MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #53

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

...TUESDAY AUGUST 5 2025 1:30 AM EDT...

Tropical activity remains elevated across the Atlantic basin with one active tropical storm and two concurrent areas of interest as follows:

(1) Tropical Storm Dexter continues east-northeast across the open northwest Atlantic... see Dexter section below for more details on the storm.

(2) The segment of frontal boundary currently offshore of the southeastern United States may evolve into a tropical disturbance which then moves toward shore late this week... see area of interest #15 section below for more details.

(3) The National Hurricane Center is monitoring the tropical wave of low pressure currently over the far eastern tropical Atlantic for signs of development... see area of interest #14 section below for more information.

Elsewhere in the Atlantic basin... noting the following:

(1) A surface trough of low pressure has continued west into the central Bahamas. The associated thunderstorm activity however remains to the east rather than collocated with the trough as the area of regional maximal upper outflow remains at that location. Therefore if the surface trough persists... it is more likely to end up being absorbed by area of interest #15 rather than develop beforehand.

(2) The models are in agreement that in about 4 days a large tropical wave of low pressure emerges from the west coast of Africa as a large rotating gyre. Upper winds across the eastern and central tropical Atlantic will remain supportive with low shear and outflow potential induced by the ongoing upper ridge in the region... however it remains to be seen if the forecast large wave or if area of interest #14 overcomes dry Saharan air and goes on to develop.

TROPICAL STORM DEXTER... The tropical storm in the northwestern Atlantic is continuing east-northeast toward the surface ridge weakness associated with the lengthy surface front that it was born within. The future track of Dexter will depend on the evolution of the current eastern North America upper trough which has materialized from a merger between upper troughs that were over eastern Canada and the central United States. Over the next 72 hours the models agree the upper trough splits 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... and the GFS has joined the majority recently. However the CMC has left the majority and now shows the slow down/ stall idea. My current track forecast below remains a blend of the two extremes and remains rather similar to the previous due to its good performance so far... albeit I have done a slight northward adjustment given Dexter's current position relative to the previous forecast track line. Due to the strength of the surface ridge... I show an east-southeast bend between 48 and 72 hours. By 4+ days the latest model data shows an upper trough sliding across southern Canada knocking a part of the upper vorticity ribbon southeast toward Dexter... potentially absorbing the western part of the upper vorticity ribbon which would result 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. Regarding forecast strength prior to the transition... it appears Dexter has been shunted from additional strengthening due to a burst of increased shear imparted by a small upper trough from the eastern US that has not yet assimilated into the larger-scale eastern North America upper trough. Since 0000Z the thunderstorm canopy has separated from the surface center and it is probable Dexter will lose some strength tonight. However I do forecast Dexter to regain 45 mph maximum sustained winds by 0000Z tomorrow (late Tuesday/ early Wednesday) as the shear relaxes with the passage of the small upper trough. Additional strengthening through 72 hours should then be precluded by the slowing forward speed falling behind the upper wind speed... which equates to increasing shear. Regarding impact to land areas... the inability of Dexter to strengthen thus far and its far enough proximity from Bermuda has reduced the potential for storm-generated surf reaching the shores of Bermuda.

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

0 Hr Position (0000Z Aug 5)... 45 mph maximum sustained wind tropical storm centered northwest of Bermuda at 36.1N-66.2W

IOH 24 Hr Forecast (0000Z Aug 6)... 45 mph maximum sustained wind tropical storm centered north-northeast of Bermuda at 37N-62.5W

IOH 48 Hr Forecast (0000Z Aug 7)... 45 mph maximum sustained wind tropical storm centered in the northwestern Atlantic at 37.5N-61W

IOH 72 Hr Forecast (0000Z Aug 8)... 45 mph maximum sustained wind tropical storm centered in the northwestern Atlantic at 36.5N-60W

IOH 96 Hr Forecast (0000Z Aug 9)... Remnant frontal low centered in the northwestern Atlantic at 38N-58W

