MY 2025 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #4

*******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 MAY 8 2025 10:52 AM EDT...

Deep-layer cyclone is in progress south of the Azores and west of the Canary Islands... daily birdseye view posts on the Atlantic tropics continue on this site while monitoring this feature for acquisition of tropical characteristics... see area of interest #2 section below for details.

For the Gulf of America... a sprawling cut-off upper vortex will be settling into the south-central US... from this position its southeastern divergence zone will produce a broad surface low pressure field over the Gulf of America by late this weekend which then moves into the southern US from the US Gulf coast early next week while it whirls into the core of the quasi-stationary upper vortex. Note the models have trended with a more southern position of the upper vortex... which may allow for increased upper-level divergence and less shear over the north-central Gulf waters... however any well-defined subtropical or tropical low that materializes within the broad surface low pressure field at this location will have little time to develop before landfall with the US Gulf coast and therefore not declaring a tropical area of interest for the Gulf of America at this time. Regardless... 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.

AREA OF INTEREST #2... The surface frontal cyclone that formed over the western Azores yesterday has whirled into a positioned beneath the core of its parent upper vortex which is resulting in a deep-layer cyclone... and as expected the deep-layer cyclone is continuing on a general southeast to east-southeast trajectory away from the Azores and toward the Canary Islands while being slung around the southwest side of deep-layer vorticity positioned over western Europe. Note the updated forecast track in the outlook below is slightly sped up in the longer range to keep up with the latest global model consensus. Despite mild water temperatures in the region... the upper vortex is cold enough to allow the deep-layer cyclone to produce bands of showers near its center... however the intensity of this activity on the infrared satellite color scale is not quiet enough for the NHC to upgrade it to an area of interest in their tropical weather outlook. I am assigning peak odds of subtropical cyclone formation to 24 hours when the system is passing over its warmest waters along the forecast track (19 deg C). My peak odds are not higher than 20% as of this writing as would have preferred waters of at least 20 deg C for more confidence in a tropical event. Begin trimming odds down from the peak after 24 hours as the surface layer of the deep-layer cyclone will be weakening due to a lack of divergence at the core of the upper vortex... especially if it hasn't gained tropical characteristics (t-storm induced warm core upper outflow layer that helps to lower surface pressures) by then.

Regardless of acquiring tropical characteristics or not... the following impacts to land areas are expected... coastal surf continues for the Azores and will spread east into the Canary Islands through tomorrow (Friday). Given that the surface layer of the cyclone is most likely to weaken after 24 hours (unless it acquires tropical characteristics)... the Canary Islands see relaxing coastal surf with periods of rainfall as the weakening surface circulation moves in from the west by the weekend.

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

IOH 24 Hr Outlook (1200Z May 9)... 20% chance of subtropical cyclone formation (west of the Canary Islands near 33N-23W)

IOH 48 Hr Outlook (1200Z May 10)... 10% chance of subtropical cyclone formation (just west of the Canary Islands near 33N-19W)

IOH 72 Hr Outlook (1200Z May 11)... 0% chance of subtropical cyclone formation (between the Canary Islands and Morocco near 33N-12W)

*****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 8) CMC Model Run...

**For area of interest #2... moves east-southeast into the Canary Islands through 66 hours while gradually weakening.

**For surface low well south of Bermuda... gradually weakens and dissipates southwest of the island by 66 hours

**Divergence zone of upper vorticity currently over the central US produces a broad central Gulf of America surface low by 60 hours... north portion of the broad surface low develops a better-defined center making landfall over the far western Florida panhandle by 72 hours

0000Z (May 8) ECMWF Model Run...

**For area of interest #2... moves east-southeast into the Canary Islands through 72 hours while gradually weakening.

**Divergence zone of upper vorticity currently over the central US produces a broad central Gulf of America surface low by 72 hours... north portion of the broad surface low develops a better-defined center just offshore of southeastern Louisiana by 78 hours... proceeds north inland across the southeastern US in the long range while weakening below the core of the upper vorticity where supportive upper divergence is lacking

0600Z (May 8) GFS Model Run...

**For area of interest #2... moves east-southeast into the Canary Islands through 72 hours while gradually weakening.

**Divergence zone of upper vorticity currently over the central US produces a broad central Gulf of America surface low by 75 hours... the surface low then whirls northwest into the core of the upper vorticity... over Arkansas by 120 hours... while decaying due to a lack of divergence under the core region of the upper vorticity.

0600Z (May 8) NAVGEM Model Run...

**For area of interest #2... moves east-southeast into the Canary Islands through 66 hours while gradually weakening.