MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #62

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

...FRIDAY AUGUST 22 2025 11:45 PM EDT...

It has been more than 48 hours since my previous Wednesday update on the Atlantic tropics... and it has taken some time to assemble this update due to a busy time in my personal life:

(1) The above graphic was completed early Friday

(2) My forecasts were completed with satellite and computer model data available through 11:45 PM EDT Friday.

(3) This update was published early morning Saturday after completing the text giving the rationale behind the forecasts.

Regarding current tropical Atlantic areas of interest:

(1) See Hurricane Erin section below for an update on the large hurricane in the northwest Atlantic which recently transitioned into a large and still powerful remnant frontal cyclone.

(2) See area of interest #20 section below for the tropical wave of low pressure that was in the central tropical Atlantic which has dodged the Lesser Antilles to the north... and is now en route to Bermuda where it could bring tropical cyclone impacts late Sunday through early Monday.

(3) See area of interest #21 section below for the tropical wave of low pressure that has recently entered the central tropical Atlantic... this wave may bring vigorous weather to the southern Lesser Antilles Monday evening.

Elsewhere in the Atlantic basin... a portion of the surface front trailing from ex-Erin may develop into a yet another tropical area of interest near coastal Georgia in the next 24 hours. Westerly shear in the area will drop due to an increasing gap between the current eastern US upper vorticity and upper trough currently departing the northeastern US. By 48 hours such a disturbance would track northeast across the coastal Carolinas while steered by the surface frontal system generated by amplified upper trough energy approaching from Canada. After 48 hours conditions for tropical development would come to an end as the disturbance would continue northeast into cooler waters and struggles to retain its identity from the nearing large low pressure field of the surface frontal system.

HURRICANE ERIN (RECENTLY DOWNGRADED TO REMNANTS OF ERIN)... Please note that although the NHC recently downgraded Erin from tropical to non-tropical... the remnant cyclone is still a rather large and formidable system and will continue to bring impacts in the form of large swells across the north Atlantic radiating to coastal areas... more information on Erin as follows:

Evolution of Erin over last few days... large Hurricane Erin has curved increasingly north then northeast parallel to the United States east coast and into the northwest Atlantic while coming under the increased influence of an upper trough skirting across the northern then northeastern United States. When the hurricane crossed the latitude of Cape Hatteras North Carolina Thursday morning (approximately 35N latitude)... it was at its closest point to the United States east coast but not as close I previously forecasted which allowed the rain bands to stay offshore. However the large tropical storm wind field clipped the outer banks of North Carolina in the vicinity of Cape Hatteras and coastal surf was vigorous... with the surf creating coastal flooding as far north as New Jersey and New York. The hurricane had a growth spurt early in the week while underneath a sprawling upper anticyclone dropping surface pressures over a wide area... and during its initial interaction with the incoming upper trough from the northeastern United States has grown even larger. The western side of Erin's surface circulation has pulled cool air associated with the upper trough southward which has allowed it to become a more amplified trough featuring a stronger and sprawling area of upper divergence causing the further growth in storm size. Meanwhile the eastern side of Erin's surface circulation is amplifying a warm core upper ridge by pulling warm air north... reducing the distance between cold air associated with the bi-polar upper vortex between Canada and Greenland and the northward surging warm air. The increasingly sharper air temperature contrast is resulting in a stronger pressure gradient aloft... manifesting as a rather strong upper westerly jet just northeast of Erin also evacuating air away from the storm top and re-enforcing the size and strength of Erin. After Erin reached a category 2 peak intensity with 110 mph maximum sustained winds on Wednesday... it only slowly weakened to category 1 max sustained winds through today despite the south half of the circulation losing thunderstorms while ingesting cooler drier air and while racing northeast toward cooler water due to the favorable upper wind dynamics. The National Hurricane Center downgraded Erin from a tropical hurricane to non-tropical frontal cyclone at 5 PM EDT today despite an increase in thunderstorms in the still moist north half of the circulation at the time... as a satellite scan of winds showed the formation of fronts (elongated surface troughs with air mass contrasts on either side) extending east and southwest of the center... this for example can be seen in the CIMSS 850 mb mid-level vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=).

