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 2022 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #128

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


...THURSDAY OCTOBER 13 2022 4:55 PM EDT...

Note... this update is released 36 hours instead of the usual 24 hours after the previous update due to internet outages at my residence.


Tropical Storm Karl has undergone an eastward shift in its forecast track while meandering in the Bay of Campeche... see Karl section below for more information regarding the corresponding shift in impacts to parts of southeastern Mexico. Elsewhere... continuing to monitor a surface trough of low pressure in the open central Atlantic for signs of future development... see area of interest #38 section below for more information. See area of interest #40 section below for information regarding a tropical wave of low pressure in the eastern tropical Atlantic which is also being monitored for signs of development.


New to this site this year... I will be sequentially numbering up areas of interest for possible Atlantic tropical development. In this scheme... will reset back to #1 at the start of next year (January 2023). The current areas of interest in this blog post are designated #38 and #40 as the other numbers were used in previous birdseye view posts. This scheme is to reduce confusion as Atlantic tropical activity increases during the peak of the hurricane season... when multiple simultaneous areas of interest begin and end which previously required shuffling around the area of interest numbers from update to update.


TROPICAL STORM KARL... Satellite image when Karl acquired a peak strength of 60 mph maximum sustained winds on Wednesday afternoon... image taken at 2006Z October 12:

Tropical Storm Karl located in the Bay of Campeche has been a challenging storm to forecast. On Wednesday the tropical storm drifted more northward and less westward than prior forecasts... perhaps as the circulation center reformed toward its sheared-off thunderstorm activity weighted toward the east side of the circulation and/or was strong/tall enough to be dragged by the upper westerly shearing winds. The tropical storm subsequently appeared to shrink in size... perhaps just enough to dodge the worst of the shearing winds lurking toward the north... as a result allowing it to surprisingly pull its now smaller area of thunderstorms closer to the center strengthen to 60 mph maximum sustained winds. As of today (Thursday)... so far the tropical storm has begun a south-southeastward drift toward the eastern Bay of Campeche as the upper westerly flow over Karl has turned more northwesterly... and Karl remains strong/tall enough to remain coupled to the upper flow. The change in the upper flow's direction is a result of the upper vortex associated with the current North American frontal cyclone digging southward into the northeastern Gulf of Mexico. As the upper vortex slowly retreats northeastward in the short-term... a cell of tropical upper ridging from Mexico will be allowed to expand eastward toward Karl. As a sufficiently strong/tall tropical storm... Karl over the next 48 hours is now expected to arc southward in a clockwise fashion toward the Tabasco/Veracruz border region on the east side of the expanding upper ridge cell. An initial southward kick will also be provided in the surface flow by the frontal cyclone's cold front to dive into the northern Gulf of Mexico as Karl's earlier eastward deviation in track now puts it close enough to the front to ineract with it. While models currently agree on dissiapting Karl after landfall at the aforementioned border region... I currently project the land interaction will weaken Karl just enough to allow it to become shallower and de-couple from the upper flow... with the surface flow taking over and moving Karl increasingly northwestward and close to the Veracruz Bay of Campeche coast from 48 to 96 hours (also note that the anticyclonic core of the upper ridge cell approaching from the west will have overspread Karl... neutralizing its ability to steer Karl even if it were still strong/tall). The surface flow in that time will be controlled by the southwest quadrant of the surface ridge to build behind the cold front and a frontal low to approach from the southwestern US and northern Mexico (frontal low supported by a small upper vortex that slides into the southwestern US from the Pacific). Should Karl indeed stick around the Veracruz coast from 48 to 96 hour timeframe... it should be brought to an end by 120 hours as a southward-diving surface ridge... to be supported by the western convergence zone of an amplified upper trough to move across western Canada which will be diving south while merging with the west side of the current North American upper vortex... shoves Karl on a more westward track and further inland. Note that although Karl by 96+ hours will have tracked into upper westerlies on the north side of the regional upper ridge cell... the land interaction and dose of upper westerly shear should keep Karl weak/shallow such that Karl should have no change to be dragged into the Gulf of Mexico at 120 hours by the upper westerlies.


Regarding intensity... Karl has weakened from Wednesday's 60 mph maximum sustained wind peak as the current upper northwesterly flow has sheared off the thunderstorm activity to the south of Karl's center. However the shear is not aggressive with Karl continuing to fire strong thunderstorms near the circulation center... thus it hasn't weakend below 50 mph maximum sustained winds. Per the above track forecast discussion... the core of an upper ridge cell should appraoch from the west (from mainland Mexico) which should reduce the shear with time... especially just before landfall time at the Veracruz/Tabasco border region... therefore I forecast Karl to regain 60 mph maximum sustained winds just before its current forecast landfall which takes my intensity forecast a notch above the NHC official forecast as of this writing. In the 48 to 96 hour window I hang on to Karl as a tropical depression as my current forecast track keeps it inland but close to the Veracruz coastline... with dissipation by 120 hours once the forecast track bends westward and further inland.


