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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.**********

...TUESDAY OCTOBER 22 2019 11:28 AM EDT...

See areas of interest sections below for an update on the remnants of Tropical Storm Nestor and the tropical wave currently heading toward the western Caribbean Sea which may later merge with the tail end of a cold front to produce a slow-moving tropical disturbance over Belize and southeastern Mexico in the coming days. Elsewhere...the tropical wave that once produced tropical depression fifteen is currently in the central tropcial Atlantic near 45W and has been producing an expansive area of thunderstorms over the last day in an area of upper divergence ahead of a cut-off upper trough in the central Atlantic. However tropical cyclone development here is not expected as the cut-off upper trough digs southward and increases wind shear in the region in response to amplification of the upper ridge expanding from the Gulf of Mexico.

AREA OF INTEREST #1...The remnant circulation of what was Tropical Storm Nestor this morning is analyzed as a broad non-tropical frontal low currently located offshore of the northeastern United States coast. The circulation is now supported by upper divergence between upper northerlies on the east side of upper ridging amplifying in the warm sector of the impressive central US frontal cyclone...and the upper westerlies turning towards the upper trough in the north-central Atlantic. I have updated my outlook positions below to be further east due to Nestor's current position...but finally Nestor has ended its eastward drift and is turning back westward toward the northeastern US coast due to surface ridging to the north supported by the convergence zone of a passing shortwave upper trough. The eastward adjustment in track means Nestor is likely to be absorbed by a frontal low to the west to form along the northeastern US coast instead of transitioning into the dominant frontal low in the region (the western frontal low is to be supported by upper divergence on the southeast side of the large upper trough associated with the central US frontal cyclone). Because Nestor's remnant circulation has not redeveloped thunderstorms and will soon be absorbed...tropical development here is no longer possible and this is my final statement on Nestor on this blog.

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

IOH 24 Hr Outlook (1200Z Oct 23)...0% chance of tropical cyclone formation (absorbed by frontal low to the west while located offshore of Cape Cod Massachusetts near 40N-69W)

AREA OF INTEREST #2...The tropical wave currently moving through the western Caribbean Sea is beginning to reproduce thunderstorms at a location between Honduras and the Cayman Islands this an area of split flow upper divergence between easterlies on the south side of upper ridging to the north amplifying in the warm sector of the central US frontal cyclone and northwesterlies turning towards the lengthy cut-off upper trough extending from the central Atlantic. The central US frontal cyclone itself will whirl too far north to pull the track northward during the forecast period...therefore the first part of the forecast brings this system steadily west-northwestward into Belize...southeastern Mexico...and the Bay of Campeche. I show a 0% chance of tropical cyclone formation till a cell of the aforementioned upper ridging is forecast to collocate directly over this disturbance...which will maximize upper outflow to produce thunderstorms and keep wind shear low. This upper ridge cell will be due to the warm air ahead of a cold front and upper trough to pivot southeastward toward the Gulf of Mexico and Bay of Campeche on the back side of the central US frontal cyclonic system. By 72+ hours...the tail end of the cold front will likely merge with this disturbance and perhaps help kick up thunderstorm activity...with this disturbance potentially taking an atypical southeastward track back into southeastern Mexico from the Bay of Campeche by 96+ hours due to strong surface high pressure building to the west and north behind the cold front. This idea is supported by the latest NAVGEM model run...while the more reliable GFS is beginning to suggest this disturbance evolving into a broad low pressure located further north and similar in characteristic to last week's Tropical Storm Nestor where the northern part of the circulation is supported by the divergence zone of the cold front's upper trough. Thus my updated forecast track in the outlook below is nudged northward for 72+ hours. If the more reliable models such as the GFS do not join the NAVGEM and continue to show a more northward solution...then additional northward adjustments may be needed in the later outlook positions. My peak odds of tropical cyclone development are slightly raised to 10% with the NAVGEM model now suggesting tropical cyclone formation in the manner described in the outlook below. My tepid rise in the odds is due to the NAVGEM not typically being a reliable model for tropical development. Regardless of tropical cyclone development or not...heavy flash flooding rainfall over Belize...the Yucatan peninsula of well as the Mexican provinces of Tabasco and Campeche maybe a concern over the next few days should this disturbance develop plenty of thunderstorms while meandering erratically over the region.

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

IOH 24 Hr Outlook (1200Z Oct 23)...0% chance of tropical cyclone formation (coast of Belize near 17N-88W)

IOH 48 Hr Outook (1200Z Oct 24)...5% chance of tropical cyclone formation (coast of Campeche near 18.5N-91W)

IOH 72 Hr Outlook (1200Z Oct 25)...10% chance of tropical cyclone formation (Bay of Campeche offshore of Tabasco and Campeche near 20N-92.5W)

IOH 96 Hr Outlook (1200Z Oct 26)...10% chance of tropical cyclone formation (coast of Campeche near 19N-91W)

IOH 120 Hr Outlook (1200Z Oct 27)...0% chance of tropical cyclone formation (Yucatan peninsula near 19N-89W)

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