MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #52

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

...MONDAY AUGUST 4 2025 3:30 AM EDT...

Increased tropical activity across the Atlantic basin continues with now one active tropical storm and two concurrent areas of interest as follows:

(1) Tropical Storm Dexter has formed along the lengthy frontal boundary spanning the north Atlantic and southeastern United States... the new tropical storm is on its way to pass north of Bermuda... see Dexter section below for more information on the new tropical cyclone. This frontal boundary may host another tropical disturbance offshore of the southeastern United States in the days ahead... see area of interest #15 section below for details.

(2) The National Hurricane Center is monitoring the tropical wave of low pressure currently exiting western Africa as computer models continue to suggest its possible development when it later roams the open central Atlantic... see area of interest #14 section below for more information.

Elsewhere... divergent upper winds occurring in a break of the Caribbean to Atlantic upper vorticity string triggered increased thunderstorms and a surface trough of low pressure north of the northeastern Caribbean Islands on Sunday. Since then the surface trough has continued west and decoupled from the thunderstorms while pushed by the currently expanding Atlantic surface ridge... and in the most recent hours the thunderstorm activity has decayed. Therefore tropical development is not anticipated from this disturbance.

TROPICAL STORM DEXTER... Infrared Satellite image of newly-formed Tropical Storm Dexter as of 0440Z Monday August 4. The band of low-level clouds... seen as white colors in this infrared scheme... defining the surface frontal boundary Dexter formed from is in between the blue lines. As such Dexter appears positioned just ahead of (southeast of) the frontal cloud band:

A lengthy surface front remains positioned across the southeastern United States and north Atlantic... one of the dominant features along the front is a surface low pressure spin that continues to produce thunderstorm activity while moving east-northeast into the waters northwest of Bermuda. This feature has maintained a thunderstorm canopy since 1200Z Sunday and was finally upgraded by the National Hurricane Center to Tropical Storm Dexter as of 11 PM EDT. Nighttime infrared satellite frames suggest Dexter is a smidgen just ahead of the front rather than along it as the comma-shaped thunderstorm canopy is just southeast of the low-level cloud band defining the front... reference the above satellite frame from 0440Z as an example. The National Hurricane Center in their 11 PM EDT advisory agrees with this notion which went into the upgrade to a tropical cyclone rather than a non-tropical surface low along the front... and it is probable the 0000Z NHC TAFB surface analysis which shows the pre-Dexter surface low still along the front will likely be updated to show Dexter now just ahead of the front in the upcoming 0600Z surface analysis. The future track of Dexter will depend on the interaction between the series of upper troughs to the northwest. In the short-term an upper trough that recently dived southeast into eastern Canada from central Canada will be merging with current upper troughs approaching from the central and eastern US to make an eastern North America upper trough. Then by the middle of the forecast period and through day 4 the eastern North America upper trough proceeds to split into three pieces per the latest model trends... one in the far northeast corner of the Atlantic... another an east-west ribbon of upper vorticity strung across the northwest Atlantic... and a weak upper trough stalled over the eastern US. The question is whether Dexter continues east-northeast out to sea while caught in the deep-layer weakness associated with the upper vorticity ribbon and remainder eastern part of the surface front to be maintained by the divergence ahead of the ribbon... or whether Dexter slows down its east-northeast progress or even stalls while becoming pinned by a surface ridge to the north that builds in the western convergence zone of the initial piece of energy that swings to the northeast Atlantic and is then maintained by convergence behind the upper vorticity ribbon. The majority of the models still show a continuous east-northeast track out to sea while the GFS is still leaning toward the slow down/ stall idea. My current track forecast below remains a blend of the two extremes and remains rather similar to the previous forecast from special update #51A (https://www.infohurricanes.com/post/my-2025-atlantic-hurricane-season-birdseye-view-post-51a-special-update). Due to the strength of the surface ridge... I show an east-southeast bend between 72 and 96 hours. By 5+ days the latest model data shows an upper trough sliding across southern Canada knocking a part of the upper vorticity ribbon southeast toward Dexter... eventually absorbing the western part of the upper vorticity ribbon which results in a robust upper trough whose southeastern elongated upper divergence zone helps to transition Dexter into a less tropical and more elongated remnant low while also moving the remnant low faster to the east-northeast. Prior to the transition... I forecast Dexter to strengthen into a high-end tropical storm through 48 hours as it continues to maintain its favorable position with respect to the southwesterly upper jet where the jet enhances its northern outflow. Through day 4 the forecast track keeps this system from outright walking into the jet where it would be shredded as a tropical cyclone by high shear. However Dexter won't be immune from shear either as there is still lighter shear south of the jet whose effect will be worsened toward day 3 and 4 where the forecast track has the slowest forward speed falling behind the upper wind speed. I depict a tropical cyclone holding on to equilibrium strength in the light shear as a lower-end tropical storm in the day 3 and 4 window.

