MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #23

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

...UPDATE...TUESDAY JUNE 24 2025 11:20 AM EDT...

Left... visible satellite image of the central Atlantic surface low pressure swirl as it develops into Tropical Storm Andrea. Right... more recent visible satellite image of newly-declared Tropical Storm Andrea after losing its thunderstorm activity:

The central Atlantic low pressure swirl... tagged as area of interest #6 in this blog post... has been upgraded to Tropical Storm Andrea by the National Hurricane Center as of 11 AM EDT... the first tropical cyclone of the 2025 Atlantic Hurricane Season. Maximum sustained winds are estimated to be 40 mph... minimum central surface pressure is estimated to be 1014 mb... and as of the 11 AM advisory the tropical cyclone was centered at 36.6N-48.9W. Even though Andrea has recently lost its thunderstorms... the NHC advisory states that it did maintain enough thunderstorm activity overnight to be upgraded to a tropical cyclone. Noting the tropical cyclone remains underneath the boosting eastern divergence zone of the nearby small upper vortex that helped it to develop the overnight thunderstorms... thus the recent loss of the thunderstorms may be due to a cool pool of waters at or just below 22 deg C seen in the sea-surface temperature map at the coordinates of the tropical cyclone (https://www.nhc.noaa.gov/tafb/sst_loop/14_atl.png). By tonight conditions become more hostile as Andrea encounters the suppressive southeastern convergence zone of warm core upper ridging now expanding into the northwest Atlantic... therefore I agree with the NHC 11 AM EDT forecast that Andrea is downgraded into a remnant low by 24 hours... if not sooner.

...TUESDAY JUNE 24 2025 2:11 AM EDT...

See area of interest #6 section below for information on the ongoing area of interest in the open central Atlantic being monitored for possible tropical development... positioned near 35N-53W as of 0000Z earlier this evening.

For the western Atlantic tropical latitudes (western Caribbean and Bay of Campeche) and eastern Pacific... the current string of upper vorticity along 25N latitude will continue to weaken while isolated from high-latitude cold air due to the current eastern US heat wave upper ridge. This will allow for an increasingly defined upper anticyclone in the vicinity of Central America in 4+ days. In the days ahead will be watching for possible eastern Pacific and/or western Caribbean/Bay of Campeche tropical development as the outflow of the upper anticyclone promotes regional thunderstorms and lower surface pressures. The NHC is currently monitoring for the next eastern Pacific development in their tropical weather outlook which will likely spring up from the tropical low near 9N-90W... for more on the possible eastern Pacific development see outlook at hurricanes.gov as this site is focused on Atlantic basin tropical development. Meanwhile not declaring an area of interest for the Atlantic basin side (western Caribbean/ Bay of Campeche) until the global models are in better agreement on development in that area and/or future satellite observations during future updates warrant.

AREA OF INTEREST #6... Infrared satellite image from early Monday June 23 (0800Z) when the central Atlantic tropical low was at peak organization last evening:

Much respect for the tenacious small central Atlantic surface low pressure spin which continues northeast in the flow around the eastern Atlantic deep-layer ridge. Despite becoming exposed to westerly shear on the south side of a small cut-off upper vortex deposited to its north last evening... the small area of sheared off thunderstorms on its east side grew in size and organization and stayed near enough to the center for the NHC to bump up odds of tropical cyclone formation to 70%. Knowing that persistence is required for the NHC to upgrade this system to a tropical cyclone... was waiting till 8 AM EDT Monday to decide whether or not to raise my odds of tropical cyclone formation... however by then the thunderstorm activity was fading and by Monday afternoon the NHC was trimming down odds of tropical cyclone formation. Tonight the surface low does not look like its ready to be written off yet... abruptly an area of increasing thunderstorms has develop over and north of the surface center despite the surface low recently entering waters below 26 deg C. Previous upper wind forecasts suggested that by now this system would be sliding underneath a suppressive southwest-to-northeast elongated area of upper vorticity... instead the upper feature has ended up being a circular upper vortex whose southeastern divergence zone appears to now be enhancing the surface low and offsetting the fact that water temps are just below 26 deg C. Noting this past 1200Z ECMWF model suggested tropical cyclone formation within the timeframe that is now the next 12 hours perhaps due to this upper wind dynamic... and I have raised my odds of tropical cyclone formation to above 50% for that timeframe. By 24 hours the westerly flow on the south side of the approaching southeastern Canada frontal low will have wafted in warm air associated with the current eastern US upper ridge... resulting in expanding warm core upper ridging across the northwest Atlantic. At the 24-hour position the surface low is over even cooler waters and underneath the southeastern suppressive convergence zone of the northwest Atlantic upper ridging... and I drop odds of development to 0%. The fact that conditions are hostile for development by 24 hours means there is little time left for tropical cyclone formation... which is why my peak odds of tropical cyclone formation in this update are barely above 50%.

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

IOH 12 Hr Outlook (1200Z Jun 24)... 60% chance of tropical cyclone formation (central Atlantic near 36N-50W)

IOH 24 Hr Outlook (0000Z Jun 25)... 0% chance of tropical cyclone formation (central Atlantic near 39N-46.5W)

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

Formation chance through 48 hours... 40%

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/).

1200Z (Jun 23) CMC Model Run...

**For area of interest #6... While moving northeast continuously weakens through 48 hours while losing identity to current southeast Canada frontal low as that frontal low later enters the north Atlantic

1200Z (Jun 23) ECMWF Model Run...

**For area of interest #6... While moving northeast tropical cyclone formation suggested near 37N-49.5W at 24 hours while potentially enhanced by the southeastern divergence zone of small upper vortex to the north... while continuing northeast it subsequently weakens through 54 hours while losing identity to current southeast Canada frontal low as that frontal low later enters the north Atlantic

1800Z (Jun 23) GFS Model Run...

**For area of interest #6... While moving northeast continuously weakens through 39 hours while losing identity to current southeast Canada frontal low as that frontal low later enters the north Atlantic

1800Z (Jun 23) NAVGEM Model Run...

**For area of interest #6... While moving northeast continuously weakens through 36 hours while losing identity to current southeast Canada frontal low as that frontal low later enters the north Atlantic

**While current eastern Pacific tropical low persists and additional Caribbean tropical low materializes offshore of northwestern Colombia by 42 hours... while orbiting the adjacent eastern Pacific circulation the Caribbean tropical low continues west-northwest over northeastern Nicaragua and eastern Honduras by 78 hours... then makes landfall over the southeastern Yucatan peninsula of Mexico by 96 hours... enters the southwestern Gulf of America by 126 hours and then turns north toward southeastern Louisiana by 168 hours while gradually strengthening into a tropical cyclone