Forecast for remnant frontal cyclone of Erin... in the short-term ex-Erin continues to race east-northeast past Newfoundland and into the open north Atlantic due to the formidable upper westerly jet mentioned in the previous paragraph. As it does so the northwest quadrant of the surface circulation pulls in cold air associated with what is the current northeastern US upper trough and bi-polar upper vortex between Canada and Greenland... fusing those upper features into a singular upper vortex near ex-Erin with time. Once ex-Erin whirls into the core of the upper vortex at a position south of Iceland by 72 hours... the remnant frontal cyclone will finally begin its post-mature decay phase due to a lack of divergence at the upper vortex core. Once the upper vortex shifts east... gradually decaying ex-Erin will begin drifting southeast toward mainland Europe in the northwesterly flow on the back side of the vortex. The models are in good agreement on ex-Erin's track through 72 hours... and have some disagreement on the angle of the southeast track toward mainland Europe for the long range.

Regarding the impact to land areas... surf affecting the shores of the northeastern United States... Atlantic Canada... and Bermuda reduces in the next 24 hours as ex-Erin zooms east-northeast. By Sunday and Monday surf radiating from ex-Erin reaches the shores of the Azores... western Europe... Iceland... and southeastern Greenland. This is my final statement on Erin on this blog as it is no longer a tropical system... future statements regarding impacts to land areas from ex-Erin will be carried on the home page bulletins of this site.

AREA OF INTEREST #20... The large tropical wave of low pressure/ gyre that was over the open central Atlantic earlier this week was expected to bend increasingly north in track while approaching the longitudes of the Lesser Antilles island chain due to the surface ridge weakness associated with the presence of Erin. The large system has gradually consolidated into a smaller circulation but still has some north-south elongation... and has lifted northward to a greater extent than previously forecast such that its shower and thunderstorm activity has completed cleared the Lesser Antilles and attention to potential impacts to land areas has shifted to Bermuda instead. Normally a shallower developing tropical system is steered by low-level winds... perhaps this system has a tall enough structure to be steered by the inverted upper trough to the west... and/or the inverted upper trough reaches low enough into the atmosphere to influence the steering of this system. In the next 24 hours the inverted upper trough flips to a normal mid-latitude type upper trough while attempting to link with the mid-latitude upper trough currently supporting ex-Erin... and may produce light southwesterly shear over this area of interest while potentially having an elongated eastern divergence zone that keeps this area of interest in its current north-south elongated state... as such I do have odds of tropical cyclone formation just barely above 50%. Between 24 and 48 hours the SW/NE tilted upper trough splits into one half dragged northeast by the upper trough tied to ex-Erin and the southwest half drifting northwest toward the upper trough energy approaching from Canada. It is during this time this elongated area of interest has its best chance to become a circular system with well-defined center as an upper anticyclone with an upper outflow maximum develops between the upper trough halves... and I have my peak odds of tropical cyclone formation during this time but not quiet as high as the NHC as not all global model runs on Friday agreed on tropical cyclone formation. The steering features after 48 hours will be a strengthening north Atlantic surface ridge to be produced by the back convergent side of the upper trough/vortex tied to ex-Erin and approaching upper trough energy from Canada and associated surface frontal system. The north Atlantic surface ridge appears strong enough to nudge the track of this area of interest into Bermuda between 48 and 72 hours which is what I depict in my outlook below... then the track bends increasingly north then northeast toward the southeastern corner of Newfoundland in the flow ahead of the approaching frontal system after 72 hours. The upper trough associated with the frontal system may increase the southwesterly shear in as soon as 72 hours... albeit the forward speed of this area of interest may be fast enough to keep up with the upper southwesterly winds and mitigate the shear which is why I still have odds of tropical cyclone formation above 50% at that point. Odds decrease to 0% from 72 to 120 hours as southwesterly shear increases... as this system enters waters below 26 deg C just at or just after 96 hours... and as this system increasingly loses identity to the much larger low pressure field of the incoming frontal system.

With the updated outlook... Bermuda is at risk of seeing heavy rainfall... gusty winds... and coastal surf late Sunday through early Monday even if this elongated north-south tropical low pressure system does not quiet become circular enough to be considered a tropical cyclone.

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

IOH 24 Hr Outlook (0000Z Aug 24)... 60% chance of tropical cyclone formation (midway between Bermuda and the northern Lesser Antilles near 25N-63W)

IOH 48 Hr Outlook (0000Z Aug 25)... 70% chance of tropical cyclone formation (just south-southeast of Bermuda near 30N-64.5W)

IOH 72 Hr Outlook (0000Z Aug 26)... 60% chance of tropical cyclone formation (north-northeast of Bermuda near 35N-64W)

IOH 96 Hr Outlook (0000Z Aug 27)... 20% chance of tropical cyclone formation (northwestern Atlantic near 40N-60.5W)

IOH 120 Hr Outlook (0000Z Aug 28)... 0% chance of tropical cyclone formation (southeastern Newfoundland near 47N-53.5W)

