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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 2023 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #83

Updated: Sep 24, 2023

*******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...SATURDAY SEPTEMBER 23 2033 10:05 PM EDT...

The birdseye view chart below has been updated to now include the surface and upper-level analysis as of 1800Z today.


Tropical Depression Seventeen was upgraded to Tropical Storm Philippe with 40 mph maximum sustained winds as of 5 PM EDT.


Ophelia was downgraded to a 35 mph maximum sustained wind tropical depression centered over southeastern Virginia as of 8 PM EDT. The following are the peak wind gusts (in mph) recorded at each of the following National Weather Service stations (weather.gov) over the last several hours:

**Myrtle Beach (northeastern SC)... sustained 29... gust 36 (10:56 PM EDT Sept 22)

**Wilmington (southeastern NC)... sustained 28... gust 49 (2:53 AM EDT Sept 23)

**Morehead City (southeastern NC)... sustained 37... gust 62 (4:58 AM EDT Sept 23)

**Hatteras (eastern NC)... sustained 31... gust 48... (7:51 AM EDT Sept 23)

**Nags Head (northeastern NC)... sustained 31... gust 44 (2:05 PM EDT Sept 23)

**Lumberton (southeastern NC)... sustained 24... gust 39 (10:56 PM EDT Sept 22)

**Fayetteville (eastern NC)... sustained 28... gust 39 (2:53 AM EDT Sept 23)

**Raleigh (central NC)... sustained 18... gust 38 (3:51 AM EDT Sept 23)

**Virginia Beach (southeastern VA)... sustained 29... gust 52 (7:56 PM EDT Sept 22)

**Virginia Beach (southeastern VA)... sustained 21... gust 37 (3:56 PM EDT Sept 23)

**Wakefield (southeastern VA)... sustained 6... gust 28 (12:54 AM EDT Sept 23)

**Richmond (eastern VA)... sustained 21... gust 35 (9:54 AM EDT Sept 23)

**Accomac (Delmarva Peninsula VA)... sustained 10... gust 25 (3:55 PM EDT Sept 23)

**Elkton (northeast corner of MD)... sustained 28... gust 40 (8:51 PM EDT Sept 23)

**Washington DC... sustained 28... gust 38 (3:52 PM EDT Sept 23)

**Dover DE... sustained 26... gust 39 (4:55 PM EDT Sept 23)

**Atlantic City (southeastern NJ)... sustained 23... gust 41 (6:54 PM EDT Sept 23)

**Trenton (west-central NJ)... sustained 17... gust 32 (3:53 PM EDT Sept 23)


...SATURDAY SEPTEMBER 23 2023 4:25 PM EDT...

Note the usual surface analysis and upper air charts for the above birdseye view chart are still under construction and will be released later this evening. This update is released now without those parts of the chart to ensure a timely release of this update.


See Tropical Storm Ophelia section below for an update on the tropical storm that has made landfall in North Carolina early today... Ophelia will bring impacts to parts of the mid-Atlantic and northeastern US through the remainder of this weekend. Elsewhere... the broad tropical wave of low pressure moving into the central tropical Atlantic has become a tropical cyclone... see tropical depression seventeen section below for more information. See Area of Interest #39 section below for more information on the latest eastern Atlantic tropical wave of low pressure now being monitored for signs of development over the course of the next few days.


TROPICAL STORM OPHELIA... While continuing northward in the flow between the current southeastern United States upper trough and surface ridge now moving into the Atlantic from the northeastern United States... the center of Tropical Storm Ophelia made landfall at 6:20 AM EDT this morning on the North Carolina coast near Emerald Island located just west of Cape Lookout. Ophelia just fell short of hurricane strength while making landfall with 70 mph maximum sustained winds... as colorized infrared satellite imagery suggested Ophelia's core thunderstorms were dwindling while the storm ingested cooler drier air assoicated with the upper trough. As of 11 AM EDT Ophelia's center was over eastern North Carolina while having weakened further to 50 mph maximum sustained winds due to the landfall... and as of 2 PM EDT Ophelia has weakened further to 45 mph maximum sustained winds while the center was approaching the eastern North Carolina/Virginia border. Going forward the southeastern United States upper trough and eastern Canada upper trough will merge into a lengthy southwest-northeast tilted upper trough... with Ophelia's northward track increasingly bending eastward in the flow on the east side of the trough. In the next 24 hours Ophelia will transition into a remnant frontal low supported by the eastern divergence zone of the titled upper trough. The eastward deflection in track will be supported by a blocking surface ridge to dive in from Canada (the blocking ridge will be generated by the western convergence zone of the tilted upper trough. Although Ophelia has been moving a bit faster to the north than my prior forecast... the models have converged on the eastward-bending track crossing over southern New Jersey instead of further north due to the strength of the blocking surface ridge... and so my updated forecast track has Ophelia's center also crossing southern New Jersey. The more southward long-range position of Ophelia keeps it more aligned with the divergence zone ahead of the tilted upper trough... and so the decay rate of Ophelia's remnant frontal low may be slower than previously thought.


