*******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.**********
...FRIDAY SEPTEMBER 23 2022 5:49 AM EDT...
URGENT - The tropical wave in the southeastern Caribbean Sea tagged as area of interest #30 in this blog post is showing signs of quickly organizing into a tropical cyclone. This means rapid development of this system into a strong hurricane affecting Jamaica... the Cayman Islands... western Cuba... and possibly the Florida Keys and south Florida once this system enters a better upper wind environment is increasing. See area of interest #30 section below for more information. Update as of 5 AM EDT... area of interest #30 is now tropical depression nine... still refer to area of interest #30 section below for information on the new depression.
Major Hurricane Fiona is now brining tropical storm to hurricane force winds over Bermuda as of this writing. See Fiona section below for more information the hurricane... including expected historic impacts to the Atlantic Canada region to arrive this weekend.
Tropical Storm Gaston is expected to slide southeastward across the Azores in the next 24 hours while retaining strength and tropical characteristics. See Gaston section below for more information.
In addition to the above systems... also monitoring multiple areas of interest as follows:
(1) See area of interest #32 section below for a tropical wave of low pressure being monitored for signs of development in the far eastern Atlantic waters offshore of west-central and northwest Africa.
(2) See area of interest #33 section below for a tropical low pressure area expected to meander aimlessly in the eastern and central tropical Atlantic over the next five days. This feature also has potential to become a tropical cyclone.
(3) A tropical wave of low pressure is currently over western Africa in the vicinity of 6W longitude. Tropical cyclone formation of this feature is not expected once it moves into the eastern tropical Atlantic in about 48 hours... as it will be competing for surface inflow with area of interest #32 to the northwest.
(4) Another tropical wave of low pressure is currently over central Africa in the vicinity of 5E longitude. There is some potential for this tropical wave to develop in the eastern tropical Atlantic in approximately 4+ days as area of interest #32 will have exited the region and the tropical upper ridge in the region... featuring low shear and upper outflow... is expected to persist.
New to this site this year... I will be sequentially numbering up areas of interest for possible Atlantic tropical development. In this scheme... will reset back to #1 at the start of next year (January 2023). The current areas of interest in this blog post are designated #30... #32... and #33 as the other numbers were used in previous birdseye view posts. This scheme is to reduce confusion as Atlantic tropical activity increases during the peak of the hurricane season... when multiple simultaneous areas of interest begin and end which previously required shuffling around the area of interest numbers from update to update.
MAJOR HURRICANE FIONA... While located west-southwest of Bermuda...the western outflow of Hurricane Fiona remains restricted by upper southwesterly flow in advance of a cut-off upper trough currently offshore of the southeastern United States and in advance of a major upper trough now approaching from eastern Canada. As these two trough push closer into Fiona... I previously anticipated the outflow blockage would increase and thus cause Fiona to weaken. While the colorized infrared satellite pictures over the last several hours show Fiona's west side struggling and the eye becoming ragged and cloud filled at times... aircraft reconnaissance shows the pressure of Fiona incredibly remaining in the low-to-mid 930s of mb and maximum sustained winds in the eyewall still being at category 4 130 mph. I suspect the strong southerly upper flow in advance of the Canadian upper trough is helping to ventilate the northern outflow of the hurricane such that Fiona is keeping its low surface pressure and intense eyewall winds. The eastern side of Fiona has overspread Bermuda tonight... and observations at the island (weather.bm/observations.php) show that sustained winds reached 40+ mph storm force just after midnight local time. The latest observation as of this writing shows a sustained wind of 44 mph with a gust to 62 mph. Over the next few hours expect the potential for hurricane-force (75+ mph) gusts as the eye makes its closest pass to Bermuda... followed by gradually improving weather and coastal ocean conditions throughout the day on Friday as the hurricane accelerates northward and away. I have nudged my updated forecast track eastward due to the current position of Fiona relative to the previous forecast. The current northeast track of the hurricane is expected to bend more north as Fiona gets funneled into the southerly flow out ahead of the major upper trough approaching from eastern Canada... sending it right into the sprawling divergence maximum on the trough's east side. The tremendous upper divergence will allow Fiona to grow into a large and powerful non-tropical remnant frontal cyclone once over cooler water... and the west side of the remnant cyclone will pull cold air associated with the trough southward and cause it to amplify further into an upper vortex. In turn this would mean the remnant cyclone between 24 and 48 hours swings northwest in track... right into Atlantic Canada... while whirling into the center of the forming upper vortex.