Regarding impact to land areas... surf generated by Dexter could reach the shores of Bermuda today and Tuesday.

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

0 Hr Position (0000Z Aug 4)... 45 mph maximum sustained wind tropical storm centered at 34.3N-69.4W

IOH 24 Hr Forecast (0000Z Aug 5)... 60 mph maximum sustained wind tropical storm centered northwest of Bermuda at 35.2N-66W

IOH 48 Hr Forecast (0000Z Aug 6)... 60 mph maximum sustained wind tropical storm centered north-northeast of Bermuda at 36.2N-62.5W

IOH 72 Hr Forecast (0000Z Aug 7)... 45 mph maximum sustained wind tropical storm centered in the northwestern Atlantic at 36.5N-61W

IOH 96 Hr Forecast (0000Z Aug 8)... 45 mph maximum sustained wind tropical storm centered in the northwestern Atlantic at 36N-60W

IOH 120 Hr Forecast (0000Z Aug 9)... Remnant frontal low centered in the northwestern Atlantic at 37.5N-58W

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

Peak Strength (1200Z Aug 4)... 50 mph maximum sustained wind tropical storm centered northwest of Bermuda at 35.1N-67.7W

4-Day Position (0000Z Aug 8)... 40 mph maximum sustained wind dissipating non-tropical remnant low centered in the north Atlantic at 40.5N-50.8W

AREA OF INTEREST #14... The tropical wave of low pressure getting ready to move into the eastern tropical Atlantic from the west coast of Africa has lost its thunderstorm activity to dry Saharan air. This feature continues to be mentioned in the National Hurricane Center tropical weather outlook and with increasing odds of tropical cyclone formation as the usually more reliable GFS/ ECMWF model consensus is showing a stronger development signal... and the CMC has begun to join in. Short-term forecast is steady to the west... perhaps with a west-southwest slant... as the steering Atlantic surface ridge reaches a peak strength under the convergence associated with the current Atlantic upper vorticity string and before the string begins to weaken and break up from its isolation with high-latitude cold air. A piece of the decaying upper vorticity string becomes a mid-ocean upper vortex to the northwest... and the long-term forecast track has some uncertainty as their is variation from model to model on the strength of the mid-ocean surface ridge weakness to be induced by a combination of the divergence on the east side of the upper vortex and what is forecast to be the remnant frontal low of Dexter. If this system were to be also stronger/ taller as the recent bullish ECMWF model runs have been showing the upper southerly flow on the east side of the upper vortex could also tug this system north. For now I have a slight northward slant in the west track in days 3 to 5 until it is clearer how strong the mid-ocean ridge weakness ends up being. It is interesting that as of late the GFS/ ECMWF/ CMC consensus suggest that instead of the tropical wave developing... an adjacent tropical low to the west develops and becomes the dominant feature... albeit the tropical wave could tug on the tropical low and then merge with it. This raises the question of whether or not the NHC in future outlooks re-locates the initial position of this area of interest to the west? Also not clear on the triggering mechanism that would support focused thunderstorms and formation of such a tropical low as the regional current and forecast upper wind profile has a broad area of upper anticyclonic outflow rather than a focused area... and ongoing surges of dry Saharan air have done a pretty good job in capping tropical development in the eastern and central tropical Atlantic over the last several days. Therefore only cautiously raising my peak odds of tropical cyclone formation to 20% in this update cycle.

