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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 

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MY 2024 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #20

*******Note that forecast 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.*********


...MONDAY JUNE 17 2024 10:45 PM EDT...

The Atlantic tropics are quiet active for mid-June while now monitoring three concurrent areas of interest as follows:


See area of interest #5 section below for an update on the large gyre of low pressure that has moved into the Bay of Campeche from the Yucatan. See area of interest #7 section below for another gyre that could materialize over the Caribbean and Central America... and head toward the Gulf of Mexico in the immediate wake of area of interest #5. Together... both gyres are forecast to produce a dangerously extended period of heavy rainfall across western Central America and eastern Mexico over the next several days.


See area of interest #6 section below for an update on the tropical disturbance that is materializing in the western Atlantic with the support of a cut-off upper vortex materializing in the region. This disturbance is forecast to shift west toward the northwestern Bahamas and southeastern United States coastal region by Friday and Saturday.


AREA OF INTEREST #5 (POTENTIAL TROPICAL CYCLONE ONE)... Over the last 36 hours... the broad surface low pressure over the southern Yucatan peninsula has worked its way into the eastern Bay of Campeche. Initially during this timeframe... this system featured a secondary eastern Pacific circulation in the Gulf of Tehuantepec which has since been pulled in and absorbed by the eastern Bay of Campeche center. Moreover the regional thunderstorms covering western Central America... southeastern Mexico... the western Caribbean... and Bay of Campeche have become considerably better organized into curved bands wrapped around the eastern Bay of Campeche center. This system does not quiet qualify to be a tropical cyclone as the surface center is not yet tightly defined (instead their continue to be multiple surface swirls)... however winds have increased to tropical storm force on the north side (due to the pressure gradient between the eastern Bay of Campeche low pressure and steering surface ridge which has moved into the Atlantic waters offshore of the northeastern US)... therefore the National Hurricane Center is now handling this area of interest as potential tropical cyclone one... as it has a high potential to develop a better-defined surface center soon which would allow its upgrade to tropical storm status. This allows the NHC to issue tropical storm advisories which are now in effect for coastal south Texas and northeastern Mexico in case this system indeed becomes a tropical storm at the last minute before landfall.


Steering setup continues to be complex with the aforementioned surface ridge offshore of the northeastern US... the current western US frontal low... another surface ridge that will build in the wake of the western US frontal low... and the possiblity of another surface gyre of low pressure forming just to the east (see area of interest #7 section below for information on the forecast future gyre). The CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor&zoom=&time=) currently does not show much spin east of this area of interest... therefore my updated forecast track in the outlook below is shifted north closer to the model consensus while giving less credence to the surface vorticity to the east and more credence to the aforementioned mid-latitude features. As a result the forecast track angle is generally west-northwest toward the surface ridge weakness associated with the current western US frontal low... with the frontal low and its upper trough not able to fully curve the track of this system north while lifting quickly to the northeast and away (while failing to defeat the current eastern North America heat wave upper ridge). Instead the surface ridge that then builds behind the frontal low finishes the job by continuing to push this area of interest west-northwest into northeastern Mexico by 72+ hours. Regarding odds of tropical cyclone formation... sea surface temps are rather warm and this system is forecast to remain under low shear and outflow beneath upper ridging all the way until it makes landfall with northeastern Mexico. And given the rather improved organization of this system... I agree with the NHC increasing odds of tropcial cyclone formation to 80% as of this writing.


Regardless of whether or not this area of interest develops into a tropical cyclone... this area of interest will contribute to additional heavy rainfall with flash flooding potential across eastern Mexico and western Central America over the next 96 hours. The pressure gradient between steering surface ridging to the north and this system's surface low pressure center will cause gusty winds and coastal surf to push into southern Texas and Tamaulipas through 72 hours (this is where the NHC has tropical storm advisories as of this writing). Note that should this system develop a more conventional center with central wind field as seen with tropical storms... the central wind field would bring similar coastal surf and gusty wind impacts as far south as Veracruz by 72 hours. Note this region may not be done with inclement weather conditions after this area of interest moves into northeastern Mexico as another disturbance potentially develops in its wake... see area of interest #7 section below for more information.

