MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #59

*******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 AUGUST 16 2025 11:30 PM EDT...

Note the text of this update was completed at 11:30 PM EDT... three hours later than I previously planned... as severe thunderstorms in my community (located in the Great Lakes region of North America) had caused a power outage.

The Atlantic tropics remain quiet active with Hurricane Erin explosively intensifying into a category 5 earlier today while entering the waters just north of the northeastern Caribbean Islands. Alongside the intensifying hurricane... their have been three areas of interest that are/ were being watched for tropical development over the last couple of days as follows:

(1) See Hurricane Erin section below for an update on the powerful hurricane... including on impacts expected across the northeastern Caribbean islands... Bermuda... the Bahamas... and the east coast of continental North America.

(2) See area of interest #17 section below for a frontal low east of North Carolina the National Hurricane Center is monitoring for signs of tropical development.

(3) Sea area of interest #18 section below for a final update on the western Gulf of America surface trough that made landfall at the Texas/ Mexico border on Friday... the trough was being monitored for tropical development before the landfall.

(4) See area of interest #19 section below for more information on the currently developing northwest Atlantic deep-layer cyclone that could acquire tropical characteristics in the short-term before moving into cooler water.

Elsewhere in the Atlantic basin... noting the following regarding the eastern and central tropical Atlantic:

(1) The tropical wave of low pressure that was southwest of the Republic of Cabo Verde Islands in the previous update is now approaching 40W longitude... and has not developed so far due to dry Saharan air and while aligned with the weakest part of the current tropical Atlantic upper ridge axis where upper outflow is muffled... the weakening of the upper ridge is due to upper vorticity being pushed south by the warm core upper anticyclone of powerful Hurricane Erin. The upper vorticity is expected to continuing revolving around the upper anticyclone... eventually becoming a westward-moving inverted upper trough moving in tandem with the surface wave and hence continuing to suppress the outflow of the surface wave. This surface wave is therefore not forecast to develop.

(2) The tropical wave of low pressure which recently departed the west coast of Africa has ingested dry Saharan air in its northwest half... watching to see if the remainder showers and thunderstorms in the southeast half of the circulation show signs of development. The GFS model insists on developing this tropical wave when it later moves into the central tropical Atlantic in the long range.

(3) Another tropical wave of low pressure is spotted over western Africa while moving toward southern Mali and will be entering the eastern tropical Atlantic in 48 hours.

(4) Regarding the model runs in the computer model summary section below... the CMC prefers the current western Africa wave while holding on to it as a tropical low through day 7... the ECMWF did not develop either wave... and the GFS and NAVGEM prefer the wave which recently departed the west coast of Africa with the GFS developing it into a tropical cyclone when it later enters the central tropical Atlantic and the NAVGEM holding on to it as a tropical low through day 7. The National Hurricane Center (NHC) has recently issued a new area of interest for the eastern and central tropical Atlantic as of 8 PM EDT tonight... to avoid further delays in releasing this update I have released it without an outlook on this brand new area of interest. In my next update on the Atlantic tropics I will be tagging it as area of interest #20 as it will be the twentieth Atlantic tropical area of interest tracked on this site this year... noting the NHC did not specify which of the above-mentioned waves is associated with the new area of interest and prior to my next update I will be deciding whether the current wave just offshore of Africa... or the wave currently over western Africa... will be used as the initial position for the new area of interest.

MAJOR HURRICANE ERIN... Satellite imagery of Hurricane Erin from 5 PM to 11 PM EDT (2100Z to 0300Z) as it went from peak organization at category 5 strength to a still ferocious category 4 due to an eye wall replacement cycle:

