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 and also the birdseye view posts from earlier this hurricane season. 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 #166

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


...THURSDAY OCTOBER 24 2019 10:51 AM EDT...

See areas of interest #1 section below for an update on the tropical disturbance developing over the Bay of Campeche. See the other area of interest sections below for additional areas being monitored for subtropical or tropical cyclone formation.


AREA OF INTEREST #1...The tropical wave that was moving across southeastern Mexico is now over the Bay of Campeche and is quickly evolved into an organized tropical low pressure spin...therefore I have begun a tropical cyclone formation forecast as outlined below. My updated forecast track is a northwestward adjustment over the previous due to the current position of the tropical low pressure. This development has occurred with the aid of low shear and outflow from an upper ridge axis associated with warmer air out ahead of a stalled front that has settled just to the north of this disturbance over the last 24 hours. Over the next 24 hours I forecast a slow northwestward drift under the influence of the surface ridge passing over the southeastern United States. After that time...the tail end of the front currently over the central US will sweep across the Gulf of Mexico with a strong surface ridge to the west to build behind the front...which should cause this system to drift back eastward through 72 hours. After that time...the steering situation becomes murky as the front moves northeastward and away while the strong surface ridge erodes out ahead of a frontal cyclone forecast to develop over central Canada. And in the upper-levels during this timeframe...the front's upper trough moves away such that this system is nestled in weak upper-level steering beneath the aforementioned upper ridge axis in the region. Thus I show a stalled system between 72 and 96 hours. By 120 hours...the surface cold air advection on the west side of central Canada frontal cyclone is currently forecast to amplify its parent upper trough southward into the Gulf of Mexico while simultaneously sending another surface cold front into the Gulf...so I forecast a northeastward drift to begin by that time from deep-layered southwesterly flow ahead of the front and amplifying upper trough. Regarding forecast strength...I show brisk strengthening into a tropical storm in the next 24 hours under the current favorable atmospheric conditions...followed by a flattening in strength between 24 and 48 hours from increasing southwesterly shear as the upper trough of the central US front moves closer to the northwestern Gulf of Mexico. However by 72 and 96 hours I forecast additional strengthening...possibly into a hurricane...as this system slides eastward underneath the favorable upper ridge axis while the upper ridge axis itself regains real estate when the central US frontal upper trough moves northeastward and away. I show weakening at 120 hours from another round of increasing southwesterly shear when the upper ridge axis retreates southeastward from the amplification of the upper trough of the forecast central Canada frontal cyclone. Interests in the northern Yucatan peninsula of Mexico should be mindful that this system could become a slow-moving tropical cyclone that affects the region from 48 to 120 hours...which could result in a prolonged period of heavy rain and gusty potentially damaging winds.

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

0 Hr Position (1200Z Oct 24)...Organizing tropical low pressure centered in the Bay of Campeche at 21N-93W

IOH 24 Hr Forecast (1200Z Oct 25)...50 mph maximum sustained wind tropical storm under light southwesterly shear centered in the western Gulf of Mexico at 22N-95W

IOH 48 Hr Forecast (1200Z Oct 26)...50 mph maximum sustained wind tropical storm under light southwesterly shear centered in the central Gulf of Mexico at 22N-92.5W

IOH 72 Hr Forecast (1200Z Oct 27)...60 mph maximum sustained wind tropical storm centered offshore of the northwestern Yucatan peninsula at 22N-90W

IOH 96 Hr Forecast (1200Z Oct 28)...75 mph maximum sustained wind hurricane centered offshore of the northwestern Yucatan peninsula at 22N-90W

IOH 120 Hr Forecast (1200Z Oct 29)...60 mph maximum sustained wind sheared tropical storm centered north of the Yucatan peninsula at 23N-87.5W


AREA OF INTEREST #2...A surface cold front is currently pivoting eastward across the northwestern Atlantic waters south-southeast of Nova Scotia while driven by a broad frontal low pressure and its upper trough located over eastern Canada. Computer models continue to agree a very large and intense frontal cyclone will form along this front over the next few days while settling at a location west of the Azores islands. The genesis of this storm is expected to be from an impressive upper divergence zone to form on the east side of the upper trough currently over eastern Canada as that trough later enters the northern Atlantic and amplifies into a rather impressive and large cut-off upper vortex. This will be in response to amplification of upper ridging over eastern Canada in the warm sector of a strong frontal cyclone forecast to form over central Canada in 72 through 120 hours. Forecast positions of this storm shown in the outlook below are based on the location of the divergence zone of the amplifying upper trough through 96 hours from this morning's 0600Z GFS model run...followed by an assumption that this system whirls into the center of the cut-off upper vortex at 120 hours (the GFS has the cut-off upper vortex center in the vicnity of 40N-35W at 120 hours). I currently have the peak odds of subtropical cyclone formation only at 10% as the current forecast position of the storm center is over 21 deg C waters...about 5 deg too cool for typical tropical development. However thunderstorms may still fire at the core of the storm by day 5 (120 hours) should the cut-off upper vortex be cold enough to drive instability. Regardless of acquisition of tropical characteristics or not...this storm is expected to bring large sea swells in the north-central Atlantic reaching the shores of the Azores islands...with the circulation possibly being large enough to deliver gusty winds to the islands in 4 to 5 days (96 to 120 hours) even while centered well west of the islands.

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

IOH 24 Hr Outlook (1200Z Oct 25)...0% chance of subtropical cyclone formation (northwestern Atlantic to the south-southeast of Newfoundland)

IOH 48 Hr Outlook (1200Z Oct 26)...0% chance of subtropical cyclone formation (northwestern Atlantic near 40N-51W)

IOH 72 Hr Outlook (1200Z Oct 27)...0% chance of subtropical cyclone formation (central Atlantic near 36N-41W)

IOH 96 Hr Outlook (1200Z Oct 28)...0% chance of subtropical cyclone formation (central Atlantic near 39N-35W)

IOH 120 Hr Outlook (1200Z Oct 29)...10% chance of subtropical cyclone formation (central Atlantic near 40N-35W)


AREA OF INTEREST #3...A tropical wave emerging from western Africa into the eastern tropical Atlantic is producing a large thunderstorm cluster and cyclonic rotation with the support of low shear and upper outflow of an upper ridge in the region...therefore have begun an outlook for tropical cyclone formation for this disturbance. The current central Atlantic frontal cyclone headed to the Azores and a second more impressive frontal cyclone to form west of the Azores (area of interest #2) will keep the surface ridging in the region weak such that this system will move slowly west-northwest...but the frontal cyclones appear they will be too far such that an outright turn to the north for this disturbance is not likely. Southwesterly wind shear should increase by 96 hours as from the amplifying upper trough associated with the second frontal clcone (area of interest #2) such that I drop the odds of tropical cyclone formation to 0% by that time.

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

IOH 24 Hr Outlook (1200Z Oct 25)...0% chance of tropical cyclone formation (eastern tropical Atlantic near 10N-19W)

IOH 48 Hr Outlook (1200Z Oct 26)...10% chance of tropical cyclone formation (south of the Republic of Cabo Verde Islands near 11N-24W)

IOH 72 Hr Outlook (1200Z Oct 27)...10% chance of tropical cyclone formation (southwest of the Republic of Cabo Verde Islands near 12N-27W)

IOH 96 Hr Outlook (1200Z Oct 28)...0% chance of tropical cyclone formation (eastern tropical Atlantic near 13N-30W)

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