BIRDSEYE VIEW POSTS

Since 2012 on the now retired Weather Underground blogs, I have been posting annotated "birdseye view" charts of the Atlantic basin, with a detailed explanation and forecasting that references the chart. From there you may know me as "NCHurricane2009." While I now do these "birdseye view" posts here, I will continue to do comments at Yale Climate Connections via Disqus where the former Weather Underground community has moved to. Feel free to reply to me there, at my Disqus feed at this link, or via e-mail at IOHurricanes@outlook.com 

 
 
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MY 2022 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #91

*******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.**********


...SATURDAY SEPTEMBER 3 2022 3:45 AM EDT...

September continuing to be a more active month for the Atlantic tropics in this 2022 season... with the second day of the month bringing in a second tropical cyclone named Earl just after Danielle formed on the first day of the month. Danielle has reached hurricane strength in the open north Atlantic... see Danielle section below for more information. While taking a curving path in the western Atlantic... Tropical Storm Earl could bring bring coastal sea swells to the northeastern Caribbean islands... the Bahamas... and Bermuda in the days ahead... see Earl section below for more information.


Elsewhere...monitoring the following areas of interest for tropical development in the days ahead:

(1) See area of interest #22 and #23 sections below for closing statements on the disturbances in the eastern tropical Atlantic and eastern Bay of Campeche.

(2) Over western Africa... satellite imagery shows a western tropical wave of low pressure nearing the west coast of Africa and a second wave to the east near 1W longitude. Models are undecided on which of the two waves will have development potential... with the eastern wave being favored on Thursday and now the western wave being favored in model solutions by Friday evening. Will monitor both waves for any signs of development as they approach and move into the eastern tropical Atlantic in the days ahead... declaring an area of interest for tropical development as needed.

(3) The frontal cyclone that has recently moved into the far northwest Atlantic from northeastern Canada previously drove a cold front into the western Atlantic. The front has since decayed into a surface trough which features a surface low pressure northeast of Bermuda. This surface low continues to be supported by split flow upper divergence between southwesterlies out ahead of the frontal cyclone's upper trough and northwesterlies on the northeast side of a nearby upper ridge to the south. Instead of continuing east toward Danielle... it now appears the surface low has become stationary and will soon turn southwest due to the influence of the surface ridge currently parked near the US New England coast. This track will carry the surface low into shearing upper westerly flow being generated by the south side of the frontal cyclone's upper trough... as well as an additional upper trough to approach the region from its current position over central Canada. Therefore no tropical development is expected from this surface low.


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 #22 and #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.


HURRICANE DANIELLE...Since the previous update Danielle’s impressive burst of intensification ramped down while the thunderstorm activity in the circulation gradually faded. The intensification was just enough to bring Danielle to minimal category 1 hurricane strength since 5 PM EDT on Friday. What remains of the thunderstorm activity is essentially a small ring around the eye. The stationary hurricane is persisting off of its warm core anticyclonic upper outflow tucked just southeast of the parent upper vorticity that triggered the pre-cursor circulation of Danielle. The eastern divergence zone of the parent upper vorticity is also likely playing a role in supporting Danielle.


The reduction of Danielle’s thunderstorm activity could be a reflection of not so favorable thermodynamic conditions caused by the hurricane being parked over marginally warm waters. The water temperatures in the area may also be cooling due to the stationary hurricane’s winds upwelling cooler water beneath the sea surface. As a result I generally agree with the NHC forecast as of this writing which now only peaks Danielle as a category 1 hurricane with 85 mph maximum sustained winds. However if in fact the sea surface temperatures are already cooling... then it would not surprise me if Danielle has already peaked in intensity at its current estimated 75 mph maximum sustained winds.


By day 3... the 1800Z GFS has the southern fracture of the current upper trough near the east Canada coast near Danielle but in a weaker state with two fragments. However by day 4 these two fragments and the parent upper vorticity of Danielle coalesce into an amplified upper trough with Danielle interacting with the east side of the amplified trough. And by day 5 the amplified upper trough becomes re-enforced as the current central Canada upper trough approaches and merges with it. In the interaction with the amplified upper trough... Danielle is expected to finally move northeast in 3+ days. The amplified nature of the trough will allow Danielle to get 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 at 72+ 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 by day 5.