Regarding forecast intensity... I have once again nudged my updated forecast upward due to Fiona's current strength relative to the previous forecast. Despite all the upper air support discussed in the previous paragraph... still expect Fiona to slowly weaken going forward due to decreasing sea surface temperatures along the forecast track. The upper air support will unfortunately not let Fiona weaken fast enough such that Atlantic Canada is in for a ferocious and historic non-tropical frontal cyclone version of Fiona this weekend.
Regarding impact to land areas:
(1) Fiona will bring coastal swells and rip currents to the United States mid-Atlantic and northeast coastline through this weekend. The west side of the ferocious remnant frontal cyclone could also bring gusty winds to Maine this weekend.
(2) For Bermuda... see first paragraph of this Fiona discussion for the tropical storm force impacts currently underway.
(4) Fiona will transition to a ferocious and likely historic non-tropical frontal cyclone that pivots north across Atlantic Canada this weekend. Damaging hurricane force winds are likely across eastern Nova Scotia... Prince Edward Island... western Nefoundland... and eastern Quebec. Gale force winds with some damage potential are likely across New Brunswick... western Nova Scotia... eastern Newfoundland... and Labrador. Across all of these areas... expect immense coastal surf with storm surges due to the forecast large size and strength of Fiona's remnant cyclone. Heavy rainfall with flash flooding potential is another hazard to consider. I recommend preparations in the region should finish by Friday evening.
Update as of 3:45 AM EDT... wind gusts over Bermuda are reaching hurricane force. The lastet observation (weather.bm/observations.php) shows a sustained wind of 58 mph gusting to 74 mph.
Update as of 5 AM EDT... sustained winds over Bermuda are increasing further while nearing 60 mph. Hurricane-force gusts remain at 75 mph. The hurricane has weakened slightly to category 3 125 mph maximum sustained winds... however this does not mitigate the current impacts ongoing in Bermuda and the expected historic impacts to Atlantic Canada slated for this weekend.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0000Z Sep 23)...130 mph maximum sustained wind major hurricane centered west-southwest of Bermuda at 31.9N-68.1W
IOH 24 Hr Forecast (0000Z Sep 24)...110 mph maximum sustained wind hurricane centered at 41.5N-59.8W
IOH 48 Hr Forecast (0000Z Sep 25)...Hurricane-force remnant frontal cyclone centered in the Gulf of St. Lawerence at 47.5N-60.5W
TROPICAL STORM GASTON...While over 23 deg C waters just northwest of the central Azores... below the typical 26 deg C needed for tropical storms... Gaston's shower and thunderstorm core as well as its current strength is being maintained by the eastern divergence zone of a shortwave upper trough in the region. In the short-term expecting Gaston's track to follow the supporting shortwave upper trough it is clearly coupled to. As such... the east side of Fiona and east side of the sprawling frontal low currently approaching the north Atlantic from eastern Canada will pull plenty of warm air northward into the far north Atlantic... resulting in the amplification of a far north Atlantic warm core upper ridge that in turn pushes Gaston's supporting shortwave upper trough on a more southward angle. Therefore expecting Gaston to pivot southeastward into the Azores in the next 24 hours. The amplified north Atlantic upper ridge will also push the current northeast Atlantic upper trough southeastward into Europe... with the European upper trough and Gaston's shortwave upper trough merging into a southwest-northeast elongated string of upper vorticity between 24 and 48 hours. This will finally bring an end to the shortwave's distinct supportive eastern divergence zone... and Gaston should finally lose its thunderstorms over the below-26 deg C water and weaken to a shallow remnant low that begins to reverse southwest and westward in track while steered by the surface ridge currently building to the north.
