MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #61

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

...WEDNESDAY AUGUST 20 2025 12:30 PM EDT...

Note the forecast text below for Hurricane Erin... and the two current areas of interest following behind Erin... were completed late Tuesday evening through early this morning. However I released this update later after completing the above graphics... I was not able to complete the graphics earlier due to a busy overnight in my personal life:

(1) For Hurricane Erin in the western Atlantic... since completing last night's forecast... the hurricane has begun to re-intensify as expected and as of the 11 AM EDT advisory had top-end category 2 maximum sustained winds of 110 mph. See the Erin section below for more information on this large hurricane... including on impacts across Bermuda... the Bahamas... and the east coast of continental North America.

(2) For area of interest #20 in the central tropical Atlantic associated with a large tropical wave of low pressure... the National Hurricane Center has not changed their odds of tropical cyclone formation since 2 AM EDT. The tropical wave however has developed a little more concentrated thunderstorm activity near 14N-49W in recent hours. See area of interest #20 section below for more information on this wave including on its potential impacts to the Lesser Antilles... Virgin Islands... and Puerto Rico in the days ahead.

(3) For area of interest #21 in the eastern tropical Atlantic associated with a compact tropical wave of low pressure producing persistent concentrated and organized thunderstorms... the National Hurricane Center as of 8 AM EDT raised their odds of tropical cyclone formation to 40%. See area of interest #21 section below for more information on this wave.

HURRICANE ERIN... Left... infrared satellite image of Hurricane Erin disrupted by northwesterly wind shear. Right... more recent infrared satellite image of Hurricane Erin re-organizing after northwesterly shear has relaxed:

While passing to the northeast of the Bahamas... Hurricane Erin finally turned increasingly north while responding to the ridge weakness associated with the tail ends of the surface fronts driven by the pair of frontal lows near southeast Newfoundland and north Atlantic. By early Monday their was anticipation that Erin could re-intensify while having finished an eye wall replacement cycle... and aircraft recon did confirm Erin reached a second peak intensity of category 4 140 mph maximum sustained winds as of 11 AM EDT Monday. However while reaching the second peak the hurricane became increasingly disorganized on infrared satellite while losing its well-defined eye... with the thunderstorms also becoming increasingly lopsided to the southeast of the center by Monday evening/ early Tuesday. The intensity of the hurricane proceeded to gradually wind down from Monday evening through now... and Erin is now a category 2 with 100 mph maximum sustained winds. Erin has also substantially grown in size with the aid of the overhead sprawling upper anticyclone dropping surface pressures over a wide area... therefore the hurricane is still capable of producing dangerously large swells across a sprawling area of the western Atlantic without being of major hurricane (category 3+) intensity. NHC advisory discussions on Monday and Tuesday cited ingestion of dry Saharan air to the northeast which disrupted the inner core organization and hence the initial loss of the well-defined eye... and northwesterly shear (northwestern upper outflow blockage) which caused the thunderstorms to be lopsided to the southeast of center... as the reasons for the hurricane's weakening. Upper wind data showed a stronger presentation of the current eastern US upper ridge relative to previous model projections... pushing the upper vorticity band that was along 35N latitude closer to Erin which resulted in the northwestern upper outflow blockage. In recent hours the disrupting upper vorticity band is splitting in half... the eastern half is being pulled away into southeastern center of the current northeast Canada coastal bi-polar upper vortex... and the western half is being pushed away into the Gulf of America by the eastern US upper ridge. Erin has already responded by re-developing a more symmetrical thunderstorm distribution. Erin has not re-intensified just yet as it needs time to re-establish an organized inner core from the previous disruption... thus I agree with the NHC on Erin not intensifying past a bottom-end category 3 (115 mph max sustained winds) in the next 36 hours and before reaching more hostile conditions discussed in the next paragraph.

