BIRDSEYE VIEW POSTS

Since 2012 on the Weather Underground (www.wunderground.com) 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 via Disqus on Weather Underground at www.wunderground.com/cat6. You can see my Disqus feed at this link for my latest comments. Feel free to reply to me with your disqus account or e-mail at IOHurricanes@outlook.com 

 
 
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MY 2019 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #136

*******Note that forecasts 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.**********


...MONDAY SEPTEMBER 23 2019 1:00 PM EDT...


See Jerry...Karen...and Lorenzo sections below for all active tropical cyclones in the Atlantic basin. See areas of interest sections below for all other areas being monitored for tropical cyclone formation. The recent escalation in tropical activity in the Atlantic is coinciding with the Madden Jullian Oscillation (MJO) mode favoring increased thunderstorms in the Atlantic tropics...expect elevated tropical activity in the Atlantic basin in the next week (https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml).


TROPICAL STORM JERRY...Preparations for some damaging wind from Tropical Storm Jerry in Bermuda should be continuing and completed by today as the heavy weather on Jerry's east side will overspread Bermuda by 24 hours. Jerry has been moving north-northwest in the last 24 hours...a combination of the westward push of surface ridging to the north and the upper southwesterly flow trying to turn Jerry more north and east...generated out ahead of the upper trough in the western Atlantic/Gulf of Mexico. The upper southwesterly flow is shearing thunderstorms eastward from Jerry's swirl center...thus preventing Jerry from re-strengthening thus far. My updated track forecast is adjusted westward in the short-term as Jerry is west of my previous forecast track. A turn to the northeast and east is still expected as an upper trough is still expected to consolidated in the western Atlantic...with divergence on the east side of this trough creating a break in the surface ridging to the north and allowing Jerry to be steered fully by the upper westerly winds. This upper trough will consolidate as the current western Atlantic/Gulf of Mexico upper trough splits into two vortices...with the eastern North America upper trough (associated with the eastern US frontal system) merging with the eastern of the two vortices. The more west position of Jerry does mean the tropical storm is likely to slip out of the grip of the considated upper trough by 48+ hours...therefore it is more likely the conslidated upper trough will generate a seperate non-tropical low pressure area northeast of Jerry with its upper divergence instead of making Jerry itself transition to non-tropical. This seperate non-tropical low and upper northwesterly flow on the back side of the upper trough is likely to keep Jerry pushed further south than previously thought for the later part of the forecast period...thus my later forecast points are shifted south and west. My 120 hour forecast point suggests a north bend in the track...and this is due to the atlantic surface subtropical ridge which by then would be southeast of Jerry. Regarding intensity...I still forecast Jerry to regain 70 mph maximum sustained winds in the next 24 hours because of supportive divergence on the east side of the aforementioned upper trough expected to consolidate. But by 48+ hours...with Jerry now expected to slip away from the upper trough...I show a burst of initial weakening from upper convergence on the back side of the trough...followed by gradual weakening as the shear lightens (but does not disappear for re-strengthening) in the wake of the upper trough and under the northeast side of the large cell of upper ridging expected in the western Atlantic. By 96+ hours...cooler waters should cause Jerry to lose thunderstorms and fade into a remnant low pressure.

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

0 Hr Position (1200Z Sep 23)...65 mph maximum sustained wind tropical storm under westerly shear and divergence centered southwest of Bermuda at 28.1N-68.0W

IOH 24 Hr Forecast (1200Z Sep 24)...70 mph maximum sustained wind tropical storm centered just west of Bermuda at 32.5N-67.5W

IOH 48 Hr Forecast (1200Z Sep 25)...50 mph maximum sustained wind tropical storm under light westerly shear and upper convergence centered just north of Bermuda at 34N-64W

IOH 72 Hr Forecast (1200Z Sep 26)...50 mph maximum sustained wind tropical storm under light westerly shear centered at 35N-58.5W

IOH 96 Hr Forecast (1200Z Sep 27)...40 mph maximum susatained wind tropical storm under light westerly shear and over cooler waters centered at 36N-48.5W