*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT***********************

Formation chance through 48 hours... 80%

Formation chance through 7 days... 90%

AREA OF INTEREST #21... The vigorous tropical wave that was over the eastern tropical Atlantic Wednesday is now in the central tropical Atlantic. Its spin maximum has been deflected south from 12N to 10.5N latitude due to the cyclonic flow of another tropical wave to the east that recently rolled off of the west coast of Africa. Unlike previous model projections the tropical wave of interest has escaped the grip of the wave to the east and it has arrived into the central tropical Atlantic early. As the tropical wave nears the Lesser Antilles the inverted upper trough to the northwest (not to be confused with the other inverted upper trough beside area of interest #20) slows down while entering the western Atlantic while flipping to a normal upper trough while attempting to link with the amplified upper trough energy to approach from Canada. The western convergence zone of the western Atlantic upper trough will increase surface pressures to the southwest of area of interest #20 by 72 hours which prevents this tropical wave of interest from curving north... and through day 5 the this tropical wave of interest then continues west across the Caribbean due to the eastern US surface ridge produced by the back convergence zone of the amplified upper trough energy departing eastern Canada.

Regarding odds of tropical cyclone formation... the NHC did not upgrade this system to a tropical cyclone in the Wednesday through Friday period as it did not quiet have a well-defined center in satellite scans of winds... however it was quiet close to meeting this criteria. As of late this system is further away from tropical cyclone status as the thunderstorms that were over and southwest of the spin maximum have gradually faded from regional dry Saharan air... and on the CIMSS 850 mb vorticity product this system is further from having a well-defined center while becoming increasingly elongated southwest-to-northeast (https://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=). I still have my peak odds of tropical cyclone formation higher than the NHC as upper winds are still conducive while this system is embedded in low shear/ upper outflow in anticyclonic flow next to the inverted upper trough mentioned in the previous paragraph... and as this system moves into lower concentrations of dry Saharan air... however I have not set them higher than 40% as the global model runs do not develop this system. Odds are lowered once this system enters the Caribbean where it will encounter convergent (suppressive) upper northeasterly flow on the southeast side of the current northwestern Caribbean upper ridge. After day 5 development prospects also do not look good as the upper vorticity currently over the eastern US is pushed southeast in the flow on the back side of the amplified upper trough energy to depart eastern Canada around that time... followed by the flow on the back side of yet another amplified upper trough that follows closely behind. The southeast migrating upper vorticity from the eastern US in turn erodes the northwest Caribbean upper ridge... resulting in non-divergent northerly flow overtop this area of interest in the long range as it continues across the Caribbean.

Interests in the southern Lesser Antilles should be aware of this tropical wave as it has potential to bring heavy rain and gusty winds Monday evening even if it quiet does not become a tropical cyclone.

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

IOH 24 Hr Outlook (0000Z Aug 24)... 40% chance of tropical cyclone formation (central tropical Atlantic near 11N-50W)

IOH 48 Hr Outlook (0000Z Aug 25)... 40% chance of tropical cyclone formation (east of the southern Lesser Antilles near 11.5N-56W)

IOH 72 Hr Outlook (0000Z Aug 26)... 40% chance of tropical cyclone formation (beside southern Lesser Antilles near 12N-61W)

IOH 96 Hr Outlook (0000Z Aug 27)... 20% chance of tropical cyclone formation (southeastern Caribbean Sea near 12.5N-66.5W)

IOH 120 Hr Outlook (0000Z Aug 28)... 10% chance of tropical cyclone formation (central Caribbean near 13N-72.5W)

*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT***********************

Formation chance through 48 hours... 20%

Formation chance through 7 days... 30%

AREA OF INTEREST #22... Satellite image from 0930Z Thursday August 21 showing Hurricane Erin and tropical waves of interest following behind. The small central Atlantic surface low that the National Hurricane Center was monitoring... tagged as area of interest #22 on this site... is also shown:

An open central Atlantic frontal low developed on Wednesday due to divergent upper westerly flow on the southeast edge of the large upper vortex center that produced what is the current north Atlantic frontal cyclone. Through Friday this frontal low continued northeast into the Azores where it proceeded to lose its identity along the surface front driven by the north Atlantic frontal cyclone... however before its identity loss tail end of its front became a small tropical low near 30N-50W that got the attention of the National Hurricane Center on Thursday. This is the twenty-second tropical Atlantic area of interest tracked on this site this year. The small tropical low became embedded beneath upper anticyclonic outflow spreading in behind the aforementioned large upper vortex and north Atlantic frontal cyclone which allowed it to produce a circular thunderstorm burst. By Friday the center of the warm core upper anticyclonic flow shifted northwest due to the warm southerly flow ahead of what is now ex-Erin... placing the tropical low below suppressive convergent upper northeasterlies that killed off its thunderstorms and this feature is already dissipating (the swirl cannot be seen on infrared satellite and was fading on visible satellite before sunset... and the CIMSS 850 mb vorticity product shows its spin is fading... https://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=). Noting the dissipating tropical low did not chase its parent frontal low that went into the Azores... instead the Atlantic surface ridge has expanded west toward the tropical low also due to upper convergence of the upper northeasterlies... and the dissipating tropical low is turning north in the flow between the Atlantic surface ridge and ex-Erin. This is my first and also final statement on this short-lived area of interest as it is already dissipating.

...COMPUTER MODEL SUMMARY...

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

1200Z (Aug 22) CMC Model Run...

**For Hurricane Erin (recently downgraded to remnants of Erin)... remnant frontal cyclone zooms northeast into waters south of Iceland by 78 hours... becomes quasi-stationary at this location through 102 hours while making a cyclonic loop underneath overhead upper vorticity... while weakening underneath the western convergence zone of the passing upper vorticity moves southeast into western Europe with centroid of the weakening remnant cyclone making landfall on coast of France at 168 hours

**For area of interest #20... north apex of tropical wave separates while turning north and becomes a tropical low near 28N-61.5W at 42 hours with tropical cyclone formation shortly thereafter... the gradually strengthening compact tropical cyclone passes east of Bermuda by 72 hours then weakens to a remnant low while reaching the cooler waters due south of Newfoundland by 114 hours... remnant low turns northeast and passes just southeast of Newfoundland and eventually loses identity to incoming low pressure field of large frontal system approaching from Canada by 132 hours

**For area of interest #21... no development shown

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

0000Z (Aug 22) ECMWF Model Run...

**Checked this ECMWF model run at tropical tidbits as the above-mentioned source had data from several forecast timestamps missing (https://www.tropicaltidbits.com/analysis/models/?model=ecmwf&region=atl&pkg=mslp_pcpn&runtime=2025082200&fh=18)

**For Hurricane Erin (recently downgraded to remnants of Erin)... remnant frontal cyclone zooms northeast into waters south of Iceland by 102 hours... becomes quasi-stationary at this location through 132 hours while making a cyclonic loop underneath overhead upper vorticity... while weakening underneath the western convergence zone of the passing upper vorticity moves southeast toward western Europe with centroid of the weakening remnant cyclone approaching the coast of France at 168 hours

**For area of interest #20... north apex of tropical wave separates while turning north and becomes a tropical low near 27N-62W at 51 hours... the tropical low passes east of Bermuda by 81 hours then turns northeast while losing identity by 108 hours to cold front extending from eastern Canada frontal low

**For area of interest #21... no development shown

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

1200Z (Aug 22) GFS Model Run...

**For Hurricane Erin (recently downgraded to remnants of Erin)... remnant frontal cyclone zooms northeast into waters south of Iceland by 78 hours... becomes quasi-stationary at this location through 102 hours while making a cyclonic loop underneath overhead upper vorticity... while weakening underneath the western convergence zone of the passing upper vorticity drifts east-southeast toward the British Isles and loses identity to another frontal cyclone approaching from the west by 156 hours

**For area of interest #20... north apex of tropical wave separates while turning north and becomes a tropical low near 24.5N-62.5W at 27 hours... tropical cyclone formation at 27.5N-63W at 45 hours and as a compact tropical cyclone proceeds to quickly gain high-end tropical storm strength to hurricane strength... the compact tropical cyclone passes east of Bermuda at 75 hours... weakens to a remnant low by 117 hours while reaching cooler waters due south of Newfoundland... remnant low passes just southeast of Newfoundland at 126 hours and loses identity to incoming low pressure field of large frontal system approaching from Canada shortly thereafter

**For area of interest #21... no development shown

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

1200Z (Aug 22) NAVGEM Model Run...

**For Hurricane Erin (recently downgraded to remnants of Erin)... remnant frontal cyclone zooms northeast into waters south of Iceland by 84 hours... becomes quasi-stationary at this location through 120 hours while making a cyclonic loop underneath overhead upper vorticity... while weakening underneath the western convergence zone of the passing upper vorticity drifts east-southeast toward the British Isles through 168 hours

**For area of interest #20... no development shown

**For area of interest #21... no development shown

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