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

Peak Strength (1200Z Aug 7)... 50 mph maximum sustained wind tropical storm transitioning into a remnant non-tropical frontal low while centered in the north Atlantic at 41.2N-52.9W

5-Day Position (0000Z Aug 10)... 45 mph maximum sustained wind remnant non-tropical frontal low centered in the northeast Atlantic at 49N-29W

AREA OF INTEREST #14... The tropical wave of low pressure in the eastern tropical Atlantic remains largely absent from thunderstorm activity due to dry Saharan air... and the global models in the last 24 hours have largely trended away from developing this system. However the National Hurricane Center has retained this wave as an area of interest in their tropical weather outlook. Noting yesterday's model runs... and more recently this past 1800Z GFS model run... insists that an adjacent tropical low to the west develops and becomes the dominant feature in the short-term... and in the longer term the tropical wave used to define this area of interest of interest tugs on it and then merges with it. A look back at previous satellite imagery suggests another tropical wave west of this area of interest emerged from Africa on August 1 which has likely moved west-southwest away from the dry Saharan air due to the cyclonic flow of this area of interest. Perhaps then the models have been hinting at the adjacent wave to the west being able to develop increased thunderstorms while taking advantage of the ongoing broad upper anticyclonic outflow in the region and increased distance from the Saharan air layer... and indeed an east-west area of thunderstorms has increased along 10N latitude and southwest of this area of interest. Even so remaining skeptical of tropical development potential as this area of interest tugs the adjacent wave to the west-southwest on a northward trajectory back closer to the dry Saharan air prior to absorbing it. From 72 to 120 hours the models show a faster track and more north angle consistent with this area of interest being flung by the northeast side of the adjacent wave as it absorbs it. The west extent of the steering Atlantic surface ridge will tend to be weaker during the forecast period due to what is expected to be the remnant non-tropical low of Dexter and surface front trailing from ex-Deter. Also noting the current Atlantic upper vorticity string weakens and breaks up from its isolation with high-latitude cold air... with a piece of the decay becoming a mid-ocean upper vortex whose eastern divergence zone may contribute to the weakened west side of the steering surface ridge. All in all the weakened west side of the ridge also supports a north slant in the long range forecast track... however I only show a slight north slant as the models have also trended with a less impressive ridge weakness. Moreover the probability of this system being strong/ tall enough to couple with the upper southerlies on the east side of the mid-ocean upper vortex is quiet low given the recent model consensus trending away from development. I have slipped my peak odds of tropical cyclone formation back down to 10% given the recent model trends and dry Saharan air that lies along the forecast path.

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

IOH 24 Hr Outlook (0000Z Aug 6)... 0% chance of tropical cyclone formation (south-southwest of the Republic of Cabo Verde Islands near 12N-25W)

IOH 48 Hr Outlook (0000Z Aug 7)... 0% chance of tropical cyclone formation (eastern tropical Atlantic near 12N-30W)

IOH 72 Hr Outlook (0000Z Aug 8)... 10% chance of tropical cyclone formation (eastern tropical Atlantic near 13N-35W)

IOH 96 Hr Outlook (0000Z Aug 9)... 10% chance of tropical cyclone formation (central tropical Atlantic near 15N-41.5W)

IOH 120 Hr Outlook (0000Z Aug 10)... 10% chance of tropical cyclone formation (central tropical Atlantic near 16N-50W)

*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM 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. The models are in relatively good agreement on a surface low materializing along the front and offshore of the southeastern United States in about 48 hours. The trigger appears to be from the band of upper vorticity currently at 60W 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 25% chance of tropical cyclone formation as this system will have little time over water between its formation at 48 hours and currently forecast landfall at 96 hours... this is a little higher than my previous update as this past 1800Z GFS model run explicitly showed tropical cyclone formation. Could raise odds further in future updates if other models also show a stronger development signal... 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 6)... 0% chance of tropical cyclone formation (offshore of the southeastern United States near 30.5N-78.5W)

IOH 48 Hr Outlook (0000Z Aug 7)... 0% chance of tropical cyclone formation (offshore of the southeastern United States near 30.5N-77.5W)

IOH 72 Hr Outlook (0000Z Aug 8)... 25% chance of tropical cyclone formation (offshore of the southeastern United States near 31N-79W)

IOH 96 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 8 PM 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 4) CMC Model Run...