The explosive intensification of Erin from a category 1 to 5 hurricane... as it moved into the waters just north of the northeastern Caribbean Islands... was documented in special update #58A (https://www.infohurricanes.com/post/my-2025-atlantic-hurricane-season-birdseye-view-post-58a-special-update). Since then aircraft reconnaissance has reported no additional intensification and spotted a second eye wall attempting to form around the current pinhole eye... signs that Erin will go through an eye wall replacement cycle in the hours ahead that likely dips the intensity back into category 4 strength. Noting during the earlier intensification process it appeared the thunderstorm latent heat release of the hurricane weakened the cool-core band of tropical-latitude upper vorticity to the northwest... reducing its steering effect and allowing the hurricane to bend more west and less north in track. It is also apparent the western Atlantic surface ridge weakness being induced by the arrival of the frontal system from the northeastern US and eastern Canada (the same frontal system containing areas of interest #17 and #19) has not matured enough yet to affect the hurricane's track... in fact upper southerlies streaming from the inflamed tropical-latitude upper ridge caused by Erin's thunderstorm latent heat release are likely converging with the mid-latitude upper ridge center just offshore of the southeastern US... keeping surface pressures elevated enough to delay the weakening of the western Atlantic to Gulf surface ridge that was in place. However the dissipation of that surface ridge is inevitable after 12 hours and Erin is still expected to turn north. For the early half of the forecast period... the northward turn will be due to the surface layer steering as what will be left of the tropical-latitude upper vorticity band decays into a distant upper vortex over Florida... and the mid-latitude upper vorticity left behind over the eastern US by the upper trough that recently departed eastern Canada will split into one east-west string ingested into the west side of the amplified upper trough associated with area of interest #19... and another east-west string stuck over North Carolina/ Tennessee... with Erin in the gap between the mid-latitude upper vorticity through day 3. This also translates into a vast area of low shear/ upper outflow along Erin's forecast track during that timeframe... and Erin still hasn't reached the warmest waters along the forecast path and will do so on days 2 to 3 (there is a warmer 30 deg C patch southwest of Bermuda... see https://www.nhc.noaa.gov/sst/). As a result my forecast intensity callout through day 3 is a high-end category 4 which is what I currently project the average intensity of Erin will be as its intensity fluctuates from eye wall replacement cycles. By days 4 upper westerly flow in Erin's environment begins to increase as southward cold air transport from a north Atlantic frontal cyclone pushes an upper vortex center southward closer to Erin... the increase in westerly flow is also helped by a shortwave upper trough over the northern US that is shoved toward Erin by the encroaching upper vortex. At this point I begin to lower the intensity projection from possible western outflow blockage/ shear... and then by day 5 the upper westerlies should increase further which results in higher shear and a more northeast track. Noting that after day 5 Erin is likely to transition into a powerful and large non-tropical frontal cyclone as it speeds toward cooler water... perhaps maintaining category 1 hurricane-force intensity even after transition... while supported by the southeastern divergence zone of the upper vortex.

Regarding the impact to land areas:

(1) Heavy rainfall from Erin's southern outer bands has ended over the northern Lesser Antilles... and is now over Puerto Rico and the Virgin Islands. Over the next 48 hours rainfall from the outer bands shifts across the northeastern half of the Dominican Republic then the southeastern Bahamas. Heavy-rain induced mudslides over mountainous terrain cannot be ruled out.

(2) The potential for direct impacts to Bermuda... such as gusty winds and heavy rain... for the middle part of this upcoming week has ended.

(3) Erin as a powerful hurricane at first... then as a large and still powerful non-tropical frontal cyclone after day 5... will produce widespread surf across the western Atlantic. Surf is currently affecting the shores of the northeastern Caribbean Islands... and will reach the shores of the Bahamas... southeastern US... and Bermuda by late this weekend through the early part of this upcoming week. By Thursday surf should reach the shores of the northeastern US and Atlantic Canada

Update as of 11 PM EDT... the eye wall replacement cycle has caused intense Hurricane Erin to fluctuate downward from its prior category 5 peak (160 mph max sustained winds with 915 mb surface pressure) to a category 4 with 140 mph maximum sustained winds and 937 mb surface pressure. The rain bands on the south side of the hurricane have grown is size... and is likely to now include all of the Dominican Republic in the heavy rainfall/ mudslide risk zone instead of just the northeast half.