Regarding impact to land areas:

(1) Gusty winds with isolated damage potential and coastal surf will be a concern for the remainder of the weekend across northeastern North Carolina... southeastern Virgnia... eastern Maryland... and Delaware... and possibly as far north as New Jersey as the decay rate of the remnant frontal low of Ophelia may be on the slower side as discussed above.

(2) Based on the latest radar imagery and forecast... the potential for heavy rainfall... with possible occurrences of flash flooding... for the remainder of the weekend has shifted west and north to a corridor covering north-central North Carolina... central Virginia... Maryland... Delaware... New Jersey... Pennsylvania... southern New York... Massachusetts... Connecticut... Rhode Island... southern Vermont... and southern New Hampshire.

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

0 Hr Position (1200Z Sep 23)... 50 mph maximum sustained wind tropical storm centered over eastern North Carolina at 35.6N-77.2W

IOH 24 Hr Forecast (1200Z Sep 24)... Weakening frontal low centered over southern New Jersey at 39.8N-74.5W

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

Loss of Tropical Cyclone Status (1200Z Sep 24)... 35 mph maximum sustained wind frontal low centered over southern Maryland at 38.2N-76.6W


TROPICAL DEPRESSION SEVENTEEN... The broad tropical wave of low pressure heading toward the central tropical Atlantic has seen a more consolidated center develop toward the thunderstorms on the north side of its circulation... and as of 11 AM EDT the National Hurricane Center upgraded this system to tropical depression seventeen. The center of the new depression is a little northwest of my previous forecast and my updated one below is adjusted accordingly for the short-term. The model guidance has shifted more eastward in the long range and my updated long-range track is adjusted in that direction. The track forecast calls for an increase in the north angle of this system's westward track after 24 hours under the influence of the current central Atlantic upper vorticity... followed by the development of a surface ridge weakness in the open central Atlantic triggered by the eastern divergence zone of a lengthy western Atlantic upper trough that will materialize from the merger between the current southeastern US and eastern Canada upper troughs. A look at the current 200 mb upper-level setup suggests the new depression should be embedded in a low shear environment beneath the current eastern tropical Atlantic upper ridge... however satellite imagery shows the canopy of curved thunderstorm bands is dislodged east of the surface center. This could mean that below the 200 mb layer there is a band of upper westerly shearing winds connecting the current eastern and central Atlantic upper vorticity. Therefore for the next 48 hours I show only gradual strengthening... followed by weakening between 48 and 72 hours as this system moves closer to stronger shear associated with the central Atlantic upper vorticity. By 96 and 120 hours the westerly shear across this system may let up as the central Atlantic upper vorticity becomes tilted southwest-to-northeast under the influence of a strengthening Caribbean upper ridge cell... changing the upper winds over this system from westerly to southwesterly. Thus I show some recovery in strength for that timeframe... but not much as the southwesterly shear may still be strong. Noting the intensity guidance in the global models is higher than yesterday by day 5... with some guidance suggesting hurricane strength by then... however I cannot justify this at this time given the amount of southwesterly shear forecast by day 5.


Noting this system may produce coastal surf for the northern Lesser Antilles by the middle of this upcoming week.