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

IOH 24 Hr Outlook (1800Z Jun 18)... 80% chance of tropical cyclone formation (central Bay of Campeche near 20N-93W)

IOH 48 Hr Outlook (1800Z Jun 19)... 80% chance of tropical cyclone formation (offshore of northern Veracruz near 21N-96W)

IOH 72 Hr Outlook (1800Z Jun 20)... 80% chance of tropical cyclone formation (Gulf coast of Mexico at Veracruz/Tamaulipas border near 22N-98W)

IOH 96 Hr Outlook (1800Z Jun 21)... 0% chance of tropical cyclone formation (interior northeastern Mexico near 23N-100W)

******National Hurricane Center (hurricanes.gov) official forecast as of 5 PM EDT***************************

Peak Strength (1800Z Jun 19)... 45 maximum sustained wind tropical storm centered offshore of northeastern Mexico at 23.4N-96.4W

Landfall (0600Z Jun 20)... 45 mph maximum sustained wind tropical storm centered on the central Tamaulipas coast at 23.8N-97.7W

Dissipation (1800Z Jun 21)... 25 mph maximum sustained wind dissipating remnant low centered over interior northeastern Mexico at 24N-101.4W

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

Formation chance through 48 hours... 80%

Formation chance through 7 days... 80%


AREA OF INTEREST #6... The south part of the upper trough currently in the western Atlantic is in the process of evolving into a cut-off upper vortex between Bermuda... the Bahamas... and northern Caribbean Islands thanks to the heat wave upper ridge building over eastern North America (this heat wave is being fanned by warm surface southerly flow ahead of the current western US frontal low). Divergence on the east side of the developing cut-off vortex has triggered a southwest-northeast titled surface trough with a similarly titled band of shower and thunderstorm activity positioned in the vicinity of 26N-65W as of 1800Z this evening. Through 96 hours the upper vortex is forecast to retrograde west-southwest around the SW/NE tilted eastern North America upper ridge while at the same time the surface trough moves west-northwest toward the northwestern Bahamas and southeastern US coastline while pushed by the NW/SE tilted surface ridge currently offshore of the northeastern US... followed by the next NW/SE tilted surface ridge that quickly fills in behind the current western US frontal system. The models and NHC outlook tropical cyclone formation probabilities have backed down since my previous update... as the models show the surface trough aligning with the northeast side of the upper vortex where supportive upper divergence is forecast to be lackluster... and I carry 0% odds of tropical cyclone formation through 48 hours. Between 48 and 72 hours the surface trough may escape the opressive part of the upper vortex as the forecast track between the surface trough and upper vortex have different tilt angles as noted above... thus I pull odds of development above 0%. However I selected low 10% odds of development as oppressive upper winds already come back in by 96 hours when another part of the western Atlantic upper trough breaks off into a small upper vortex that moves in over this system.


Between 96 and 120 hours the next upper trough and surface frontal system in the mid-latitude westerlies pushes in from western North America... the flow ahead of this system has potential to bend the track of this disturbance northward which is what I show in the outlook below. Meanwhile the small and suppressive overhead upper vortex at 96 hours continues retrograding westward and away... therefore I pull odds of tropical cyclone formation back up to 10% by 120 hours as this system potentially finds breathing room in the upper-level wind field.


Given the above-discussed and dynamic and uncertain upper wind forecast... there is an equal probability that this system brings heavy rainfall to the northwestern Bahamas and parts of the coastal southeastern United States by Friday and this weekend... and also an equal probability that the impacts from this system to land areas could end up being negligble. Interests in this region can check back for the latest forecast on this area of interest in future updates.