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

0 Hr Position (1800Z Aug 16)... 160 mph maximum sustained wind major hurricane centered north-northeast of the Virgin Islands at 20N-64W

IOH 24 Hr Forecast (1800Z Aug 17)... 150 mph maximum sustained wind major hurricane centered east of the southeastern Bahamas at 21.5N-68.5W

IOH 48 Hr Forecast (1800Z Aug 18)... 150 mph maximum sustained wind major hurricane centered northeast of the southeastern Bahamas at 24N-70W

IOH 72 Hr Forecast (1800Z Aug 19)... 150 mph maximum sustained wind major hurricane centered in the western Atlantic at 27.5N-71W

IOH 96 Hr Forecast (1800Z Aug 20)... 135 mph maximum sustained wind major hurricane centered west of Bermuda at 32N-71W

IOH 120 Hr Forecast (1800Z Aug 21)... 105 mph maximum sustained wind hurricane centered in the northwestern Atlantic to the north-northeast of Bermuda at 38N-62W

*****National Hurricane Center (hurricanes.gov) official forecast of 5 PM EDT***********************

5-Day Position (1800Z Aug 21)... 115 mph maximum sustained wind major hurricane centered north of Bermuda at 36.8N-65W

AREA OF INTEREST #17... The surface trough of low pressure that made landfall on the Mississippi and Louisiana Gulf coast Tuesday evening turned east-northeast across the southeastern United States... then into waters offshore of North Carolina... while gravitated toward the tail end of the surface front that recently moved into the Atlantic from the northeastern US and eastern Canada. The CIMSS 850 mb mid-level vorticity product confirms that the spin maximum of the surface trough since its US Gulf coast landfall retained its identity along the front (see 5-day animation at the following address... https://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=). At the surface... the spin maximum is currently being analyzed as a low pressure center along the front. About 24 hours ago the National Hurricane Center upgraded the frontal low to a tropical area of interest in their tropical weather outlook as it produced rounds of thunderstorm activity... albeit the frontal low appeared elongated southwest-to-northeast as typically seen with a weak low along a front. Because this is the same feature that made landfall on the US Gulf coast on Tuesday... and the feature was earlier tagged as the seventeenth tropical Atlantic area of interest tracked on this site this year... it is being tagged as area of interest #17 in this update.

The frontal low of interest is currently not the dominant feature along the front... instead that is the rapidly developing northwest Atlantic frontal cyclone tagged as area of interest #19. The frontal cyclone is still driving the surface front south... as such the net motion of the frontal low of interest is east-southeast. This should continue until the frontal low loses its identity to the incoming low pressure field of Hurricane Erin in 48+ hours. Thunderstorm activity associated with the frontal low of interest has decreased over the last several hours... and westerly shear unfavorable to tropical development is likely to increase in the next 24 hours as the upper vorticity currently over the southeast US approaches and settles into an east-west band along 35N latitude. I currently assess time has ran out for tropical development due to the negative outlook (increase in shear soon... followed by loss of identity by 48 hours)... and I have a 0% chance of tropical cyclone formation. This is my planned final statement on this area of interest unless it somehow remains mentioned in the NHC tropical weather outlook by my next update on the Atlantic tropics.

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

IOH 24 Hr Outlook (1800Z Aug 17)... 0% chance of tropical cyclone formation (between North Carolina and Bermuda near 33N-71W)

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

Formation chance through 48 hours... 10%

Formation chance through 7 days... 10%

AREA OF INTEREST #18... Not much to say now regarding the weak surface trough of low pressure that was moving northwest across the southwestern Gulf of America... although organized thunderstorm activity did re-develop during the early half of Friday aircraft recon found the surface trough by 11:10 AM EDT that day did not have a closed spin and was northwest of previous position estimates... already bringing it to landfall by 2 PM EDT in the vicinity of the Texas/ Mexico border. Since then the surface trough has dissipated. That is because the upper winds did not help in maintaining the inland remnants... the inverted upper trough that was moving in tandem with this disturbance merged with upper vorticity left behind over the eastern US... and upper convergence west of the upper vorticity axis and overtop the position of this former disturbance meant quick dissipation was inevitable. Due to dissipation... I show no forecast track and it was not initialized in the batch of computer models in the computer model summary section below to mention it there. This is my final statement on this area of interest on this blog.

