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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 

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*******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 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 dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.**********

...SUNDAY OCTOBER 20 2019 1:11 PM EDT...

See areas of interest sections below for an update on the remnants of Tropical Storm Nestor and the tropical wave currently moving through the central Caribbean Sea.

AREA OF INTEREST #1...The remnant circulation of Nestor this morning and early afternoon has been analyzed as a broad non-tropical frontal low moving northeastward through the Carolinas. The cut-off upper trough that had been over the circulation is moving eastward and away into the western Atlantic while the circulation continues northeastward along the west side of the surface ridge in the region. Instead of Nestor's circulation continuing to fade away in the western convergence zone of the cut-off upper trough...that zone of convergence has produced a surface ridge in the northeastern Gulf of Mexico while Nestor's circulation redeveloped some thunderstorms last evening under a broad area of upper divergence well ahead of the upper trough regime settling over the western US. This thunderstorm activity is now racing northeastward into the northeastern US as heavy rainfall. My updated track in the outlook below is adjusted westward in the short-term to account for the fact Nestor has been tracking more west...but later on is the same as before to account for the more eastward solutions shown in the model runs. However I have been reluctant to completely join these eastward model solutions due to the blocking influence of the surface ridge to the east...and another surface ridge to form to the north when a fracture of the upper troughing over the western US quickly passes to the north and creates surface pressure rises with its western convergence...and because Nestor has been tending to track more westward...thus my updated track remains west of the model consensus. In the next 48 hours...warm core upper ridging is expected to build over Nestor while it settles over the waters offshore of the mid-Atlantic US coast...due to warm air advection ahead of the pair of frontal lows over the western US and central Canada. And with Nestor being just northwest of the warm Gulf Stream while experiencing lower shear and upper outflow of the upper ridging...I assess that Nestor has a shot at re-acquiring tropical characteristics during this time. It is also during this timeframe that the remannt low of Nestor will be in weak steering due to the aforementioned blocking surface ridges. By 72 hours Nestor is likely to accelerate into the northeastern US coast from Cape Cod Massachusetts to Maine while the western US frontal low nears and captures this system. Whatever is left of Nestor by that time will likely be supported by the divergence zone of the frontal low's upper trough while transitioning into a non-tropical feature along the frontal low's cold front.

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

IOH 24 Hr Outlook (1200Z Oct 21)...5% chance of tropical cyclone formation (just offshore of Maryland and Delaware near 37.5N-74W)

IOH 48 Hr Outlook (1200Z Oct 22)...10% chance of tropical cyclone formation (just offshore of Mayrland and Delaware near 37.5N-73W)

IOH 72 Hr Outlook (1200Z Oct 23)...0% chance of tropical cyclone formation (just northeast of Cape Cod Massachusetts near 41.5N-69.5W)

AREA OF INTEREST #2...The tropical wave currently moving into the central Caribbean Sea continues to produce disorganized pockets of thunderstorms while disrupted by the split halves of an upper trough in the region. However...upper-level winds are likely to generally improve for this tropical wave as the southwestern part of the split upper trough retrogrades westward and away in expansive upper ridging to build in warm air advection ahead of the frontal lows currently over central Canada and the western US. However computer models continue to not be on board for showing tropical cyclone I only have peak odds of tropical cyclone formation at 10% during the five day forecast period...with odds dipped to 5% at day 5 due to land interaction with the Yucatan peninsula. Regarding the track of this disturbance...Nestor and the aforementioned frontal lows are forecast to quickly eject too far north to influence the steering...thus leaving this system to continue west-northwest under the tropical surface low-latitude easterlies during the forecast period. Regardless of tropical cyclone formation or not...this tropical wave has potential to bring heavy rainfall to Jamaica...the Cayman Islands...and Yucatan peninsula in the coming days should the tropical wave redevelop widespread thunderstorms.

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

IOH 24 Hr Oulook (1200Z Oct 20)...0% chance of tropical cyclone formation (southeast of Jamaica near 17N-76W)

IOH 48 Hr Oulook (1200Z Oct 21)...0% chance of tropical cyclone formation (southwest of Jamaica and south of the Cayman Islands near 18N-80W)

IOH 72 Hr Outlook (1200Z Oct 22)...10% chance of tropical cyclone formation (southwest of the Cayman Islands near 19N-84W)

IOH 96 Hr Outook (1200Z Oct 23)...10% chance of tropical cyclone formation (east coast of the Yucatan Peninsula at 20N-87.5W)

IOH 120 Hr Outlook (1200Z Oct 24)...5% chance of tropical cyclone formation (in the southern Gulf of Mexico just northwest of the Yucatan peninsula near 21N-91W)

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