Regarding impacts to land areas:

(1) Heavy rainfall and flash flood risk... the eastward shift in Karl's forecast track brings back the flash flooding risk for western Yucatan... Campeche... Chiapas... Oaxaca... Tabasco... and southeastern Veracruz through Sunday. At further east locations the flash flooding risk may end by Saturday morning as Karl bends more west in track. By early next week... should Karl in fact linger as a northwestward-tracking tropical cyclone along the Veracruz coast... the flooding risk would shift toward northern Veracruz... Tlaxacala... Hildalgo... eastern San Luis... and southern Tamaulipas by early next week. The potential for rainfall for northern Tamaulipas and southern Texas has ended with the latest forecast track shift. Note that in mountainous terrain that heavy rainfall could also result in mudslides.

(2) Gusty tropical storm force winds with damage potential and coastal surf... the east shift in Karl's track has shifted tropical storm advisories away from northern Veracruz and into southeastern Veracruz and Tabasco. Interests in southeastern Veracruz and Tabasco should now be preparing for possible tropical storm force winds to arrive by late Friday and early Saturday. Interests that prepared earlier in northern Veracruz should remain prepared and vigilant in case the long-range forecast track shifts back west in the 48 to 96 hour period per the above track forecast discussion. Coastal surf will be an additional hazard for southeastern Veracruz and Tabasco. If Karl gains sufficient strength... some coastal swells may propagate as far east as the Campeche province coast and as far west as the northern Veracruz coast.


Update as of 2 PM EDT... Karl's intensity has decreased slightly to 45 mph maximum sustained winds.

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

0 Hr Position (1200Z Oct 13)... 50 mph maximum sustained wind tropical storm centered in the Bay of Campeche at 21.7N-93.9W

IOH 24 Hr Forecast (1200Z Oct 14)... 50 mph maximum sustained wind tropical storm centered in the eastern Bay of Campeche at 19.8N-93.5W

IOH 48 Hr Forecast (1200Z Oct 15)... 60 mph maximum sustained wind tropical storm centered just offshore of the Veracruz/Tabasco border at 18.9N-94.5W

IOH 72 Hr Forecast (1200Z Oct 16)... 35 mph maximum sustained wind tropical depression centered over southeastern Veracruz and just inland from the Bay of Campeche coast at 18.5N-95.5W

IOH 96 Hr Forecast (1200Z Oct 17)... 35 mph maximum sustained wind tropical depression centered over northern Veracruz and just inland from the Bay of Campeche coast at 20N-97.5W

IOH 120 Hr Forecast (1200Z Oct 18)... Inland remnant low over east-central Mexico centered at 21.2N-99.2W


AREA OF INTEREST #38... The broad surface trough of low pressure in the open central Atlantic... currently located in the vicinity of 30N-54W... persists with the support of the eastern divergence zone of the upper trough in the region. The warm sector of the frontal cyclone currently over North America is expected to build an amplifying western Atlantic upper ridge... which in turn will cause the upper trough to amplify which will reduce shear and increase the supporting upper divergence over the surface trough. Therefore will be watching for the surface trough to potentially evolve into an organizing subtropical or tropical disturbance to be supported by the amplifying upper trough. The forecast track in the outlook below through 36 hours shows an eastward shift of the surface trough corresponding to an eastward shift of the supporting upper trough. By 36+ hours the amplifying western Atlantic upper ridge is forecast to further amplify the upper trough into a cut-off vortex that moves southeastward and away... while at the same time surface ridging will persist to the north of this system. As a result the forecast track in the outlook below shows a northward hook around the east side of the cut-off upper vortex between 36 and 60 hours... and then a northwest then north acceleration around the southwest and west sides of the surface ridging at 60+ hours after the upper vortex moves out of the region. Conditions for development will remain favorable through 72 hours as the northwest track moves this system under the low shear and upper outflow environment of the amplifying west Atlantic upper ridge. My peak odds of tropical cyclone formation for this area of interest remains at a low 10% as models do not show this system developing as of this writing. I have lowered short-term odds of development to 0% as this system does not currenlty have a well-defined surface spin and will need some time to develop one. Odds are brought back down to 0% at 96 hours as this system moves north into water temps below 26 deg C.