AREA OF INTEREST #19... An upper trough has recently moved into the northwest Atlantic from eastern Canada/ northeastern US. Upstream of it... northward warm air transport ahead of a frontal low over eastern Canada is leading to amplifying upper ridging which in turn is amplifying the northwest Atlantic upper trough... and increasing divergence on the east side of the amplifying upper trough is resulting in a rapidly developing surface frontal cyclone. As the upper air pattern continues to amplify... a portion of the northwest Atlantic upper trough will soon become a cut-off upper vortex... and whatever energy that does not become a part of the northwest Atlantic vortex merges with the current large-scale northeast Atlantic upper vortex. In the next 24 hours the surface frontal cyclone will be whirling beneath the core of the northwest Atlantic upper vortex which effectively results in a deep-layer cyclone. The initial position of the surface frontal cyclone is a little northwest of the previous forecast... and my updated forecast track in the outlook below is adjusted accordingly. The updated track keeps the surface frontal cyclone/ deep-layer cyclone barely over warm 26 deg C in the next 24 hours and I have trimmed down odds of subtropical cyclone formation to 10%. By 48 hours the surface center is over waters below 26 deg C... and upper air temps will not be cold enough to support core thunderstorms/ instability... at that point I drop odds of subtropical cyclone formation to 0%. The subtropical instead of tropical designation is used in the outlook below as that is the usual outcome of deep-layer cyclones that gain tropical characteristics. In the long range... per the latest model data... the upper layer of the deep-layer cyclone becomes the eastern center in a bi-polar upper vortex while the amplified upper trough currently approaching from central Canada becomes the western center. Note it is possible the non-tropical remnant surface layer of the cyclone arcs north toward the waters south of Greenland while caught by the bi-polar upper vortex... or it is also possible the non-tropical remnant turns east while ingested into the large-scale northeast Atlantic upper vortex in which case the remnant weakens quickly due to the upper convergence under the west side of that upper vortex.

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

IOH 24 Hr Outlook (1800Z Aug 17)... 10% chance of subtropical cyclone formation (north Atlantic near 40.8N-49W)

IOH 48 Hr Outlook (1800Z Aug 18)... 0% chance of subtropical cyclone formation (north Atlantic near 45N-42W)

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

Not in the official outlook

...COMPUTER MODEL SUMMARY...

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

1200Z (Aug 16) CMC Model Run...

**For Major Hurricane Erin... continues west-northwest and passes just northeast of the southeastern Bahamas by 48 hours... subsequently curves north into the waters between North Carolina and Bermuda by 114 hours... then turns northeast toward a north Atlantic frontal cyclone that is born over Newfoundland and by 168 hours absorbs it while itself becoming an exceptionally large and powerful non-tropical remnant frontal cyclone centered at 50N-42W

**For area of interest #17... frontal low offshore of North Carolina drifts east then begins to lose its identity to Hurricane Erin incoming from the south after 66 hours

**For area of interest #19... the rapidly developing northwest Atlantic frontal cyclone becomes a deep-layer cyclone near 40N-49.5W through 24 hours once a portion of the nearby upper trough becomes a vortex stacked overhead... the surface layer of the cyclone continues northeast then increasingly north into the waters SSE of the south tip of Greenland through 102 hours while absorbed by developing frontal cyclone from the west developing over Newfoundland/ North Atlantic.

**Tropical wave which recently departed west coast of Africa becomes a large tropical low just southwest of the Republic of Cabo Verde Islands by 42 hours... however opens back to a wave without further development in the long range

**Additional tropical wave emerges from west coast of Africa at 60 hours... becomes a large tropical low centered over the southeastern Republic of Cabo Verde Islands at 96 hours... tropical low continues WSW then WNW in the long range and reaches 15N-38W by 168 hours

**Yet another tropical wave emerges from west coast of Africa by 132 hours and becomes a tropical low just northeast of the Republic of Cabo Verde Islands through 168 hours

0000Z (Aug 16) ECMWF Model Run...

