MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #8

*******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 JUNE 4 2025 2:08 AM EDT...

See area of interest #4 section below for an update on the disturbance in the vicinity of Florida and the northwestern Bahamas poised to move across the waters near the southeastern United States coast in the days ahead... this system is being monitored for signs of tropical development. Elsewhere noting the following:

(1) A portion of the current northwestern Atlantic upper trough will soon become a cut-off upper vortex due to the strength of the neighboring eastern North America upper ridge. The eastern divergence zone of the materializing upper vortex is already producing a rapid-forming surface low pressure which will soon whirl into the core of the upper vortex... resulting in a deep-layer low. The deep-layer low is not likely to acquire tropical characteristics as the combination of 22 deg C waters and not so cold upper air layer (200 mb heights above 1200 dekameters) will not be enough for instability needed for thunderstorms and tropical characteristics.

(2) Regarding the central Caribbean waters toward Central America... in a few days some of the models suggest the cold-core northwest Florida cut-off upper vortex will be fading due to prolonged isolation from high-latitude cold air. This would allow a central Caribbean upper ridge cell to expand to the south of the fading upper vortex... the outflow of which could trigger a central Caribbean tropical disturbance. The GFS model continues to lead this idea... may have to also initiate a new area of interest in the central Caribbean in the days ahead if other models come into agreement or if future satellite observations were to warrant.

AREA OF INTEREST #4... The disturbance in the vicinity of the Florida peninsula and northwestern Bahamas has evolved into an east-west elongated surface trough... and continues to be supported by the eastern divergence zone of upper-level energy that has settled over northwestern Florida as an upper vortex. The surface trough lacks a well-defined center per the latest CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=) and satellite imagery which shows an elongated comma shaped region of cloudiness with embedded scattered showers and thunderstorms. The settlement of the supporting upper vortex at a further west location than the previous forecast would suggest the need to adjust the forecast track west... however the centroid of the elongated comma shaped region appears to be near 27.5N-80W (just offshore of east-central Florida) which is also where the NHC shows the initial position of the disturbance in their tropical weather outlook... and this is aligned with my previous forecast track... therefore the updated one I show below is the same as previous. Several hundred miles to the northeast... a northwestern Atlantic frontal low has rapidly materialized and will soon stack with its supporting upper trough/vortex to make a deep-layer cyclone. The upper-level western convergence zone of the deep-layer cyclone will soon transition the current eastern US surface ridge into a blocking surface ridge to the northeast... sending the disturbance northward instead of northeastward in the next 24 hours. In the long range (48+ hours)... the track bends increasingly faster to the northeast as the next upper trough and its surface front in the mid-latitudes... currently over central Canada and the central US... approaches and erodes the blocking surface ridge... replacing it with deep-layer southwesterly flow in the environment. The long-range forecast track has some uncertainty as (1) it is unknown exactly where the best-defined center will materialize on the surface trough... and (2) the central Canada upper trough breaks down into multiple shortwave upper troughs due to its low strength relative to the current eastern North America upper ridge it displaces... and models can have a difficult time in forecasting the positions of the shortwave upper troughs in such a scenario. The NHC suggests a low 10% chance of tropical cyclone formation perhaps as the model consensus has converged on a long-range track along the Carolina coast... I have slightly higher 15% peak odds of cyclone formation as my forecast track allows this system to be a little more offshore. For 0000Z June 5 I have lowered odds of tropical cyclone formation to 5% as this system has not made enough progress in the short-term for development that soon... and by 72 hours I trim development odds below the 15% peak as the northeast speed of the disturbance is low enough to be sheared by the upper southwesterlies. The northeast acceleration is enough to reduce the effect of the shear by 96 hours... however by that point the approaching surface front's low pressure field is too close that this system is likely to lose its identity by then.

Regarding impact to land areas:

(1) Rainfall... due to the above-mentioned more western position of the supporting upper vortex and associated eastern divergence zone... periods of rainfall have continued across the Florida peninsula and the northwestern Bahamas. The western-shifted corridor of rainfall has potential to overspread southeastern Georgia... and some inland areas in the eastern Carolinas in addition to the coastal Carolinas through Friday evening.

(2) Coastal surf and rip currents are possible from northeastern Florida to the Carolinas if tropical cyclone formation occurs... toward tonight further south and toward Friday evening further north. For the coastal Carolina rain event Thursday evening to Friday evening... gusty winds are possible in squalls of heavy rain should tropical cyclone formation occur.

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

IOH 24 Hr Outlook (0000Z Jun 5)... 5% chance of tropical cyclone formation (just offshore of northeastern Florida near 30N-80W)

IOH 48 Hr Outlook (0000Z Jun 6)... 15% chance of tropical cyclone formation (just offshore of South Carolina near 32N-79W)

IOH 72 Hr Outlook (0000Z Jun 7)... 10% chance of tropical cyclone formation (just south of Cape Hatteras North Carolina near 34.5N-75.5W)

IOH 96 Hr Outlook (0000Z Jun 8)... 0% chance of tropical cyclone formation (northwestern Atlantic near 36.5N-70W)

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

Formation chance through 48 hours... 10%

Formation chance through 7 days... 10%

...COMPUTER MODEL SUMMARY...

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

1200Z (Jun 3) CMC Model Run...

**For area of interest #4... the east-west surface trough currently straddling the Florida peninsula lifts north into the Carolina and Georgia coast through 60 hours... while continuing northeast into offshore waters it is absorbed into frontal low approaching from the mid-Atlantic US by 96 hours

1800Z (Jun 3) ECMWF Model Run...

**For area of interest #4... the east-west surface trough currently straddling the Florida peninsula lifts north into the Georgia and South Carolina through 42 hours... the northeast end of the surface trough intensifies into a surface low over far eastern North Carolina by 60 hours... surface low turns northeast into waters offshore of the mid-Atlantic US through 90 hours (data beyond 90 hours not available at above-mentioned source... the 1200Z run which usually has longer range data is down at the above-mentioned source)

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

**For area of interest #4... the east-west surface trough currently straddling the Florida peninsula lifts north into the Carolina coast through 45 hours... northeast end of the surface trough intensifies into a surface low over coastal North Carolina by 63 hours... surface low continues north-northeast into the waters offshore of the mid-Atlantic US through 90 hours while losing identity to large frontal low approaching from NE US

**In long range the current NW Florida upper vortex that has triggered the formation of area of interest #4 weakens which allows for a tropical upper ridge cell to expand in its wake in the central Caribbean... by 156 hours the outflow of the upper ridge cell contributes to formation of a broad tropical low centered just offshore of the Nicaragua/Honduras border

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

**For area of interest #4... evolves into a weak surface low making landfall at the Georgia/South Carolina border by 30 hours... surface low moves north-northeast into eastern North Carolina through 54 hours then turns east into the waters just offshore of Cape Hatteras by 72 hours where it possibly becomes a tropical cyclone... while turning north-northeast into cooler waters offshore of the mid-Atlantic the possible tropical cyclone weakens while becoming absorbed by frontal low approaching from the NE US by 96 hours.