*******Note that forecast 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.*********
...SUNDAY AUGUST 18 2024 2:52 AM EDT...
See Ernesto section below for an update on the northward-moving western Atlantic tropical cyclone which recently passed over Bermuda and is expected to bring impacts to Nova Scotia and Newfoundland by Monday while transitioning into a non-tropical frontal cyclone.
For the tropical latitudes of the Atlantic... monitoring tropical waves of low pressure as follows:
(1) Tropical waves of low pressure are currently in the open Atlantic at 53W and 28W longitude... neither wave is showing signs of development while ingesting dry Saharan air.
(2) Satellite imagery over Africa (https://www.goes.noaa.gov/FULLDISK/GMIR.JPG) shows a large and vigorous tropical wave of low pressure over western Africa. The wave is expected to emerge into the Atlantic in the next couple of days. Computer models do not develop this wave as its forecast to stay far north enough to ingest dry air associated with the north Africa Sahara desert.
HURRICANE ERNESTO (RECENTLY DOWNGRADED TO TROPICAL STORM ERNESTO)... While pulling northeast from Bermuda… Ernesto has under-performed in terms of intensity while further weakening to a tropical storm with 70 mph maximum sustained winds. Despite being in a pocket of lower shear between the passing northwest Atlantic upper trough to the north and small upper vortex left behind by the upper trough to the southwest… Ernesto is now only left with a thin ring of showers and thunderstorms around the center on infrared satellite. This is apparently due to Ernesto ingesting dry sinking air produced by the western convergence zone of both upper features. In the next 24 hours the northeast track is expected to deflect on a more north angle as the blocking surface ridge induced by the western convergence zone of the passing northwest Atlantic upper trough merges with the Atlantic surface ridge... creating a solid wall to the east of Ernesto that temporarily blocks eastward progress. During this time the tropical storm becomes overspread by a warm core upper ridge in the warm sector of the next surface frontal system/upper trough to approach from eastern North America… providing a more expansive upper outflow environment that might help Ernesto rebuild thunderstorms and mix out the dry air. Therefore I agree with the NHC forecast as of this writing which calls for Ernesto to regain 80 mph maximum sustained winds… the only difference is that I show this 12 hours sooner and before the storm crosses the 26 deg C isotherm into cooler waters. Between 24 and 48 hours the approaching eastern North America upper trough and warm core upper ridge over Ernesto shift east... with Ernesto increasingly curving eastward in the southwesterly flow between the two and then eventually straight east across the open north Atlantic while rounding the north side of the ridge. My updated forecast track is shifted east based on Ernesto’s current position… which still allows for coastal surf across Nova Scotia and Newfoundland by Monday but keeps the swath of heavy rain and gusty winds more limited toward southeastern Newfoundland. Expecting the transition to non-tropical frontal cyclone status to be completed by 48+ hours due to passage over cooler water. The remnant frontal cyclone is likely to gradually decay as the forecast track keeps the storm away from the supportive eastern divergence zone of the eastern North America upper trough. Models also agree that the gradually weakening ex-Ernesto loses its identity to a larger frontal low that roams the North Atlantic… to be supported by the divergence zone of the approaching eastern North America upper trough.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0000Z Aug 18)… 70 mph maximum sustained wind tropical storm centered northeast of Bermuda at 33.9N-63.3W
IOH 24 Hr Forecast (0000Z Aug 19)… 80 mph maximum sustained wind hurricane centered in the northwestern Atlantic at 38.5N-62.5W
IOH 48 Hr Forecast (0000Z Aug 20)… Remnant frontal cyclone centered south of Newfoundland at 44.8N-56.2W
*****National Hurricane Center (hurricanes.gov) official forecast as of 11 PM EDT************************
Peak Strength (1200Z Aug 19)… 80 mph maximum sustained wind hurricane centered in the northwestern Atlantic at 41.3N-58.8W
3-Day Position (0000Z Aug 21)... 45 mph maximum sustained wind remnant frontal low becoming absorbed by larger frontal low to the north while located at 50.4N-36.9W
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
1200Z (Aug 17) CMC Model Run...
**For Hurricane Ernesto… by 54 hours is located south-southeast of Nova Scotia (42N-59W)... while gradually transitioning into a remnant non-tropical frontal cyclone the center deflects more east in track but passes just offshore of southeastern Newfoundland between 66 and 72 hours… while racing east in open North Atlantic loses identity to larger frontal cyclone to the north by 102 hours
**Vigorous tropical wave of low pressure emerges from western Africa at 48 hours at an unusually far north location (Mauritania/Western Sahara border)...passes just north of the Republic of Cabo Verde Islands at 90 hours as a broad tropical low… while continuing west-southwest across the eastern tropical Atlantic weakens back to a wave with no development shown in the long range
1200Z (Aug 17) ECMWF Model Run...
**For Hurricane Ernesto… by 54 hours is located south-southeast of Nova Scotia (42.5N-58.5W)… while gradually transitioning into a remnant non-tropical frontal cyclone the center deflects more east in track but passes just offshore of southeastern Newfoundland at 66 hours… while racing east in open North Atlantic loses identity to larger frontal cyclone to the north by 114 hours as it nears the northern British Isles
**Vigorous tropical wave of low pressure emerges from western Africa at 48 hours at an unusually far north location (Mauritania/Western Sahara border)... passes just north of the Republic of Cabo Verde Islands at 84 hours as a broad tropical low… while continuing west-southwest across the eastern tropical Atlantic weakens back to a wave with no development shown in the long range
1800Z (Aug 17) GFS Model Run...
**For Hurricane Ernesto... by 45 hours is located south-southeast of Nova Scotia (42N-58.5W)… while gradually transitioning into a remnant non-tropical frontal cyclone the center deflects more east in track but passes just offshore of southeastern Newfoundland at 57 hours… while racing east in open North Atlantic loses identity to larger frontal cyclone to the north by 102 hours as it nears the British Isles
1800Z (Aug 17) NAVGEM Model Run...
**For Hurricane Ernesto... located southeast of Newfoundland (45N-51W) by 60 hours... shortly thereafter transitions into a gradually weakening non-tropical frontal cyclone that races east across the open North Atlantic and reaches 46.5N-28.5W at 96 hours… weakens further to a remnant frontal low that dives southeast to the waters midway between Portugal and the Azores (36.5N-16W) by 144 hours… as a decaying surface trough moves southwest to a position west of the Canary Islands (31N-20W) through 168 hours
**Vigorous tropical wave of low pressure emerges from western Africa at 48 hours at an unusually far north location (Mauritania/Western Sahara border)... passes just north of the Republic of Cabo Verde Islands at 96 hours as a broad tropical low… tropical low continues west-southwest to 17.5N-33.5W through 144 hours… weakens back to a wave near 17.5N-34W by 156+ hours
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