*******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.*********
...UPDATE...SATURDAY AUGUST 17 2024 8:50 AM EDT...
The surface and upper air charts that were not previously included in this update (to ensure the update was released in a timely manner) have now been added. The following are recent events with Hurricane Ernesto in the western Atlantic:
Satellite image of Hurricane Ernesto as of 1200Z... as its center begins to pull northeastward away from Bermuda:
Hurricane Ernesto's center made a direct strike over Bermuda early this morning... as of this writing the center of circulation is now pulling northeastward away from Bermuda with the back southwestern side of the storm to continue bringing winds and coastal surf to the island throughout the remainder of this morning. As the hurricane moved into Bermuda it weakened to a category 1 with 85 mph maximum sustained winds while water vapor imagery showed the hurricane ingested sinking dry air produced by the western convergence zone of the nearby small upper trough/vortex to the west. Therefore the intensity forecast I provided on Friday in the update below will need to be lowered. Noting the National Museum Bermuda (NMB) around 2 AM Bermuda local time recorded 75 knot (86 mph) sustained winds with gusts as high as 95 knots (109 mph)... https://weather.bm/tools/graphics.asp?name=NMB%20GRAPH&user=
...FRIDAY AUGUST 16 2024 4:20 PM EDT...
See Hurricane Ernesto section below for an update on the northward-moving western Atlantic hurricane expected to strike Bermuda in the next 24 hours... the hurricane will also bring impacts to Nova Scotia and Newfoundland by Monday as it transitions into a non-tropical frontal cyclone.
For the tropical latitudes of the Atlantic... monitoring tropical waves of low pressure as follows:
(1) A tropical wave of low pressure is currently crossing the Lesser Antilles into the eastern Caribbean Sea... development is not expected as the outflow of Hurricane Ernesto is pushing suppressing upper vorticity southwestward into the path of the surface tropical wave.
(2) Tropical waves of low pressure are currently in the open Atlantic at 45W and 25W longitude... neither wave is showing signs of development while ingesting dry Saharan air.
(3) Satellite imagery over Africa (https://www.goes.noaa.gov/FULLDISK/GMIR.JPG) shows a large and vigorous tropical wave of low pressure which has recently moved into western Africa from central Africa. The wave is expected to emerge into the Atlantic in about three to four days (early this upcoming week). Computer models also 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... Ernesto is continuing its general northward trek across the western Atlantic... and as of this writing is angling increasingly northeastward toward Bermuda... while dragged by the upper southwesterlies associated with the upper trough now in the northwestern Atlantic and while it chases the surface ridge weakness (surface front) being generated by the divergence zone of the upper trough. Overnight (Thursday night to Friday morning) the hurricane managed to strengthen to a category 2 with 100 mph maximum sustained winds... however for much of today wind shear imparted by the upper trough eroded away thunderstorms from the southwest half of the circulation such that Ernesto stopped strengthening. The shear seemed to be enhanced by a small upper vortex deposited by the upper trough and just west of the hurricane. Going forward... particularly after 48 hours... the upper trough and surface ridge weakness leaves behind Ernesto... with the blocking surface ridge induced by the western convergence zone of the departing upper trough merging with the Atlantic surface ridge... creating a solid wall to the east of Ernesto that deflects the northeast track of the storm into a straight north angle. Noting that Ernesto has been moving faster to the northeast compared to previous forecasts... perhaps from the kick associated with the aforementioned small upper vortex... such that the hurricane is closing in on Bermuda faster than previously expected. Based on the recent track history it appears the core of the hurricane will pass over or very near Bermuda within the next 18 hours and then be just northeast of the island by 24 hours... and my updated track forecast below reflects this. Regarding the 48-hour intensity forecast... in the most recent satellite frames the hurricane appears to be improving while for the first time showing a traditional large eye and thunderstorms recovering in the west side of the circulation... this could be an indication Ernesto is finding an area of lower shear in between the small upper vortex to the west and passing upper trough to the north. By 48 hours... the upper air pattern over Ernesto improves further while overspread by a warm core upper ridge (low shear and outflow environment) in the warm sector of the next surface frontal system/upper trough to approach from eastern North America. Therefore as done in my previous post #67... I currently forecast Ernesto to gradually strengthen into a category 3 hurricane after passing Bermuda and heading into the northwest Atlantic. I do not call for an intensity higher than category 3 as by 48 hours the storm will be nearing lower oceanic heat content while approaching the 26 deg C sea surface temperature isotherm.
Beyond 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. Because Ernesto has tracked faster towards the north as noted in the prior paragraph... the latter part of the forecast track is also shifted northward closer to southeastern Canada... and now calls for the center to pass directly over southeastern Newfoundland. I depict a weakening hurricane from 48 to 72 hours due to the effects of increased southwesterly shear and cooler waters... and expect the transition to non-tropical frontal cyclone status to be completed by 96 hours. 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... albeit the weakening rate may be slowed if ex-Ernesto's surface northwest quadrant manages to pull down enough high-latitude cold air to generate its own supportive shortwave cool-core upper trough.