Expect tropical storm force winds and coastal sea swells to be a concern across the Azores over the next 24 hours. Weather conditions to improve afterwards as Gaston pulls southwestward and away.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0000Z Sep 23)...65 mph maximum sustained wind tropical storm centered north of the western Azores at 41N-31.4W
IOH 24 Hr Forecast (0000Z Sep 24)...65 mph maximum sustained wind tropical storm centered over the central Azores at 38.5N-27W
IOH 48 Hr Forecast (0000Z Sep 25)...Remnant low centered south of the Azores at 36.5N-29W
AREA OF INTEREST #30 (RECENTLY UPGRADED TO TROPICAL DEPRESSION NINE)...The vigorous tropical wave of low pressure that has been traversing westward across the southeastern Caribbean Sea has developed a well-defined swirl of low pressure that is now passing just north of the ABC Islands (Aruba... Bonaire... and Curacao). While northeasterly shearing flow on the south side of the current north Caribbean upper ridge is keeping thunderstorm activity pushed off to the southwest side of the circulation... this system already resembles a sheared tropical depression or storm as the thunderstorms are of high intensity on infrared satellite pictures and making attempts at covering the center of circulation. I anticipate this system being upgraded to a tropical depression or tropical storm later this morning... if not later today. As such I have begun a tropical cyclone formation forecast as outlined below with specific track and intensity points. Models agree on a general west-northwest track across the Caribbean due to the ridge weakness induced by Hurricane Fiona. Once this weakness closes with Fiona's northward and away lift in track... the current northwest US upper vortex and a major upper trough currently moving into western Canada will merge... with the eastern divergence zone of the potent upper trough creating another surface ridge weakness over the eastern US that continues the west-northwest track of this system. While nearing the weakness... the north angle of the forecast track notably increases by days 4 and 5. Also to note... the forecast track in the 72 hour timeframe is slightly lifted northward relative to my previous forecast due to the latest model data coming in concerning the current warm air mass upper ridge over the southeastern United States and cut-off upper trough just offshore of the southeastern United States. The lastest model runs show the potent upper trough that moves into the eastern US having a more southward reach... hence displacing the warm air mass upper ridge further south which in turn displaces the cut-off upper trough further south as a patch of upper vorticity that moves into the west side of this system's environment. This now means the southerly flow of this upper vorticity patch should pull this system a little more north in the 72 hour window. In the longer range (96+ hours)... that setups this system to be closer to the surface ridge weakness to be induced by the potent eastern US upper trough... potentially coaxing this system on a direct north track into the weakens that takes it across western Cuba and toward the Florida Keys/southwest Florida peninsula. Moreover the upper southerly flow across the south side of the potent upper trough may already help bend the track more eastward into the Florida peninsula in the 120+ hour timeframe. These ideas are reflected in my forecast track update below.
A walkthrough of the intensity forecast below... based on the latest satellite imagery this system is getting off to a good start despite the presence of northeasterly shear mentioned in the previous paragraph. Therefore I expect this system to already approach/enter hurricane strength in the 48 to 72 hour window when the forecast track takes this system more directly below the axis of the northern Caribbean upper ridge where shear is lower. I just keep this system below category 2 hurricane strength at 72 hours as the western outflow of this system potentially gets blocked by the patch of upper vorticity to move toward the west side of its environment. However this patch of cool core upper vorticity is expected to dissipate by 96 hours while it remains cut-off from high-latitude cold air... therefore I currently forecast that a combination of low shear and improving upper outflow... combined with warm western Caribbean water... should allow for rapid intensification into a major hurricane by 96 hours. I slow down the intensification rate from 96 to 120 hours as there is some potential for light westerly shear once this system nears the upper westerly flow of the potent upper trough to settle into the eastern US. My current intensity forecast projects dangerous category 3 to 4 hurricane strength in the 4 to 5 day window.
Regarding impacts to land areas:
(1) Heavy rains across the ABC Islands (Aruba... Bonaire... and Curacao) should continue to wind down from east to west throughout the morning as this system pulls west-northwest and away.