******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********

0 Hr Position (0000Z Sep 3)... 75 mph maximum sustained wind hurricane centered at 37.9N-43.5W

IOH 24 Hr Forecast (0000Z Sep 4)... 85 mph maximum sustained wind hurricane centered at 38N-44W

IOH 48 Hr Forecast (0000Z Sep 5)... 85 mph maximum sustained wind hurricane centered at 38.5N-44W

IOH 72 Hr Forecast (0000Z Sep 6)... 75 mph maximum sustained wind hurricane centered at 40.5N-43W

IOH 96 Hr Forecast (0000Z Sep 7)... 70 mph maximum sustained wind tropical storm gradually transitioning into a frontal cyclone while centered at 44.5N-40.5W

IOH 120 Hr Forecast (0000Z Sep 8)...Non-tropical remnant frontal cyclone centered at 47N-39W


AREA OF INTEREST #20 (RECENTLY UPGRADED TO TROPICAL STORM EARL)... The broad tropical low pressure that has been sliding west across the central tropical Atlantic over the last several days finally gotten around to developing a well-defined center of surface rotation detected by aircraft recon missions late Friday. Aircraft reconnaissance also measured minimal tropical storm force winds in the thunderstorm activity east of the center. As a result the broad tropical low is now Tropical Storm Earl as it nears the northern Lesser Antilles and northeastern Caribbean islands. Meanwhile thunderstorm activity west of the center is absent due to wind shear being imparted by upper vorticity lingering to the northwest. Although the convergent west side of the upper trough currently near the east coast of Canada is building a surface ridge near the US New England coast and north of Earl... the tropical storm is likely to bend north in track while strong/tall enough to be steered by the east side of the lingering upper vorticity. Eventually the south side of the current central Canada upper trough will slide into the western Atlantic and team up with the lingering upper vorticity to turn Earl northeastward. The updated forecast track is the same as the previous in the short term... and slowed in terms of forward speed in the long term to be more aligned with the latest model consensus which has changes regarding the approaching central Canada upper trough. Essentially a stronger upper ridge is now anticipated over North America in the days ahead... which will cut-off the approaching south part of the upper trough over the southern US. Eventually some of the upper trough escapes the grip of the North American upper ridge... but a smaller portion than in prior forecasts such that the upper westerly steering flow is weaker which causes a slower northeast acceleration of Earl for the later part of the forecast period.


Even though Earl became a tropical storm a little sooner than in my prior forecast... my updated one below remains unchanged as Earl does not appear to be in a hurry to intensify due to ongoing westerly wind shear. There is an opporutnity for some strengthening in the next 48 hours as the shearing upper vorticity continues to weaken while remaining cut-off from high-latitude cold air. Westerly shear may make a little resurgence across the western Atlantic by day 3 as the southern portion of the current east Canada coastal upper trough slides across the northwest Atlantic... therefore the intensity forecast for the timeframe suggests a little weakening. Wind shear in the later part of the forecast period appears to be lower than previously thought... with a delayed arrival of the south part of the current central Canada upper trough due to a stronger North America upper ridge... and when the trough arrives it will be more amplified due to the stronger ridge which not only keeps shear lower but also increases upper divergence over Earl. Therefore re-strengthening is suggested by day 5 in the forecast below.


Regarding impact to land areas... the center of Earl on its current track will pass just north of the Lesser Antilles and northeastern Caribbean islands. Therefore impacts to the northern Lesser Antilles... Virgin Islands... Puerto Rico... north coast of the Dominican Republic... and also the Bahamas and Bermuda will likely be limited to coastal sea swells this weekend and into the early to mid part of this upcoming week.

******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********

0 Hr Position (0000Z Sep 3)...40 mph maximum sustained wind tropical storm centered just northeast of the northern Lesser Antilles at 18.4N-60.3W

IOH 24 Hr Forecast (0000Z Sep 4)...45 mph maximum sustained wind tropical storm centered in the western Atlantic at 20.5N-63.5W

IOH 48 Hr Forecast (0000Z Sep 5)...60 mph maximum sustained wind tropical storm centered in the western Atlantic at 22.8N-66.5W

IOH 72 Hr Forecast (0000Z Sep 6)...50 mph maximum sustained wind tropical storm centered in the western Atlantic at 25.5N-66W

IOH 96 Hr Forecast (0000Z Sep 7)...50 mph maximum sustained wind tropical storm centered south of Bermuda at 28N-64.5W

IOH 120 Hr Forecast (0000Z Sep 8)...60 mph maximum sustained wind tropical storm centered southeast of Bermuda at 28.5N-60.5W


