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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 #18

Updated: Jun 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.*********


...FRIDAY JUNE 14 2024 4:05 PM EDT...

For the Atlantic basin... continuing to monitor two areas of interest for possible tropical cyclone formation as follows:


See area of interest #4 section below for an update on the tropical low pressure currently offshore of the southeastern United States. See area of interest #5 section below for more information on possible tropical cyclone formation in the days ahead from what is currently the broad surface low pressure area centered over the southern Yucatan peninsula.


AREA OF INTEREST #4... Satellite imagery of the tropical low pressure system offshore of the southeastern United States as of 1141Z... when it reached its pinnacle organization for today:

In response to the elongated divergence zone of the upper vorticity currently over the southeastern United States... the tropical low parked in the offshore western Atlantic waters proceeded to become elongated over much of the last 24 hours. However at around 1200Z this morning this system appeared to be developing a better-defined surface center south-southeast of Cape Hatteras North Carolina which was parked next to an area of showers and thunderstorms flaring up just to the east. Since then tropical cyclone formation has failed to occur as the southwesterly vertical shear in the region was enough to then pull the nearby activity further away from this center... and the activity has also weakened and become less organized in recent hours. The regional upper divergence is forecast to become further elongated in the next 24 hours as much of the current southeastern US upper vorticity merges with the approaching high-latitude upper trough from eastern Canada... which will likely keep this system elongated instead of focused and circular which would be a hinderance to tropical development. In addition the forecast track has shifted northward due to the current position of the aforementioned best-defined center relative to the previous forecast... which by 24 hours now brings this system north of the narrow band of warm 26+ deg C Gulf stream waters. The thermodynamic picture by 24 hours is also unfavorable for tropical development as this system merges with the surface cold front associated with the high-latitude upper trough... hence ingesting cooler drier air behind the front. Therefore tropical cyclone formation is not expected going forward... and I plan this to be my final update on this area of interest unless it continues to be mentioned in the NHC tropical weather outlook by my next update.


Noting that once this system merges with the cold front... the remnants are expected to transition into a strengthening non-tropical frontal low supported by the divergence zone of the high-latitude upper trough... or alternatively the remnants of this system will lose its identity to a strengthening non-tropical low that quickly forms in the region. This non-tropical system could bring coastal surf across the northeastern US and Atlantic Canada coastlines over the next couple of days... with gusty winds likely across Newfoundland by Sunday.

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

IOH 24 Hr Outlook (1800Z Jun 15)... 0% chance of tropical cyclone formation (offshore of the northeastern United States near 39N-70W)

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

Formation chance through 48 hours... 10%

Formation chance through 7 days... 10%


AREA OF INTEREST #5... A broad surface low pressure area persists over the southern Yucatan peninsula which has featured multiple swirls reaching as far west as the eastern Bay of Campeche over the last 24 hours. To the southeast... a southern Caribbean tropical wave of low pressure has lost its identity to the southern Yucatan system while it made landfall on the Nicaragua east coast and without much fanfare... therefore I am now centering the initial position of this area of interest with the southern Yucatan feature which has caused an overall westward shift to my updated forecast track in the outlook below.


A string of upper vorticity which has been shoved into the southeastern US and western Gulf of Mexico over the last couple of days... under the force of upstream warm core upper ridging associated with the warm sector of the currently developing western North America surface frontal system... has displaced the core of the regional tropical upper ridge cell southeastward into the western Caribbean Sea. Upper divergence between the northwest side of the tropical upper ridge and out ahead of the western Gulf upper vorticity has triggered a thunderstorm complex now overspreading the northwestern Caribbean and western Cuba which will soon overspread south Florida and the northwestern Bahamas. Watch out for possible flash flooding from heavy rainfall in this region over the next 24 hours... particularly over the saturated southern Florida grounds which has already seen rainfall flooding from area of interest #4 in previous days. Meanwhile westerly shear imparted by the western Gulf upper vorticity has kept the southern Yucatan surface low pressure area void of organized activity... and as the upper vorticity over the southeastern US merges with the high-latitude upper trough from eastern Canada westerly shear imparted by the south side of the merged upper trough should shut down any tropical development of any surface low pressure disturbance that materializes over southern Florida or the northwestern Bahamas. After 24 hours... upper convergence on the back southwestern side of the merged western Atlantic upper trough should also prevent tropical development toward south Florida and northwestern Bahamas.


