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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 #16

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


...WEDNESDAY JUNE 12 2024 2:07 PM EDT...

The 2024 Atlantic Hurricane Season is picking up the pace while now having two areas of interest being monitored for possible tropical cyclone formation as follows:


A surface trough of low pressure spans from the Yucatan peninsula to the Florida peninsula. The northeastern part of the trough has potential to develop once it moves into waters offshore of the southeastern United States... see area of interest #4 section below for more information. The southwestern portion of the trough is forecast to merge with the Caribbean tropical waves currently departing northwestern South America... resulting in an elongated tropical low pressure area from the Bay of Campeche to Central America that could eventually develop over the next several days... see area of interest #5 section below for more information.


AREA OF INTEREST #4... For the eastern Gulf of Mexico surface low pressure system... satellite animation over the last several hours has shown the maximum spin continued northeast and has made landfall across the northern part of the Florida peninsula. There is little activity associated with the maximum spin... instead the thunderstorm activity has become further removed and is now south of the spin while in a west-southwest to east-northeast tilted axis aligned with a linear area of upper divergence between northwesterlies arcing around the northeast side of the regional tropical upper ridge and westerlies streaming toward the upper trough heading into the northwest Atlantic.


Further development of this system will require a relaxation of the westerly wind shear... and this is still forecast to happen to a certain degree while upper divergence increases as the nearby string of upper vorticity over the southeastern US gains amplitude while merging with a high-latitude upper trough currently materializing over central Canada... and also due to upstream amplification of western US warm upper ridging (the upstream upper ridge becomes bolstered by a surface frontal system that materializes over western North America under the support of the gradually merging northeast Pacific and north Canada upper vortices). However because this system has become less organized while the maximum spin is now more decoupled from the thunderstorms... and because the forecast westerly shear never fully ceases... I have lowered my peak odds of tropical cyclone formation to 20%. Even though the maximum spin is currenlty west of my previous forecast... my updated track is faster to the northeast as the models are trending with the current spin maxima dissipating while a new one materializes in the strengthening thunderstorms currently observed offshore of northeastern Florida... also the models are trending with a further northeast position in regards to the area of maximal upper divergence. The northeast track will be induced by the the southwesterly flow ahead of a surface cold front to be induced by the aforemenitoned high-latitude upper trough currently materializing over central Canada. The thermodynamic picture becomes less favorable for tropical cyclone formation at 72+ hours when this system moves northeast into waters below 26 deg C... and while this system merges with the incoming cold front and ingests cooler drier air behind the front. This is when I end the outlook by lowering odds of tropical cyclone formation to 0%.


Given the northeast-adjusted track forecast and models trending with a slower formation of a cut-off upper vortex on the south side of the upper trough tied to the cold front... it has become unlikely that the remnants of this system become entangled with the upper vortex and makes a comeback as a subtropical system (between Bermuda and the Caribbean) in the long range.


Regardless of tropical cyclone formation or not... the primary hazard is the ongoing heavy rainfall and potential flash flooding across the southern Florida peninsula and northwestern Bahamas. The rainfall in this region should relax over the next day or so as this system continues its northeast track.

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

IOH 24 Hr Outlook (1200Z Jun 13)... 0% chance of tropical cyclone formation (offshore of northeastern Florida near 30N-77.5W)

IOH 48 Hr Outlook (1200Z Jun 14)... 20% chance of tropical cyclone formation (offshore of the southeastern United States near 32.5N-72.5W)

IOH 72 Hr Outlook (1200Z Jun 15)... 0% chance of tropical cyclone formation (north-northwest of Bermuda near 35N-66W)

*****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 #5... Models have come into agreement that the pair of Caribbean surface tropical waves currently departing northwestern South America will merge with the surface trough that has been parked near the Yucatan peninsula of Mexico... resulting in a northwest-to-southeast tilted tropical low pressure system spanning the Bay of Campeche and Central America. In their 7-day tropical weather outlook... the National Hurricane Center has added this forecast system as an area of interest for possible future tropical development... this will now mark the fifth tropical Atlantic area of interest tracked on this site this year.


Per the area of interest #4 section above... upper ridging is expected to amplify over the western US in the days ahead which will push a portion of the current southeastern US upper vorticity into the western Gulf of Mexico. In turn this will displace the regional tropical upper ridge cell and its maximum region of supporting upper outflow southeastward toward Central America in the short-term... therefore my 5-day outlook below assumes the elongated tropical low pressure system has its best shot at developing a better-defined center in the Caribbean waters toward Central America. Whatever center does develop will tend to take a west-northwest track while at first pushed by the southwest edge of the current Atlantic surface ridge... followed by the southwest edge of a surface ridge forecast to build in the convergence zone along the back side of the upper trough that absorbs area of interest #4. I keep my peak odds of tropical cyclone formation at 10% as this broad system will need time to develop a better-defined center... and wait till 72 hours to assign those odds. Odds are dropped back to 0% once I forecast the possible better-defined center to make landfall across Belize and the southern Yucatan peninsula. Noting in the long range (toward day 7)... the possible better-defined center moves into the Bay of Campeche waters. However by then... upper winds would remain favorable for development as the disrputive western Gulf upper vorticity will be lifted northward and away by an upper trough that moves into the central US (the upper vorticity currently offshore of Califonria and Baja California eventually makes its way into the central US as a trough once the current northeast Pacific upper vortex and north Canada polar upper vortex finally merge... which increases the steering westerly flow across the western and central US).