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

0 Hr Position (1200Z Sep 23)... 35 mph maximum sustained wind tropical depression centered in the eastern tropical Atlantic at 15.6N-38.8W

IOH 24 Hr Forecast (1200Z Sep 24)... 45 mph maximum sustained wind tropical storm centered in the central tropical Atlantic at 16N-43.5W

IOH 48 Hr Forecast (1200Z Sep 25)... 50 mph maximum sustained wind tropical storm centered in the central tropical Atlantic at 17.5N-47.5W

IOH 72 Hr Forecast (1200Z Sep 26)... 40 mph maximum sustained wind tropical storm centered in the central tropical Atlantic at 18.5N-52W

IOH 96 Hr Forecast (1200Z Sep 27)... 50 mph maximum sustained wind tropical storm centered in the central tropical Atlantic at 20.5N-54W

IOH 120 Hr Forecast (1200Z Sep 28)... 50 mph maximum sustained wind tropical storm centered in the central Atlantic at 22.5N-55W

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

5-Day Position (1200Z Sep 28)... 65 mph maximum sustained wind tropical storm centered in the central Atlantic at 23N-54.5W


AREA OF INTEREST #39... The latest tropical wave of low pressure in the eastern tropical Atlantic emerged from the west coast of Africa within the last day and its center of rotation is currently near 11N-23.5W. Although global models in prior days suggested this wave could develop... the global models have backed off in showing this as of this morning. Despite this... the NHC has added this tropical wave as an area of interest in their tropical weather outlook as of 2 PM EDT today... this marks the thirty-ninth tropical Atlantic area of interest tracked on this site this year. Forecast track in the outlook below is initially westward... followed by more of a north angle in the track after 72 hours while gravitated toward the surfacde ridge weakness associated with what is now tropical depression seventeen. Short-term development potential is likely to be tepid as the nearby eastern Atlantic upper vorticity could sag southward toward the northeast quadrant of the tropical wave and under the influence of tropical depression seventeen's ouflow... with the upper vorticity potentially inhibiting outflow of this wave toward the northeast. Therefore through 72 hours I agree with the NHC in showing development odds no higher than 20%. After 72 hours the forecast track takes this system away from the upper vorticity and into a better upper outflow environment... therefore I show odds of development higher than the NHC guidance from 2 PM EDT. However I cap my peak development odds at 30% due to most models preferring not to develop this wave as of this writing.

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

IOH 24 Hr Outlook (1200Z Sep 24)... 10% chance of tropical cyclone formation (eastern tropical Atlantic near 11.5N-28.5W)

IOH 48 Hr Outlook (1200Z Sep 25)... 20% chance of tropical cyclone formation (eastern tropical Atlantic near 12N-33.5W)

IOH 72 Hr Outlook (1200Z Sep 26)... 20% chance of tropical cyclone formation (eastern tropical Atlantic near 12.5N-38.5W)

IOH 96 Hr Outlook (1200Z Sep 27)... 30% chance of tropical cyclone formation (central tropical Atlnatic near 14N-41.5W)

IOH 120 Hr Outlook (1200Z Sep 28)... 30% chance of tropical cyclone formation (central tropical Atlantic near 16.5N-45W)

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


0000Z (Sep 23) CMC Model Run...

**For Tropical Storm Ophelia... transitions into a weakening remnant frontal low that turns eastward and offshore from Delaware at 48 hours... remnant frontal low loses identity along front while located near 37.5N-69W at 66 hours.

**For Tropical Depression Seventeen... located near 23N-55W at 120 hours as a hurricane

**For Area of Interest #39... no development shown


0000Z (Sep 23) ECMWF Model Run...

**For Tropical Storm Ophelia... transitions into a weakening remnant frontal low that turns eastward and offshore from southern New Jersey at 54 hours... remnant frontal low loses identity offshore of New Jersey shortly thereafter.

**For Tropical Depression Seventeen... located near 21.5N-55.5W at 120 hours as a tropical storm

**For Area of Interest #39... no development shown


1200Z (Sep 23) GFS Model Run...

**For Tropical Storm Ophelia... transitions into a weakening remnant frontal low that turns eastward and offshore from southern New Jersey at 45 hours... remnant frontal low loses identity offshore of New Jersey by 60 hours

**For Tropical Depression Seventeen... located near 25.5N-51.5W at 120 hours as a more compact tropical cyclone approaching hurricane strength

**For Area of Interest #39... no development shown


0600Z (Sep 23) NAVGEM Model Run...

**For Tropical Storm Ophelia... transitions into a weakening remnant frontal low that turns eastward and offshore from southern New Jersey at 48 hours... remnant frontal low moves east-southeast to 36.5N-57W through 120 hours and becomes absorbed by adjacent frontal low developing to the northeast shortly thereafter.

**For Tropical Depression Seventeen... located near 22N-55W at 120 hours as a strong hurricane

**For Area of Interest #39... no development shown

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