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 #114

*******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 SEPTEMBER 28 2022 3:52 AM EDT...

Major Hurricane Ian is producing substantial impact to the Florida peninsula and the Keys... see Ian section below an update on this dangerous hurricane. Elsewhere monitoring the following areas for signs of development:

(1) See area of interest #33 section below for information on a tropical low pressure area that has been meandering aimlessly in the eastern tropical Atlantic. This feature has a high chance of tropical cyclone formation.

(2) See area of interest #34 section below for an update on tropical wave activity in the vicinity of western Africa and the far eastern tropical Atlantic.


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 is designated #33 and #34 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.


MAJOR HURRICANE IAN... Ian remains a dangerous hurricane in the southeastern Gulf of Mexico as its eastern side continues to overspread the Florida Keys and peninsula. In special update #113A released Tuesday early afternoon... it appeared Ian was ready to rapidly intensify while it maintained a circular core of thunderstorms symmetrically distributed around a clearing eye... with the northern outflow of the hurricane remaining enhanced by upper southwesterly flow ahead of the current eastern United States upper trough. It also appeared the intensification was starting with the surface pressure dropping to the upper 940s of mb. However an abrupt eye wall replacement cycle has occurred which resulted in the eye looking less organized on tonight's infrared satellite pictures... and it appeared thunderstorms on the west side were beginning to shrink as if the upper southwesterly flow was beginning to shear the hurricane...albeit the most recent satellite frames show a blow-up of thunderstorm activity on the west side so its debatable as to whether the shear has begun or not. The surface pressure has also risen back to the low 950s of mb. All of this resulted in a tepid intensification from 115 to 120 mph maximum sustained winds since special update #113A. Therefore in this update I lower the intensity forecast... however note this is still a dangerous major category 3 hurricane. The latest model data also suggests an ongoing shift in the surrounding weather systems that will steer Ian... so the track forecast is also updated as follows:


Ever since Ian departed Cuba... Ian's eye has leaned more eastward in its northward track than anticipated. Comparing yesterday's 18Z GFS prediction for the current timeframe... versus how things are actually setup... shows the eastern US upper trough is actually leaving behind a slightly less amplified version of a cut-off upper trough over the southeast US (cut-off feature currently in the vicinity of Louisiana/Mississippi). The less amplified cut-off upper trough has resulted in more westerly and less southerly upper flow across the western Gulf of Mexico... pushing the hurricane on a more eastward angle. Therefore the updated forecast track in the short-term is once again adjusted eastward... bringing the eye of the hurricane onshore on the west coast of Florida a little sooner and further south toward Port Charlotte instead of Tampa Bay. Models still agree that the current eastern US upper trough and associated surface ridge weakness will leave behind Ian... trapping Ian south of a blocking surface ridge that builds under the western convergent side of the departing upper trough. This results in a 36-hour period of slow northeastward motion across the Florida peninsula in the timeframe that is now 12 to 48 hours away... a combination of Ian being embedded in steering upper southerly flow ahead of the leftover cut-off upper trough while the blocking surface ridge resists Ian's northward progress. Since special update #113A... the period of slow motion has expanded from a 24 to now a 36-hour period in response to a current upper trough feature which has come into Alaska a little more amplified than previously shown. As it move eastward across Canada... the more amplified upper trough produces a stronger surface frontal system whose warm sector builds stronger upper ridging across central Canada. In turn... this stronger Canadian upper ridge more aggressively breaks up the departing eastern US upper trough into upper vorticity features... with these features taking longer to shift eastward while pinned down by the stronger Canadian upper ridge. And because the blocking surface ridge north of Ian is supported by the convergent back side of these departing upper vorticity features... it too takes longer to move eastward out of Ian's way and hence explaining the prolonged slow motion of the storm.


The late part of the forecast track has also changed with Ian taking a more aggressive westward hook into Georgia/South Carolina after its initially more eastward short-term forecast track causes it moves offshore of northeast Florida. This westward hook is also caused by the more amplified version of the upper trough to slide across Canada from its current position over Alaska... as the western convergent side of the amplified upper trough now produces a stronger Canadian surface ridge in the long-range to help Ian's westward turn. Also northerly flow on Ian's west side will pull the cool air associated with the leftover southeast US cut-off upper trough southward. In conjunction with an amplifying central US upper ridge wave to be built up in the warm sector of a western US frontal system... the leftover cut-off upper trough over the southeast US is expected to amplify into a vortex whose northeast quadrant will also help pull Ian westward.


