane.
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 #23 as I used up the other numbers in prior birdseye view posts this year. 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.
TROPICAL STORM DANIELLE...The relatively new north-central Atlantic surface low... designated as area of interest #26 in the previous birdseye view post... has continued to over-achieve as of early Thursday and into Thursday afternoon. While located out ahead of (just south-southeast of) its parent upper vorticity string... in the early morning hours the small surface low redeveloped increased thunderstorms across its southeastern half which proceeded to wrap around the circulation. At the core of the circulation a persistent banding type eye feature became established... and even persists at this hour. The circulation was promptly upgraded by the National Hurricane Center (NHC) to tropical depression five at 5 AM EDT... and then Tropical Storm Danielle at 11 AM EDT. Despite the genesis of the surface low being traced to upper divergence out ahead of the aforementioned parent cool core upper vorticity string... the fully tropical designation is warranted as the ongoing ring of thunderstorm activity around the banding type eye has established enough latent heat release to generate warm core upper outflow extending as high as the 200 mb layer of the atmosphere. The surprise early formation of the rather tall warm core has occurred in a small area between the ongoing central Atlantic upper vorticity string to the south and the parent string of upper vorticity looming just to the north-northwest. The southern outflow of Danielle is also able to ventilate into the central Atlantic upper vorticity to the south.
I agree with the NHC 5 AM EDT advisory package which shows a peak intensity projection of 90 mph high-end category 1 hurricane force winds. However I currently forecast Danielle to reach this intensity sooner due to the current favorable above-described upper outflow pattern... with the models now expecting Danielle to keep this pattern for the next 72 hours. The models have backed off on the parent cool core upper vorticity to the north-northwest overrunning Danielle from the top... and now have this vorticity coalescing into a small upper vortex west of the tropical storm which simply dissipates by 72 hours perhaps while picking up on and respecting Danielle's current levels of thunderstorm latent heat release. The upper vorticity due south of Danielle is expected to shift east while merging with the ongoing upper vorticity in the eastern Atlantic allowing Danielle's eastern and southern quadrants to potentially have outflow channels extending into those features. It would not surprise me if Danielle achieves category 2 strength in the next 72 hours... however I have refrained from this in the current intensity forecast as Danielle is and will continue to be generally stationary over marginally warm waters... with the stationary storm's winds potentially upwelling cooler water beneath the surface.
By days 4 and 5... a northeast track is finally expected to become established with the approach of the current upper trough over eastern Canada. The latest model data shows an amplified upper trough such that Danielle gets the benefits of upper divergence on the east side of the trough without excess wind shear. Therefore as Danielle moves into waters below 26 deg C just after 96 hours... the supportive divergence zone of the trough will keep Danielle's weakening rate slow. The large size of the upper divergence zone should also cause Danielle to expand in size by creating an outer non-tropical low pressure circulation around Danielle's tropical core. The tropical warm core will eventually fade over cooler water... but the process could take some time due to the low shear environment that would be unable to push the thunderstorms away from the center. But once that process is completed... Danielle will be a large and still strong non-tropical frontal cyclone heading towards the northeast Atlantic. I currently expect the transition to non-tropical to be completed just after day 5.
Update as of 5 PM EDT... the National Hurricane Center has upgraded Danielle to a stronger tropical storm with 60 mph maximum sustained winds. I have now increased the intensity forecast to show Danielle reaching a category 2 peak of 105 mph maximum sustained winds within the next 72 hours. Also noting the NHC has bumped up their intensity forecast to show Danielle reaching a category 2 peak of 100 mph maximum sustained winds.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1800Z Sep 1)...60 mph maximum sustained wind tropical storm centered at 38.1N-44.5W
IOH 24 Hr Forecast (1800Z Sep 2)...90 mph maximum sustained wind hurricane centered at 38N-44W
IOH 48 Hr Forecast (1800Z Sep 3)...105 mph maximum sustained wind hurricane centered at 38N-44W
IOH 72 Hr Forecast (1800Z Sep 4)...105 mph maximum sustained wind hurricane centered at 38N-44W
IOH 96 Hr Forecast (1800Z Sep 5)...90 mph maximum sustained wind hurricane centered at 40.2N-43W
IOH 120 Hr Forecast (1800Z Sep 6)...85 mph maximum sustained wind hurricane gradually transitioning into a frontal cyclone while centered at 44N-41W
AREA OF INTEREST #20...Over the last 24 hours and despite obtaining a less elongated and more circular circulation... the broad tropical low pressure system in the open central Atlantic has not made much progress in developing further. The updated forecast track in the outlook below is nudged eastward in the short-term to account for the current position of the tropical low... and remains the same for the longer-term as there are no changes in the forecast steering pattern. The westward track of this system will bend increasingly towards the north as it first rounds the southwestern side of the Atlantic surface ridge. The current eastern Canada frontal system is currently heading into the western Atlantic... however by day 2 it will be departing northeastward out of the region upon which time a surface ridge is expected to build in its wake. However an ongoing north angle in track is expected at 2+ days as this system is likely to be tall/strong enough to be steered by the upper vorticity currently located to the northwest. A complete turn to the north and then north-northeast is anticipated by days 4 and 5 as an additional upper trough... associated with an additional frontal system currently over western Canada... eventually heads into the western Atlantic and teams up with the lingering upper vorticity.