Beyond 24 hours... the focus in the region should return to the surface low pressure over the southern Yucatan which could then take advantage of expanding upper outflow in the wake of the departing western Gulf upper vorticity (during that timeframe the western Gulf upper vorticity should shift northward and away while captured by the upper trough now approaching from Utah and Arizona). Hence through 72 hours I forecast the southern Yucatan surface low to mature into a better-defined center that can then be steered westward into the Bay of Campeche by the southwest quadrant of the surface ridge that builds under the convergence zone of the aforementioned western Atlantic upper trough. Noting through 120 hours my forecast track is angled south toward southern Veracruz instead of further north toward the ridge weakness associated with the western North America frontal system as the core of the regional tropical upper ridge will tend to lag behind to the east while slowly moving back toward the Gulf of Mexico in the wake of the departed western Gulf upper vorticity... with many of the models allowing the maximal outflow at the upper ridge core to drop surface pressures to the east of this area of interest through day 5. My forecast track assumption for now is that another steering surface low pressure gyre will materialize just east of this area of interest that would help keep the track of this area of interest dragged further south. It is even possible this adjacent gyre becomes yet another area of interest for the Bay of Campeche beyond day 5... stay tuned.


Regarding odds of tropical cyclone formation... models are in increased agreement on developing this system in the Bay of Campeche... and the NHC has raised their odds of tropical cyclone formation to 50% for the long range window (toward day 7). In this update I am only increasing my peak odds of tropical cyclone formation to 20%... waiting to see if this area of interest develops a better-defined center before considering higher odds.


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 western 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 (1800Z Jun 15)... 0% chance of tropical cyclone formation (southern Yucatan peninsula near 19N-89W)

IOH 48 Hr Outlook (1800Z Jun 16)... 0% chance of tropical cyclone formation (southwestern Yucatan peninsula near 19N-90W)

IOH 72 Hr Outlook (1800Z Jun 17)... 20% chance of tropical cyclone formation (eastern Bay of Campeche near 19.5N-92W)

IOH 96 Hr Outlook (1800Z Jun 18)... 20% chance of tropical cyclone formation (western Bay of Campeche near 19.8N-95W)

IOH 120 Hr Outlook (1800Z Jun 19)... 0% chance of tropical cyclone formation (southern Veracruz near 19.8N-97W)

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

Formation chance through 48 hours... 0%

Formation chance through 7 days... 50%


...COMPUTER MODEL SUMMARY...

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


0000Z (Jun 14) CMC Model Run...

**For area of interest #4... over next 12 hours the elongated surface low offshore of the southeastern US briefly develops a better-defined center offshore of southeastern North Carolina... subsequenlty merges with incoming cold front to the west through 36 hours while moving into the waters offshore of the northeastern US... moves across central Newfoundland through 60 hours while intensifying into an elongated non-tropical frontal cyclone... through 96 hours the remnant frontal cyclone accelerates north-northwest into the waters between Greenland and northern Canada and becomes absorbed by north Canadian frontal cyclone to the west soon after.

**For area of interest #5... through 60 hours the current surface low over the southern Yucatan peninsula has an WNW/ESE elongated signature while developing an ESE center just offshore of Belize and another in the central Bay of Campeche near 20N-94W... through 90 hours the ESE center becomes the dominant while moving across the northern Yucatan peninsula... the dominant center proceeds west-northwest across the northern Bay of Campeche and becomes a tropical cyclone just offshore of northern Veracruz through 138 hours... tropical cyclone makes landfall shortly thereafter and disspates rapidly at 144+ hours

**Broad low pressure field persists across Bay of Campeche and adjacent regions in wake of area of interest #5 (150 to 168 hours)


0000Z (Jun 14) ECMWF Model Run...