**For Tropical Storm Dexter... proceeds to weaken to a more elongated and sheared remnant low north-northeast of Bermuda by 42 hours... under force of building surface ridge to the north the remnant low drifts south toward the waters immediately northeast of Bermuda by 102 hours... remnant low proceeds east-northeast into the open central Atlantic from 102 to 168 hours

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

**For area of interest #15... no development shown

**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 144 hours while becoming a large tropical low... centroid of large tropical low positioned near 14N-31W at 168 hours

1200Z (Aug 4) ECMWF Model Run...

**For Tropical Storm Dexter... reaches peak strength while reaching 39N-60.5W at 42 hours... while passing southeast of Newfoundland through 84 hours wraps in cool air associated with upper vorticity to the northwest and as a result transitions to a remnant frontal cyclone supported by divergence ahead of the upper vorticity... proceed to race east-northeast across the far north Atlantic with the center of remnant frontal cyclone passing just north of the British Isles from 156 to 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 weak surface low near 30.5N-76W... surface low turns northwest and makes landfall at the NC/ SC border at 120 hours... inland weakening surface low turns north into east-central North Carolina through 138 hours... then proceeds across central Virginia and reaches the central Maryland/ Pennsylvania border by 168 hours

**Large tropical wave emerges from west coast of Africa at 90 hours... moves into the waters just south of the Republic of Cabo Verde islands through 114 hours while becoming a large tropical low... centroid of large tropical low positioned near 10N-40W at 168 hours

1800Z (Aug 4) GFS Model Run...

**For Tropical Storm Dexter... continues east-northeast and reaches 38N-56.5W by 84 hours where it transitions into a more elongated and less tropical remnant low... while passing southeast of Newfoundland through 114 hours the remnant low wraps in cool air associated with upper vorticity to the northwest and as a result transitions to a strengthening remnant frontal cyclone supported by divergence ahead of the upper vorticity... while continuing east-northeast into the far north Atlantic through 150 hours loses identity to larger frontal cyclone centered southeast of Greenland

**For area of interest #14... through 75 hours tropical wave currently at 20W longitude gradually merges with developing tropical low to the west... the merged system proceeds west-northwest as a weak tropical low/ amplified wave and reaches the waters north of the northeastern Caribbean Islands by 168 hours

**For area of interest #15... through 51 hours the surface front trailing from Dexter consolidates into an inverted surface trough near 28.5N-75W... proceeds west-northwest toward the GA/ SC border where at landfall time (117 hours) becomes a small tropical cyclone... through 132 hours the weakening inland remnant low continues northwest along the GA/ SC border... after drifting north into northwestern South Carolina by 138 hours the inland remnant low dissipates

**Large tropical wave emerges from west coast of Africa at 84 hours... moves into the waters just south of the Republic of Cabo Verde islands through 117 hours while becoming a large tropical low... centroid of large tropical low near 10N-40W at 162 hours shortly after which time it weakens to a large tropical wave

1800Z (Aug 4) NAVGEM Model Run...

**For Tropical Storm Dexter... initialized as a broad surface low instead of a tropical cyclone... continues east-northeast and reaches 36.5N-63W by 30 hours where it transitions into a more elongated and less tropical remnant low... shortly thereafter loses identity along remaining eastern part of surface front that Dexter formed from

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

**For area of interest #15... through 48 hours the surface front trailing from Dexter consolidates into a weak surface low near 31N-73.5W... the surface low continues north into the waters southeast of Massachusetts through 168 hours

**Large tropical wave emerges from west coast of Africa at 84 hours... moves into the waters just south of the Republic of Cabo Verde islands through 168 hours while becoming a large tropical low