Regarding the intensity forecast... it turns out the previous forecast from full update #113 was accurate with Ian being at 120 mph maximum sustained winds as of 0000Z earlier this evening. This is also the timeframe I expected Ian to peak in intensity while in the Gulf of Mexico as I expect wind shear to increase with the approach of the leftover cut-off upper trough over the southeastern US... therefore I project weakening going forward. The shear will only be exacerbated as Ian slows down and falls behind the upper southwesterly wind speed being generated ahead of the cut-off upper trough. However for those in the Port Charlotte region of western Florida... do not let your guard down as Ian's current high intensity will result in it needing time for its winds and coastal storm surge to wind down... therefore dangerous coastal storm surge and damaging winds are still on the table. I have trended with a slightly faster weakening rate in the short-term relative to full update #113 as the adjusted forecast track brings Ian into the Florida peninsula a little sooner. I have also trended upward with the intensity in the longer range... with Ian's center now expected to re-emerge on the other side of the Florida peninsula and back over water while at the same time the shear relaxes and upper divergence increases due to the amplification of the leftover southeast US cut-off upper trough (how this trough amplifies is mentioned in the previous paragraph). However I do not expect Ian to rapidly re-strengthen as its core will need some time to recover from a long period of exposure to the Florida peninsula landmass and the wind shear. The end result is Ian is now anticipated to make landfall at the Georgia/South Carolina border region as a high-end tropical storm.


Regarding impacts to land areas:

(1) Weather conditions and coastal surf across western Cuba will continue to gradually improve tonight as Ian lifts northward and away.

(2) The Florida Keys are being buffeted by tropical storm to hurricane force conditions (wind and coastal storm surge) on the east side of Ian. Expect weather conditions to only gradually improve today as Ian slows down its forward speed.

(3) For the Florida peninsula... the east side of Ian has already overspread the southern half of the peninsula and will overspread all of the peninsula by later today. The expected slow down in the forward speed will subject the peninsula to prolonged impacts such as high rainfall totals creating a risk of major flash flooding... do not drive your car into a water-covered roadway if you encounter one. Much of the west coast of the Florida peninsula will see increasing wind and coastal surf over the next several hours... with the worst of the coastal storm surge and wind now expected further south in the vicinity of Port Charlotte due to the latest shift in Ian's track. The latest shift in the forecast track means the east side of the peninsula will also see more tropical storm force winds with some damage potential... as well as more coastal surf. The east side of Ian has and will continue to be at risk of producing tornadoes due to vertical wind shear between surface southerly flow on the east side of the storm and upper southwesterly flow overspreading Ian... have a way to watch or listen to local media with live coverage to know if you are under a tornado warning... and be prepared to quickly shelter in the lowest-level and interior-most location of your building. The tornado risk looks to overspread southern and central parts of the Florida peninsula... with the latest shift in the forecast track making it harder for Ian to lift its tornadic east side into the northern parts of the peninsula. Preparations in the southern half of the peninsula should have been completed by now as severe weather has already moved into the area... and the northern half should have finished preparing by now or be rushing preparations to completion.

(4) For the Florida panhandle... the latest shift in the storm track still will allow for coastal surf for the eastern half of the panhandle. The far eastern panhandle may also see high rainfall totals and flooding as Ian slows its forward speed.

(5) The risk for heavy rainfall and flooding and tropical storm force wind has reduced for southwestern Georgia... however has increased for southeastern Georgia. Coastal Georgia is also at increased risk for coastal surf. Timing of impacts for southeastern Georgia is late Thursday through early Saturday. Prepare now... and finish preparing by late tonight.

(6) Coastal South Carolina and coastal southern North Carolina can expect coastal surf to develop late Thursday through early Saturday. Stronger coastal surf... along with tropical storm force winds with some damage potential... is now expected across southern South Carolina where preparations should now be underway. Finish preparing by late tonight.

(7) Some heavy rainfall with isolated flash flooding potential is possible across northern Georgia... the Carolinas... and eastern Tennessee by Sunday if the current forecast holds.


The following are recent wind reports at National Weather Service stations across southern Florida listed in mph.