**For area of interest #4... elongated surface low offshore of the southeastern US merges with incoming cold front to the west through 36 hours while moving into the waters offshore of the northeastern US... moves across eastern Newfoundland through 60 hours while intensifying into an elongated non-tropical frontal cyclone... the remnant frontal low subsequently curves north-northwest into the waters between north Canada and Greenland where it gradually dissipates through 132 hours.

**For area of interest #5... through 60 hours the current surface low over the southern Yucatan peninsula has an WNW/ESE elongated signature while spanning as far WNW as the Bay of Campeche and as far ESE as the Caribbean waters offshore of Belize... the broad surface low subsequently moves northwest across the western Gulf of Mexico and consolidates into a tropical cyclone offshore of northeastern Mexico through 132 hours... tropical cyclone curves west and makes landfall on the coast of Tamaulipas at 156 hours where it dissipates inland shortly thereafter.


1200Z (Jun 14) GFS Model Run...

**For area of interest #4... becomes short-lived tropical depression east-southeast of Cape Hatters North Carolina at 9 hours... susbsequently merges with incoming cold front to the west and while crossing eastern Newfoundland through 39 hours completes its transition into an elongated non-tropical frontal low... proceeds to arc north-northwest into the waters offshore of southwestern Greenland where it gradually dissipates through 117 hours

**For area of interest #5... through 45 hours the current surface low over the southern Yucatan peninsula has an WNW/ESE elongated signature while developing an ESE center just offshore of Belize and another in the central Bay of Campeche near 18.8N-93.5W... the ESE center proceeds to become the dominant while sliding across Belize... northern Guatemala... the southwestern Yucatan peninsula... and into the central Bay of Campeche through 99 hours... becomes a tropical cyclone just offshore of southern Veracruz through 123 hours shortly after which time it makes landfall and dissipates inland.

**South part of the western Atlantic frontal upper trough that absorbs AOI #4 becomes a large cut-off vortex by 96 hours due to the force of the warm upper ridge over eastern North America tied to the warm sector of a developing large-scale western North America frontal system and also due to the force of the tropical upper ridge cell over AOI #5... divergence along northeast edge of upper vortex supports a circular surface low near 40N-55W around 96 hours (water temps below 26 deg C and upper air temps forecast to be warm and stabilizing with 200 mb heights above 1200 dekameters... therefore surface low likely doesn't become tropical)... under the force of ongoing eastern North America upper ridge the upper vortex splits into southwestern and northeastern vortices with the surface low whirling west into the core of the northeastern vortex where a lack of upper divergence causes its decay... the surface low as a result dissipates near 40N-60W by 132 hours.

**The southwestern of the pair of western Atlantic upper vortices noted above retrogrades southwest into western Cuba through 150 hours where the southeastern divergence zone of the vortex triggers a south-central Caribbean disturbance... the disturbance matures into a tropical low east of Nicaragua through 159 hours as the westward-retrograding upper vortex gives room for an expanding area of anticyclonic outflow over the disturbance... disturbance matures further into a small tropical cyclone centered offshore of the Nicaragua/Honduras border by 168 hours.


0000Z (Jun 14) NAVGEM Model Run...

**For area of interest #4... elongated surface low offshore of the southeastern US merges with incoming cold front to the west through 30 hours while moving into the waters offshore of the northeastern US... intensifies into a remnant non-tropical frontal cyclone while moving across eastern Newfoundland through 54 hours... through 114 hours arcs north-northwest into the waters between Greenland and north Canada and becomes absorbed by north Canadian frontal cyclone to the west around that time.

**For area of interest #5... Southern part of the current broad tropical low centered over the southern Yucatan peninsula becomes an eastern Pacific trpoical cyclone at 72 hours located just southwest of the Mexico/Guatemala border... tropical cyclone moves northeast and weakens to an inland remnant low over northern Guatemala through 102 hours while orbiting the remainder of the broad circulation... the remnant low loses its identity within the broad circulation shortly thereafter with the broad circulation later organizing into a possible tropical cyclone in the southwestern Gulf of Mexico and near 22.5N-94W at 132 hours.

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