The updated intensity forecast is lowered a notch to reflect the lack of development progress over the last 24 hours and the fact that global models... except the GFS... have pulled out of developing this system. There is an opporutnity for development in the next 72 hours as the upper vorticity to the northwest continues to weaken while remaining cut-off from high-latitude cold air... which will keep wind shear on the lower side. As the shear surges by days 4 and 5 with the upper trough from western Canada arriving and teaming up with the remainder of the upper vorticity... the intensity projection is lowered.
Regarding impact to land areas... this system on its current forecast track will pass just northeast of the Lesser Antilles tomorrow and Saturday. The southwest quadrant of the tropical low pressure's circulation lacks thunderstorm activity due to the light southerly shear being imparted by the upper vorticity lingering to the northwest of the tropical low. Therefore impacts to the northern Lesser Antilles will likely be limited to coastal sea swells. Coastal sea swells could also spread across the Virgin Islands... Puerto Rico... north coast of the Dominican Republic... Bahamas... and Bermuda later in the weekend and into early next week. However coastal sea swells at these land areas could be lessened by the fact this system is less likely to become a hurricane before the wind shear increases as it has not made much development progress in the last 24 hours.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1800Z Sep 1)...Tropical low centered in the central tropical Atlantic at 16.5N-55W
IOH 24 Hr Forecast (1800Z Sep 2)...Tropical low centered just northeast of the northern Lesser Antilles at 18.5N-59W
IOH 48 Hr Forecast (1800Z Sep 3)...45 mph maximum sustained wind tropical storm centered in the western Atlantic at 20.5N-63W
IOH 72 Hr Forecast (1800Z Sep 4)...60 mph maximum sustained wind tropical storm centered in the western Atlantic at 22.5N-66W
IOH 96 Hr Forecast (1800Z Sep 5)...50 mph maximum sustained wind tropical storm centered in the western Atlantic at 26N-66W
IOH 120 Hr Forecast (1800Z Sep 6)...50 mph maximum sustained wind tropical storm centered south-southeast of Bermuda at 30N-64W
AREA OF INTEREST #22...The tropical disturbance in the western Caribbean continues to be latched on to a tropical wave of low pressure moving through the area. The tropical wave is moving into Belize and Yucatan peninsula of Mexico... and will soon arrive in the Bay of Campeche. Watching to see if an area of split flow upper divergence becomes established in the bay... between the west side of a string of upper vorticity spanning the southeastern Gulf of Mexico and northern Caribbean Islands and southeast side of an upper ridge lingering over the western Gulf of Mexico and Texas. If this ends up being the case... the tropical wave could become enhanced. However none of the models forecast tropical cyclone formation... and so my odds of development are set at a slim margin of 5%. This disturbance has been tracking west-northwest around the southwest side of the Atlantic surface ridge. A more westward track into Veracruz is shown by the end of the forecast as steering surface ridging over North America increases after the quick departure of the current eastern and western Canada frontal systems.