**Key West FL... sustained 39... gust 60... now

**Key West FL... sustained 52... gust 75... 10:53 PM EDT

**Marathon FL... sustained 30... gust 55... now

**Fort Lauderdale FL... sustained 28... gust 37... 1:53 AM EDT

**Miami FL... sustained 12... gust 39... 1:53 AM EDT

**West Palm Beach FL...sustained 23... gust 30... 1:53 AM EDT

**Fort Pierce FL... sustained 10... gust 17... now

**Naples FL... sustained 21... gust 40... 12:53 AM EDT

**Fort Myers FL... sustained 18... gust 29... 12:53 AM EDT

**Punta Gorda FL... sustained 29... gust 40... now

**Sarasota FL... sustained 17... gust 32... now

**Clearwater Beach FL... sustained 12... gust 16... now

**Sebring FL... sustained 18... gust 24... now


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

0 Hr Position (0000Z Sep 28)...120 mph maximum sustained wind major hurricane centered just northwest of the Florida Keys at 24.9N-82.9W

IOH 24 Hr Forecast (0000Z Sep 29)...95 mph maximum sustained wind hurricane centered inland on the western Florida peninsula just north of Port Charlotte and just southeast of Tampa Bay at 27.2N-82.3W

IOH 48 Hr Forecast (0000Z Sep 30)...60 mph maximum sustained wind tropical storm centered over the northern part of the central Florida peninsula at 28.2N-81.2W

IOH 72 Hr Forecast (0000Z Oct 1)...65 mph maximum sustained wind tropical storm centered offshore of of northeastern Florida and Georgia at 30.2N-80W

IOH 96 Hr Forecast (0000Z Oct 2)...35 mph maximum sustained wind tropical depression centered over western South Carolina and just north of the Georgia/South Carolina border at 34N-82.3W

IOH 120 Hr Forecast (0000Z Oct 3)...Remnant low centered over western North Carolina at 35.5N-80.5W


AREA OF INTEREST #33...The wandering tropical low pressure spin in the eastern Atlantic is making another run at trying to become a tropical depression while firing strong thunderstorm bursts. Noting the bursts remain lopsided to the northeast side of the circulation. The above birdseye view chart shows upper-level winds at the 200 mb layer of the atmosphere which is what I normally use to assess wind shear... and it would seem based on this system's current position that it is tucked below the tropical upper ridge axis in the region where shear would be low. However a large upper vortex remains north of this system and close by... perhaps it is producing upper southwesterly flow over this system and below the 200 mb layer that is dragging the thunderstorm activity off to the northeast.


This system has remained generally stationary while in a saddle point of conflicting steering between the broad surface low pressure area to the northeast supported by the aforementioned upper vortex and Atlantic surface ridge that for days has been trying to push this system west. Albeit this system has drifted a little bit to the northeast toward the broad surface low pressure area... and so my updated forecast track points are nudged eastward accordingly. The cold core upper vortex feature will weaken while remaining isolated from cold air thanks to the ongoing warm core north Atlantic upper ridge. The strength of this upper ridge will also stretch the weakening vortex into an elongated southwest-to-northeast string of upper vorticity. Therefore as the upper vortex and associated surface low pressure area to the northeast weakens... the Atlantic surface ridge will finally be able to push this system west. However an increasing north angle is depicted in the developing west track as the surface ridge will itself develop a weakness to the northwest as the current frontal system over the northeastern US will have moved offshore. And as this system potentially becomes a stronger/taller tropical cyclone... the upper southwesterly flow ahead of the aforementioned upper vorticity string would also coax this system on a more northward track. The upper southwesterly flow is expected to become a detriment to this system in the long range by shearing it. Once this system weakens to a shallow feature under the shear and the surface ridge weakness closes with the departure of the frontal system... the recovering surface ridge should turn the weakening system more westward. This explains the more west angle in track at 72+ hours.


Regarding intensity... the NHC has raised odds of tropical cyclone formation to 80% as of this writing due to this system's increased thunderstorm bursts... and it still seems reasonable that the current light southwesterly shear should abate in the short-term as the cold core upper vortex to the north begins to weaken. Therefore for now... I am continuing with a track and intensity forecast for this system assuming that it will still become a tropical cyclone at some point... but have once again lowered the peak intensity as this system failed to become a tropical cyclone thus far. The steady strength between 24 and 48 hours... followed by weakening from 48 to 72 hours is a reflection of this system moving into increasing shearing upper southwesterly flow. Note that I have increased the amount of time this system hangs around as a weakened tropical depression... and I even suggest a slight increase in the depression's strength from 72 to 96 hours. This is because the latest model runs depict a more amplified western Atlantic upper ridge in the late part of the forecast period... I speculate this maybe due to Ian's eastward shift in the forecast such that its outflow perhaps amplifies this upper ridge? The end result is the more amplified upper ridge causes the remainder of the shearing upper vorticity string in this system's environment to also amplify into a small upper vortex (in the 72 to 96 hour window) whose east side would have lower shear and increased upper divergence. However I end up dissipating this system by 120 hours as it continues west directly below the small upper vortex where upper divergence is lacking.