(2) Interests in Jamaica and the Cayman Islands need to closely watch this system for possible tropical storm to hurricane force conditions in the Sunday to Monday timeframe. Preparations here may need to be underway by Friday night and Saturday.
(3) Interests in western Cuba... the southern Florida peninsula... and Florida Keys need to also closely watch this system for possible tropical storm to hurricane force conditions in the Tuesday to Wednesday timeframe. Life-threatening and extreme wind and coastal storm surge is a possible hazard in this region in close proximity to the center of circulation... however the forecast position of the center of circulation is not set in stone yet.
Update as of 5 AM EDT... this system is now tropical depression nine and will likely become a tropical storm later this morning or afternoon. The NHC official forecast track as of this writing is similar to what is outlined below and shows a still-dangerous category 2 hurricane by day 5.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0000Z Sep 23)...Tropical low centered just northeast of Aruba Bonaire and Curacao at 12.5N-67.5W
IOH 24 Hr Forecast (0000Z Sep 24)...50 mph maximum sustained wind tropical storm centered in the south-central Caribbean Sea at 13.5N-71W
IOH 48 Hr Forecast (0000Z Sep 25)...70 mph maximum sustained wind tropical storm centered in the central Caribbean Sea at 14.5N-75.5W
IOH 72 Hr Forecast (0000Z Sep 26)...90 mph maximum sustained wind hurricane centered southwest of Jamaica at 17N-79.5W
IOH 96 Hr Forecast (0000Z Sep 27)...120 mph maximum sustained wind major hurricane centered just west of the Cayman Islands and south of the Isle of Youth of western Cuba at 19.5N-82.5W
IOH 120 Hr Forecast (0000Z Sep 28)...135 mph maximum sustained wind major hurricane centered just offshore of northwestern Cuba and just southwest of the Florida Keys at 23.9N-83W
AREA OF INTEREST #32... The vigorous tropical wave of low that had been moving west-northwest across western Africa is now just offshore with a broad center of spin offshore of Senegal in the vicinity of 15N-19.5W. While thunderstorm clusters have covered the east side of the circulation... the west side has suffered ingestion of dry Saharan air. Various model runs in prior days suggested the low pressure circulation would quickly ramp up into a tropical cyclone that becomes strong/tall enough to couple with upper southerly flow on the east side of a current upper trough fragment in the region. Similar to Gaston... these model runs also suggested this system maintain strength and tropical characteristics offshore of northwestern Africa where water temps are below 26 deg C with the aid of the eastern divergence zone of the upper trough fragment. Note that after the upper trough fragment dissipates by day 2 while it remains cut-off from high latitude cold air... models quickly replace it with a more substantial upper trough that is a fusion between the current northeast and northwestern Atlantic upper troughs... and the shortwave upper trough currently interacting with Gaston. These troughs fuse together under the force of the north Atlantic warm upper ridge forecast to develop (see Gaston section for more information on this ridge). The more substantial upper trough would continue the aid to this system in the 3+ day window should it in fact be a tropical cyclone offshore of northwestern Africa. However the reality of the dry Saharan air that usually dominates the region offshore of northwestern Africa is finally settling into the model runs... which (except for the GFS) have walked away from showing tropical cyclone formation. At the same time the thunderstorm clusters on the east side of the circulation are signs this system is still trying to develop despite dry Saharan air. Therefore I have increased my odds of tropical cyclone formation to 40%... preferring to stay below the 50% mark in this update due to the latest models that have become less aggressive with developing this system. My forecast track is also adjusted more northward and less westward to complement the higher odds of tropical cyclone formation... consistent with a stronger/taller system that moreso couples to the upper southerly flow in the region. I end development odds at 72 hours as my current forecast track walks this system into hostile southwesterly shear on the southeast side of the more substantial upper trough to become established in the region. However note that should this system develop sooner and turn north more quickly... it would stay east of this hostile shear zone and last longer as a bonafide tropical system.