Once again updated forecast track projections for Erin have shifted west. The west lean in Erin's north track looks to be sustained for some time due to the easterly component of upper winds rounding the aforementioned upper vorticity retrograding toward the Gulf... and easterly component of surface winds due south of the surface ridge over eastern Canada and surface ridge to build behind the current Great Lakes surface frontal system and its shortwave upper trough. The upper flow of associated with the shortwave upper trough will cause Erin's turn to the northeast... the question is exactly when. For my updated forecast track... I have Erin approach the North Carolina Outer Banks and mid-Atlantic United States coast closer than the model consensus as Erin's thunderstorm latent heat release re-enforces the upper anticyclonic ridge directly overhead... and as the current eastern US upper ridge merges with the overhead upper ridge which will only re-enforce it. This may make it more difficult for the shortwave upper trough to dislodge the upper ridge and hence could delay the northeast turn of the hurricane... and I have a special 36-hour forecast point reflecting Erin's closest point to the United States east coast. Note between 24 and 36 hours I forecast no additional strengthening of the hurricane as the incoming shortwave upper trough begins to shear the hurricane. For the longer range... Erin pulls the cold air associated with the shortwave upper trough southward... which causes it to become a more bonafide amplified upper trough with increasing upper divergence that should slow the weakening rate of Hurricane Erin despite shearing the hurricane... and my forecast intensity for 0000Z Aug 23 is still the same as the previous despite Erin's lower initial intensity due to its prior Monday/ Tuesday weakening. By day 4 transition into a hurricane-force non-tropical remnant frontal cyclone supported by the amplifying upper trough should be completed as Erin speeds into cooler water. The upper flow in Erin's longer-term environment may be more southerly than westerly if in fact the shortwave upper trough encounters more robust upper ridging ahead of it as noted above... therefore in addition to my short-term track being closer to the US east coast... my long-range forecast position also leans north of the current model consensus.

Regarding the impact to land areas:

(1) Erin as a large and strong hurricane at first... then as a large and still powerful non-tropical frontal cyclone by day 4... will produce widespread and dangerous surf across the western Atlantic. Surf is currently affecting the shores of the Bahamas... southeastern United States coast... and Bermuda. By tomorrow (Thursday) through Saturday surf should reach the shores of the northeastern United States and Atlantic Canada

(2) Within the last 48 hours tropical storm advisories have been raised across the Outer Banks of North Carolina... southeastern Virginia... and southeastern Maryland. Due to the westward-nudged updated forecast track and large-sized circulation of Hurricane Erin... the tropical storm advisory region may see more direct impacts such as coastal storm surge... heavy rainfall... and gusty winds with the peak of impacts by tomorrow (Thursday) morning... preparations should be rushed to completion today. Note parts of the North Carolina Outer Banks were placed under evacuation orders within the last 48 hours due to the concern of coastal storm surge flooding... if within the tropical storm advisory area pay close attention to local news media and government officials particularly in regards to the coastal storm surge threat.

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

0 Hr Position (0000Z Aug 20)... 100 mph maximum sustained wind hurricane centered offshore of the southeastern United States at 27.7N-73W

IOH 24 Hr Forecast (0000Z Aug 21)... 115 mph maximum sustained wind major hurricane centered east of the Carolinas at 32N-74W

IOH 36 Hr Forecast (1200Z Aug 21)... 115 mph maximum sustained wind major hurricane centered southeast of Cape Hatteras North Carolina at 33.8N-74.5W

IOH 48 Hr Forecast (0000Z Aug 22)... 105 mph maximum sustained wind hurricane centered offshore of the mid-Atlantic United States coast at 36N-72.5W

IOH 72 Hr Forecast (0000Z Aug 23)... 85 mph maximum sustained wind hurricane transitioning into a hurricane-force remnant frontal cyclone while centered in the northwestern Atlantic at 39N-62W

IOH 96 Hr Forecast (0000Z Aug 24)... Hurricane-force remnant frontal cyclone centered southeast of Newfoundland at 45N-49W

*****National Hurricane Center (hurricanes.gov) official forecast of 11 PM EDT***********************

Peak Strength (1200Z Aug 21)... 115 mph maximum sustained wind major hurricane centered east-southeast of Cape Hatteras North Carolina at 33.8N-72.2W

5-Day Position (0000Z Aug 23)... 60 mph maximum sustained wind remnant frontal cyclone centered in the north Atlantic at 44.8N-42.6W

AREA OF INTEREST #20... The large tropical wave of low pressure that was in the eastern tropical Atlantic earlier this week is now in the central tropical Atlantic... and continues to resemble an oblong southwest to northeast oblong gyre. The greatest concentration of thunderstorms remained in the southwest part of the circulation for much of Monday and Tuesday... however in recent hours the concentrated activity fizzled and now there is simply scattered thunderstorms in the large circulation. The loss of concentrated thunderstorm activity has dashed the potential for short-term tropical cyclone formation... and in my updated outlook below I have lowered short-term odds of tropical cyclone formation. During the 5-day forecast period there is some northward angle in the projected track as this large tropical wave/ gyre of interest approaches the surface ridge weakness associated with Hurricane Erin... however Erin is not expected to completely turn this system north as it accelerates northeast and away. Instead the upper vortex currently making landfall on the west coast of Canada... and the surface frontal system it will generate... will eventually move toward the western Atlantic and cause the complete turn to the north just after day 5.