Regarding impact to land areas:
(1) For Bermuda... preparations for hurricane-force winds with damage potential and strong coastal surf should have been completed by now as Ernesto is expected to directly strike the island within the next 24 hours.
(2) For southeastern Canada... impacts are expected by Monday. Coastal surf is expected for Nova Scotia and Newfoundland. A swath of heavy rainfall and gusty winds is expected to overspread eastern Nova Scotia and southern Newfoundland... with the highest risk of wind damage toward the southeastern corner of Newfoundland.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1800Z Aug 16)... 100 mph maximum sustained wind hurricane centered just southwest of Bermuda at 30N-66.1W
IOH 24 Hr Forecast (1800Z Aug 17)... 110 mph maximum sustained wind hurricane centered just northeast of Bermuda at 33.5N-64W
IOH 48 Hr Forecast (1800Z Aug 18)... 120 mph maximum sustained wind major hurricane centered in the northwestern Atlantic at 37N-63.5W
IOH 72 Hr Forecast (1800Z Aug 19)... 85 mph maximum sustained wind hurricane transitioning into a non-tropical frontal cyclone while centered southeast of the eastern tip of Nova Scotia at 44.5N-59W
IOH 96 Hr Forecast (1800Z Aug 20)... Remnant frontal cyclone centered in the open north Atlantic at 50.2N-41.5W
*****National Hurricane Center (hurricanes.gov) official forecast as of 11 AM EDT************************
Landfall (1200Z Aug 17)... 85 mph maximum sustained wind hurricane centered over Bermuda at 32.5N-64.9W
5-Day Position (1200Z Aug 21)... 45 mph maximum sustained wind remnant frontal low centered in the northeast Atlantic at 52N-26W
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
0000Z (Aug 16) CMC Model Run...
**For Hurricane Ernesto… center passes over Bermuda at 36 hours and by 96 hours is located just south of Newfoundland (44N-56W)... 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 102 hours... by 120 hours and while in open north Atlantic loses identity to larger frontal cyclone developing to the north.
**Current eastern Atlantic tropical wave of low pressure passes over the Republic of Cabo Verde Islands through 30 hours as a broad tropical low... weakens back to a wave shortly thereafter with no development shown in the long range.
0000Z (Aug 16) ECMWF Model Run...
**For Hurricane Ernesto… center passes just west of Bermuda at 36 hours and is located just offshore of Nova Scotia (43N-59W) by 90 hours... 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 102 hours... remnant frontal cyclone moves rapidly east across the open north Atlantic while gradually weakening as another developing frontal cyclone to the northwest becomes the dominant... loses identity to the dominating frontal cyclone by 168 hours while passing over the northern British Isles.
**Current eastern Atlantic tropical wave of low pressure passes over the southern Republic of Cabo Verde Islands through 12 hours as a broad tropical low... weakens back to a wave shortly thereafter with no development shown in the long range.
**Vigorous tropical wave of low pressure emerges from western Africa at 78 hours at an unusually far north location (Mauritania/Western Sahara border)... passes north of the Republic of Cabo Verde Islands at 114 hours as a broad tropical low... tropical low continues west-southwest to 17.5N-34W by 162 hours
0600Z (Aug 16) GFS Model Run...
**For Hurricane Ernesto... center passes over Bermuda at 30 hours and is located just south of Newfoundland by 87 hours (44.5N-56.5W)... 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 96 hours... remnant frontal cyclone moves rapidly east across the open north Atlantic while gradually weakening as another developing frontal cyclone to the northwest becomes the dominant... loses identity to the dominating frontal cyclone by 147 hours while located in the northeastern Atlantic to the west of the British Isles
0600Z (Aug 16) NAVGEM Model Run...
**For Hurricane Ernesto... center passes just southeast of Bermuda at 24 hours and is located southeast of Newfoundland (44.5N-49W) by 96 hours... shortly thereafter transitions into a non-tropical frontal cyclone that races east across the open north Atlantic in tandem with a developing frontal low to the northwest... the remnant frontal cyclone of Ernesto makes landfall across the northern British Isles by 168 hours
**Current eastern Atlantic tropical wave of low pressure passes over the southern Republic of Cabo Verde Islands through 24 hours as a broad tropical low... weakens back to a wave shortly thereafter with no development shown in the long range.
**Vigorous tropical wave of low pressure emerges from western Africa at 90 hours at an unusually far north location (Mauritania/Western Sahara border)... moves southwest into the Republic of Cabo Verde Islands through 144 hours as a broad tropical low... broad tropical low continues west to 15N-30W through 168 hours
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