MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #9

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

...THURSDAY JUNE 5 2025 11:59 AM EDT...

See area of interest #4 section below for an update on the disturbance that recently made landfall in the Carolinas.

For the Caribbean Sea… the GFS model has dropped showing tropical development potential for the days ahead. The latest model consensus is the southern half of the currently decaying Florida upper trough joins with some upper vorticity to be left by the current NW Atlantic deep-layer cyclone to extend the current trans-Atlantic upper vorticity band westward across the Caribbean. The overhead upper vorticity will tend to suppress activity across the Caribbean… but noting split flow upper divergence between the west side of the upper vorticity band and east end of the Mexico upper ridge cell will tend to produce thunderstorms across Central America and far eastern Pacific. Any tropical development in the region in the days ahead is therefore likely in the eastern Pacific rather than the Caribbean.

AREA OF INTEREST #4... The east-west surface trough that was in the vicinity of the Florida peninsula... supported by the eastern divergence zone of the currently decaying northwest Florida upper trough... saw increasing spin at its east end near 30N-80W about 12 hours ago as seen in satellite animation and the CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=). Since then the flow around the remainder western part of the surface trough and surface ridge that has recently moved into the western Atlantic from the eastern US hooked the spin maximum northward into a landfall into the southern tip of South Carolina as of this morning. What's left of this spin maximum (surface low pressure center) has merged with the tail end of the surface cold front driven by the current northwestern Atlantic deep-layer low... and in the latest NHC TAFB surface analyses is analyzed as a surface frontal low parked just inland from the Georgia/South Carolina border. Because of the landfall the NHC has removed this system from their tropical weather outlook (i.e. the NHC is no longer monitoring this system for signs of tropical cyclone formation). Going forward the northern half of the NW Florida upper trough and the surface frontal low move northeastward in tandem in deep-layer southwesterly flow ahead of the surface front and upper trough approaching from the eastern US and central Canada. By 24 hours the surface frontal low should be positioned over the Outer Banks of North Carolina... and still supported by a combination of the eastern divergence zone of the upper trough fragment and the outflow of adjacent upper ridging to the east. At this position the southern half of the circulation would still be in contact with warm Gulf stream waters and the upper ridging would help reduce the upper southwesterly shear... however this window is too brief for tropical development as by 36 hours the upper trough fragment moves faster (as the upper flow is faster than the surface) and already overtops the surface frontal low with hostile wind shear. By 48 hours the surface frontal low should be offshore of the northeastern US... and is expected to gain strength due to split flow upper divergence between northwesterlies flowing into the back side of the passing upper trough fragment and southwesterlies ahead of the approaching central Canada upper trough. At this point the surface frontal low will not have yet merged with the incoming surface front featuring notably cooler and drier air behind it... however still not expecting tropical development at the 48-hour point either as the surface frontal low will be departing the warmest part of the Gulf stream. With tropical development no longer expected... this is my planned final statement on this area of interest on this blog.

Primary impact from this system is heavy rainfall currently across North Carolina... some of this rainfall will transfer across southeastern Virginia in the next 24 hours after which time all rainfall departs the United States as this system continues northeast into offshore waters.

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

IOH 24 Hr Outlook (1200Z Jun 6)... 0% chance of tropical cyclone formation (Cape Hatteras North Carolina near 35N-75.2W)

*****National Hurricane Center (hurricanes.gov) official outlook as of 8 AM EDT***********************

Not in the official outlook

...COMPUTER MODEL SUMMARY...

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

0000Z (Jun 5) CMC Model Run...

**For area of interest #4... After making landfall at the GA/SC border turns east-northeast across the far eastern Carolinas and into the Outer Banks of North Carolina by 36 hours... after merging with incoming front to the northwest the remnant frontal low accelerates northeast across offshore waters and makes landfall in Newfoundland by 96 hours... strengthens further into a remnant frontal cyclone that passes just south of the southern tip of Greenland and into the waters south of Iceland through 168 hours

1800Z (Jun 4) ECMWF Model Run...

**For area of interest #4... After making landfall at the GA/SC border turns east-northeast across the far eastern Carolinas and onto the US Atlantic coast at the NC/VA border by 42 hours... after merging with incoming front to the northwest the remnant frontal low accelerates northeast across offshore waters and makes landfall in the eastern tip of Nova Scotia by 90 hours (data beyond 90 hours not available at above-mentioned source... the subsequent 0000Z run which usually has longer range data is down at the above-mentioned source)

0000Z (Jun 5) GFS Model Run...

**For area of interest #4... After making landfall at the GA/SC border turns east-northeast across the far eastern Carolinas and into the Outer Banks of North Carolina by 36 hours... after merging with incoming front to the northwest the remnant frontal low accelerates northeast across offshore waters and makes landfall in the eastern tip of Nova Scotia by 81 hours... shortly thereafter the remnant frontal low loses its identity to larger frontal low developing just to the north

0000Z (Jun 5) NAVGEM Model Run...

**For area of interest #4... After making landfall at the GA/SC border turns east-northeast across the far eastern Carolinas and into the Outer Banks of North Carolina by 42 hours... after merging with incoming front to the northwest the remnant frontal low accelerates northeast across offshore waters and loses its identity along the front while positioned south of Newfoundland by 108 hours