Within the next five days I do forecast a steepened north angle in the track after 48 hours... this has to do with the interaction with the inverted upper trough currently to the west of this area of interest. For the first 48 hours the interaction is minimal as the inverted upper trough continues west and away while pushed by the south side of Hurricane Erin's upper anticyclonic outflow. Then at 72 hours the inverted upper trough stalls and flips into a normal mid-latitude type upper trough while attempting to link with the mid-latitude shortwave upper trough that will be recurving Erin northeastward... this allows this area of interest to catch up to the upper trough and potentially develop a better-defined center in its north side due to upper divergence maximum on the east side of the upper trough... hence explaining the steepened north angle in my forecast track. This is probably why the models that do develop this area of interest (for example the GFS and NAVGEM in the computer model summary section below) prefer to develop the north side of this area of interest. Note from 72 to 120 hours the upper trough in question is shown to split in half... with the northeast half ingested into the upper trough recurving Erin and the southwest half drifting northwest toward the energy approaching from western Canada... during this time the above-described interaction where this system may try to develop with the help of the upper trough's divergence zone continues with the remainder southwest half of the upper trough. The upper trough could impart some southwesterly shear to this area of interest... however not particularly strong enough to inhibit tropical development as the upper trough itself is forecast to be weak. Despite this I have lowered my long-term odds of tropical cyclone formation to 50% as some recent global model runs have dropped developing this system altogether.

The Lesser Antilles... Virgin Islands... and Puerto Rico are at risk of seeing periods of possibly flash flooding heavy rainfall from this system for the late part of this week into the weekend. The highest potential for gusty winds and coastal surf is toward the north... for the northern Lesser Antilles... Virgin Islands... and Puerto Rico as the northern part of the circulation appears to have the highest potential for tropical development as discussed above.

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

IOH 24 Hr Outlook (0000Z Aug 21)... 0% chance of tropical cyclone formation (central tropical Atlantic near 13N-51W)

IOH 48 Hr Outlook (0000Z Aug 22)... 10% chance of tropical cyclone formation (east of the Lesser Antilles near 14N-56W)

IOH 72 Hr Outlook (0000Z Aug 23)... 30% chance of tropical cyclone formation (beside the northern Lesser Antilles near 17N-61.2W)

IOH 96 Hr Outlook (0000Z Aug 24)... 40% chance of tropical cyclone formation (north-northeast of Puerto Rico near 20.5N-65.5W)

IOH 120 Hr Outlook (0000Z Aug 25)... 50% chance of tropical cyclone formation (western Atlantic near 23.5N-69W)

*****National Hurricane Center (hurricanes.gov) official outlook as of 2 AM EDT***********************

Formation chance through 48 hours... 10%

Formation chance through 7 days... 60%

AREA OF INTEREST #21... During previous update #59 was noting a tropical wave that was over western Africa approaching southern Mali (https://www.infohurricanes.com/post/my-2025-atlantic-hurricane-season-birdseye-view-post-59). By Monday night the tropical wave had moved offshore from Africa and became a notable feature while quickly become better organized with concentrated thunderstorm activity... the National Hurricane Center proceeded to add the wave as an area of interest in their tropical weather outlook at the time and this is the twenty-first tropical Atlantic area of interest tracked on this site this year. Computer models insist the wave will have a slowing west-southwest track while caught in the cyclonic flow of the adjacent tropical wave to the east now approaching from western Africa. By day 5 in the outlook below... I assume the two waves will finish merging which should result in a faster forward motion towards the west as the merged feature is pushed by the steering Atlantic surface ridge. One negative factor for this area of interest is dry Saharan air which so far has not had much impact in this system maintaining organized thunderstorm activity... and the south component of the forecast track angle may help reduce the interaction with the dry air. The other negative factor relates to waves of upper vorticity that have been left behind southwest of the Azores and over the Canary Islands. Warm southerly flow ahead of the current pair of north Atlantic frontal lows... followed by warm southerly flow ahead of what will be ex-Erin... will result in enough mid-latitude warm core Atlantic upper ridging that bundles the waves of upper vorticity together and pushes the bundled upper vorticity south into the Atlantic tropical upper ridge axis. A potentially disruptive inverted upper trough to the east of this area of interest is forecast to materialize on the south side in the weakened part of the Atlantic tropical upper ridge. Because the forecast track below calls for a faster forward motion by day 5... there remains separation between this area of interest and the potentially disruptive inverted upper trough chasing it and I call for non-zero odds of tropical cyclone formation through day 5. I have set my odds at 40%... higher than the NHC's outlook as of 2 AM EDT... as the tropical wave has maintained concentrated organized thunderstorm activity. I did not set odds higher than this as most of the global model runs preferred to not develop this wave.