**For Major Hurricane Erin... continues west-northwest and passes just northeast of the southeastern Bahamas by 72 hours... subsequently curves north into the waters between North Carolina and Bermuda by 126 hours... then turns northeast toward a north Atlantic frontal cyclone that is born over Newfoundland and by 156 hours is positioned due south of Newfoundland while itself transitioning into a large powerful non-tropical frontal cyclone

**For area of interest #17... frontal low offshore of North Carolina moves east into the waters northwest of Bermuda and then begins to lose its identity to Hurricane Erin incoming from the south after 66 hours

**For area of interest #19... the rapidly developing northwest Atlantic frontal cyclone becomes a deep-layer cyclone near 40N-48.5W through 48 hours once a portion of the nearby upper trough becomes a vortex stacked overhead... the surface layer of the cyclone continues northeast and while midway between the south tip of Greenland and the British Isles at 132 hours loses identity along warm front extending east from the developing frontal cyclone over Newfoundland/ North Atlantic.

1200Z (Aug 16) GFS Model Run...

**For Major Hurricane Erin... continues west-northwest and passes just northeast of the southeastern Bahamas by 48 hours... subsequently curves north into the waters between North Carolina and Bermuda by 105 hours... then turns northeast toward a north Atlantic frontal cyclone that is born over Newfoundland and by 168 hours absorbs it while itself becoming an exceptionally large and powerful non-tropical remnant frontal cyclone centered at 55N-39W

**For area of interest #17... frontal low offshore of North Carolina drifts east then begins to lose its identity to Hurricane Erin incoming from the south after 57 hours

**For area of interest #19... the rapidly developing northwest Atlantic frontal cyclone becomes a deep-layer cyclone near 40.2N-48.8W through 30 hours once a portion of the nearby upper trough becomes a vortex stacked overhead... the surface layer of the cyclone continues northeast then increasingly north into the waters SSE of the south tip of Greenland through 93 hours while merging with developing frontal cyclone from the west developing over Newfoundland/ North Atlantic.

**Tropical wave which recently departed west coast of Africa becomes a WSW/ENE elongated trough while southwest of the Republic of Cabo Verde Islands by 48 hours while becoming entangled with next tropical wave that emerges from Africa... as it continues west the WSW end of the trough undergoes rapid tropical cyclone formation near 12.5N-53.5W at 120 hours... as a briskly strengthening compact tropical cyclone moves into the central Lesser Antilles by 150 hours and is a potentially intense compact hurricane in the northeast Caribbean by 168 hours

**Next tropical wave emerges from west coast of Africa at 48 hours and initially moves WNW instead of west while embedded in the cyclonic flow on the northeast end of the adjacent surface trough... by 168 hours the tropical wave resumes a more west heading while becoming a tropical low that reaches 15N-45W

1200Z (Aug 16) NAVGEM Model Run...

**For Major Hurricane Erin... continues west-northwest and passes just northeast of the southeastern Bahamas by 54 hours... subsequently curves north into the waters between North Carolina and Bermuda by 114 hours... then turns northeast toward a north Atlantic frontal cyclone that is born over Newfoundland and by 168 hours absorbs it while itself becoming an exceptionally large and powerful non-tropical remnant frontal cyclone centered at 50.5N-49W

**For area of interest #17... frontal low offshore of North Carolina drifts east-southeast then begins to lose its identity to Hurricane Erin incoming from the south after 54 hours

**For area of interest #19... the rapidly developing northwest Atlantic frontal cyclone becomes a deep-layer cyclone near 39.5N-48.5W through 30 hours once a portion of the nearby upper trough becomes a vortex stacked overhead... the surface layer of the cyclone continues east-northeast into the British Isles through 168 hours while gradually weakening

**Tropical wave which recently departed west coast of Africa becomes a large tropical low centered just southwest of the Republic of Cabo Verde Islands at 42 hours... large tropical low continues west-northwest and reaches position just east of the northern Lesser Antilles by 168 hours

**Additional tropical wave emerges from west coast of Africa at 108 hours and proceeds to become a large tropical low positioned just west-southwest of the islands by 168 hours