*******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.**********
...SATURDAY OCTOBER 19 2019 12:46 PM EDT...
Nestor loses tropical characteristics while making landfall on the Florida panhandle...see remnants of Nestor section below for more details. See area of interest section below for more details on the tropical wave currently moving through the eastern Caribbean Sea. Elsewhere...the eastern Atlantic tropical wave that produced tropical depression fifteen a few days ago is producing increased thunderstorms in the vicinity of 11N-37W while interacting with the divergence zone of a persistent cut-off upper trough in the region. However tropical cyclone development here is not expected as wind shear from the cut-off upper trough will be elevated...especially as the trough becomes later re-enforced by the upper trough currently entering the western Atlatnic from eastern North America.
REMNANTS OF NESTOR...As I was putting this post and forecast together...Tropical Storm Nestor about to make landfall on the Florida panhandle was downgraded to a remnant non-tropical low pressure. This is because the heaviest thunderstorm clouds are now far removed from the center in the southeastern Gulf of Mexico...south Florida...and western Atlantic waters offshore of the southeastern United States. This thunderstorm activity is supported by divergence on the east side of the cut-off upper trough moving through the southeastern United States...but the center of Nestor has tracked more northward and decoupled from this zone of divergence likely from the blocking influence of the eastern US surface ridge passing by to the north. The center of Nestor will be making landfall just west of Apalachicola instead of just to east as I forecasted yesterday...therefore my updated forecast track below is adjusted westward. I have notably lowered the intensity forecast as the increasingly northward track on the west side of the aforementioned surface ridge will keep Nestor away from the support of the cut-off upper trough...and may even suppress Nestor in the next 24 hours with its western upper convergence zone. The National Hurricane Center in the 11 AM EDT advisory noted that a well-defined center is becoming incrasingly harder to find...and this could be signifying that the divergence zone of the cut-off upper trough is dropping surface pressures to the east...so it is quiet possible Nestor broadens even further in the next 24 hours...extending eastward into the Atlantic while moving through the coastal Carolinas and producing maximum sustained winds offshore higher than I show at the 24 hour forecast position should such an eastern lobe be boosted by the divergence zone. In 48 to 72 hours...warm core upper ridging is expected to build over the remnant low of Nestor while it moves into the waters offshore of the mid-Atlantic US coast...due to warm air advection ahead of the current central Canada frontal low and another frontal low to eject from the western US into Canada. And with the remnant low being near the warm Gulf stream and under the low shear/upper outflow of the upper ridging...I assess that Nestor could re-acquire tropical characteristics during this time...therefore in my next post tomorrow I plan to give a tropical cyclone formation outlook on the remnant low of Nestor. It is also during this time that the remannt low of Nestor will be in weak steering between the surface ridge to the east and new surface ridging building to the north under the western convergence of the upper trough associated with the current central Canada frontal low as that upper trough passes by to the north..but I speculate a westward drift will occur during that time as the second of the two frontal lows drops surface pressures to the west while significantly intensifying. By 96 hours for now I show a northeastward track across Cape Cod Masschusetts while the second frontal low captures this system...and show slight strengthening as the amplfied upper trough of the frontal low potentially supports Nestor with its divergence zone while transitioning it to a non-tropical feature along the frontal low's cold front.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1200Z Oct 19)...50 mph maximum sustained wind tropical storm losing tropical characteristics centered just offshore of the Florida panhandle at 29.3N-86.3W
IOH 24 Hr Forecast (1200Z Oct 20)...35 mph maximum sustained wind surface low centered over the North Carolina/South Carolina Border at 34N-79W
IOH 48 Hr Forecast (1200Z Oct 21)...35 mph maximum sustained wind surface low centered offshore of Maryland...Delaware...and New Jersey at 37N-73W
IOH 72 Hr Forecast (1200Z Oct 22)...35 mph maximum sustained wind surface low centered offshore of Maryland...Delaware...and New Jersey at 37.5N-73.5W
IOH 96 Hr Forecast (1200Z Oct 23)...40 mph maximum sustained wind non-tropical frontal low centered just northeast of Cape Cod Massachusetts at 41.5N-69.5W
AREA OF INTEREST #1...The tropical wave in the eastern Caribbean Sea has seen an overall decrease in thunderstorms...but still has pockets of activity due to divergence between the split halves of the upper trough in the area it has recently weakened with its thunderstorm latent heat release. The upper-level wind forecast looks generally favorable to 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 low currently over central Canada...followed by another strengthening frontal low to eject from the western US into Canada during the forecast period. However computer models continue to not be on board for showing tropical cyclone development...so I only have slowly increasing odds of development in the outlook below. 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 the Dominican Republic...Haiti...Jamaica...the Cayman Islands...and Yucatan peninsula in the coming days should the tropical wave redevelop widespread thunderstorms.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Oulook (1200Z Oct 19)...0% chance of tropical cyclone formation (just south of the Dominican Republic near 16N-71W)
IOH 48 Hr Oulook (1200Z Oct 20)...0% chance of tropical cyclone formation (southeast of Jamaica near 17N-76W)
IOH 72 Hr Oulook (1200Z Oct 21)...5% chance of tropical cyclone formation (southwest of Jamaica and south of the Cayman Islands near 18N-80W)
IOH 96 Hr Outlook (1200Z Oct 22)...10% chance of tropical cyclone formation (southwest of the Cayman Islands near 19N-84W)
IOH 120 Hr Outook (1200Z Oct 23)...15% chance of tropical cyclone formation (east coast of the Yucatan Peninsula at 20N-87.5W)