On a final note... should this system in fact become a tropical cyclone... it has potential to kick up surf on the shores of the Republic of Cabo Verde Islands... Senegal... Mauritania... and Western Sahara later today... this weekend... and through early next week.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Sep 24)...40% chance of tropical cyclone formation (northeast of the Republic of Cabo Verde Islands near 18N-22.5W)
IOH 48 Hr Outlook (0000Z Sep 25)...40% chance of tropical cyclone formation (north of the Republic of Cabo Verde Islands near 20N-24W)
IOH 72 Hr Outlook (0000Z Sep 26)...0% chance of tropical cyclone formation (eastern Atlantic near 22N-26W)
AREA OF INTEREST #33...The center of the tropical low pressure drifting aimlessly westward in the eastern tropical Atlantic was located in the vicinity of 10.5N-34W as of 0000Z earlier this past evening. Their continue to be signs of organization while it fires thunderstorm activity over and just northwest of its center of circulation... albeit the intensity of the thunderstorms continues to wax and wane instead of remaining steady such that a tropical cyclone has not formed. The westward progress of this system around the Atlantic surface ridge has been painfully slow while it gets tugged by the large circulation of area of interest (AOI) #32 to the east. A further slow down in the west drift... and perhaps a reversal of the drift toward an northeastward tendency cannot be ruled out in the longer range as a substantial upper trough will interact with AOI #32 in 3+ days whose eastern divergence zone will help AOI #32 build an expanding surface ridge weakness to the northeast of this system. Even without the expanding surface ridge weakness... if indeed this system goes on to become a tropical cyclone it could be strong/tall enough to couple with upper westerly steering flow associated with the substantial upper trough. Beyond 5 days the end result of this system is highly uncertain as it is located in a saddle point between two steering tendencies. Does it finally accelerate northeast as a stronger/taller system influenced by the upper trough? Or does it slip out of the grip of the upper trough and finally proceed west under the influence of the Atlantic surface ridge? Only time will tell.
I retain 40% odds of tropical cyclone formation due to the ongoing signs of organization associated with this disturbance. Would like to see the thunderstorm activity persist instead of repeatedly waxing and waning before suggesting odds higher than 50%.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0000Z Sep 24)...40% chance of tropical cyclone formation (eastern tropical Atlantic near 11N-36W)
IOH 48 Hr Outlook (0000Z Sep 25)...40% chance of tropical cyclone formation (eastern tropical Atlantic near 11.5N-38W)
IOH 72 Hr Outlook (0000Z Sep 26)...40% chance of tropical cyclone formation (central tropical Atlantic near 12N-40W)
IOH 96 Hr Outlook (0000Z Sep 27)...40% chance of tropical cyclone formation (central tropical Atlantic near 12.5N-41W)
IOH 120 Hr Outlook (0000Z Sep 28)...40% chance of tropical cyclone formation (central tropical Atlantic near 13.5N-40W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z (Sep 22) CMC Model Run...
**For Major Hurricane Fiona... passes just northwest of Bermuda at 24 hours... swings more north in track and moves into eastern Nova Scotia at 48 hours while transitioning into a large remnant frontal cyclone... while continuing northward across eastern Quebec... inland Labrador and into far north waters offshore of northeastern Canada the remnant frontal cyclone weakens to a frontal low through 120 hours.
**For Tropical Storm Gaston... dives south at a location just west of the Azores and begins weakening at 36 hours... weakening remnant low accelerates west and opens to a trough near 39.8N-39W at 120 hours.
**For area of interest #30... tropical cyclone formation suggested just southeast of Jamaica at 60 hours... while intensifying into a strong tropical storm center passes just west of Jamaica through 78 hours... moves northwest across the Cayman Islands through 90 hours while strengthening into a compact hurricane... hurricane curves north into western Cuba at 108 hours... hurricane centered just southeast of the Florida Keys at 120 hours.
**For area of interest #32... tropical low moves north-northwest and reaches 21N-22W at 60 hours... turns west and weakens to a remnant trough near 22.5N-29W at 114 hours.
**For area of interest #33... becomes tropical depression near 13.5N-38.5W at 60 hours... drifts erratically north and becomes a strong compact tropical storm near 14.5N-38W at 120 hours
1200Z (Sep 22) ECMWF Model Run...
