MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #28

*******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 JULY 2 2025 4:55 AM EDT...

The low-latitudes of the tropical Atlantic... particularly between the Lesser Antilles islands and west coast of Africa... are being precluded from tropical development in the foreseeable future by ongoing surges of dry Saharan air. Turning to the mid-latitudes of the Atlantic for possible tropical development in the days ahead as follows:

(1) See area of interest #8 section below for more information on the area of interest the National Hurricane Center has marked in their tropical weather outlook which spans the waters offshore of the southeastern US and Florida panhandle.

(2) The same surface frontal system/ upper trough associated with area of interest (AOI) #8 may drop off a small cut-off upper vortex west of Bermuda in the days ahead... the upper divergence zone of which could lead to surface pressure falls and yet another tropical area of interest to the east of AOI #8. Currently not declaring a new area of interest for this scenario as the models are currently not in agreement on this idea.

AREA OF INTEREST #8... A surface cold front currently positioned across the eastern United States is being supported by the eastern divergence zone of an upper trough currently positioned over the Great Lakes region and eastern Canada. The National Hurricane Center continues monitoring the potential for this surface front to trigger tropical development in waters offshore of the southeastern United States or Florida panhandle over the next few days. Note this surface front is the eighth area of interest I have tracked on this site this year in regards to possible Atlantic basin tropical development.

Observing a mid-level trough of low pressure has developed over the northeastern Gulf of America and is expected to merge with the current eastern US surface front... more details as follows: Noting that ahead of the surface front a weakening cut-off upper vortex has settled offshore of the southeastern US after previously tracking northwest near the Bahamas (the vortex is weakening from prolonged isolation from high-latitude cold air). The eastern divergence zone of the vortex was producing pockets of thunderstorms offshore of the southeastern US and due north of the western Bahamas... and a pattern of divergence between the west edge of the vortex and east edge of the upper anticyclone that has been over former tropical cyclone Barry and current eastern Pacific tropical cyclone Flossie produced repeated rounds of thunderstorms over the northeastern Gulf of America... and more recently this activity has evolved into a mid-level trough of low pressure seen in the CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/atlantic/movies/wg8vor4/wg8vor4_loop.html) and some rotation in whatever low clouds remain over the northeastern Gulf that can be seen in nighttime infrared satellite animation. The main focus of this area of interest continues to be the current eastern US surface front... however the mid-level trough over the northeastern Gulf looks likely to merge with the front and be maintained through 72 hours by split flow upper divergence between the southwest end of upper vorticity to separate from the frontal upper trough and south side of upstream upper ridging to develop over the eastern/ central US.

Still expecting a surface spin maximum to materialize along the surface front in the vicinity of the Carolinas... and become the dominant feature of this area of interest instead of the northeastern Gulf of America mid-level trough... more details as follows: Noting the upstream central/ eastern upper ridging mentioned at the end of the previous paragraph is to be produced by northward warm air transport ahead of an upstream surface frontal system moving across central Canada... and in recent model runs is shown to be further north such that the upper vorticity that separates from the frontal upper trough retrogrades southwestward across the inland southeastern US and toward Louisiana instead of over offshore waters. In the short-term watching for a spin maximum to develop along the North Carolina segment of the eastern US surface front due to split flow upper divergence between southwesterlies ahead of the frontal upper trough and northerlies streaming into the currently weakening upper vortex offshore of the southeastern US. In the 48 to 72 hour window this spin maximum should be pushed south into waters offshore of the Carolinas by the surface ridge to build to the west... under the support of the back convergence zone of the frontal upper trough. During this time the spin maximum (i.e. defined surface low pressure area) becomes maintained by the eastern divergence zone of the upper vorticity retrograding southwest toward Louisiana... the recent track of the upper vorticity shown in the models is more favorable for tropical development offshore of the Carolinas as the upper vorticity does not overtop this system and squash upper outflow... and wind shear relaxes when the vorticity moves away from this area of interest and toward Louisiana... this is probably why the NHC has raised development odds in their recent outlooks... I have also done so but not as high as the NHC as I am waiting to see if models continue to show the same track of the upper vorticity. Recent model runs are also leaning toward a defined tropical surface low pressure offshore of the Carolinas instead of the northeastern Gulf of America... that seems to make sense with the current forecast track of the upper vorticity which will keep westerly shear levels unfavorable for tropical development elevated over the northern Gulf for longer when compared to the waters offshore of the Carolinas. Noting the surface ridge to the west of this area of interest passes to the north and merges with the Atlantic surface ridge to the east... however before merging with the Atlantic ridge I forecast the surface low offshore of the Carolinas to be pushed west closer to shore by the south side of the passing surface ridge in the 72 to 120 hour window. Noting low confidence during this part of the forecast track due to potential conflict between the passing surface ridge and Atlantic surface ridge. To make steering matters even more complicated... models are also increasingly showing that the upstream eastern/ central US upper ridge cuts-off another part of the frontal upper trough into a cut-off upper vortex to the northeast or east of this system... with the cut-off upper vortex's eastern divergence zone possibly making another tropical surface low... such a system could try to tug the surface low offshore of the Carolinas east while the passing surface ridge to the north does the opposite and we just end up quasi-stationary in 72 to 120 hours instead of moving toward the Carolina coast.