AREA OF INTEREST #22...The tropical disturbance that was moving across the Yucatan peninsula of Mexico is now entering the eastern Bay of Campeche. However the surface trough/tropical wave of this disturbance is not able to compete with the organizing tropical disturbance to the southwest in the eastern Pacific... being generated by south side of the adjacent surface trough/tropical wave. Ironically this adjacent surface trough/tropical wave was associated with this disturbance when it was in the western Caribbean a few days ago... before it continued off to the west and left this disturbance behind. Given the dominance of the nearby eastern Pacific disturbance... tropical cyclone formation in the Bay of Campeche is not anticipated and this is my final statement on this area of interest on this blog.

******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********

IOH 24 Hr Outlook (0000Z Sep 4)...0% chance of tropical cyclone formation (central Bay of Campeche near 19.8N-94W)


AREA OF INTEREST #23...The center of rotation of the tropical low pressure spin in the eastern Atlantic passed 20N-30W... and is essentially a part of the dry saharan air layer while an embedded swirl of dust and low clouds lacking thunderstorm activity. In addition to the dry air... this system will turn increasingly northwest toward the surface ridge weakness being generated by Hurricane Danielle... exposing it to westerly shearing winds on the north side of the tropical upper ridge in the region. Therefore tropical cyclone formation from this system is not anticipated... and this is my final statement on this area of interest on this blog.

******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********

IOH 24 Hr Outlook (0000Z Sep 4)...0% chance of tropical cyclone formation (eastern tropical Atlantic near 21N-35W)


...COMPUTER MODEL SUMMARY...

Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)


1200Z (Sep 2) CMC Model Run...

**For Hurricane Danielle... begins moving northeast at 72 hours...reaches 43N-39W at 120 hours

**For area of interest #20...tropical cyclone formation suggested north of Puerto Rico and east of the eastern Bahamas at 22N-67W... turns north and acquires hurricane strength near 23.5N-68W at 102 hours...reaches 24N-68.5W at 120 hours

**For area of interest #22...no development shown

**For area of interest #23...tropical low weakens to a tropical wave near 20N-39W at 54 hours

**Tropical wave emerges from west coast of Africa at 54 hours...organizes into a broad tropical low just south of the Republic of Cabo Verde Islands at 84 hours... tropical low becomes compact and more organized with time and reaches 18N-46W at 168 hours

**Tropical wave emerges from west coast of Africa at 114 hours... organizes into a tropical low just south of the Republic of Cabo Verde Islands at 144 hours... tropical low reaches 12N-40W at 168 hours


1200Z (Sep 2) ECMWF Model Run...

**For Hurricane Danielle... begins moving north-northeast at 72 hours... reaches 43N-40.5W at 120 hours.

**For area of interest #20... tropical low reaches 22.5N-69.5W at 120 hours

**For area of interest #22... no development shown

**For area of interest #23... tropical low weakens to a tropical wave near 24N-43W at 96 hours

**Tropical wave emerges from west coast of Africa at 24 hours... while passing over the Republic of Cabo Verde Islands between 48 and 72 hours organizes into a tropical low... tropical low reaches 19.5N-38.5W at 120 hours


1800Z (Sep 2) GFS Model Run...

**For Hurricane Danielle... begins moving northeast at 60 hours... reaches 46N-39.5W at 120 hours

**For area of interest #20... tropical low slides across the northern Lesser Antilles... Virgin Islands... and north coast of Puerto Rico through 39 hours... drifts north and tropical cyclone formation suggested near 23N-65.5W at 99 hours... tropical cyclone located at 25.5N-63W 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 dissipates near 21N-44.5W at 96 hours

**Tropical wave emerges from west coast of Africa at 48 hours... gradually organizes into broad tropical low that reaches 15N-36W at 120 hours


1800Z (Sep 2) NAVGEM Model Run...

**For Hurricane Danielle... begins moving northeast at 54 hours... reaches 45N-39.8W at 120 hours

**For area of interest #20... tropical cyclone formation suggested near 21.2N-65.5W at 42 hours...turns north and then northeast and reaches hurricane strength near 25N-65W at 90 hours...reaches 26.5N-61.5W 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 24N-41.5W at 72 hours

**Tropical wave emerges from west coast of Africa at 48 hours...organizes into tropical low just southeast of the Republic of Cabo Verde Islands at 66 hours... tropical low reaches 22N-36.5W at 120 hours

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