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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 #62

Writer's picture: NCHurricane2009NCHurricane2009

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


...UPDATE...THURSDAY AUGUST 8 2024 2:30 PM EDT...

The following are recent updates regarding Tropical Storm Debby and areas of interest elsewhere in the Atlantic tropics:


(1) The birdseye view chart has been updated below to include the surface and upper air charts... the update was released very early this morning without those charts to allow the update to be released in a more timely manner.


(2) Tropical Storm Debby's center of circulation has continued north-northwest into the central North Carolina/South Carolina border region. In addition to tropical storm force wind gusts across northeastern South Carolina and southeastern North Carolina... storm force gusts this morning were also reported further north across the remainder of central and eastern North Carolina into communities such as Raleigh... Chapel Hill... Charlotte... Greensboro... Hatteras... Morehead City... and Elizabeth City (wind data from National Weather Service Stations... weather.gov). Due to directional wind shear favoring severe thunderstorms and tornadoes (between mid-latitude upper westerlies and surface southerly flow on Debby's east side)... tornado warnings were frequent across eastern North Carolina with tornado watches now shifted north across eastern Virginia as of this writing. Due to the landfall Debby has weakened to a minimal tropical storm with 40 mph maximum sustained winds as of this writing. For the rest of today and into the weekend... what is expected to be the remnant frontal low of Debby may re-gain some strength over land while boosted by the divergence zone of the upper trough that would be supporting it... therefore watching for a stretch of possible heavy rainfall... gusty winds... and coastal surf developing across the mid-Atlantic and northeastern United States (from Virginia all the way to Maine) as well as the southeastern Quebec/New Brunswick region of Canada.


(3) For the area of interest tagged as #16 in this blog... the Caribbean tropical wave of low pressure has now making landfall in Central America across northern Nicaragaua and eastern Honduras and has also become less organized. Therefore its potential to develop when it re-emerges over water offshore of Belize has ended. And if the computer models continue to consisently show suppressing upper vorticity rolling into the Gulf of Mexico and Bay of Campeche... where this area of interest will end up in the logner range... will likely be cancelling this area of interest altogether in my next full update on the Atlantic tropics.


(4) For the new area of interest tagged as #17 in this blog post... noting the National Hurricane Center in their tropical weather outlook also introduced it as an area of interest minutes after this post was initially published. Therefore this area of interest is now marked as a simultaneous NHC area of interest in the updated birdseye view chart below. As of 2 PM EDT the NHC has 0% and 40% odds of tropical cyclone formation for the 2-day (48-hour) and 7-day windows respectively... and the NHC has continuously been rising the 7-day odds of tropical cyclone formation since they introduced this area of interest with 20% odds at 2 AM EDT.


...THURSDAY AUGUST 8 2024 1:45 AM EDT...


See Tropical Storm Debby section below for more information on its forecast and expected impacts across the eastern United States from the Carolinas to Maine in the days ahead. For the tropical latitudes of the Atlantic basin… see areas of interest #16 and #17 on a pair of tropical waves of low pressure now being monitored for possible development in the days ahead.


TROPICAL STORM DEBBY... After moving northeast into the waters just offshore of South Carolina… Debby is beginning its north-northwest turn into the Carolinas tonight. The storm slowly re-strengthened to 45 mph maximum sustained winds through early Wednesday… then abruptly aircraft recon data showed the storm had re-gained 60 mph maximum sustained winds by 11 AM EDT. Although Debby has not re-developed a thunderstorm core… it has seen a gradual increase in thunderstorm pockets and bands throughout its circulation particularly during the afternoon and evening… and it is noteworthy that Debby’s strengthening in the morning was prior to the thunderstorm increase. Perhaps then Debby got a boost from non-tropical sources… specifically from the divergence zone of the local upper trough that has been located just west of the storm. No additional strengthening is anticipated as the storm is now making landfall into the Carolinas… and over the next 24 hours the track is north-northwest further inland under the combined influences of the local upper trough to the west... surface ridge to the north over the Great Lakes... and attraction toward the ridge weakness associated with a frontal low now developing west of the surface ridge which will soon be over the Great Lakes/eastern Canada region. Through 48 hours a re-curvature and acceleration to the north-northeast across inland areas of the mid-Atlantic and northeastern United States is expected as Debby transitions into a remnant frontal low supported by the divergence zone of the US/Canada border region upper trough tied to aforementioned frontal low. Models agree on ex-Debby losing its identity while it’s in the vicinity of southeastern Quebec or New Brunswick in 72 hours to the aforementioned frontal low incoming from the west or to another frontal low/upper vortex system slated to dive southeast in the waters between northeast Canada and western Greenland.