Whatever surface trough is present from the northeastern Gulf to the waters offshore of the Carolinas should lift generally north into the southeastern US (from Florida panhandle through the Carolina coast) beyond day 5 in the flow between the Atlantic surface ridge and next surface front to be driven into the region by the central Canada frontal system mentioned in the previous paragraph. At this time the most likely area to see notable weather from the surface trough appears to the coastal Carolinas as that area of the trough is more likely to see tropical development as discussed at length above.

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

IOH 24 Hr Outook (0000Z Jul 3)... 0% chance of tropical cyclone formation (eastern North Carolina near 35.5N-78W

IOH 48 Hr Outlook (0000Z Jul 4)... 0% chance of tropical cyclone formation (just offshore of southeastern North Carolina near 33.5N-77W)

IOH 72 Hr Outlook (0000Z Jul 5)... 0% chance of tropical cyclone formation (offshore of the Carolinas near 33N-77W)

IOH 96 Hr Outlook (0000Z Jul 6)... 10% chance of tropical cyclone formation (just offshore of the Carolinas near 33N-78W)

IOH 120 Hr Outlook (0000Z Jul 7)... 20% chance of tropical cyclone formation (just offshore of South Carolina near 33N-79W)

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

Formation chance through 48 hours... 0%

Formation chance through 7 days... 40%

...COMPUTER MODEL SUMMARY...

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

0000Z (Jul 2) CMC Model Run...

**For area of interest #8... tail end of current eastern US surface front becomes an oblong broad surface low covering the northeastern Gulf of America... northern Florida... and waters offshore of Georgia by 84 hours due to the elongated eastern divergence zone of upper vorticity separating from frontal upper trough at a location over the inland SE US... the oblong surface low gradually becomes circular as it hooks north into eastern South Carolina by 126 hours... vigorous frontal system moving east from central Canada drives surface front across the eastern US with this front first lifting the eastern South Carolina surface low northward into the inland mid-Atlantic US and then absorbing the surface low by 162 hours.

1200Z (Jul 1) ECMWF Model Run...

**For area of interest #8... tail end of current eastern US surface front becomes a SW/NE oblong broad surface low near 30N-77.5W by 96 hours due to the elongated eastern divergence zone of upper vorticity separating from frontal upper trough at a location over the coastal SE US... the oblong circulation becomes more circular by 120 hours while quasi-stationary near 30N-78W... through 168 hours drifts slowly north-northeast toward North Carolina Outer Banks in flow ahead of slowly-approaching front driven across the eastern US by frontal system ejecting from central Canada

**The frontal upper trough that generates area of interest #8 also leaves behind a cut-off upper vortex midway between the US east coast and Bermuda by 120 hours... eastern divergence zone of cut-off upper vortex contributes to formation of small tropical surface low just southwest of Bermuda by 168 hours

0000Z (Jul 2) GFS Model Run...

**For area of interest #8... tail end of current eastern US surface front becomes a broad northeastern Gulf of America surface low by 75 hours due to split flow upper divergence between upper vorticity separating from frontal upper trough and southeast side of upstream upper ridge over the eastern US... the upper vorticity retrogrades southwest across the southeastern US with this vorticity pulling the northeastern Gulf surface low northeast across northern Florida and onto the northeast Florida coast by 99 hours... before merging with greater Atlantic surface ridge to the east a passing surface ridge to the north pushes the surface low northwest into southern Georgia by 120 hours... vigorous frontal system moving east from central Canada drives surface front across the eastern US with this front absorbing the southern Georgia surface low by 138 hours

1800Z (Jul 1) NAVGEM Model Run...

**For area of interest #8... tail end of current eastern US surface front becomes an oblong broad surface low covering the northeastern Gulf of America... northern Florida... and waters offshore of the southeastern US by 66 hours due to the elongated eastern divergence zone of upper vorticity separating from frontal upper trough at a location over the inland SE US... northeast end of the oblong circulation becomes a circular surface low offshore of the Carolinas by 102 hours... the next surface front that moves across the eastern US slowly approaches and slowly pushes the offshore surface low to a position south of the North Carolina Outer Banks by 168 hours