MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #5

*******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...SATURDAY MAY 10 2025 5:30 PM EDT...

Infrared satellite imagery of northern Gulf of America disturbance making landfall across the southeastern United States:

The broad surface low pressure area that developed across the western Gulf of America yesterday has quickly moved northeast into the United States Gulf coast while flung around the east side of its parent upper vortex... the central area made landfall early this morning at the Mississippi/Alabama coastal region without a well-defined center and subtropical cyclone formation is now no longer possible. The inland remains of this system are bringing areas of heavy rainfall across the southeastern United States. Earlier this afternoon this system produced tornado watches and warnings for the central Florida panhandle... southwestern Georgia… and southeastern Alabama due to a combination of vertical shear (upper flow more westerly than the surface) and instability (brought in by low-level warmth and Gulf moisture from the south pulled in by surface circulation). Refer to the National Weather Service (weather.gov) and/ or your local news media for the latest regarding impacts from the inland remains of this system going forward. This is my final update on the Atlantic tropics till the start of the hurricane season in June… or unless another tropical area of interest develops in the Atlantic basin before then.

...FRIDAY MAY 9 2025 11:20 AM EDT...

Continuing daily updates on the Atlantic tropics due to two areas of interest:

(1) See area of interest #2 section below for an update on the deep-layer cyclone heading toward the Canary Islands.

(2) See area of interest #3 section below for information on a new western Gulf of America disturbance quickly heading northeast toward the US Gulf coast (southeastern Louisiana to Florida panhandle region).

AREA OF INTEREST #2... The deep-layer cyclone currently positioned south-southeast of the Azores is swinging east-southeast toward the Canary Islands while pulled around the southwest side of deep-layer vorticity over western Europe. The surface layer of the cyclone is going through a typical post-mature decay due to the lack of divergence beneath the core of the upper-layer vortex. Although sea surface temps are 19 deg C... the overhead upper vortex is cold enough to add some instability for bands of showers and t-storms that have been in progress in the circulation... particularly on the circulation's north side. However this activity has not been sufficient to be upgraded to an area of interest by the National Hurricane Center and the surface layer of the cyclone will continue weakening going forward. Therefore dropping odds of subtropical cyclone formation to 0%... and this is my final statement on this area of interest on this blog. Any coastal surf being generated by this system across the Azores and Canary Islands should relax over the next 24 hours... with showers rolling into the Canary Islands from the west.

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

IOH 24 Hr Outlook (1200Z May 10)... 0% chance of subtropical cyclone formation (just west of the Canary Islands near 32N-19W)

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

Not in the official outlook

AREA OF INTEREST #3... Adding a new area of interest for the disturbance currently positioned over the western Gulf of America which is quickly shifted northeast toward the US Gulf coast (southeastern Louisiana to Florida panhandle region). The disturbance has been initialized as a developing surface low pressure field with widespread thunderstorm activity... induced by the southeastern divergence zone of a south-central US upper vortex... albeit the upper vortex has recently re-joined with a SW/NE tilted upper trough from eastern Canada. The northwestern convergence zone of the upper trough is supporting a SW/NE oblong continental surface ridge. Although the southeast side of this ridge has been pumping in cold air from the north supporting the cold core upper trough... the west side of the ridge is pushing warm air northward over the western US which will support ongoing amplification of warm core upper ridging there. In turn the amplifying western US upper ridge will force the south-central US upper vortex to re-separate from the eastern Canada upper trough. Over the last couple of days the models have trended with a stronger western US upper ridge that pushes the upper vortex closer to the Gulf of America... which will support increased upper divergence and less shear over a pocket of the north-central Gulf. And as of this morning the models have trended toward a well-defined surface low pressure center forming here and the midst of the thunderstorm activity... therefore the surface low may have subtropical characteristics while supported non-tropically by the upper divergence and tropically by any warm core upper outflow induced by the thunderstorm latent heat release. Although water temps in the northern Gulf are just below the 26 deg C threshold for tropical activity... the boosting upper divergence should make up for that. However assigning a low 10% chance of subtropical cyclone formation as any well-defined surface low that develops will have little time over water. After 24 hours... the surface low weakens inland over the south-central US while whirling into the core of the upper vortex where upper divergence is lacking.

Regardless of subtropical development or not... this weather pattern means periods of heavy rainfall through early next week... which could result in flash flooding over parts of the southeastern US... especially for already-saturated grounds from southeastern Louisiana to the Florida panhandle caused by previous rains this weather pattern has already produced in previous days.

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

IOH 24 Hr Outlook (1200Z May 10)... 10% chance of subtropical cyclone formation (Alabama coast near 30.2N-88W)

IOH 48 Hr Outlook (1200Z May 11)... 0% chance of subtropical cyclone formation (northern Louisiana/Alabama border near 32N-91W)

*****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 (May 9) CMC Model Run...

**For area of interest #2... moves east-southeast into the Canary Islands through 48 hours while gradually weakening.

**For area of interest #3... divergence zone of upper vorticity currently over the central US produces a well-defined surface low pressure center over the southeast Louisiana coast at 30 hours... through 66 hours the surface low whirls northwest into the core of the upper vorticity... over northern Louisiana... while weakening due to a lack of upper divergence at this location

0000Z (May 9) ECMWF Model Run...

**For area of interest #2... moves east-southeast into the Canary Islands through 48 hours while gradually weakening.

**For area of interest #3... divergence zone of upper vorticity currently over the central US produces a well-defined surface low pressure center over the US Gulf coast... at the FL/ AL border... through 36 hours... through 66 hours the surface low whirls northwest into the core of the upper vorticity... over SW Mississippi... while weakening due to a lack of upper divergence at this location

0600Z (May 9) GFS Model Run...

**For area of interest #2... moves east-southeast into the Canary Islands through 42 hours while gradually weakening.

**For area of interest #3... divergence zone of upper vorticity currently over the central US produces a broad surface low centered over far southern Alabama at 39 hours... through 57 hours the surface low whirls northwest into the core of the upper vorticity... over northern Louisiana... while weakening due to a lack of upper divergence at this location

0600Z (May 9) NAVGEM Model Run...

**For area of interest #2... moves east-southeast into the Canary Islands through 48 hours while gradually weakening.

**For area of interest #3... divergence zone of upper vorticity currently over the central US produces a broad surface low but with a defined centered just south of southeastern Louisiana by 24 hours... then through 84 hours whirls cyclonically over inland Louisiana... beneath the core of upper vorticity... while weakening due to a lack of upper divergence at this location

**Same upper vorticity that triggers area of interest #3 pivots east across the southeastern US through 114 hours... eastern divergence zone of the upper vorticity produces a surface low with possible tropical characteristics just offshore of the NC/SC border at 126 hours... through 168 hours the possible tropical low makes a cyclonic loop inland over southeastern NC then back offshore as the upper vorticity shifts further east and overhead... with the low weakening due to a lack of divergence beneath the now-overhead upper vorticity.