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

0 Hr Position (0000Z Sep 28)...Tropical low centered at 14.8N-34.5W

IOH 24 Hr Forecast (0000Z Sep 29)... 45 mph maximum sustained wind tropical storm centered at 16.2N-36.5W

IOH 48 Hr Forecast (0000Z Sep 30)... 45 mph maximum sustained wind tropical storm centered at 18.8N-40W

IOH 72 Hr Forecast (0000Z Oct 1)... 30 mph maximum sustained wind tropical depression centered at 21.8N-43W

IOH 96 Hr Forecast (0000Z Oct 2)... 35 mph maximum sustained wind tropical depression centered at 23N-46W

IOH 120 Hr Forecast (0000Z Oct 3)... Remnant trough located near 23N-49.5W


AREA OF INTEREST #34...A tropical wave of low pressure offshore of western Africa is producing a small patch of thunderstorms just southeast of the Republic of Cabo Verde Islands. An additional wave over western Africa approaching from 10W longitude is producing some activity along parts of the west African coast. These two waves are not showing signs of organizing into a cohesive disturbance in the offshore waters... and the prior models which suggested development in this region no longer do so. Therefore in this update... I am cancelling this area of interest.

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

IOH 24 Hr Outlook (0000Z Sep 29)...0% chance of tropical cyclone formation (vicinity of western Africa coast near 10N-15W)


...COMPUTER MODEL SUMMARY...

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


1200Z (Sep 27) CMC Model Run...

**For Major Hurricane Ian... center makes landfall on Tampe Bay Florida at 60 hours... quickly weakens to a high-end tropical storm centered over northern Florida by 72 hours... gradually weakens to a tropical depression while the center moves into central Georgia by 102 hours... weakens to a remnant low centered over the northern Georgia/South Carolina border at 114 hours... remnant low begins to shift east into the Carolinas by 120 hours.

**For area of interest #33... tropical low pivots north and then northwest... weakens to a trough near 20N-40W at 66 hours.

**For area of interest #34... no development shown


1200Z (Sep 27) ECMWF Model Run...

**For Major Hurricane Ian... center makes landfall at Port Charlotte Florida just after 24 hours and weakens to a top-end tropical storm centered inland just east of Tampa Bay Florida by 48 hours... center of tropical storm moves just offshore of northeast Florida at 72 hours... whirls northwestward into and across Georgia and weakens to an inland tropical depression over central Georgia at 96 hours... weakens to a remnant low over eastern Tennessee by 120 hours

**For area of interest #33... tropical low pivots north and then northwest... weakens to a trough near 18N-43W at 48 hours.

**For area of interest #34... no development shown


1800Z (Sep 27) GFS Model Run...

**For Major Hurricane Ian... center passes just west of the Florida Keys at 6 hours... center wobbles east for a landfall at Port Charlotte Florida at 30 hours... while continuing an east drift the hurricane weakens to a top-end tropical storm over the central Florida peninsula at 48 hours... center then drifts north-northeast and moves just offshore of the northeast Florida coast at 69 hours while still a strong tropical storm... makes landfall at this strength at the Georgia/South Carolina border at 81 hours... while continuing northwest across the Georgia/South Carolina border weakens to a remnant low over the northern part of the border at 93 hours... broadening remnant low located over the North Carolina/Tennessee border at 108 hours... remnant low turns east and moves across the Carolinas through 120 hours.

**For area of interest #33... tropical low pivots north and then northwest... weakens to a trough near 17.5N-37.5W at 45 hours.

**For area of interest #34... no development shown


1800Z (Sep 27) NAVGEM Model Run...

**For Major Hurricane Ian... center passes just west of the Florida Keys at 12 hours... makes landfall at Port Charlotte at 30 hours... after weakening to a lower-end hurricane the center moves just offshore of northeast Florida at 54 hours... as a strengthening hurricane the center makes landfall over the southern tip of South Carolina at 72 hours... whirls northwest across western South Carolina and weakens to a remnant low by 96 hours over far western North Carolina... remnant low turns increasingly east and moves into central North Carolina at 120 hours.

**For area of interest #33... tropical low moves northwest and weakens to a trough near 17.5N-36W at 36 hours.

**For area of interest #34... no development shown

**Tropical wave emerges from west coast of Africa at 114 hours... tropical cyclone formation suggested offshore of Senegal at 144 hours... tropical cyclone turns increasingly north in track and reaches waters east-northeast of the Republic of Cabo Verde Islands near 17.5N-21W at 168 hours

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