**For Major Hurricane Fiona... passes just northwest of Bermuda at 24 hours... swings more north in track and moves into eastern Nova Scotia at 48 hours while transitioning into a large remnant frontal cyclone... while continuing northward across eastern Quebec... inland Labrador and into far north waters offshore of northeastern Canada the remnant frontal cyclone weakens to a frontal low through 120 hours.
**For Tropical Storm Gaston... dives south into the westernmost Azores at 48 hours while maintaining strength... moves west-northwest and then north-northwest with weakening remnant low reaching 43N-38.5W at 120 hours.
**For area of interest #30... tropical cyclone formation suggested just south of Jamaica at 72 hours... strengthens into a hurricane while moving northwest across the Cayman Islands through 96 hours... after crossing western Cuba the center reaches waters midway between western Cuba and the Florida Keys at 120 hours.
**For area of interest #32... tropical low moves north-northwest and reaches 22.5N-21W at 48 hours... reaches 27N-20.5W at 72 hours... turns west-southwest and then west and weakens to remnant trough near 25N-26W at 120 hours.
**For area of interest #33... tropical low becomes better defined near 14N-38W at 120 hours
1800Z (Sep 22) GFS Model Run...
**For Major Hurricane Fiona... passes just northwest of Bermuda at 18 hours... swings more north in track and moves into eastern Nova Scotia at 42 hours while transitioning into a large remnant frontal cyclone... while continuing northward across eastern Quebec... inland Labrador and into the waters offshore of southwest Greenland weakens to a small frontal low through 120 hours.
**For Tropical Storm Gaston... dives south into the westernmost Azores at 30 hours while maintaining strength... weakening remnant low accelerates west and reaches 39.5N-41.2W at 120 hours.
**For area of interest #30... tropical cyclone formation suggested near 14N-78.5W at 60 hours... becomes a compact hurricane just southwest of the Cayman Islands at 87 hours... center moves over the western tip of Cuba at 114 hours as a potentially strong hurricane... centered just offshore of northwestern Cuba at 120 hours.
**For area of interest #32... tropical low moves north-northwest and becomes a tropical cyclone near 19N-20W at 24 hours... subsequently weakens to a remnant low which dissipates offshore of Western Sahara at 81 hours.
**For area of interest #33... becomes a tropical depression near 12N-37.5W at 51 hours... tropical depression moves erratically north-northwest and reaches 14.8N-40W at 120 hours.
**Tropical wave emerges from west coast of Africa at 81 hours... organizes into a tropical low near 11.5N-21W at 120 hours.
1800Z (Sep 22) NAVGEM Model Run...
**For Major Hurricane Fiona... passes just northwest of Bermuda at 18 hours... swings more north in track and moves into eastern Nova Scotia at 42 hours while transitioning into a large remnant frontal cyclone... cyclone begins to weaken while bending north-northeast in track and moves into the west-central coast of Newfoundland at 60 hours... cyclone moves north across east coast of Labrador at 72 hours... cyclone weakens to a frontal low offshore of northeastern Canada through 120 hours.
**For Tropical Storm Gaston... dives south into the central Azores through 30 hours... subsequently turns southwest... west... and then eventually north with weakening remnant low reaching 44N-44.5W at 120 hours.
**For area of interest #30... tropical low becomes better defined west of Jamaica and south of the Cayman Islands at 84 hours... lifts north across western Cuba and becomes a tropical storm just offshore of southeastern Florida at 114 hours... tropical storm centered midway between southeast Florida and the western Bahamas at 120 hours.
**For area of interest #32... tropical low moves north-northwest and reaches 14.5N-21.5W at 90 hours... tropical low turns west and weakens to a trough near 25N-25W at 108 hours.
**For area of interest #33... tropical low drifts east-northeast toward area of interest #32 and becomes a tropical depression near 13N-33.5W at 84 hours... becomes a tropical storm near 14.8N-31W at 120 hours.
**Tropical wave emerges from west coast of Africa at 132 hours... organizes into a tropical low over the Republic of Cabo Verde Islands through 168 hours.
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