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

IOH 24 Hr Outlook (1800Z Jun 18)... 0% chance of tropical cyclone formation (western Atlantic near 26N-68W)

IOH 48 Hr Outlook (1800Z Jun 19)... 0% chance of tropical cyclone formation (western Atlantic near 27N-71.5W)

IOH 72 Hr Outlook (1800Z Jun 20)... 10% chance of tropical cyclone formation (east-northeast of the northwestern Bahamas near 27.5N-76W)

IOH 96 Hr Outlook (1800Z Jun 21)... 0% chance of tropical cyclone formation (offshore of northeastern Florida near 28.5N-78.5W)

IOH 120 Hr Outlook (1800Z Jun 22)... 10% chance of tropical cyclone formation (just offshore of coastal Georgia near 31.2N-81.5W)

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

Formation chance through 48 hours... 10%

Formation chance through 7 days... 20%


AREA OF INTEREST #7... The NHC TAFB surface analysis through 1200Z earlier today has shown an area of low surface pressures extending east from area of interest (AOI) #5... as far east as the central Caribbean. This is aligned with a maximal area of supporting outflow associated with the core of the regional tropical upper ridge. Models have been hinting that this field of low surface pressures could become enhanced into another tropical disturbance that generally chases AOI #5 courtesy of divergence zones around the periphery of a large western Atlantic upper vortex that moves in from the northeast (see area of interest #6 section above for more information on this vortex). As such I was in the process of declaring a new area of interest... and the NHC has also added this area of interest into their tropical weather outlook as of 8 PM EDT tonight. This will mark the seventh tropical Atlantic area of interest tracked on this site this year.


My forecast track for this area of interest is generally west-northwest from the central Caribbean and into the Yucatan peninsula through day 5 while steered by the same surface ridges that steer area of interest #6. Note that after day 5 this system may bend more north in track while moving into the Gulf of Mexico from the Yucatan thanks to a surface frontal system and upper trough pushing in from western North America (not to be confused with the current western US frontal low... instead the next frontal system behind that one). Through 48 hours my forecast position aligns with boosting split flow upper divergence between the southwest side of the incoming upper vortex and southeast side of the eastern North America upper ridge... however northerly shear is likely to be excessive for tropical cyclone formation and I have 0% odds during that window. By 72+ hours the upper vortex accelerates westward and away while weakening from its prolonged isolation from high-latitude cold air... this results in this area of interest being enhanced by the southeastern divergence zone of the departing upper vortex at 72 hours but with excess southerly wind shear such that I still show 0% chance of tropical cyclone formation. The shear relaxes and anticyclonic outflow over this disturbance expands once the decaying upper vortex finishes moving away... and by 96 hours is when I show odds of development above 0% during the next five days. My development odds are at a low 10% as this system would have a narrow window to develop as the upper winds become favorable only right before landfall with Belize or the Yucatan peninsula of Mexico. Beyond day 5... a second small upper vortex surges toward the Gulf of Mexico (see area of interest #6 section above for more info on this second vortex). There is some uncertainty as to how favorable the upper winds would be for this system to develop in the Gulf after day 5 as the southwest side of the vortex could induce some unfavorable westerly wind shear.


Regardless of tropical cyclone formation or not... the main takeaway for this area of interest is that it could prolong heavy rainfall with flash flooding potential across western Central America and southeastern Mexico for several more days.

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

IOH 24 Hr Outlook (1800Z Jun 18)... 0% chance of tropical cyclone formation (south-central Caribbean Sea near 12.5N-80W)

IOH 48 Hr Outlook (1800Z Jun 19)... 0% chance of tropical cyclone formation (Caribbean Central America coast at Nicaragua/Honduras border near 15N-83.5W)

IOH 72 Hr Outlook (1800Z Jun 20)... 0% chance of tropical cyclone formation (western Caribbean and offshore of northeastern Honduras near 16.5N-85W)

IOH 96 Hr Outlook (1800Z Jun 21)... 10% chance of tropical cyclone formation (western Caribbean and offshore of southern Quintana Roo near 18N-86.8W)

IOH 120 Hr Outlook (1800Z Jun 22)... 0% chance of tropical cyclone formation (southern Yucatan peninsula near 19N-89W)

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

Formation chance through 48 hours... 0%

Formation chance through 7 days... 20%


...COMPUTER MODEL SUMMARY...