Regardless of whether or not this area of interest develops into a tropical cyclone... periods of heavy rainfall with flash flooding potential cannot be ruled out across Central America and southeastern Mexico in the days ahead.

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

IOH 24 Hr Outlook (1200Z Jun 13)... 0% chance of tropical cyclone formation (east of Nicaragua near 13N-81.2W)

IOH 48 Hr Outlook (1200Z Jun 14)... 0% chance of tropical cyclone formation (northeastern Nicaragua near 14N-84W)

IOH 72 Hr Outlook (1200Z Jun 15)... 10% chance of tropical cyclone formation (just inland of the Honduras norht coast near 15.5N-86.2W)

IOH 96 Hr Outlook (1200Z Jun 16)... 10% chance of tropical cyclone formation (coastal Belize near 16.5N-88.5W)

IOH 120 Hr Outlook (1200Z Jun 17)... 0% chance of tropical cyclone formation (southwestern Yucatan peninsula near 18.8N-90.5W)

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

Formation chance through 48 hours... 0%

Formation chance through 7 days... 30%


...COMPUTER MODEL SUMMARY...

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


0000Z (Jun 12) CMC Model Run...

**For area of interest #4... tropical cyclone formation suggested near 30.5N-76W at 36 hours... at 72 hours weakens to a remnant low located near 33.5N-71W accelerating northeastward ahead of incoming surface cold front to the west... merges with front and transitions into a remnant non-tropical frontal low while located near 41N-61W at 96 hours... strengthens into remnant non-tropical frontal cyclone whose center passes just southeast of Newfoundland at 120 hours

**For area of interest #5... surface trough currently over the Yucatan peninsula merges with pair of tropical waves currently over northwestern South America through 120 hours which results in NW/SE tilted surface trough from the Bay of Campeche to the north coast of Honduras... SE part of the surface trough becomes a tropical low that makes landfall over northern Belize at 132 hours... tropical low crosses the southern Yucatan peninsula and enters the eastern Bay of Campeche through 168 hours (tropical cyclone formation suggested shortly thereafter)


0000Z (Jun 12) ECMWF Model Run...

**For area of interest #4... surface low continues northeast parallel to the southeastern United States coast and becomes a tropical cyclone near 33N-72W at 60 hours... subsequently merges with cold front incoming from the west and transitions into a non-tropical frontal cyclone that makes landfall over south-central Newfoundland just after 102 hours... frontal cyclone located midway between Newfoundland and Greenland at 120 hours

**For area of interest #5... surface trough currently over the Yucatan peninsula merges with pair of tropical waves currently over northwestern South America through 96 hours which results in NW/SE tilted surface trough from the Bay of Campeche to the south-central Caribbean... tropical low develops along surface trough in western Bay of Campeche near 19.8N-95W at 132 hours... while drifting slowly northwest the tropical low becomes a tropical cyclone that reaches 22.5N-96W by 168 hours


0600Z (Jun 12) GFS Model Run...

**For area of interest #4... becomes a compact and short-lived tropical depression near 31.5N-75W at 48 hours... the remnant low subsequently accelerates east-northeast and merges with front at 84 hours while located north-northwest of Bermuda... remnant frontal low continues east-northeast across open central Atlantic and reaches 36.5N-47.5W at 144 hours... remnant frontal low subsequenlty retrogrades west under influence of deep-layer ridging to the northwest and weakens under the upper convergence on the southeast side of the ridge while reaching 37.5N-50W at 168 hours

**For area of interest #5... surface trough currently over the Yucatan peninsula merges with pair of tropical waves currently over northwestern South America through 66 hours which results in NW/SE tilted surface low pressure envelope from the Bay of Campeche to the south-central Caribbean... through 78 hours the envelope develops three centers (eastern Pacific tropical cyclone south-southwest of Gulf of Tehuantepec... eastern Pacific tropical cyclone just offshore of El Salvador... and south-central Caribbean tropical low)... through 120 hours the pair of eastern Pacific tropical cyclones orbit each other while making landfall across western Central America and eventually merge into an inland tropical low over southeastern Mexico while the south-central Caribbean tropical low is pulled by the eastern Pacific circulations northwestward to the waters offshore of the Nicaragua/Honduras border... the tropical low over southeastern Mexico subsequently moves northwest across the western Bay of Campeche while gradually absorbing the Caribbean circulation and becomes a tropical cyclone just offshore of northern Veracruz by 162 hours

**Tropical wave currently at 35W longitude crosses the Atlantic tropical belt and southern Caribbean waters... develops into a south-central Caribbean tropical low near 11N-79W under supportive divergence on the southeast side of regional upper vorticity (upper vorticity is southern cut-off of frontal upper trough that absorbs AOI #4)


0600Z (Jun 12) NAVGEM Model Run...

**For area of interest #4... surface low stays weak while moving northeast parallel to the southeastern United States coast and reaches 31.5N-74.5W at 72 hours... becomes absorbed by incoming cold front to the west shortly thereafter where it loses its identity.

**For area of interest #5... surface trough currently over the Yucatan peninsula merges with pair of tropical waves currently over northwestern South America through 90 hours which results in NW/SE tilted surface trough from the Bay of Campeche to the coast of Nicaragua... western part of the surface trough gradually develops into a broad tropical low over the Bay of Campeche through 168 hours

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