top of page
Home: Text

BIRDSEYE VIEW POSTS

Since 2012 on the now retired Weather Underground blogs, I have been posting annotated "birdseye view" charts of the Atlantic basin, with a detailed explanation and forecasting that references the chart. From there you may know me as "NCHurricane2009." While I now do these "birdseye view" posts here, I will continue to do comments at Yale Climate Connections via Disqus where the former Weather Underground community has moved to. Feel free to reply to me there, at my Disqus feed at this link, or via e-mail at IOHurricanes@outlook.com 

Home: Text
Home: Blog2
Search

MY 2024 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #109

Writer's picture: NCHurricane2009NCHurricane2009

*******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...WEDNESDAY OCTOBER 30 2024 2:11 PM EDT...

The surface and upper air charts valid for October 29 have been added below.


…TUESDAY OCTOBER 29 2024 11:59 PM EDT...

As we move into early November… watching for possible tropical development in the open central Atlantic and Caribbean Sea… see areas of interest #44 and #45 sections below for more information.


AREA OF INTEREST #44... The combination of outflow provided by the ongoing western Caribbean upper ridge/ anticyclone and convergence of numerous surface tropical waves of low pressure passing thru has supported scattered thunderstorms across Central America and far western Caribbean over the last couple of days. A well-defined low-level spin has not developed so far in the Caribbean as seen in the CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=)… and through the next 48 hours the momentum for a possible low-level low pressure spin shifts east toward the central Caribbean (SSW of Jamaica) as upper vorticity currently over Florida shifts southeast and becomes an upper vortex parked over the northern Caribbean Islands… with split flow upper divergence between the southwest side of the upper vortex and east side of the aforementioned upper anticyclone potentially helping with surface pressure falls. I have extended the period of 0% odds of development as the latest models do not have the upper vortex drift east enough to drop wind shear levels in the central Caribbean in the short-term. And in the long-term toward day 5 the upper vortex begins to pivot west under the influence of another upper ridge that builds over eastern North America in the wake of the current central North America upper trough/ surface frontal system… once that system later moves into the North Atlantic late in the forecast period. The track forecast in days 3 to 5 in my outlook below is a cyclonic orbit around the south side of the west pivoting upper vortex… as the area of split flow upper divergence is shown in the models to cyclonically move around the south side of the upper vortex… then by day 5 momentum for possible tropical development will be in the eastern divergence zone of the west moving upper vortex… especially as the vortex moves west enough to begin dropping shear levels around that time. I have low 10% development odds at day 5 as models have delayed possible Caribbean development to just after day 5. Additional note… from now through day 5 tropical development could occur sooner and further northeast over the northern Caribbean Islands (Hispaniola to northern Lesser Antilles) in a pocket of low shear and upper divergence on the east side of the upper vortex as some recent model runs suggest… if so may have to shift the outlook forecast points notably northeast in future updates.


Given the current outlook... interests across Jamaica… Hispaniola (Haiti and the Dominican Republic)… Puerto Rico… Virgin Islands… and northern Lesser Antilles should be on alert for possible periods of prolonged heavy rainfall with flood potential and possible tropical cyclone formation in the days ahead.

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

IOH 24 Hr Outlook (0000Z Oct 31)… 0% chance of tropical cyclone formation (between Central America and Jamaica near 15N-80.5W)

IOH 48 Hr Outlook (0000Z Nov 1)… 0% chance of tropical cyclone formation (south-southwest of Jamaica near 15.5N-79W)

IOH 72 Hr Outlook (0000Z Nov 2)… 0% chance of tropical cyclone formation (south-southwest of Jamaica near 15N-79W)

IOH 96 Hr Outlook (0000Z Nov 3)… 0% chance of tropical cyclone formation (south-central Caribbean near 13.5N-78.5W)

IOH 120 Hr Outlook (0000Z Nov 4)… 10% chance of tropical cyclone formation (south-southwest of Jamaica near 15N-79W)

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

Formation chance through 48 hours… 0%

Formation chance through 7 days… 40%


AREA OF INTEREST #45… Due to the strength of the current eastern North America upper ridge… various model runs continue to suggest a large portion of the current northwest Atlantic upper trough will become a cut-off upper vortex that heads east-southeast toward the surface front in the open central Atlantic. The potentially focused eastern divergence zone of such a vortex would trigger a surface cyclone along the front with possible tropical characteristics even though water temps in the region are in the low-20s of deg C… due to the cold de-stabilizing temps of the upper vortex (200 mb heights well below 1200 dekameters) which would help with thunderstorm generation. Therefore adding an area of interest for the central Atlantic… the forty-fifth such area of interest tracked on this site this year.


Through 48 hours the surface cyclone would whirl into the core of the potential upper vortex where it then reaches peak strength and begins to weaken due to the lack of divergence beneath the upper vortex core. Beyond that time the current central North America surface frontal system and upper trough break through the current eastern North America upper ridge and moves toward this system… lifting this system (surface cyclone and potential upper vortex) increasingly east then northeast into the open northeast Atlantic. By 120 hours this system becomes absorbed by the incoming surface frontal system and upper trough. My peak odds of subtropical development are shown at 72 hours when the surface cyclone is at peak strength… with decaying odds shown thereafter as the surface cyclone loses development potential with time as it weakens should it continue to fail to acquire tropical characteristics. Noting that if it does acquire fully tropical character by firing sustained thunderstorms that generate a latent heat release driven warm core outflow layer just below the potential upper vortex… the outflow layer would help the surface cyclone in holding peak strength for longer. Noting that in the model mix captured in the model summary section below… the CMC and ECMWF show possible tropical development while the NAVGEM and GFS failed to do so while not quiet showing an upper vortex materializing… with the NAVGEM tossing the surface cyclone north into even cooler waters in the flow ahead of an upper trough… and the GFS having a multi-center surface frontal low instead of a distinct surface cyclone due to the lack of a focused upper divergence zone that a circular upper vortex would otherwise provide. Because the usually more reliable GFS and ECMWF are split on tropical development… in this update cycle I kept peak odds of subtropical or tropical development below 50%.