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


1200Z (Jun 17) CMC Model Run...

**For area of interest #5... center of broad tropical low makes landfall near Tamaulipas/Veracruz border by 72 hours without tropical cyclone formation... rapidly dissipates inland shortly thereafter

**For area of interest #6... no development shown

**For area of interest #7... Broad low pressure field persists across Bay of Campeche... western Caribbean... and adjacent regions in wake of area of interest #5 (72 to 108 hours)... Bay of Campeche portion of circulation becomes the dominant by 120 hours with tropical cyclone formation suggested offshore of northern Veracruz through 168 hours


0000Z (Jun 17) ECMWF Model Run...

**For area of interest #5... center of broad tropical low makes landfall near Tamaulipas/Veracruz border by 84 hours without tropical cyclone formation... rapidly dissipates inland shortly thereafter.

**For area of interest #6... no development shown

**For area of interest #7... Broad low pressure field persists across Bay of Campeche... western Caribbean... and adjacent regions in wake of area of interest #5 (84 to 138 hours)... eastern Bay of Campeche portion of circulation becomes the dominant by 150 hours which begins to drift north into the western Gulf of Mexico through 168 hours


1200Z (Jun 17) GFS Model Run...

**Fore area of interest #5... broad tropical low moves across western Gulf of Mexico and develops a compact center on its north side and just offshore of southern Texas by 27 hours... the compact center (possibly a tropical cyclone) orbits west-southwest around remainder of broad circulation which causes it to make landfall just south of the Texas/Mexico border by 45 hours (the compact circulation dissipates shortly thereafter)... the remainder of the broad circulation then makes landfall across northern Veracruz at 81 hours and dissipates shortly thereafter.

**For area of interest #6... develops into a possible compact tropical depression near 26.5N-64W at 36 hours... weakens to a remnant low through 63 hours while reaching 28.5N-69W while slipping underneath northeast side of parent upper vortex where upper divergence is lacking... while continuing west-northwest the surface low escapes the north side of the upper vortex and thus persists through 117 hours while reaching the waters just offshore of the Carolinas... surface low subsequenlty curves north into far eastern North Carolina through 144 hours where it loses its identity ahead of approaching frontal system to the west.

**For area of interest #7... By 84 hours the upper vortex that produces the surface circulation associated with AOI #6 has retrograded southwestward into Yucatan peninsula... split flow upper divergence between the west side of the upper vortex and south side of the eastern North America upper ridge keeps Bay of Campeche surface pressures low in the immediate wake of AOI #5 while at the same time divergence on the east side of the vortex produces a tropical low offshore of northern Nicaragua... through 108 hours the Bay of Campeche surface circulation shifts east into Guatemala and Belize while taking advantage of expanding outflow in the wake of the rapidly retrograding upper vortex with the Guatemala/Belize surface circulation pulling the smaller circulation offshore of northern Nicaragua northwestward toward the northeastern Yucatan peninsula... through 123 hours both circulations merge while moving into the eastern Bay of Campeche... tropical cyclone formation suggested in the western Bay of Campeche near 20N-94W at 141 hours... due to surface ridge weakness associated with frontal system moving across eastern North America the tropical cyclone drifts northwest to 23N-95W through 168 hours


1200Z (Jun 17) NAVGEM Model Run...

**For area of interest #5... broad tropical low moves across western Gulf of Mexico and then makes landfall across the Veracruz/Tamaulipas coastline as an elongated surface trough through 66 hours... dissipates inland shortly thereafter

**For area of interest #6... no development shown

**For area of interest #7... Broad low pressure field persists across Bay of Campeche... western Caribbean... and adjacent regions in wake of area of interest #5 (66 to 78 hours)... western Caribbean portion of circulation becomes the dominant while making landfall across Belize... Guatemala... and the southern Yucatan peninsula through 102 hours... the circulation proceeds into the southwestern edge of the Gulf of Mexico where it becomes a tropical cyclone near 21.5N-93.8W at 126 hours... tropical cyclone proceeds to drift northwest to 25N-94.5W through 168 hours

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