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

IOH 24 Hr Outlook (0000Z Aug 21)... 40% chance of tropical cyclone formation (eastern tropical Atlantic near 12N-29W)

IOH 48 Hr Outlook (0000Z Aug 22)... 40% chance of tropical cyclone formation (eastern tropical Atlantic near 11.5N-32.5W)

IOH 72 Hr Outlook (0000Z Aug 23)... 40% chance of tropical cyclone formation (eastern tropical Atlantic near 11N-36W)

IOH 96 Hr Outlook (0000Z Aug 24)... 40% chance of tropical cyclone formation (eastern tropical Atlantic near 11N-39W)

IOH 120 Hr Outook (0000Z Aug 25)... 40% chance of tropical cyclone formation (eastern tropical Atlantic near 11N-44W)

*****National Hurricane Center (hurricanes.gov) official outlook as of 2 AM EDT***********************

Formation chance through 48 hours... 30%

Formation chance through 7 days... 30%

...COMPUTER MODEL SUMMARY...

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

1200Z (Aug 19) CMC Model Run...

**For Hurricane Erin... begins passing just east of the North Carolina Outer Banks by 48 hours... subsequently turns east-northeast across the open North Atlantic and transitions into more elongated remnant frontal cyclone near 42N-49W at 114 hours... remnant cyclone continues east and by 168 hours regains a more circular structure just northwest of the Iberian peninsula of Europe as part of the remnant cyclone's supporting upper trough becomes a cut-off upper vortex overhead (if upper air temps of the vortex are cold enough may support instability/t-storms and re-acquisition of tropical characteristics)

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

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

1200Z (Aug 19) ECMWF Model Run...

**For Hurricane Erin... begins passing just east of the North Carolina Outer Banks by 54 hours... subsequently turns east-northeast across the open North Atlantic and transitions into more elongated remnant frontal cyclone near 43N-54W at 120 hours... remnant cyclone continues east and reaches the waters just north of the Azores by 168 hours while losing identity to another frontal cyclone developing just to the north

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

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

1800Z (Aug 19) GFS Model Run...

**For Hurricane Erin... begins passing just east of the North Carolina Outer Banks by 42 hours... subsequently turns east-northeast across the open North Atlantic and transitions into more elongated remnant frontal cyclone near 40.5N-53.5W at 90 hours... remnant cyclone swings increasingly north into the waters south of Iceland through 168 hours

**For area of interest #20... tropical wave axis reaches the Lesser Antilles at 72 hours... north apex of the tropical wave separates while turning northwest and becomes a tropical low near 21N-65.2W at 96 hours... the tropical low turns increasingly north and becomes a tropical cyclone near 25N-66W at 123 hours... continues north while becoming a compact hurricane that passes just west of Bermuda at 156 hours... compact hurricane accelerates north-northeast and reaches 36.5N-64.5W at 168 hours

**For area of interest #21... possibly becomes a tropical depression near 12N-27.5W at 21 hours... weakens back to a tropical low near 11.5N-29W at 33 hours... through 72 hours the remnant tropical low becomes quasi-stationary and loses identity along a WSW/ENE surface trough that materializes from the merger between the tropical low and adjacent tropical waves to the east.

**Through 66 hours the current northern US shortwave upper trough gains increasing SW/NE tilt under the force of amplifying upstream upper ridging with the SE divergence zone of the tilted upper trough creating a surface front extending southwest from Erin... through 87 hours the tail end of the surface front becomes a possibly tropical low just offshore of Georgia... the tropical low drifts northeast in the flow ahead of approaching large frontal system over eastern Canada and becomes a compact tropical cyclone positioned just SE of Cape Fear North Carolina at 108 hours... while continuing northeast transitions into the waters ENE of Cape Hatteras North Carolina transitions into a less tropical low supported by the eastern divergence zone of the large frontal system's upper trough by 132 hours... while barely keeping its identity the remnant non-tropical low continues north-northeast across Nova Scotia and into the northern Gulf of St Lawrence through 168 hours

1800Z (Aug 19) NAVGEM Model Run...

**For Hurricane Erin... initially continues north-northwest then by 48 hours sharply curves northeast into the waters midway between North Carolina and Bermuda... subsequently turns east-northeast across the open North Atlantic and transitions into more elongated remnant frontal cyclone near 45N-41.2W at 120 hours... remnant cyclone swings more east in track and is positioned northeast of the Azores by 168 hours

**For area of interest #20... the southwest to northeast tilted tropical wave axis positioned across the eastern Caribbean... northern Lesser Antilles... and waters northeast of the northern Lesser Antilles by 66 hours... northeast end of tropical wave becomes a tropical low north of Puerto Rico at 102 hours... tropical cyclone formation suggested near 21.5N-66.5W at 114 hours... tropical cyclone proceeds to intensify while moving northwest to 26N-70.5W through 168 hours

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