Due to the recent re-strengthening… gusty winds with some damage potential cannot be ruled out for northeastern South Carolina and southeastern North Carolina in the next 24 hours… with surf across the Carolina coast and heavy bands of rainfall/flood potential across all of the Carolinas being additional hazards to consider. For the Friday and into the weekend... what is expected to be the remnant frontal low of Debby may re-gain some strength over land while boosted by the divergence zone of the upper trough supporting it... therefore watching for a stretch of possible heavy rainfall... gusty winds... and coastal surf that could develop across the mid-Atlantic and northeastern United States (from Virginia all the way to Maine) as well as the southeastern Quebec/New Brunswick region of Canada.


The following are the strongest winds (in mph) at each of the following National Weather Service stations (weather.gov) recorded so far:

**Hilton Head (southern tip of SC)... sustained 25... gust 44... 7:50 PM EDT August 5

**Charleston (central SC coast)... sustained 15... gust 26… 12:35 AM EDT August 7

**Allendale (inland southern SC)... sustained 18... gust 33... 1:15 AM EDT August 6

**Florence (inland NE SC)… sustained 24… gust 38… 10:53 PM EDT August 7

**Georgetown (coastal NE SC)… sustained 22… gust 30… 8:15 AM EDT August 7

**Myrtle Beach (coastal NE SC)… sustained 14… gust 30… 12:56 PM EDT August 7

**Wilmington (coastal SE NC)… sustained 26… gust 44… 8:53 PM EDT August 7

**Morehead City (coastal SE NC)… sustained 17… gust 29… 8:58 AM EDT August 7

**Jacksonville (inland SE NC)… sustained 21… gust 35… 10:56 PM EDT August 7

**Fayetteville (inland SE NC)… sustained 26… gust 43… 10:49 PM EDT August 7

**Raleigh (inland central NC)… sustained 15… gust 23… 4:51 PM EDT August 7

**Greenville (inland east-central NC)… sustained 8… gust 24… 11:10 PM EDT August 7

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

0 Hr Position (0000Z Aug 8)… 60 mph maximum sustained wind tropical storm centered just offshore of South Carolina at 32.7N-79.4W

IOH 24 Hr Forecast (0000Z Aug 9)… 40 mph maximum sustained wind tropical storm centered over the central part of the North Carolina/South Carolina border at 35N-80W

IOH 48 Hr Forecast (0000Z Aug 10)… Remnant frontal low centered over the Maryland/Pennsylvania border at 39.8N-77W

*****National Hurricane Center (hurricanes.gov) official forecast as of 11 PM EDT************************

3-Day Position (0000Z Aug 11)... 35 mph maximum sustained remnant frontal low losing its identity while entering the Gulf of St Lawrence from southeastern Quebec at 49N-64W


AREA OF INTEREST #16... The Caribbean tropical wave of low pressure has finished accelerating west-southwest into the gyre of low pressure that was attempting to develop in the southern Caribbean… and the two features have now merged. Going forward the track of this disturbance is expected to be west-northwest across Central America and the western Caribbean… then into southeastern Mexico and the Bay of Campeche due to a combination of this system initially feeling the surface ridge weakness of Debby... followed by this system rounding the southwest side of the North America surface ridge expected to build behind what will be ex-Debby. By day 5 a northward turn across east-central and northeastern Mexico is shown as this system finishes rounding the North America ridge. The NHC has cancelled this area of interest from their tropical weather outlook as models have dropped developing this system… however I think canceling this area of interest altogether is premature as satellite animation and CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor&zoom=&time=) shows this system still has concentrated low-level rotation and this system will remain under a broad upper anticyclone covering the western Caribbean and Gulf of Mexico featuring low shear and outflow. My odds of tropical cyclone thru 48 hours fluctuate depending on the amount of land interaction with Central America along the forecast track… with less interaction (higher development odds) at 48 hours. For the Bay of Campeche segment of the forecast (72 and 96 hours)… I cap odds of development at 10% as their is a possibility that some of the upper vorticity currently over the southeastern US... or some upper vorticity left behind by the upper trough that ultimately supports ex-Debby... gets pushed south into the Gulf of Mexico/Bay of Campeche region... and toward this area of interest... by the ongoing southwestern US upper ridge which could make upper winds less favorable for development via outflow suppression.


Given the latest outlook... interests in Nicaragua... Honduras... northern Guatemala… Belize... the Yucatan peninsula of southeastern Mexico... the Isthmus of Tehuantepec region of southeastern Mexico… and Veracruz should continue monitoring the progress of this area of interest in the days ahead for possible heavy rainfall and gusty wind impacts.