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

IOH 24 Hr Outlook (0000Z Aug 5)... 0% chance of tropical cyclone formation (east-southeast of the Republic of Cabo Verde Islands near 12.5N-20W)

IOH 48 Hr Outlook (0000Z Aug 6)... 0% chance of tropical cyclone formation (south-southwest of the Republic of Cabo Verde Islands near 12N-25W)

IOH 72 Hr Outlook (0000Z Aug 7)... 0% chance of tropical cyclone formation (eastern tropical Atlantic near 12N-30W)

IOH 96 Hr Outlook (0000Z Aug 8)... 10% chance of tropical cyclone formation (eastern tropical Atlantic near 13N-35W)

IOH 120 Hr Outlook (0000Z Aug 9)... 20% chance of tropical cyclone formation (central tropical Atlantic near 14N-40W)

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

Formation chance through 48 hours... 0%

Formation chance through 7 days... 50%

AREA OF INTEREST #15... The same surface front which Tropical Storm Dexter formed from may produce another tropical disturbance offshore of the southeastern United States in the days ahead... and on Sunday the National Hurricane Center has added an area of interest at this location in their tropical weather outlook. This marks the fifteenth tropical Atlantic area of interest tracked on this site this year. Noting the frontal low that was moving into the Atlantic from the Florida/ Georgia border late Saturday/ early Sunday has since fizzled out. The models are in good agreement on a new frontal low materializing offshore of the southeastern United States in 72 hours. The trigger appears to be from the band of upper vorticity currently at 55W longitude retrograding west around the current mid-latitude Atlantic upper ridge as an inverted upper trough and toward the surface frontal boundary... with the western divergence zone of the inverted upper trough helping to trigger the frontal low. After its formation... the same surface ridge that potentially slows down Dexter's eastward progress is likely to steer the frontal low... and the forecast track in the outlook below shows a west-northwest track of the frontal low into the southeastern United States while rounding the southwest side of the ridge (see above Dexter section for more information on the surface ridge). Currently assigning a low 20% chance of tropical cyclone formation as this system will have little time over water between its formation at 72 hours and currently forecast landfall at 120 hours. Will only assign higher odds in future updates if a stronger model signal showing tropical development emerges... or if future satellite observations were to show organized thunderstorm activity as the frontal low of interest forms.

Regarding impact to land areas... there is a possibility of a wave of heavy rainfall arriving to southeastern Georgia and southern South Carolina from the southeast on Friday given the current forecast. The potential for gusty winds and surf for coastal areas of this region is currently low due to the currently low odds of tropical cyclone formation.

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

IOH 24 Hr Outlook (0000Z Aug 5)... 0% chance of tropical cyclone formation (offshore of the southeastern United States near 30.5N-78.5W)

IOH 48 Hr Outlook (0000Z Aug 6)... 0% chance of tropical cyclone formation (offshore of the southeastern United States near 30.5N-78.5W)

IOH 72 Hr Outlook (0000Z Aug 7)... 0% chance of tropical cyclone formation (offshore of the southeastern United States near 30.5N-77.5W)

IOH 96 Hr Outlook (0000Z Aug 8)... 20% chance of tropical cyclone formation (offshore of the southeastern United States near 31N-79W)

IOH 120 Hr Outlook (0000Z Aug 9)... 0% chance of tropical cyclone formation (just inland over the Georgia/ South Carolina border near 32N-81.2W)

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

Formation chance through 48 hours... 0%

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 3) CMC Model Run...

**For Tropical Storm Dexter... through 30 hours passes north-northwest of Bermuda... through 96 hours turns east and becomes more elongated and less tropical in nature while reaching 38N-55W... the non-tropical remnant low continues east-northeast and becomes absorbed by another non-tropical frontal low developing to the northeast while reaching 40N-40W at 156 hours

**For area of interest #14... no development shown while adjacent tropical low forms to the west and becomes the dominant feature

**For area of interest #15... through 72 hours the surface front trailing from Dexter consolidates into an inverted surface trough near 30N-73.8W... the surface trough turns west... northwest... then north into North Carolina Outer Banks through 156 hours... surface trough evolves into weak surface low while continuing north along Virginia coast and into Delmarva peninsula through 168 hours