IOH 120 Hr Forecast (1200Z Sep 28)...Remnant low centered at 40N-40W


TROPICAL STORM KAREN...Preparations for gusty winds with some damage should be underway and completed by today in Puerto Rico as Tropical Storm Karen is becoming more consolidated and better organized this morning while heading northwestward toward the island. Peripherial heavy rain bands with some flash flooding will be possible over the Virgin Islands and the eastern tip of the Dominican Republic in 24 hours as well. The last 24 hours have seen noteworthy changes with Tropical Storm Karen...as it transitions from a large/broad tropical storm with disroganized clouds under northelry shear on the east side of a cell of tropical upper ridging...to a much more compact and organizing tropical storm while moving into lighter shear and upper outflow directly below of the upper ridging. Upper winds look to me to be rather favorable for strengthening thru the forecast period as the upper trough Jerry is set to interact with will leave behind a cut-off upper vortex well to the west of Karen such that Karen should not get sheared...and with the compact structure of Karen which can be capable of rapid strengthening I still forecast the tropical storm to reach 60 mph maximum sustained winds by tomorrow by the time it reaches Puerto Rico and become a major hurricane by day 5. I do not show a strength above category 3 (120 mph winds) in the next 5 days as the expected slow motion of Karen may cause it to upwell cooler waters...and because the NHC official forecast which is based on a consensus of intensity models is hesistent to even bring Karen to hurricane strength in the first place. My forecast track is adjusted northward overall due to Karen's current position. Karen is turning increasinglyl north into the surface ridge weakness caused by Tropical Storm Jerry. While it is expected that Jerry will still leave behind Karen...I have adjusted the later part of my forecast track to be further east as Jerry and Karen will be closer to each other for a longer period of time than I previously thought yesterday (due to the more north position of Karen and more south position of Jerry expected in the long run). The surface ridging over the eastern and central US will shift into the western Atlantic north of Karen in the wake of Jerry...helping to turn Karen back westward by 120 hours. But the late part of the forecast shows an erratic/slow motion as the surface ridge will initially be weak due to a large and strong upper trough/surface frontal cyclone over central Canada. However in the longer range...the frontal cyclone's cold air advection will amplify the upper trough into a vortex...with the vortex sending the cyclone northward such that the surface ridging north of Karen rebuilds. This means we can expect the surface ridge to likely push Karen westward after 120 hours.

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

0 Hr Position (1200Z Sep 23)...40 mph maximum sustained wind tropical storm centered in the eastern Caribbea Sea at 14.9N-64.8W

IOH 24 Hr Forecast (1200Z Sep 24)...60 mph maximum sustained wind tropical storm centered over western Puerto Rico at 18N-66.5W

IOH 48 Hr Forecast (1200Z Sep 25)...75 mph maximum sustained wind hurricane centered north of Puerto Rico at 22.5N-66W

IOH 72 Hr Forecast (1200Z Sep 26)...100 mph maximum sustained wind hurricane centered south of Bermuda at 25N-64W

IOH 96 Hr Forecast (1200Z Sep 27)...120 mph maximum sustained wind major hurricane centered south-southeast of Bermuda centered at 25N-63W

IOH 120 Hr Forecast (1200Z Sep 28)...120 mph maximum susateind wind major hurricane centered south of Bermuda at 25N-65W


TROPICAL STORM LORENZO...The organized tropical wave in the eastern tropical Atlantic has strengthened into tropical depression thirteen and then very recently to Tropical Storm Lorenzo in the last 24 hours. Upper-level winds will be favorable for additional strengthening in the next 72 hours as the upper vortex in the central Atlantic is expected to continue to retrograde westward and away...then northwestward and away while merging with the upper trough set to interact with Tropical Storm Jerry...leaving Lorenzo under a favorable cell of tropical upper ridging with low shear and upper outflow. By 96+ hours...the latest modeling suggests more interaction between Lorenzo and the southern reaches of the aforementioned upper trough...therefore I am expecting the western outflow of Lorenzo to be intially blocked during this interaction and thus show initial weakening during that timeframe. The interaction consists of Lorenzo being strong/tall enough to be steered by the upper trough...with the upper trough reaching far south enough to pull Lorenzo northward...and Lorenzo's thunderstorm latent heat release currently forecast to break the cold core upper trough in half. By 120 hours...I show further strengthening into a major hurricane as Lorenzo should be in low shear and enhanced upper outflow between three upper vortices...two of them being the split halves of the upper trough...and the third being a fragment of the upper trough currently over North America (specifically the central US) which is currently forecast to be northwest of Lorenzo by that timeframe. Just after 120 hours...Lorenzo appears it will continue northwestward under the influence of the upper vortex to the northwest. My updated forecast track is nudged southwestward in the early part to account for Lorenzo's current position...followed by a northward adjustment in the late part of the forecast to reflect the increased chance of interaction with the upper trough.