Regardless of tropical development or not… this system will bring coastal surf to the Azores  by Saturday while passing just north of the islands.

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

IOH 24 Hr Outlook (0000Z Oct 31)… 0% chance of subtropical cyclone formation (central Atlantic near 37.5N-40W)

IOH 48 Hr Outlook (0000Z Nov 1)… 0% chance of subtropical cyclone formation (central Atlantic near 37.5N-41W)

IOH 72 Hr Outlook (0000Z Nov 2)… 40% chance of subtropical cyclone formation (well west of the Azores near 38.5N-38.5W)

IOH 96 Hr Outlook (0000Z Nov 3)… 20% chance of subtropical cyclone formation (just north of the western Azores near 41.5N-30W)

IOH 120 Hr Outlook (0000Z Nov 4)… 0% chance of subtropical cyclone formation (northeast Atlantic near 45N-25W)

*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM 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/).


1200Z (Oct 29) CMC Model Run...

**For area of interest #44... tropical low develops in the south-central Caribbean near 11.5N-80.5W by 66 hours… through 126 hours the tropical low becomes larger/broader and shifts northeast while merging with surface trough that develops over northern Caribbean Islands… south part of broad tropical low becomes a tropical cyclone near 13.5N-76W at 144 hours… while gradually strengthening the tropical cyclone whirls north-northwest closer to south coast of Jamaica through 168 hours

**For area of interest #45… Large portion of the current NW Atlantic upper trough becomes cut-off upper vorticity that moves toward current central Atlantic surface front… the divergence zone of the vorticity develops a rapidly-forming surface frontal cyclone near 39.5N-41W by 48 hours… while cyclonically orbiting in the flow associated with the upper vorticity the surface cyclone moves SE to 38.5N-39W by 60 hours where it becomes a possible tropical cyclone with the aid of the de-stabilizing cold upper air temps… the possible tropical cyclone then moves slowly northeast into the waters NW of the Azores through 108 hours while weakening… while shifting east into the waters N of the Azores through 132 hours the weakening system loses identity to frontal system that leaves North America and crosses the North Atlantic late in the forecast period


1200Z (Oct 29) ECMWF Model Run...

**For area of interest #44... tropical low develops in the south-central Caribbean near 12.5N-79W by 60 hours… through 168 hours the tropical low becomes larger/broader and shifts slowly northeast while merging with surface trough that develops over northern Caribbean Islands

**For area of interest #45… Large portion of the current NW Atlantic upper trough becomes cut-off upper vorticity that moves toward current central Atlantic surface front… the divergence zone of the vorticity develops a rapidly-forming surface frontal cyclone near 38.2N-42W by 54 hours… while cyclonically orbiting in the flow associated with the upper vorticity the surface cyclone moves SE to 37N-39W by 66 hours where it becomes a possible tropical cyclone with the aid of the de-stabilizing cold upper air temps… the possible tropical cyclone then moves slowly northeast then east into the waters just NW of the Azores through 114 hours while weakening… while shifting east then northeast into open northeast Atlantic waters through 156 hours the weakening system loses identity to frontal system that leaves North America and crosses the North Atlantic late in the forecast period


1800Z (Oct 29) GFS Model Run...

**For area of interest #44… broad tropical low materializes in central Caribbean by 69 hours… north part of broad tropical low becomes the dominant while developing a better-defined center near north coast of Hispaniola at 87 hours… becomes a tropical depression while moving WSW into NW Haiti through 108 hours… the tropical depression/ weak tropical storm continues west in the passage between east Cuba and Jamaica.. then across the Cayman Islands… and into the passage between the Yucatan peninsula and west tip of Cuba through 168 hours

**For area of interest #45… no short-term tropical development shown along central Atlantic surface front as incoming NW Atlantic upper trough has an elongated upper divergence zone causing a multi-center surface frontal low instead of a focused upper divergence zone needed for a singular well-defined surface cyclone with possible tropical character.

**Upper trough/ surface frontal system that emerges from North America late in the forecast period and absorbs AOI #45 leaves behind upper vorticity north of the Caribbean Islands… by 168 hours the divergence zone of the upper vorticity triggers multiple surface tropical lows located north and northeast of the northern Caribbean Islands


1200Z (Oct 29) NAVGEM Model Run…

**For area of interest #44… Rather large/broad tropical low develops over the central Caribbean through 96 hours… through 120 hours the large systems develops three centers (south-central Caribbean… western Caribbean… central Bahamas)… through 168 hours the large system pivots west toward Yucatan and southern Gulf of Mexico while the south-central Caribbean center moves NW and becomes a tropical cyclone just SW of Jamaica.

**For area of interest #45… frontal cyclone develops in central Atlantic near 37N-39W at 30 hours… through 78 hours the frontal cyclone continues north into cooler north-central Atlantic waters where tropical development is unlikely… through 126 hours becomes absorbed by frontal system that leaves North America and crosses the North Atlantic late in the forecast period

20 views0 comments

Recent Posts

See All

Comments


bottom of page