Since yesterday on this blog and on the home page bulletins of this site... I have cancelled statements regarding impacts to land areas while this system has lacked a persistent area of concentrated thunderstorms. If the current squalls of thunderstorms developing this aftenroon across the Yucatan peninsula of Mexico becomes a persistent area once this disturbance moves into the Bay of Campeche... will consider adding an impact statement for Veracruz in future updates.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Sep 2)...0% chance of tropical cyclone formation (eastern Bay of Campeche coast of Mexico near 18.8N-91W)
IOH 48 Hr Outlook (1800Z Sep 3)...5% chance of tropical cyclone formation (central Bay of Campeche near 19.8N-94W)
IOH 72 Hr Outlook (1800Z Sep 4)...0% chance of tropical cyclone formation (central Veracruz near 20.2N-98W)
AREA OF INTEREST #23...The tropical low pressure spin that was located just offshore of Africa has finally made a westward acceleration on the south side of the steering Atlantic surface ridge. The center of rotation is passing just northwest of the Republic of Cabo Verde Islands. By day 4 an increasing turn towards the north is anticipated as the ridge develops a weakness induced by Tropical Storm Danielle. Regarding probabilities of tropical cyclone formation... this system is in an unfavorable thermodynamic setting while ingesting dry saharan air and tracking over marginally warm 26 deg C waters only just enough for tropical development. And with no signs of a core of thunderstorms developing... I have again cut odds of tropical cyclone formation to 10% from the 30% shown in the previous update. As this system turns increasingly northwest into upper westerly shearing flow on the north side of tropical upper ridging in the region and south side of upper vorticity to linger in the mid-latitudes of the eastern Atlantic... conditions will become even more hostile for tropical development. Therefore odds of development are trimmed down to 0% by day 4.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Sep 2)...10% chance of tropical cyclone formation (eastern tropical Atlantic near 19N-30W)
IOH 48 Hr Outlook (1800Z Sep 3)...10% chance of tropical cyclone formation (eastern tropical Atlantic near 19.5N-35W)
IOH 72 Hr Outlook (1800Z Sep 4)...5% chance of tropical cyclone formation (central tropical Atlantic near 20N-40W)
IOH 96 Hr Outlook (1800Z Sep 5)...0% chance of tropical cyclone formation (central Atlantic near 22.5N-41W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
0000Z (Sep 1) CMC Model Run...
**For Tropical Storm Danielle...becomes a strong tropical storm near 37.5N-45W at 54 hours... turns northeast and reaches 42N-41.5W at 120 hours.
**For area of interest #20...tropical low reaches waters just northeast of the eastern Bahamas at 144 hours...turns northeast and becomes a tropical depression near 23N-69W at 168 hours
**For area of interest #22...no development shown
**For area of interest #23...tropical low passes just north of the Republic of Cabo Verde Islands at 12 hours... weakens to a tropical wave near 25N-40W at 114 hours
**Tropical wave emerges from west coast of Africa at 120 hours... tropical cyclone formation suggested just southwest of the Republic of Cabo Verde Islands at 156 hours... tropical cyclone located at 14N-30W at 168 hours.
0000Z (Sep 1) ECMWF Model Run...
**For Tropical Storm Danielle... reaches hurricane strength near 37.5N-46W at 72 hours... turns north-northeast and reaches 40.5N-45W at 120 hours.
**For area of interest #20...tropical low weakens to a wave just east of the eastern Bahamas at 144 hours.
**For area of interest #22...short-lived tropical low develops in the south-central Bay of Campeche centered just offshore of Mexico as disturbance moves across the area... afterwards no development shown as the tropical low dissipates.
**For area of interest #23...tropical low moves west-northwest across the eastern tropical Atlantic and weakens to a wave near 23N-37.5W at 96 hours
**Tropical wave emerges from west coast of Africa at 120 hours... organizes into a broad tropical low west-southwest of the Republic of Cabo Verde Islands at 168 hours.
1200Z (Sep 1) GFS Model Run...
*For Tropical Storm Danielle... reaches hurricane strength near 37.5N-45W at 39 hours... begins to move northeast and reaches 42.5N-42.5W at 120 hours.
**For area of interest #20... tropical low passes just north of the northern Lesser Antilles at 48 hours... tropical cyclone formation suggested near 23.5N-63.8W at 81 hours... turns north-northeast and reaches 26.2N-62W at 120 hours as a hurricane
**For area of interest #22... no development shown
**For area of interest #23... tropical low moves west-northwest across the eastern tropical Atlantic and weakens to a wave near 25N-41W at 99 hours
0600Z (Sep 1) NAVGEM Model Run...
**For Tropical Storm Danielle...becomes a strong tropical storm near 36.2N-46W at 78 hours... moves northeast and reaches 41N-39.5W at 120 hours.
**For area of interest #20... tropical low weakens to a wave just east of the eastern Bahamas at 120 hours.
**For area of interest #22...no development shown
**For area of interest #23... tropical low moves west-northwest across the eastern tropical Atlantic and weakens to a wave near 25N-40W at 102 hours