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

0 Hr Position (1200Z Sep 23)...40 mph maximum sustained wind tropical storm centered south-southeast of the Republic of Cabo Verde Islands at 11.1N-24.1W

IOH 24 Hr Forecast (1200Z Sep 24)...60 mph maximum sustained wind tropical storm centered southwest of the Republic of Cabo Verde Islands at 12.1N-29W

IOH 48 Hr Forecast (1200Z Sep 25)...85 mph maximum sustained wind hurricane centered at 13N-34W

NCH2009's 72 Hr Forecast (1200Z Sep 26)...105 mph maximum sustained wind hurricane centered at 14.5N-39W

IOH 96 Hr Forecast (1200Z Sep 27)...100 mph maximum sustained wind hurricane centered at 17.5N-40.5W

IOH 120 Hr Forecast (1200Z Sep 28)...120 mph maximum sustained wind major hurricane centered at 22N-42.5W


AREA OF INTEREST #1...The tropical wave now west of Tropical Storm Lorenzo has not become better organized...therefore I have slightly lowered my odds of development over the next 120 hours. Upper-level winds will be favorable for this tropical wave to develop during the 120-hour forecast period as the upper vortex in the central Atlantic is expected to continue to retrograde westward and away...then northwestward and away as it merges with the upper trough that will be interacting with Tropical Storm Jerry...leaving this tropical wave under a favorable cell of tropical upper ridging with low shear and upper outflow. However my peak 120-hour odds of development are only at 15%...but will later increase odds only if this system develops organized thunderstorm activity or if computer model support showing development occurs. The 96 and 120 hours positions are shown to be more north (towards 15 and 20N latitude) as this system will likely move toward a low-level ridge weakness caused by Jerry and then Karen. On a final note...should Karen become a strong tropical cyclone in the western Atlantic as I currently forecast...it is possible its strong upper outflow could begin negatively shearing this tropical wave by 120 hours...which is why I nudge odds of development downward by that time.

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

IOH 24 Hr Outlook (1200Z Sep 24)...0% chance of tropical cyclone formation (tropical Atlantic near 42.5W)

IOH 48 Hr Outlook (1200Z Sep 25)...0% chance of tropical cyclone formation (tropical Atlantic near 47.5W)

IOH 72 Hr Outlook (1200Z Sep 26)...10% chance of tropical cyclone formation (tropical Atlantic near 52.5W)

IOH 96 Hr Outlook (1200Z Sep 27)...15% chance of tropical cyclone formation (tropical Atlantic near 57.5W...between 15N and 20N latitude)

IOH 120 Hr Outlook (1200Z Sep 28)...10% chance of tropical cyclone formation (just northeast of the Lesser Antilles near 20N-61W)


AREA OF INTEREST #2...A broad surface trough of low pressure that was in the northwestern Caribbean Sea is now in the Florida straits and southeastern Gulf of Mexico. This disturbance features a narrow east-west band of thunderstorms supported by divergence on the northwest side of the tropical upper ridge in the area and out ahead of an upper trough in the western Atlantic and Gulf of Mexico. This upper trough is splitting into two upper vortices due to the strength of the upper ridge over the eastern US...which will leave this disturbance to potentially develop over rather warm waters and favorable upper outflow pattern between the vortices. During the forecast period...the steering surface ridging to the north will gradually weaken from a powerful upper trough and surface frontal cyclone currently forecast to be over central Canada by 48 to 96 hours...thus the track of this system should have a slight northward angle during the next few days and be possibly slow. My forecast positions of the disturbance are based on where I currently see an area of spin in satellite animation along the surface trough at a location just northeast of the Yucatan peninsula...with the assumption this area of spin will be most likely where development occurs if it occurs at all. I do not expect development to occur by 96+ hours as this disturbance will likely move beneath the unfavorable western of the two upper vortices.

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

IOH 24 Hr Outlook (1200Z Sep 24)...0% chance of tropical cyclone formation (south-central Gulf of Mexico near 23.5N-88W)

IOH 48 Hr Outlook (1200Z Sep 25)...0% chance of tropical cyclone formation (central Gulf of Mexico near 24.5N-90W)

IOH 72 Hr Outlook (1200Z Sep 26)...10% chance of tropical cyclone formation (western Gulf of Mexico near 25.5N-92.5W)

IOH 96 Hr Outlook (1200Z Sep 27)...0% chance of tropical cyclone formation (northwestern Gulf of Mexico near 26.5N-95W)

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