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

IOH 24 Hr Outlook (0000Z Aug 9)… 10% chance of tropical cyclone formation (northeastern Nicaragua near 14.5N-84W)

IOH 48 Hr Outlook (0000Z Aug 10)… 15% chance of tropical cyclone formation (just offshore of southern Belize near 16N-88W)

IOH 72 Hr Outlook (0000Z Aug 11)… 10% chance of tropical cyclone formation (southeastern Bay of Campeche coast of Mexico near 19N-92W)

IOH 96 Hr Outlook (0000Z Aug 12)… 10% chance of tropical cyclone formation (just offshore of northern Veracruz near 20.2N-96W)

IOH 120 Hr Outlook (0000Z Aug 13)… 0% chance of tropical cyclone formation (inland northeastern Mexico near 24.5N-99W)

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

Not in the official outlook


AREA OF INTEREST #17A tropical wave of low pressure in the eastern Atlantic was crossing 30W longitude earlier this evening… and is currently disorganized due to dry Saharan air… and also due to an overhead inverted upper trough that has materialized on the south side of the regional tropical upper ridge which is a manifestation of the part of the upper ridge that has been weakened by upper vorticity currently in the northeast Atlantic. A broad area of thunderstorms is southwest of the wave axis in an area unaffected by the dry air and negative upper winds. Some computer model runs however agree on developing this tropical wave in the longer range as it moves toward the Caribbean Islands in the longer range… and I have added this wave as an area of interest on this blog… the seventeenth such Atlantic tropical area of interest tracked on this site this year.


Upper winds over the tropical wave are forecast to become more conducive for development with time as follows… (1) a northwest Atlantic warm core upper ridge materializes in the warm sector of what is forecast to be ex-Debby and the frontal low that will be approaching the Atlantic from the Great Lakes region of North America… (2) the northwest Atlantic upper ridge pushes the inverted upper trough and disrupting northeast Atlantic upper vorticity west and away faster than the tropical wave’s forward heading… with these cool core upper vorticity features also weakening with time due to prolonged isolation from high-latitude cold air… (3) the regional tropical upper ridge featuring low shear and outflow expands over this tropical wave in the wake of the retreating upper vorticity features. I raise odds of development above 0% by days 4 and 5… to give the currently disorganized wave some time to organize and to move further west where dry Saharan air concentrations tend to be lower. Forecast track is west then west-northwest as the wave rounds the south then southwest side of the steering Atlantic surface ridge.

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

IOH 24 Hr Outlook (0000Z Aug 9)… 0% chance of tropical cyclone formation (eastern tropical Atlantic near 11N-35W)

IOH 48 Hr Outlook (0000Z Aug 10)… 0% chance of tropical cyclone formation (central tropical Atlantic near 11N-40W)

IOH 72 Hr Outlook (0000Z Aug 11)… 0% chance of tropical cyclone formation (central tropical Atlantic near 11.5N-45W)

IOH 96 Hr Outlook (0000Z Aug 12)… 10% chance of tropical cyclone formation (central tropical Atlantic near 12N-50W)

IOH 120 Hr Outlook (0000Z Aug 13)… 20% chance of tropical cyclone formation (east of the Lesser Antilles near 12.5N-55W)

*****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 (Aug 7) CMC Model Run...

**For Tropical Storm Debby... makes landfall over northeastern South Carolina in next 24 hours followed by transition into a non-tropical frontal low while crossing western North Carolina and western Virginia through 48 hours… frontal low enters southwest Quebec from eastern New York by 66 hours… through 96 hours de-generates into an east-west elongated frontal low over Quebec with multiple centers

**For area of interest #16... no development shown

**For area of interest #17…. Current east Atlantic tropical wave develops into a tropical low centered just northeast of the eastern tip of the Dominican Republic by 168 hours


1200Z (Aug 7) ECMWF Model Run...

**For Tropical Storm Debby... makes landfall over northeastern South Carolina in next 24 hours followed by transition into a non-tropical frontal low while crossing western North Carolina through 42 hours… remnant frontal low turns northeast and reaches the Pennsylvania/New Jersey Border at 66 hours after which time it loses identity to a developing frontal low to the northwest by 84 hours after it crosses the Maine/New Brunswick border

**For area of interest #16... no development shown

** For area of interest #17… no development shown


1800Z (Aug 7) GFS Model Run...

**For Tropical Storm Debby... makes landfall over northeastern South Carolina in next 15 hours followed by transition into a non-tropical frontal low while crossing western North Carolina through 36 hours… remnant frontal low tracks along US/Canada border from 57 to 63 hours from Vermont to Maine then loses its identity over SE Quebec by 75 hours

**For area of interest #16… develops into a broad tropical low offshore of Nicaragua at 15 hours and degenerates back into a wave over Central America shortly thereafter… no development shown afterwards

**For area of interest #17… Current east Atlantic tropical wave develops into a tropical low near 11.2N-40.5W at 84 hours… develops into a compact tropical cyclone near 13.5N-49W at 108 hours and moves into the northern Lesser Antilles as a compact hurricane at 147 hours… after crossing the NE corner of the Caribbean the hurricane continues west-northwest into the south coast of Puerto Rico by 165 hours


1800Z (Aug 7) NAVGEM Model Run...

**For Tropical Storm Debby... makes landfall over northeastern South Carolina in next 12 hours followed by transition into a non-tropical frontal low while crossing western North Carolina through 42 hours… frontal low curves northeast into Connecticut by 66 hours then loses it’s identity to another developing frontal low to the northwest by 78 hours while located near the southern part of the Maine/New Brunswick border

**For area of interest #16... no development shown

**For area of interest #17… no development shown

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