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 #137

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


...TUESDAY SEPTEMBER 24 2019 1:46 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...Tropical storm warning remains for Bermuda even though Jerry takes a brief detour towards the west...as Jerry is still expected to turn eastward toward the island in the next 24 to 36 hours. The continued west angle in Jerry's north track is due to the westward push of surface subtropical ridging to the north...and as Jerry is strong/tall enough to be whirled westward by an upper vortex just to the southwest...which is an eastern split of the upper trough that was in the western Atlantic over the last few days. Divergence on the northeast side of this cold core vortex has been supporting Jerry over the last 24 hours...and thus one could argue that Jerry is a subtropical storm in part supported non-tropically by this divergence while it simultaneously is getting tropical support via the outflow of the warm core cell of upper ridging to the southeast. A portion of the upper trough that was over eastern North America has cut-off into a vortex over the northeastern US...with this vortex supporting a surface frontal low that is beginning to erode the surface ridging such that Jerry will soon be steered eastward by the upper westerly flow on the north side of the cell of upper ridging. It was previously thought that the upper vortex over the northeastern US would merge with the upper vortex currently southwest of Jerry to make a consolidated upper trough...but it now appears these two entities will remain seperate...thus I have raised the intensity forecast with Jerry to be located in between both vortices in the next 24 hours where shear could be lighter and upper outflow could be increased (instead of the two vortices merging into an upper trough that weakens Jerry with convergence on its back side). Once again Jerry is south and west of previous forecasting...thus the NHC and my updated forecast track is shifted south and west...with my forecast track now suggesting by 120 hours that Jerry gets caught by the northerly surface flow on the east side of the surface ridge currently over the eastern US (which will later move into the Atlantic) such that Jerry backtracks southwest...especially as that surface ridge merges with the Atlantic surface subtropical ridge in the eastern Atlantic as this morning's 0600Z GFS model run suggested. After 24 hours...I show Jerry weakening back to and then holding 60 mph maximum sustained winds...guessing that light shear on the north and east periphery of the cell of upper ridging will be enough to knock the intensity down a bit...then keeping Jerry at equilibrium strength while preventing the storm from re-strengthening.

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

0 Hr Position (1200Z Sep 24)...60 mph maximum sustained wind tropical storm centered west-southwest of Bermuda at 30.8N-69.3W

IOH 24 Hr Forecast (1200Z Sep 25)...65 mph maximum sustained wind tropical storm centered just west of Bermuda at 32N-66.5W

IOH 48 Hr Forecast (1200Z Sep 26)...60 mph maximum sustained wind tropical storm under light westerly shear centered at 34N-61W

IOH 72 Hr Forecast (1200Z Sep 27)...60 mph maximum sustained wind tropical storm under light westerly shear centered at 35N-54W

IOH 96 Hr Forecast (1200Z Sep 28)...60 mph maximum sustained wind tropical storm under light northerly shear centered at 33N-51W

IOH 120 Hr Forecast (1200Z Sep 29)...60 mph maximum sustained wind tropical storm under light northeasterly shear centered at 31N-55W