**Tropical low forms near 10.5N-29W at 42 hours... continues briskly west-northwest and reaches 20.5N-52W by 168 hours without further development

**Large tropical wave emerges from west coast of Africa at 114 hours... moves into the waters just south of the Republic of Cabo Verde islands through 168 hours while becoming a large tropical low

1200Z (Aug 3) 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=2025080312&fh=12)

**For Tropical Storm Dexter... through 39 hours passes north of Bermuda... through 105 hours turns east and becomes more elongated and less tropical in nature while reaching 37.5N-54W... shortly thereafter the non-tropical remnant low loses identity to adjacent non-tropical frontal low developing to the northeast

**For area of interest #14... no development shown while adjacent tropical low forms to the west and becomes the dominant feature

**For area of interest #15... through 72 hours the surface front trailing from Dexter consolidates into a weak surface low near 29.5N-74W... surface low turns west then northwest and weakens to an inverted surface trough while approaching the southern South Carolina coast by 156 hours... proceeds to make landfall on the southern South Carolina coast just after 168 hours

**Tropical low forms near 11N-30W at 33 hours... the trans-Atlantic upper vorticity string to the north proceeds to breakup into multiple pieces including an upper vortex to the northwest and through 120 hours turns increasingly northwest and reaches 19N-42.5W while coming under influence of the upper vortex's east side... while continuing northwest becomes a tropical cyclone near 22N-45.5W at 138 hours... the tropical cyclone turns increasingly north with aid of surface ridge weakness caused by passing frontal low to the north who also absorbed ex-Dexter and broad inverted surface trough to the northwest induced by the eastern divergence zone of the upper vortex and proceeds to reach 29.5N-48W by 168 hours while gaining hurricane strength

1800Z (Aug 3) GFS Model Run...

**For Tropical Storm Dexter... reaches position north-northwest of Bermuda and near 36.5N-66.5W through 42 hours... while becoming quasi-stationary at this location proceeds to become a more sheared and elongated remnant low through 75 hours... while drifting through 132 hours east the remnant low of Dexter proceeds to lose identity along the remainder eastern portion of the front from which it was born from.

**For area of interest #14... no development shown while adjacent tropical low forms to the west and becomes the dominant feature

**For area of interest #15... through 72 hours the surface front trailing from Dexter consolidates into a weak surface low near 29.5N-75W... surface low moves west-northwest and makes landfall on the Georgia coast by 120 hours... weakens to a surface trough drifting northwest into interior Georgia through 168 hours

**Tropical low forms near 10N-31.5W at 39 hours... proceeds to lift north to 14N-33.8W through 84 hours while merging with incoming tropical wave (area of interest #14) to the east... then under influence of steering Atlantic surface ridge the tropical low proceeds to turn west-northwest to 16.2N-39.5W through 111 hours where it becomes a tropical depression... tropical depression continues west-northwest and arrives to 19N-56W (east-northeast of the northern Lesser Antilles) at 168 hours

**Large tropical wave emerges from west coast of Africa at 114 hours... moves into the waters just south of the Republic of Cabo Verde islands through 147 hours while becoming a large tropical low... centroid of large tropical low approximately at 12.5N-31W at 168 hours

1800Z (Aug 3) NAVGEM Model Run...

**For Tropical Storm Dexter... initialized as a broad surface low instead of a tropical cyclone and as such retains that status while passing north of Bermuda through 48 hours... becomes a more elongated surface low while reaching 37.5N-60W through 84 hours... becomes a non-tropical remnant frontal low while curving increasingly northeast into the waters southeast of Newfoundland through 168 hours

**For area of interest #14... no development shown

**For area of interest #15... through 66 hours the surface front trailing from Dexter consolidates into a broad and weak surface low near 31N-72W... the broad surface low continues west-northwest toward the Carolinas while becoming an SW/NE elongated feature and makes landfall into southeastern North Carolina by 168 hours

**Large tropical wave emerges from west coast of Africa at 126 hours... moves into the waters just south of the Republic of Cabo Verde islands through 168 hours while becoming a large tropical low