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

IOH 24 Hr Outlook (1200Z Oct 14)...0% chance of tropical cyclone formation (central Atlantic near 30.5N-53W)

IOH 48 Hr Outlook (1200Z Oct 15)...10% chance of tropical cyclone formation (central Atlantic near 32.5N-52.5W)

IOH 72 Hr Outlook (1200Z Oct 16)...10% chance of tropical cyclone formation (central Atlantic near 34N-54W)

IOH 96 Hr Outlook (1200Z Oct 17)...0% chance of tropical cyclone formation (central Atlantic near 37.5N-54.5W)


AREA OF INTEREST #40... A tropical wave of low pressure that recently exited the west coast of Africa is currently in the vicinity of 7.5N-22.5W. The wave has been able to maintain thunderstorm activity with the support of outflow beneath a tropical upper ridge in the region. This upper ridge is forecast to continue expanding as the string of cool core upper vorticity to the north recedes while weakening from its ongoing lack of access to high-latitude cold air... which will allow the tropical wave to be sheltered from shear over the next 72 hours. Various model runs continue to suggest development of this wave... and now the wave is added as an area of interest in the NHC tropical weather outlook. This marks the fortieth Atlantic tropical area of interest I have tracked on this blog this year.


The Atlantic surface ridge is forecast to remain weak due to the presence of area of interest (AOI) #38 in the shorter-term... followed by the development of another low pressure system east of Bermuda as a fragment of the current North American upper vortex moves offshore as an upper trough and supports the new low pressure area with its eastern divergence zone. As a result a sluggish west-northwest track is forecast for this tropical wave of low pressure (as opposed to a faster more westward motion which would occur if the Atlantic surface ridge stays intact). From 72 to 96 hours I cap development odds at 20% as the wave moves toward shearing upper westerly winds to be induced by the cut-off upper trough associated with AOI #38. Once this cut-off cool core upper trough begins to weaken while remaining cut-off from high-latitude cold air... the shear has potential to relax between 96 and 120 hours and therefore I raise development odds further to 30% during this timeframe. Note these are slightly higher development odds than the NHC showed in their outlook as of this writing... this is my current forecast preference due to the potential drop in shear at the end of the 5-day forecast period.

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

IOH 24 Hr Outlook (1200Z Oct 14)... 0% chance of tropical cyclone formation (eastern tropical Atlantic near 8N-27W)

IOH 48 Hr Outlook (1200Z Oct 15)... 10% chance of tropical cyclone formation (eastern tropical Atlantic near 9N-31W)

IOH 72 Hr Outlook (1200Z Oct 16)... 20% chance of tropical cyclone formation (eastern tropical Atlantic near 10N-34W)

IOH 96 Hr Outlook (1200Z Oct 17)... 20% chance of tropical cyclone formation (eastern tropical Atlantic near 11N-37W)

IOH 120 Hr Outlook (1200Z Oct 18)... 30% chance of tropical cyclone formation (eastern tropical Atlantic near 12N-40W)


...COMPUTER MODEL SUMMARY...

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


0000Z (Oct 13) CMC Model Run...

**For Tropical Storm Karl... turns south and makes landfall near the Veracruz/Tabasco border at 54 hours... dissipates shortly thereafter

**For area of interest #38... no development shown

**For area of interest #40... organizes into a tropical low near 8.5N-30.5W at 54 hours... becomes a tropical cyclone near 14.5N-36W at 120 hours... weakens to a remnant low near 17N-41.2W at 156 hours.


0000Z (Oct 13) ECMWF Model Run...

**For Tropical Storm Karl... turns south-southeast and then south and makes landfall over western Tabasco just after 48 hours... dissipates shortly after the landfall.

**For area of interest #38... no development shown

**For area of interest #40... no development shown


0600Z (Oct 13) GFS Model Run...

**For Tropical Storm Karl... turns south-southeast and then southwest while weakening and makes landfall over southeastern Veracruz at 60 hours... dissipates shortly after the landfall.

**For area of interest #38... no development shown

**For area of interest #40... organizes into a tropical low near 6.5N-24W at 24 hours... tropical low located near 13.5N-36.2W at 126 hours.


0600Z (Oct 13) NAVGEM Model Run...

**For Tropical Storm Karl... turns south-southeast and then southwest and makes landfall at the Veracruz/Tabasco border at 60 hours... dissipates shortly after the landfall.

**For area of interest #38... no development shown

**For area of interest #40... organizes into a tropical low near 8N-28.5W at 36 hours... tropical cyclone formation suggested near 11.5N-36W at 96 hours... tropical cyclone located at 14N-38.5W at 120 hours.

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