TROPICAL STORM KAREN...Preparations for gusty winds in Puerto Rico for Tropical Storm Karen should have been completed by now as the heavy weather sheared south of the center is about to overspread the island. Flash flooding rain will also be a possiblity over the island...as well as the Virgin Islands and possibly the eastern tip of the Dominican Republic should the heavy thunderstorm field expand westward. Karen struggled and briefly weakened to a tropical depression under ongoing northerly shear that has yet to abate despite Karen moving toward the core of a cell of upper ridging. It appears then that Jerry and Karen are competign for upper outflow space in the same upper ridge cell...with Jerry winning the battle and shearing Karen thus far it had a much larger area of cloudiness and thunderstorms. However as Jerry's thunderstorm intensity has faded while it increasingly interacts with a cold core upper vortex...it appears Karen is making a comeback this morning with tremendous thnderstorm bursts south of the center...therefore I speculate we are switching to a situation where Karen now dominates the upper outflow space and thus I show gradual strengthening into a major hurricane by day 5...with a lowered intensity in the early part of the forecast to account for Karen's struggle over the last day. I do not show a strength above category 3 (120 mph winds) in my latest forecast 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 track forecast is adjusted slightly southward in the short term from Karen's current position...but is later on adjusted northeastward to account for the southward shift in Jerry's forecast track...meaning Karen would be pulled closer to Jerry's ridge weakness for a longer period of time. The track forecating gets interesting around 120 hours...but my best guess is Karen will begin an atypical west-southwest track by that time for a couple of reasons. First at the surface...Karen looks like it will be embedded in surface northeasterly flow between a large area of cyclonic flow to the east (from Jerry and Lorenzo) and as the surface ridge currently over the eastern US rebuilds in the western Atlantic as the strong frontal cyclone over central Canada is expected to whirl northward and away while it amplifies its supporting and steering upper trough into a vortex with its strong cold air advection. Second...because at the upper-levels the east pull from Jerry in the middle of the forecast period will help bring Karen toward the east side of the cell of upper ridging...where upper northerly flow would help drag Karen southward should it become a strong/tall tropical cyclone by that time.

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

0 Hr Position (1200Z Sep 24)...40 mph maximum sustained wind tropical storm centered just southeast of Puerto Rico and just southwest of the Virgin Islands at 17.5N-65.8W

IOH 24 Hr Forecast (1200Z Sep 25)...65 mph maximum sustained wind tropical storm centered north of Puerto Rico at 22N-66W

IOH 48 Hr Forecast (1200Z Sep 26)...95 mph maximum sustained wind hurricane centered south of Bermuda at 24.5N-64W

IOH 72 Hr Forecast (1200Z Sep 27)...110 mph maximum sustained wind hurricane centered southeast of Bermuda at 25N-61W

IOH 96 Hr Forecast (1200Z Sep 28)...120 mph maximum susateind wind major hurricane centered at 23.5N-59W

IOH 120 Hr Forecast (1200Z Sep 29)...120 mph maximum sustained wind major hurricane centered at 22.5N-63.5W


TROPICAL STORM LORENZO...Lorenzo in the open eastern tropical Atlantic continues to strengthen. Upper-level winds will be favorable for additional strengthening in the next 48 hours under a favorable cell of tropical upper ridging with low shear and upper outflow. Although Lorenzo is a hair above my previous intensity forecast...I have not raised my intensity forecast as the western bands of Lorenzo appear to have eroded from ingestion of dry saharan air to the north. By 72 to 96 hours...Lorenzo is expected to turn increasingly northward as it will be strong/tall enough to be steered by the upper vorticity currently in the central Atlantic...especially as this vorticity gets kicked eastward toward Lorenzo by the upper vortex over the northeastern US when the vortex later moves across the north Atlantic. In 72 hours...I expect Lorenzo's western outflow to be blocked by the upper vorticity...thus I show some weakening during that time. By 96 hours...modeling agrees that Lorenzo's tremendous thunderstorm latent heat release will split the cold core upper vorticity in half into two vortices...which will reduce shear and enhance upper outflow...and this is when I forecast Lorenzo will reach peak intensity. My forecast track is nudged northward in the short-term from Lorenzo's current position. For the later part of the forecast...even though the latest modeling now shows the upper vortex from the northeastern US staying well away from Lorenzo...the changes in Jerry's track forecast means a low-level ridge weakness for Lorenzo to turn northward into...and the modeling shows the northeastern of the two vortices opening into an upper trough on the north side of the cell of upper ridging...with Lorenzo tending to get dragged eastward by the resulting upper westerly flow (but with the surface Atlantic subtropical ridge preventing an eastward turn). Thus my later forecast track is shifted east of my previous...and I forecast weakening from the upper westerly flow shearing Lorezno by 120 hours.

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

0 Hr Position (1200Z Sep 24)...65 mph maximum sustained wind tropical storm centered southwest of the Republic of Cabo Verde Islands at 12.4N-29.3W

IOH 24 Hr Forecast (1200Z Sep 25)...85 mph maximum sustained wind hurricane centered at 13.5N-34W

IOH 48 Hr Forecast (1200Z Sep 26)...105 mph maximum sustained wind hurricane centered at 14.8N-39W

IOH 72 Hr Forecast (1200Z Sep 27)...100 mph maximum sustained wind hurricane centered at 18N-40.5W

IOH 96 Hr Forecast (1200Z Sep 28)...120 mph maximum sustained wind major hurricane centered at 22N-41W

IOH 120 Hr Forecast (1200Z Sep 29)...100 mph maximum susateind wind hurricane centered at 26N-40W


AREA OF INTEREST #1...The tropical wave west of Tropical Storm Lorenzo briefly saw an expansive increae in thunderstorm activity overnight...which has since started to decline this mornign and early afternoon as the tropical wave axis crosses 40W longitude. The tropical wave is east of my previous outlook...therefore my updated outlook positions are adjuted accordingly. In the short-term...upper-level winds will be favorable for this tropical wave to develop as the upper vortcity in the central Atlantic drifts northward and away toward the upper vortex currently over the northeastern US as that vortex moves across the north Atlantic...leaving this tropical wave under a favorable cell of tropical upper ridging with low shear and upper outflow. I have shifted Karen's 72 and 96 hour positions eastward while at this time forecasting it to become a major hurricane...thus I currently lower odds of development toward 0% by that timeframe as Karen's upper outlfow would unfavorably shear this system. My outlook suggests an increasingly northward track with time due to the forecast surface ridge weakness caused by Jerry and Karen.

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

IOH 24 Hr Outlook (1200Z Sep 25)...0% chance of tropical cyclone formation (tropical Atlantic near 45W)

IOH 48 Hr Outlook (1200Z Sep 26)...10% chance of tropical cyclone formation (tropical Atlantic near 50W)

IOH 72 Hr Outlook (1200Z Sep 27)...10% chance of tropical cyclone formation (tropical Atlantic near 55W...between 15N and 20N latitude)

IOH 96 Hr Outlook (1200Z Sep 28)...0% chance of tropical cyclone formation (northeast of the Lesser Antilles near 20N-57W)


AREA OF INTEREST #2...The east-west surface trough in the southeastern Gulf of Mexico appears to be consolidating into a better-organized surface low located just offshore of the Yucatan Peninsula near 22N-90W...therefore I have notably raised the odds of tropical cyclone formation and will begin a tropical cyclone formation forecast in a special update or in my next full blog update by tomorrow if this continues. As expected over the last few days...this disturbance has found itself is in a favorable environment of light shear and upper outflow between two upper vortices. I drop the odds of developemnt slightly after 24 hours as this disturbance likely gest disrupted by the south side of the western upper vortex...followed by raising the odds again by 72 hours as this system moves past the upper vortex. Odds of development are 0% by 96 hours as this system should be inland by then. I have adjusted my forecast track of this system in the short term based on extrapolation of the motion in the last 24 hours...followed by an increasignly northward track as this system roudns the southwest side of the surface ridge over the eastern US and gets caught in southerly flow out ahead of a lengthy cold front to trail from the frontal cyclone over central Canada. Interests in the Mexican province of Tamualipas and far southern Texas should monitor the progress of this disturbance. Regardless of development or not...flash flooding rain is possible in these areas and as far inland as Neuvo Leon in Mexico should this system hold together over the next few days.

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

IOH 24 Hr Outlook (1200Z Sep 25)...50% chance of tropical cyclone formation (central Gulf of Mexico near 23N-93W)

IOH 48 Hr Outlook (1200Z Sep 26)...30% chance of tropical cyclone formation (offshore of east-central Mexico near 24N-96W)

IOH 72 Hr Outlook (1200Z Sep 27)...40% chance of tropical cyclone formation (just inland just south of the Texas/Mexico border near 25.5N-98W)

IOH 96 Hr Outlook (1200Z Sep 28)...0% chance of tropical cyclone formation (inland just west of the Texas/Mexico border near 27.5N-101W)

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